1<?xml version="1.0" encoding="UTF-8"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> 4<head> 5<title>Android 4.0 Compatibility Definition</title> 6<link rel="stylesheet" type="text/css" href="cdd.css"/> 7</head> 8<body> 9<div><img src="header.jpg" alt="Android logo"/></div> 10<h1>Android 4.0 Compatibility Definition</h1> 11<!-- 12<span style="color: red; font-weight: bold;"><h2>DRAFT 3</h2></span><br/> 13<span style="color: red;">Last updated: November 17, 2012</span> 14--> 15<p>Revision 4<br/> 16Last updated: April 21, 2013 17</p> 18<p>Copyright © 2012, Google Inc. All rights reserved.<br/> 19<a href="mailto:compatibility@android.com">compatibility@android.com</a> 20</p> 21 22<h2> Table of Contents</h2> 23<div style="margin-left: 2em;"> 24 <a href="#section-1">1. Introduction</a><br/> 25 <a href="#section-2">2. Resources</a><br/> 26 <a href="#section-3">3. Software</a><br/> 27 <div style="margin-left: 2em;"> 28 <a href="#section-3.1">3.1. Managed API Compatibility</a><br/> 29 <a href="#section-3.2">3.2. Soft API Compatibility</a><br/> 30 <div style="margin-left: 2em;"> 31 <a href="#section-3.2.1">3.2.1. Permissions</a><br/> 32 <a href="#section-3.2.2">3.2.2. Build Parameters</a><br/> 33 <a href="#section-3.2.3">3.2.3. Intent Compatibility</a><br/> 34 <div style="margin-left: 2em;"> 35 <a href="#section-3.2.3.1">3.2.3.1. Core Application Intents</a><br/> 36 <a href="#section-3.2.3.2">3.2.3.2. Intent Overrides</a><br/> 37 <a href="#section-3.2.3.3">3.2.3.3. Intent Namespaces</a><br/> 38 <a href="#section-3.2.3.4">3.2.3.4. Broadcast Intents</a><br/> 39 </div> 40 </div> 41 <a href="#section-3.3">3.3. Native API Compatibility</a><br/> 42 <div style="margin-left: 2em;"> 43 <a href="#section-3.3.1">3.3.1 Application Binary Interfaces</a><br/> 44 </div> 45 <a href="#section-3.4">3.4. Web Compatibility</a><br/> 46 <div style="margin-left: 2em;"> 47 <a href="#section-3.4.1">3.4.1. WebView Compatibility</a><br/> 48 <a href="#section-3.4.2">3.4.2. Browser Compatibility</a><br/> 49 </div> 50 <a href="#section-3.5">3.5. API Behavioral Compatibility</a><br/> 51 <a href="#section-3.6">3.6. API Namespaces</a><br/> 52 <a href="#section-3.7">3.7. Virtual Machine Compatibility</a><br/> 53 <a href="#section-3.8">3.8. User Interface Compatibility</a><br/> 54 <div style="margin-left: 2em;"> 55 <a href="#section-3.8.1">3.8.1. Widgets</a><br/> 56 <a href="#section-3.8.2">3.8.2. Notifications</a><br/> 57 <a href="#section-3.8.3">3.8.3. Search</a><br/> 58 <a href="#section-3.8.4">3.8.4. Toasts</a><br/> 59 <a href="#section-3.8.5">3.8.5. Themes</a><br/> 60 <a href="#section-3.8.6">3.8.6. Live Wallpapers</a><br/> 61 <a href="#section-3.8.7">3.8.7. Recent Application Display</a><br/> 62 <a href="#section-3.8.8">3.8.8. Input Management Settings</a><br/> 63 </div> 64 <a href="#section-3.9">3.9 Device Administration</a><br/> 65 <a href="#section-3.10">3.10 Accessibility</a><br/> 66 <a href="#section-3.11">3.11 Text-to-Speech</a><br/> 67 </div> 68 <a href="#section-4">4. Application Packaging Compatibility</a><br/> 69 <a href="#section-5">5. Multimedia Compatibility</a><br/> 70 <div style="margin-left: 2em;"> 71 <a href="#section-5.1">5.1. Media Codecs</a><br/> 72 <a href="#section-5.2">5.2. Video Encoding</a><br/> 73 <a href="#section-5.3">5.3. Audio Recording</a><br/> 74 <a href="#section-5.4">5.4. Audio Latency</a><br/> 75 <a href="#section-5.5">5.5. Network Protocols</a><br/> 76 </div> 77 <a href="#section-6">6. Developer Tool Compatibility</a><br/> 78 <a href="#section-7">7. Hardware Compatibility</a><br/> 79 <div style="margin-left: 2em;"> 80 <a href="#section-7.1">7.1. Display and Graphics</a><br/> 81 <div style="margin-left: 2em;"> 82 <a href="#section-7.1.1">7.1.1. Screen Configuration</a><br/> 83 <a href="#section-7.1.2">7.1.2. Display Metrics</a><br/> 84 <a href="#section-7.1.3">7.1.3. Screen Orientation</a><br/> 85 <a href="#section-7.1.4">7.1.4. 2D and 3D Graphics Accleration</a><br/> 86 <a href="#section-7.1.5">7.1.5. Legacy Application Compatibility Mode</a><br/> 87 <a href="#section-7.1.6">7.1.6. Screen Types</a><br/> 88 <a href="#section-7.1.7">7.1.7. Screen Technology</a><br/> 89 </div> 90 <a href="#section-7.2">7.2. Input Devices</a><br/> 91 <div style="margin-left: 2em;"> 92 <a href="#section-7.2.1">7.2.1. Keyboard</a><br/> 93 <a href="#section-7.2.2">7.2.2. Non-touch Navigation</a><br/> 94 <a href="#section-7.2.3">7.2.3. Navigation keys</a><br/> 95 <a href="#section-7.2.4">7.2.4. Touchscreen input</a><br/> 96 <a href="#section-7.2.5">7.2.5. Fake touch input</a><br/> 97 <a href="#section-7.2.6">7.2.6. Microphone</a><br/> 98 </div> 99 <a href="#section-7.3">7.3. Sensors</a><br/> 100 <div style="margin-left: 2em;"> 101 <a href="#section-7.3.1">7.3.1. Accelerometer</a><br/> 102 <a href="#section-7.3.2">7.3.2. Magnetometer</a><br/> 103 <a href="#section-7.3.3">7.3.3. GPS</a><br/> 104 <a href="#section-7.3.4">7.3.4. Gyroscope</a><br/> 105 <a href="#section-7.3.5">7.3.5. Barometer</a><br/> 106 <a href="#section-7.3.6">7.3.6. Thermometer</a><br/> 107 <a href="#section-7.3.7">7.3.7. Photometer</a><br/> 108 <a href="#section-7.3.8">7.3.8. Proximity Sensor</a><br/> 109 </div> 110 <a href="#section-7.4">7.4. Data Connectivity</a><br/> 111 <div style="margin-left: 2em;"> 112 <a href="#section-7.4.1">7.4.1. Telephony</a><br/> 113 <a href="#section-7.4.2">7.4.2. IEEE 802.11 (WiFi)</a><br/> 114 <a href="#section-7.4.3">7.4.3. Bluetooth</a><br/> 115 <a href="#section-7.4.4">7.4.4. Near-Field Communications</a><br/> 116 <a href="#section-7.4.5">7.4.5. Minimum Network Capability</a><br/> 117 </div> 118 <a href="#section-7.5">7.5. Cameras</a><br/> 119 <div style="margin-left: 2em;"> 120 <a href="#section-7.5.1">7.5.1. Rear-Facing Camera</a><br/> 121 <a href="#section-7.5.2">7.5.2. Front-Facing Camera</a><br/> 122 <a href="#section-7.5.3">7.5.3. Camera API Behavior</a><br/> 123 <a href="#section-7.5.4">7.5.4. Camera Orientation</a><br/> 124 </div> 125 <a href="#section-7.6">7.6. Memory and Storage</a><br/> 126 <div style="margin-left: 2em;"> 127 <a href="#section-7.6.1">7.6.1. Minimum Memory and Storage</a><br/> 128 <a href="#section-7.6.2">7.6.2. Application Shared Storage</a><br/> 129 </div> 130 <a href="#section-7.7">7.7. USB</a><br/> 131 </div> 132 <a href="#section-8">8. Performance Compatibility</a><br/> 133 <a href="#section-9">9. Security Model Compatibility</a><br/> 134 <div style="margin-left: 2em;"> 135 <a href="#section-9.1">9.1. Permissions</a><br/> 136 <a href="#section-9.2">9.2. UID and Process Isolation</a><br/> 137 <a href="#section-9.3">9.3. Filesystem Permissions</a><br/> 138 <a href="#section-9.4">9.4. Alternate Execution Environments</a><br/> 139 </div> 140 <a href="#section-10">10. Software Compatibility Testing</a><br/> 141 <div style="margin-left: 2em;"> 142 <a href="#section-10.1">10.1. Compatibility Test Suite</a><br/> 143 <a href="#section-10.2">10.2. CTS Verifier</a><br/> 144 <a href="#section-10.3">10.3. Reference Applications</a><br/> 145 </div> 146 <a href="#section-11">11. Updatable Software</a><br/> 147 <a href="#section-12">12. Contact Us</a><br/> 148 <a href="#appendix-A">Appendix A - Bluetooth Test Procedure</a><br/> 149</div> 150 151<div style="page-break-before: always;"></div> 152 153<a name="section-1"></a><h2>1. Introduction</h2> 154<p>This document enumerates the requirements that must be met in order for 155devices to be compatible with Android 4.0.</p> 156<p>The use of "must", "must not", "required", "shall", "shall not", "should", 157"should not", "recommended", "may" and "optional" is per the IETF standard 158defined in RFC2119 [<a href="#resources01">Resources, 1</a>].</p> 159<p>As used in this document, a "device implementer" or "implementer" is a 160person or organization developing a hardware/software solution running Android 1614.0. A "device implementation" or "implementation" is the hardware/software 162solution so developed.</p> 163<p>To be considered compatible with Android 4.0, device implementations 164MUST meet the requirements presented in this Compatibility Definition, 165including any documents incorporated via reference.</p> 166<p>Where this definition or the software tests described in <a 167href="#section-10">Section 10</a> is silent, ambiguous, or incomplete, it is 168the responsibility of the device implementer to ensure compatibility with 169existing implementations.</p> 170<p>For this reason, the Android Open Source Project [<a 171href="#resources03">Resources, 3</a>] is both the reference and preferred 172implementation of Android. Device implementers are strongly encouraged to base 173their implementations to the greatest extent possible on the "upstream" source 174code available from the Android Open Source Project. While some components can 175hypothetically be replaced with alternate implementations this practice is 176strongly discouraged, as passing the software tests will become substantially 177more difficult. It is the implementer's responsibility to ensure full 178behavioral compatibility with the standard Android implementation, including 179and beyond the Compatibility Test Suite. Finally, note that certain component 180substitutions and modifications are explicitly forbidden by this document.</p> 181<a name="section-2"></a><h2>2. Resources</h2> 182<ol> 183<a name="resources01"></a><li>IETF RFC2119 Requirement Levels: <a href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a></li> 184<a name="resources02"></a><li>Android Compatibility Program Overview: <a href="http://source.android.com/compatibility/index.html">http://source.android.com/compatibility/index.html</a></li> 185<a name="resources03"></a><li>Android Open Source Project: <a href="http://source.android.com/">http://source.android.com/</a></li> 186<a name="resources04"></a><li>API definitions and documentation: <a href="http://developer.android.com/reference/packages.html">http://developer.android.com/reference/packages.html</a></li> 187<a name="resources05"></a><li>Android Permissions reference: <a href="http://developer.android.com/reference/android/Manifest.permission.html">http://developer.android.com/reference/android/Manifest.permission.html</a></li> 188<a name="resources06"></a><li>android.os.Build reference: <a href="http://developer.android.com/reference/android/os/Build.html">http://developer.android.com/reference/android/os/Build.html</a></li> 189<a name="resources07"></a><li>Android 4.0 allowed version strings: <a href="http://source.android.com/compatibility/4.0/versions.html">http://source.android.com/compatibility/4.0/versions.html</a></li> 190<a name="resources08"></a><li>Renderscript: <a href="http://developer.android.com/guide/topics/graphics/renderscript.html">http://developer.android.com/guide/topics/graphics/renderscript.html</a></li> 191<a name="resources09"></a><li>Hardware Acceleration: <a href="http://developer.android.com/guide/topics/graphics/hardware-accel.html">http://developer.android.com/guide/topics/graphics/hardware-accel.html</a></li> 192<a name="resources10"></a><li>android.webkit.WebView class: <a href="http://developer.android.com/reference/android/webkit/WebView.html">http://developer.android.com/reference/android/webkit/WebView.html</a></li> 193<a name="resources11"></a><li>HTML5: <a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/">http://www.whatwg.org/specs/web-apps/current-work/multipage/</a></li> 194<a name="resources12"></a><li>HTML5 offline capabilities: <a href="http://dev.w3.org/html5/spec/Overview.html#offline">http://dev.w3.org/html5/spec/Overview.html#offline</a></li> 195<a name="resources13"></a><li>HTML5 video tag: <a href="http://dev.w3.org/html5/spec/Overview.html#video">http://dev.w3.org/html5/spec/Overview.html#video</a></li> 196<a name="resources14"></a><li>HTML5/W3C geolocation API: <a href="http://www.w3.org/TR/geolocation-API/">http://www.w3.org/TR/geolocation-API/</a></li> 197<a name="resources15"></a><li>HTML5/W3C webdatabase API: <a href="http://www.w3.org/TR/webdatabase/">http://www.w3.org/TR/webdatabase/</a></li> 198<a name="resources16"></a><li>HTML5/W3C IndexedDB API: <a href="http://www.w3.org/TR/IndexedDB/">http://www.w3.org/TR/IndexedDB/</a></li> 199<a name="resources17"></a><li>Dalvik Virtual Machine specification: available in the Android source code, at dalvik/docs</li> 200<a name="resources18"></a><li>AppWidgets: <a href="http://developer.android.com/guide/practices/ui_guidelines/widget_design.html">http://developer.android.com/guide/practices/ui_guidelines/widget_design.html</a></li> 201<a name="resources19"></a><li>Notifications: <a href="http://developer.android.com/guide/topics/ui/notifiers/notifications.html">http://developer.android.com/guide/topics/ui/notifiers/notifications.html</a></li> 202<a name="resources20"></a><li>Application Resources: <a href="http://code.google.com/android/reference/available-resources.html">http://code.google.com/android/reference/available-resources.html</a></li> 203<a name="resources21"></a><li>Status Bar icon style guide: <a href="http://developer.android.com/guide/practices/ui_guidelines/icon_design.html#statusbarstructure">http://developer.android.com/guide/practices/ui_guideline /icon_design.html#statusbarstructure</a></li> 204<a name="resources22"></a><li>Search Manager: <a href="http://developer.android.com/reference/android/app/SearchManager.html">http://developer.android.com/reference/android/app/SearchManager.html</a></li> 205<a name="resources23"></a><li>Toasts: <a href="http://developer.android.com/reference/android/widget/Toast.html">http://developer.android.com/reference/android/widget/Toast.html</a></li> 206<a name="resources24"></a><li>Themes: <a href="http://developer.android.com/guide/topics/ui/themes.html">http://developer.android.com/guide/topics/ui/themes.html</a></li> 207<a name="resources25"></a><li>R.style class: <a href="http://developer.android.com/reference/android/R.style.html">http://developer.android.com/reference/android/R.style.html</a></li> 208<a name="resources26"></a><li>Live Wallpapers: <a href="http://developer.android.com/resources/articles/live-wallpapers.html">http://developer.android.com/resources/articles/live-wallpapers.html</a></li> 209<a name="resources27"></a><li>Android Device Administration: <a href="http://developer.android.com/guide/topics/admin/device-admin.html">http://developer.android.com/guide/topics/admin/device-admin.html</a></li> 210<a name="resources28"></a><li>android.app.admin.DevicePolicyManager class: <a href="http://developer.android.com/reference/android/app/admin/DevicePolicyManager.html">http://developer.android.com/reference/android/app/admin/DevicePolicyManager.html</a></li> 211<a name="resources29"></a><li>Android Accessibility Service APIs: <a href="http://developer.android.com/reference/android/accessibilityservice/package-summary.html">http://developer.android.com/reference/android/accessibilityservice/package-summary.html</a></li> 212<a name="resources30"></a><li>Android Accessibility APIs: <a href="http://developer.android.com/reference/android/view/accessibility/package-summary.html">http://developer.android.com/reference/android/view/accessibility/package-summary.html</a></li> 213<a name="resources31"></a><li>Eyes Free project: <a href="http://http://code.google.com/p/eyes-free">http://code.google.com/p/eyes-free</a></li> 214<a name="resources32"></a><li>Text-To-Speech APIs: <a href="http://developer.android.com/reference/android/speech/tts/package-summary.html">http://developer.android.com/reference/android/speech/tts/package-summary.html</a></li> 215<a name="resources33"></a><li>Reference tool documentation (for adb, aapt, ddms): <a href="http://developer.android.com/guide/developing/tools/index.html">http://developer.android.com/guide/developing/tools/index.html</a></li> 216<a name="resources34"></a><li>Android apk file description: <a href="http://developer.android.com/guide/topics/fundamentals.html">http://developer.android.com/guide/topics/fundamentals.html</a></li> 217<a name="resources35"></a><li>Manifest files: <a href="http://developer.android.com/guide/topics/manifest/manifest-intro.html">http://developer.android.com/guide/topics/manifest/manifest-intro.html</a></li> 218<a name="resources36"></a><li>Monkey testing tool: <a href="http://developer.android.com/guide/developing/tools/monkey.html">http://developer.android.com/guide/developing/tools/monkey.html</a></li> 219<a name="resources37"></a><li>Android android.content.pm.PackageManager class and Hardware Features List: <a href="http://developer.android.com/reference/android/content/pm/PackageManager.html">http://developer.android.com/reference/android/content/pm/PackageManager.html</a></li> 220<a name="resources38"></a><li>Supporting Multiple Screens: <a href="http://developer.android.com/guide/practices/screens_support.html">http://developer.android.com/guide/practices/screens_support.html</a></li> 221<a name="resources39"></a><li>android.util.DisplayMetrics: <a href="http://developer.android.com/reference/android/util/DisplayMetrics.html">http://developer.android.com/reference/android/util/DisplayMetrics.html</a></li> 222<a name="resources40"></a><li>android.content.res.Configuration: <a href="http://developer.android.com/reference/android/content/res/Configuration.html">http://developer.android.com/reference/android/content/res/Configuration.html</a></li> 223<a name="resources41"></a><li>android.hardware.SensorEvent: <a href="http://developer.android.com/reference/android/hardware/SensorEvent.html">http://developer.android.com/reference/android/hardware/SensorEvent.html</a></li> 224<a name="resources42"></a><li>Bluetooth API: <a href="http://developer.android.com/reference/android/bluetooth/package-summary.html">http://developer.android.com/reference/android/bluetooth/package-summary.html</a></li> 225<a name="resources43"></a><li>NDEF Push Protocol: <a href="http://source.android.com/compatibility/ndef-push-protocol.pdf">http://source.android.com/compatibility/ndef-push-protocol.pdf</a></li> 226<a name="resources44"></a><li>MIFARE MF1S503X: <a href="http://www.nxp.com/documents/data_sheet/MF1S503x.pdf">http://www.nxp.com/documents/data_sheet/MF1S503x.pdf</a></li> 227<a name="resources45"></a><li>MIFARE MF1S703X: <a href="http://www.nxp.com/documents/data_sheet/MF1S703x.pdf">http://www.nxp.com/documents/data_sheet/MF1S703x.pdf</a></li> 228<a name="resources46"></a><li>MIFARE MF0ICU1: <a href="http://www.nxp.com/documents/data_sheet/MF0ICU1.pdf">http://www.nxp.com/documents/data_sheet/MF0ICU1.pdf</a></li> 229<a name="resources47"></a><li>MIFARE MF0ICU2: <a href="http://www.nxp.com/documents/short_data_sheet/MF0ICU2_SDS.pdf">http://www.nxp.com/documents/short_data_sheet/MF0ICU2_SDS.pdf</a></li> 230<a name="resources48"></a><li>MIFARE AN130511: <a href="http://www.nxp.com/documents/application_note/AN130511.pdf">http://www.nxp.com/documents/application_note/AN130511.pdf</a></li> 231<a name="resources49"></a><li>MIFARE AN130411: <a href="http://www.nxp.com/documents/application_note/AN130411.pdf">http://www.nxp.com/documents/application_note/AN130411.pdf</a></li> 232<a name="resources50"></a><li>Camera orientation API: <a href="http://developer.android.com/reference/android/hardware/Camera.html#setDisplayOrientation(int)">http://developer.android.com/reference/android/hardware/Camera.html#setDisplayOrientation(int)</a></li> 233<a name="resources51"></a><li>android.hardware.Camera: <a href="http://developer.android.com/reference/android/hardware/Camera.html">http://developer.android.com/reference/android/hardware/Camera.html</a></li> 234<a name="resources52"></a><li>Android Open Accessories: <a href="http://developer.android.com/guide/topics/usb/accessory.html">http://developer.android.com/guide/topics/usb/accessory.html</a></li> 235<a name="resources53"></a><li>USB Host API: <a href="http://developer.android.com/guide/topics/usb/host.html">http://developer.android.com/guide/topics/usb/host.html</a></li> 236<a name="resources54"></a><li>Android Security and Permissions reference: <a href="http://developer.android.com/guide/topics/security/security.html">http://developer.android.com/guide/topics/security/security.html</a></li> 237<a name="resources55"></a><li>Apps for Android: <a href="http://code.google.com/p/apps-for-android">http://code.google.com/p/apps-for-android</a></li> 238<a name="resources56"></a><li>android.app.DownloadManager class: <a href="http://developer.android.com/reference/android/app/DownloadManager.html">http://developer.android.com/reference/android/app/DownloadManager.html</a></li> 239<a name="resources57"></a><li>Android File Transfer: <a href="http://www.android.com/filetransfer">http://www.android.com/filetransfer</a></li> 240<a name="resources58"></a><li>Android Media Formats: <a href="http://developer.android.com/guide/appendix/media-formats.html">http://developer.android.com/guide/appendix/media-formats.html</a></li> 241<a name="resources59"></a><li>HTTP Live Streaming Draft Protocol: <a href="http://tools.ietf.org/html/draft-pantos-http-live-streaming-03">http://tools.ietf.org/html/draft-pantos-http-live-streaming-03</a></li> 242<a name="resources60"></a><li>Motion Event API: <a href="http://developer.android.com/reference/android/view/MotionEvent.html">http://developer.android.com/reference/android/view/MotionEvent.html</a></li> 243<a name="resources61"></a><li>Touch Input Configuration: <a href="http://source.android.com/tech/input/touch-devices.html">http://source.android.com/tech/input/touch-devices.html</a></li> 244</ol> 245 246<p>Many of these resources are derived directly or indirectly from the Android 2474.0 SDK, and will be functionally identical to the information in that SDK's 248documentation. In any cases where this Compatibility Definition or the 249Compatibility Test Suite disagrees with the SDK documentation, the SDK 250documentation is considered authoritative. Any technical details provided in 251the references included above are considered by inclusion to be part of this 252Compatibility Definition.</p> 253 254<a name="section-3"></a><h2>3. Software</h2> 255<a name="section-3.1"></a><h3>3.1. Managed API Compatibility</h3> 256<p>The managed (Dalvik-based) execution environment is the primary vehicle for 257Android applications. The Android application programming interface (API) is 258the set of Android platform interfaces exposed to applications running in the 259managed VM environment. Device implementations MUST provide complete 260implementations, including all documented behaviors, of any documented API 261exposed by the Android 4.0 SDK [<a href="#resources04">Resources, 4</a>].</p> 262<p>Device implementations MUST NOT omit any managed APIs, alter API interfaces 263or signatures, deviate from the documented behavior, or include no-ops, except 264where specifically allowed by this Compatibility Definition.</p> 265<p>This Compatibility Definition permits some types of hardware for which 266Android includes APIs to be omitted by device implementations. In such cases, 267the APIs MUST still be present and behave in a reasonable way. See 268<a href="#section-7">Section 7</a> for specific requirements for this scenario. 269</p> 270 271<a name="section-3.2"></a><h3>3.2. Soft API Compatibility</h3> 272<p>In addition to the managed APIs from Section 3.1, Android also includes a 273significant runtime-only "soft" API, in the form of such things such as 274Intents, permissions, and similar aspects of Android applications that cannot 275be enforced at application compile time.</p> 276<a name="section-3.2.1"></a><h4>3.2.1. Permissions</h4> 277<p>Device implementers MUST support and enforce all permission constants as 278documented by the Permission reference page [<a 279href="#resources05">Resources, 5</a>]. Note that Section 10 lists additional 280requirements related to the Android security model.</p> 281<a name="section-3.2.3"></a><h4>3.2.3. Build Parameters</h4> 282<p>The Android APIs include a number of constants on the <code>android.os.Build</code> 283class [<a href="#resources06">Resources, 6</a>] that are intended to describe 284the current device. To provide consistent, meaningful values across device 285implementations, the table below includes additional restrictions on the 286formats of these values to which device implementations MUST conform.</p> 287<table> 288<tbody> 289<tr> 290<td><b>Parameter</b></td> 291<td><b>Comments</b></td> 292</tr> 293<tr> 294<td>android.os.Build.VERSION.RELEASE</td> 295<td>The version of the currently-executing Android system, in human-readable 296format. This field MUST have one of the string values defined in [<a 297href="#resources07">Resources, 7</a>].</td> 298</tr> 299<tr> 300<td>android.os.Build.VERSION.SDK</td> 301<td>The version of the currently-executing Android system, in a format 302accessible to third-party application code. For Android 4.0.1 - 4.0.2, this 303field MUST have the integer value 14. For Android 4.0.3 or greater, this field 304MUST have the integer value 15.</td> 305</tr> 306<tr> 307<td>android.os.Build.VERSION.SDK_INT</td> 308<td>The version of the currently-executing Android system, in a format 309accessible to third-party application code. For Android 4.0.1 - 4.0.2, this 310field MUST have the integer value 14. For Android 4.0.3 or greater, this field 311MUST have the integer value 15.</td> 312</tr> 313<tr> 314<td>android.os.Build.VERSION.INCREMENTAL</td> 315<td>A value chosen by the device implementer designating the specific build of 316the currently-executing Android system, in human-readable format. This value 317MUST NOT be re-used for different builds made available to end users. A typical use 318of this field is to indicate which build number or source-control change 319identifier was used to generate the build. There are no requirements on the 320specific format of this field, except that it MUST NOT be null or the empty 321string ("").</td> 322</tr> 323<tr> 324<td>android.os.Build.BOARD</td> 325<td>A value chosen by the device implementer identifying the specific internal 326hardware used by the device, in human-readable format. A possible use of this 327field is to indicate the specific revision of the board powering the device. 328The value of this field MUST be encodable as 7-bit ASCII and match the regular expression 329<code>"^[a-zA-Z0-9.,_-]+$"</code>.</td> 330</tr> 331<tr> 332<td>android.os.Build.BRAND</td> 333<td>A value chosen by the device implementer identifying the name of the 334company, organization, individual, etc. who produced the device, in 335human-readable format. A possible use of this field is to indicate the OEM 336and/or carrier who sold the device. The value of this field MUST be 337encodable as 7-bit ASCII and match the regular expression 338<code>"^[a-zA-Z0-9.,_-]+$"</code>. 339</td> 340</tr> 341<tr> 342<td>android.os.Build.CPU_ABI</td> 343<td>The name of the instruction set (CPU type + ABI convention) of native code. 344See <a href="#section-3.3">Section 3.3: Native API Compatibility</a>. 345</td> 346</tr> 347<tr> 348<td>android.os.Build.CPU_ABI2</td> 349<td>The name of the second instruction set (CPU type + ABI convention) of native code. 350See <a href="#section-3.3">Section 3.3: Native API Compatibility</a>. 351</td> 352</tr> 353<tr> 354<td>android.os.Build.DEVICE</td> 355<td>A value chosen by the device implementer identifying the specific 356configuration or revision of the body (sometimes called "industrial design") 357of the device. The value of this field MUST be encodable as 7-bit ASCII and 358match the regular expression <code>"^[a-zA-Z0-9.,_-]+$"</code>.</td> 359</tr> 360<tr> 361<td>android.os.Build.FINGERPRINT</td> 362<td>A string that uniquely identifies this build. It SHOULD be reasonably 363human-readable. It MUST follow this template: 364<br/><code>$(BRAND)/$(PRODUCT)/$(DEVICE):$(VERSION.RELEASE)/$(ID)/$(VERSION.INCREMENTAL):$(TYPE)/$(TAGS)</code><br/> 365For example: 366<br/><code>acme/mydevice/generic:4.0/IRK77/3359:userdebug/test-keys</code><br/> 367The fingerprint MUST NOT include whitespace characters. If other fields included in the 368template above have whitespace characters, they MUST be replaced in the build 369fingerprint with another character, such as the underscore ("_") character. 370The value of this field MUST be encodable as 7-bit ASCII.</td> 371</tr> 372<tr> 373<td>android.os.Build.HARDWARE</td> 374<td>The name of the hardware (from the kernel command line or /proc). It SHOULD be 375reasonably human-readable. The value of this field MUST be encodable as 7-bit ASCII and 376match the regular expression <code>"^[a-zA-Z0-9.,_-]+$"</code>.</td> 377</tr> 378<tr> 379<td>android.os.Build.HOST</td> 380<td>A string that uniquely identifies the host the build was built on, in 381human readable format. There are no requirements on the specific format of 382this field, except that it MUST NOT be null or the empty string ("").</td> 383</tr> 384<tr> 385<td>android.os.Build.ID</td> 386<td>An identifier chosen by the device implementer to refer to a specific 387release, in human readable format. This field can be the same as 388android.os.Build.VERSION.INCREMENTAL, but SHOULD be a value sufficiently 389meaningful for end users to distinguish between software builds. The value of 390this field MUST be encodable as 7-bit ASCII and match the regular expression 391<code>"^[a-zA-Z0-9.,_-]+$"</code>. 392</td> 393</tr> 394<tr> 395<td>android.os.Build.MANUFACTURER</td> 396<td>The trade name of the Original Equipment Manufacturer (OEM) of the product. 397There are no requirements on the specific format of this field, except that it 398MUST NOT be null or the empty string ("").</td> 399</tr> 400<tr> 401<td>android.os.Build.MODEL</td> 402<td>A value chosen by the device implementer containing the name of the device 403as known to the end user. This SHOULD be the same name under which the device 404is marketed and sold to end users. There are no requirements on the specific 405format of this field, except that it MUST NOT be null or the empty string 406("").</td> 407</tr> 408<tr> 409<td>android.os.Build.PRODUCT</td> 410<td>A value chosen by the device implementer containing the development name 411or code name of the product (SKU). MUST be human-readable, but is not necessarily 412intended for view by end users. The value of this field MUST be encodable as 7-bit 413ASCII and match the regular expression 414<code>"^[a-zA-Z0-9.,_-]+$"</code>.</td> 415</tr> 416<tr> 417<td>android.os.Build.SERIAL</td> 418<td>A hardware serial number, if available. The value of this field MUST be encodable 419as 7-bit ASCII and match the regular expression 420<code>"^([a-zA-Z0-9]{0,20})$"</code>.</td> 421</tr> 422<tr> 423<td>android.os.Build.TAGS</td> 424<td>A comma-separated list of tags chosen by the device implementer that 425further distinguish the build. For example, "unsigned,debug". The value of 426this field MUST be encodable as 7-bit ASCII and match the regular expression 427<code>"^[a-zA-Z0-9.,_-]+$"</code>.</td> 428</tr> 429<tr> 430<td>android.os.Build.TIME</td> 431<td>A value representing the timestamp of when the build occurred.</td> 432</tr> 433<tr> 434<td>android.os.Build.TYPE</td> 435<td>A value chosen by the device implementer specifying the runtime 436configuration of the build. This field SHOULD have one of the values 437corresponding to the three typical Android runtime configurations: "user", 438"userdebug", or "eng". The value of this field MUST be 439encodable as 7-bit ASCII and match the regular expression 440<code>"^[a-zA-Z0-9.,_-]+$"</code>.</td> 441</tr> 442<tr> 443<td>android.os.Build.USER</td> 444<td>A name or user ID of the user (or automated user) that generated the 445build. There are no requirements on the specific format of this field, except 446that it MUST NOT be null or the empty string ("").</td> 447</tr> 448</tbody> 449</table> 450<a name="section-3.2.3"></a><h4>3.2.3. Intent Compatibility</h4> 451<p> 452Device implementations MUST honor Android's loose-coupling Intent system, as 453described in the sections below. By "honored", it is meant that the device 454implementer MUST provide an Android Activity or Service that specifies a 455matching Intent filter and binds to and implements correct behavior for each 456specified Intent pattern.</p> 457<a name="section-3.2.3.1"></a><h4>3.2.3.1. Core Application Intents</h4> 458<p>The Android upstream project defines a number of core applications, such as 459contacts, calendar, photo gallery, music player, and so on. Device implementers 460MAY replace these applications with alternative versions.</p> 461<p>However, any such alternative versions MUST honor the same Intent patterns 462provided by the upstream project. For example, if a device contains an 463alternative music player, it must still honor the Intent pattern issued by 464third-party applications to pick a song.</p> 465<p>The following applications are considered core Android system 466applications:</p> 467<ul> 468<li>Desk Clock</li> 469<li>Browser</li> 470<li>Calendar</li> 471<li>Contacts</li> 472<!--<li>Email</li>--> 473<li>Gallery</li> 474<li>GlobalSearch</li> 475<li>Launcher</li> 476<!-- <li>LivePicker (that is, the Live Wallpaper picker application; MAY be omitted 477if the device does not support Live Wallpapers, per Section 3.8.5.)</li> --> 478<!-- <li>Messaging (AKA "Mms")</li> --> 479<li>Music</li> 480<!-- <li>Phone</li> --> 481<li>Settings</li> 482<!-- <li>SoundRecorder</li> --> 483</ul> 484<p>The core Android system applications include various Activity, or Service 485components that are considered "public". That is, the attribute 486"android:exported" may be absent, or may have the value "true".</p> 487<p>For every Activity or Service defined 488in one of the core Android system apps that is not marked as non-public via an 489android:exported attribute with the value "false", device implementations MUST 490include a compontent of the same type implementing the same Intent filter 491patterns as the core Android system app.</p> 492<p>In other words, a device implementation MAY replace core Android system 493apps; however, if it does, the device implementation MUST support all Intent 494patterns defined by each core Android system app being replaced.</p> 495<a name="section-3.2.3.2"></a><h4>3.2.3.2. Intent Overrides</h4> 496<p>As Android is an extensible platform, device implementations MUST allow each 497Intent pattern referenced in Section 3.2.3.2 to be overridden by third-party 498applications. The upstream Android open source implementation allows this by 499default; device implementers MUST NOT attach special privileges to system 500applications' use of these Intent patterns, or prevent third-party 501applications from binding to and assuming control of these patterns. This 502prohibition specifically includes but is not limited to disabling the 503"Chooser" user interface which allows the user to select between multiple 504applications which all handle the same Intent pattern.</p> 505<a name="section-3.2.3.3"></a><h4>3.2.3.3. Intent Namespaces</h4> 506<p>Device implementations MUST NOT include any Android component that honors any 507new Intent or Broadcast Intent patterns using an ACTION, CATEGORY, or other 508key string in the android.* or com.android.* namespace. Device implementers 509MUST NOT include any Android components that honor any new Intent or Broadcast 510Intent patterns using an ACTION, CATEGORY, or other key string in a package 511space belonging to another organization. Device implementers MUST NOT alter or 512extend any of the Intent patterns used by the core apps listed in Section 5133.2.3.1. Device implementations MAY include Intent patterns using 514namespaces clearly and obviously associated with their own organization.</p> 515<p>This prohibition is analogous to that specified for Java language classes 516in Section 3.6.</p> 517<a name="section-3.2.3.4"></a><h4>3.2.3.4. Broadcast Intents</h4> 518<p>Third-party applications rely on the platform to broadcast certain Intents 519to notify them of changes in the hardware or software environment. 520Android-compatible devices MUST broadcast the public broadcast Intents in 521response to appropriate system events. Broadcast Intents are described in the 522SDK documentation.</p> 523 524<a name="section-3.3"></a><h3>3.3. Native API Compatibility</h3> 525<a name="section-3.3.1"></a><h4>3.3.1 Application Binary Interfaces</h4> 526<p>Managed code running in Dalvik can call into native code provided in the 527application .apk file as an ELF .so file compiled for the appropriate device 528hardware architecture. As native code is highly dependent on the underlying 529processor technology, Android defines a number of Application Binary 530Interfaces (ABIs) in the Android NDK, in the file 531<code>docs/CPU-ARCH-ABIS.txt</code>. If a device implementation is compatible 532with one or more defined ABIs, it SHOULD implement compatibility with the 533Android NDK, as below.</p> 534<p>If a device implementation includes support for an Android ABI, it:</p> 535<ul> 536<li>MUST include support for code running in the managed environment to call 537into native code, using the standard Java Native Interface (JNI) 538semantics.</li> 539<li>MUST be source-compatible (i.e. header compatible) and binary-compatible 540(for the ABI) with each required library in the list below</li> 541<li>MUST accurately report the native Application Binary Interface (ABI) 542supported by the device, via the <code>android.os.Build.CPU_ABI</code> 543API</li> 544<li>MUST report only those ABIs documented in the latest version of the 545Android NDK, in the file <code>docs/CPU-ARCH-ABIS.txt</code></li> 546<li>SHOULD be built using the source code and header files available in the 547upstream Android open source project</li> 548</ul> 549<p>The following native code APIs MUST be available to apps that include 550native code:</p> 551<ul> 552<li>libc (C library)</li> 553<li>libm (math library)</li> 554<li>Minimal support for C++</li> 555<li>JNI interface</li> 556<li>liblog (Android logging)</li> 557<li>libz (Zlib compression)</li> 558<li>libdl (dynamic linker)</li> 559<li>libGLESv1_CM.so (OpenGL ES 1.0)</li> 560<li>libGLESv2.so (OpenGL ES 2.0)</li> 561<li>libEGL.so (native OpenGL surface management)</li> 562<li>libjnigraphics.so</li> 563<li>libOpenSLES.so (OpenSL ES 1.0.1 audio support)</li> 564<li>libOpenMAXAL.so (OpenMAX AL 1.0.1 support)</li> 565<li>libandroid.so (native Android activity support)</li> 566<li>Support for OpenGL, as described below</li> 567</ul> 568<p>Note that future releases of the Android NDK may introduce support for 569additional ABIs. If a device implementation is not compatible with an existing 570predefined ABI, it MUST NOT report support for any ABI at all.</p> 571<p>Native code compatibility is challenging. For this reason, it should be 572repeated that device implementers are VERY strongly encouraged to use the 573upstream implementations of the libraries listed above to help ensure 574compatibility.</p> 575 576<a name="section-3.4"></a><h3>3.4. Web Compatibility</h3> 577<a name="section-3.4.1"></a><h4>3.4.1. WebView Compatibility</h4> 578<p>The Android Open Source implementation uses the WebKit rendering engine to 579implement the <code>android.webkit.WebView</code>. Because it is not feasible 580to develop a comprehensive test suite for a web rendering system, device 581implementers MUST use the specific upstream build of WebKit in the WebView 582implementation. Specifically:</p> 583<ul> 584<li>Device implementations' <code>android.webkit.WebView</code> 585implementations MUST be based on the 534.30 WebKit build from the upstream 586Android Open Source tree for Android 4.0. This build includes a specific set 587of functionality and security fixes for the WebView. Device implementers MAY 588include customizations to the WebKit implementation; however, any such 589customizations MUST NOT alter the behavior of the WebView, including rendering 590behavior.</li> 591<li>The user agent string reported by the WebView MUST be in this format:<br/> 592 <code>Mozilla/5.0 (Linux; U; Android $(VERSION); $(LOCALE); $(MODEL) Build/$(BUILD)) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30</code> 593 <ul> 594 <li>The value of the $(VERSION) string MUST be the same as the value for <code>android.os.Build.VERSION.RELEASE</code></li> 595 <li>The value of the $(LOCALE) string SHOULD follow the ISO conventions for country code and language, and SHOULD refer to the current configured locale of the device</li> 596 <li>The value of the $(MODEL) string MUST be the same as the value for <code>android.os.Build.MODEL</code></li> 597 <li>The value of the $(BUILD) string MUST be the same as the value for <code>android.os.Build.ID</code></li> 598 </ul> 599</li> 600</ul> 601<p>The WebView component SHOULD include support for as much of HTML5 [<a 602href="#resources11">Resources, 11</a>] as possible. 603Minimally, device implementations MUST support each of these APIs associated 604with HTML5 in the WebView:</p> 605<ul> 606<li>application cache/offline operation [<a href="#resources12">Resources, 12</a>]</li> 607<li>the <video> tag [<a href="#resources13">Resources, 13</a>]</li> 608<li>geolocation [<a href="#resources14">Resources, 14</a>]</li> 609</ul> 610<p>Additionally, device implementations MUST support the HTML5/W3C webstorage 611API [<a href="#resources15">Resources, 15</a>], and SHOULD support the 612HTML5/W3C IndexedDB API [<a href="#resources16">Resources, 16</a>]. <i>Note 613that as the web development standards bodies are transitioning to favor 614IndexedDB over webstorage, IndexedDB is expected to become a required 615component in a future version of Android.</i></p> 616<p>HTML5 APIs, like all JavaScript APIs, MUST be disabled by default in a 617WebView, unless the developer explicitly enables them via the usual Android 618APIs.</p> 619 620<a name="section-3.4.2"></a><h4>3.4.2. Browser Compatibility</h4> 621<p>Device implementations MUST include a standalone Browser application for 622general user web browsing. The standalone Browser MAY be based on a 623browser technology other than WebKit. However, even if an alternate Browser 624application is used, the <code>android.webkit.WebView</code> component 625provided to third-party applications MUST be based on WebKit, as described in 626Section 3.4.1.</p> 627<p>Implementations MAY ship a custom user agent string in the standalone 628Browser application.</p> 629<p>The standalone Browser application (whether based on the upstream 630WebKit Browser application or a third-party replacement) SHOULD include support 631for as much of HTML5 [<a href="#resources11">Resources, 11</a>] as possible. 632Minimally, device implementations MUST support each of these APIs associated 633with HTML5:</p> 634<ul> 635<li>application cache/offline operation [<a href="#resources12">Resources, 12</a>]</li> 636<li>the <video> tag [<a href="#resources13">Resources, 13</a>]</li> 637<li>geolocation [<a href="#resources14">Resources, 14</a>]</li> 638</ul> 639<p>Additionally, device implementations MUST support the HTML5/W3C webstorage 640API [<a href="#resources15">Resources, 15</a>], and SHOULD support the 641HTML5/W3C IndexedDB API [<a href="#resources16">Resources, 16</a>]. <i>Note 642that as the web development standards bodies are transitioning to favor 643IndexedDB over webstorage, IndexedDB is expected to become a required 644component in a future version of Android.</i></p> 645 646<a name="section-3.5"></a><h3>3.5. API Behavioral Compatibility</h3> 647<p>The behaviors of each of the API types (managed, soft, native, and web) 648must be consistent with the preferred implementation of the upstream Android 649open source project [<a href="#resources03">Resources, 3</a>]. Some specific areas 650of compatibility are:</p> 651<ul> 652<li>Devices MUST NOT change the behavior or semantics of a standard Intent</li> 653<li>Devices MUST NOT alter the lifecycle or lifecycle semantics of a 654 particular type of system component (such as Service, Activity, 655 ContentProvider, etc.)</li> 656<li>Devices MUST NOT change the semantics of a standard permission</li> 657</ul> 658<p>The above list is not comprehensive. The Compatibility Test Suite (CTS) 659tests significant portions of the platform for behavioral compatibility, but 660not all. It is the responsibility of the implementer to ensure behavioral 661compatibility with the Android Open Source Project. For this reason, device 662implementers SHOULD use the source code available via the Android Open Source 663Project where possible, rather than re-implement significant parts of the 664system.</p> 665 666 667<a name="section-3.6"></a><h3>3.6. API Namespaces</h3> 668<p>Android follows the package and class namespace conventions defined by the 669Java programming language. To ensure compatibility with third-party 670applications, device implementers MUST NOT make any prohibited modifications 671(see below) to these package namespaces:</p> 672<ul> 673<li>java.*</li> 674<li>javax.*</li> 675<li>sun.*</li> 676<li>android.*</li> 677<li>com.android.*</li> 678</ul> 679<p>Prohibited modifications include:</p> 680<ul> 681<li>Device implementations MUST NOT modify the publicly exposed APIs on the 682Android platform by changing any method or class signatures, or by removing 683classes or class fields.</li> 684<li>Device implementers MAY modify the underlying implementation of the APIs, 685but such modifications MUST NOT impact the stated behavior and Java-language 686signature of any publicly exposed APIs.</li> 687<li>Device implementers MUST NOT add any publicly exposed elements (such as 688classes or interfaces, or fields or methods to existing classes or interfaces) 689to the APIs above.</li> 690</ul> 691<p>A "publicly exposed element" is any construct which is not decorated with 692the "@hide" marker as used in the upstream Android source code. In other 693words, device implementers MUST NOT expose new APIs or alter existing APIs in 694the namespaces noted above. Device implementers MAY make internal-only 695modifications, but those modifications MUST NOT be advertised or otherwise 696exposed to developers.</p> 697<p>Device implementers MAY add custom APIs, but any such APIs MUST NOT be in a 698namespace owned by or referring to another organization. For instance, device 699implementers MUST NOT add APIs to the com.google.* or similar namespace; only 700Google may do so. Similarly, Google MUST NOT add APIs to other companies' 701namespaces. Additionally, if a device implementation includes custom APIs 702outside the standard Android namespace, those APIs MUST be packaged in an 703Android shared library so that only apps that explicitly use them (via the 704<code><uses-library></code> mechanism) are affected by the increased 705memory usage of such APIs.</p> 706<p>If a device implementer proposes to improve one of the package namespaces 707above (such as by adding useful new functionality to an existing API, or 708adding a new API), the implementer SHOULD visit source.android.com and begin 709the process for contributing changes and code, according to the information on 710that site.</p> 711<p>Note that the restrictions above correspond to standard conventions for 712naming APIs in the Java programming language; this section simply aims to 713reinforce those conventions and make them binding through inclusion in this 714compatibility definition.</p> 715 716<a name="section-3.7"></a><h3>3.7. Virtual Machine Compatibility</h3> 717<p>Device implementations MUST support the full Dalvik Executable (DEX) 718bytecode specification and Dalvik Virtual Machine semantics [<a 719href="#resources17">Resources, 17</a>].</p> 720<p>Device implementations MUST configure Dalvik to allocate memory in 721accordance with the upstream Android platform, and as specified by the following 722table. (See <a href="#section-7.1.1">Section 7.1.1</a> for screen size and screen 723density definitions.)</p> 724 725<p>Note that memory values specified below are considered minimum values, 726and device implementations MAY allocate more memory per application.</p> 727<table> 728<tbody> 729<tr> 730<td><b>Screen Size</b></td> 731<td><b>Screen Density</b></td> 732<td><b>Application Memory</b></td> 733</tr> 734<tr> 735<td>small / normal / large</td> 736<td>ldpi / mdpi</td> 737<td>16MB</td> 738</tr> 739<tr> 740<td>small / normal / large</td> 741<td>tvdpi / hdpi</td> 742<td>32MB</td> 743</tr> 744<tr> 745<td>small / normal / large</td> 746<td>xhdpi</td> 747<td>64MB</td> 748</tr> 749<tr> 750<td>xlarge</td> 751<td>mdpi</td> 752<td>32MB</td> 753</tr> 754<tr> 755<td>xlarge</td> 756<td>tvdpi / hdpi</td> 757<td>64MB</td> 758</tr> 759<tr> 760<td>xlarge</td> 761<td>xhdpi</td> 762<td>128MB</td> 763</tr> 764</tbody> 765</table> 766 767<a name="section-3.8"></a><h3>3.8. User Interface Compatibility</h3> 768<a name="section-3.8.1"></a><h4>3.8.1. Widgets</h4> 769<p>Android defines a component type and corresponding API and lifecycle that 770allows applications to expose an "AppWidget" to the end user [<a 771href="#resources18">Resources, 18</a>]. 772The Android Open Source reference release includes a Launcher application that 773includes user interface affordances allowing the user to add, view, and remove 774AppWidgets from the home screen.</p> 775<p>Device implementations MAY substitute an alternative to the reference Launcher 776(i.e. home screen). Alternative Launchers SHOULD include built-in support for 777AppWidgets, and expose user interface affordances to add, configure, view, and 778remove AppWidgets directly within the Launcher. Alternative Launchers MAY omit 779these user interface elements; however, if they are omitted, the device 780implementation MUST provide a separate application accessible from the Launcher 781that allows users to add, configure, view, and remove AppWidgets.</p> 782<p>Device implementations MUST be capable of rendering widgets that are 4 x 4 783in the standard grid size. (See the App Widget Design Guidelines in the Android 784SDK documentation [<a 785href="#resources18">Resources, 18</a>] for details.</p> 786<a name="section-3.8.2"></a><h4>3.8.2. Notifications</h4> 787<p>Android includes APIs that allow developers to notify users of notable 788events [<a href="#resources19">Resources, 19</a>], using hardware and software 789features of the device.</p> 790<p>Some APIs allow applications to perform notifications or attract attention 791using hardware, specifically sound, vibration, and light. Device implementations 792MUST support notifications that use hardware features, as described in the SDK 793documentation, and to the extent possible with the device implementation 794hardware. For instance, if a device implementation includes a vibrator, it 795MUST correctly implement the vibration APIs. If a device implementation lacks 796hardware, the corresponding APIs MUST be implemented as no-ops. Note that this 797behavior is further detailed in <a href="#section-7">Section 7.</a></p> 798<p>Additionally, the implementation MUST correctly render all resources 799(icons, sound files, etc.) provided for in the APIs [<a 800href="#resources20">Resources, 20</a>], or in the 801Status/System Bar icon style guide [<a href="#resources21">Resources, 21</a>]. 802Device implementers MAY provide an alternative user experience for 803notifications than that provided by the reference Android Open Source 804implementation; however, such alternative notification systems MUST support 805existing notification resources, as above.</p> 806<p>Android 4.0 includes support for rich notifications, such as interactive 807Views for ongoing notifications. Device implementations MUST properly display 808and execute rich notifications, as documented in the Android APIs.</p> 809<a name="section-3.8.3"></a><h4>3.8.3. Search</h4> 810<p>Android includes APIs [<a href="#resources22">Resources, 22</a>] that allow 811developers to incorporate search into their applications, and expose their 812application's data into the global system search. Generally speaking, this 813functionality consists of a single, system-wide user interface that allows users 814to enter queries, displays suggestions as users type, and displays results. The 815Android APIs allow developers to reuse this interface to provide search within 816their own apps, and allow developers to supply results to the common global 817search user interface.</p> 818<p>Device implementations MUST include a single, shared, system-wide search 819user interface capable of real-time suggestions in response to user input. 820Device implementations MUST implement the APIs that allow developers to reuse 821this user interface to provide search within their own applications. Device 822implementations MUST implement the APIs that allow third-party applications to 823add suggestions to the search box when it is run in global search mode. If no 824third-party applications are installed that make use of this functionality, 825the default behavior SHOULD be to display web search engine results and 826suggestions.</p> 827<a name="section-3.8.4"></a><h4>3.8.4. Toasts</h4> 828<p>Applications can use the "Toast" API (defined in [<a 829href="#resources23">Resources, 23</a>]) to 830display short non-modal strings to the end user, that disappear after a brief 831period of time. Device implementations MUST display Toasts from applications 832to end users in some high-visibility manner.</p> 833 834<a name="section-3.8.5"></a><h4>3.8.5. Themes</h4> 835<p>Android provides "themes" as a mechanism for applications to apply styles 836across an entire Activity or application. Android 3.0 introduced a new "Holo" 837or "holographic" theme as a set of defined styles for application developers to 838use if they want to match the Holo theme look and feel as defined by the Android 839SDK [<a href="#resources24">Resources, 24</a>]. Device implementations MUST NOT 840alter any of the Holo theme attributes exposed to applications 841[<a href="#resources25">Resources, 25</a>].</p> 842<p>Android 4.0 introduces a new "Device Default" theme as a set of defined 843styles for application developers to use if they want to match the look and feel 844of the device theme as defined by the device implementer. Device implementations 845MAY modify the DeviceDefault theme attributes exposed to applications 846[<a href="#resources25">Resources, 25</a>].</p> 847 848<a name="section-3.8.6"></a><h4>3.8.6. Live Wallpapers</h4> 849<p>Android defines a component type and corresponding API and lifecycle that 850allows applications to expose one or more "Live Wallpapers" to the end user 851[<a href="#resources26">Resources, 26</a>]. Live Wallpapers are animations, 852patterns, or similar images with limited input capabilities that display as a 853wallpaper, behind other applications.</p> 854<p>Hardware is considered capable of reliably running live wallpapers if it 855can run all live wallpapers, with no limitations on functionality, at a 856reasonable framerate with no adverse affects on other applications. If 857limitations in the hardware cause wallpapers and/or applications to crash, 858malfunction, consume excessive CPU or battery power, or run at unacceptably 859low frame rates, the hardware is considered incapable of running live 860wallpaper. As an example, some live wallpapers may use an Open GL 1.0 or 2.0 861context to render their content. Live wallpaper will not run reliably on 862hardware that does not support multiple OpenGL contexts because the live 863wallpaper use of an OpenGL context may conflict with other applications that 864also use an OpenGL context.</p> 865<p>Device implementations capable of running live wallpapers reliably as 866described above SHOULD implement live wallpapers. Device implementations 867determined to not run live wallpapers reliably as described above MUST NOT 868implement live wallpapers.</p> 869<a name="section-3.8.7"></a><h4>3.8.7. Recent Application Display</h4> 870<p>The upstream Android 4.0 source code includes a user interface for 871displaying recent applications using a thumbnail image of the application's 872graphical state at the moment the user last left the application. Device 873implementations MAY alter or eliminate this user interface; however, a future 874version of Android is planned to make more extensive use of this 875functionality. Device implementations are strongly encouraged to use the 876upstream Android 4.0 user interface (or a similar thumbnail-based interface) 877for recent applications, or else they may not be compatible with a future 878version of Android.</p> 879<a name="section-3.8.8"></a><h4>3.8.8. Input Management Settings</h4> 880<p>Android 4.0 includes support for Input Management Engines. The Android 4.0 881APIs allow custom app IMEs to specify user-tunable settings. Device 882implementations MUST include a way for the user to access IME settings at all 883times when an IME that provides such user settings is displayed.</p> 884 885<a name="section-3.9"></a><h3>3.9 Device Administration</h3> 886<p>Android 4.0 includes features that allow security-aware applications 887to perform device administration functions at the system level, such as enforcing 888password policies or performing remote wipe, through the Android Device 889Administration API [<a href="#resources27">Resources, 27</a>]. Device 890implementations MUST provide an implementation of the <code>DevicePolicyManager 891</code> class [<a href="#resources28">Resources, 28</a>], and SHOULD support 892the full range of device administration policies defined in the Android SDK 893documentation [<a href="#resources27">Resources, 27</a>].</p> 894 895<p>If device implementations do not support the full range of device administration 896policies, they MUST NOT allow device administration applications to be enabled. 897Specifically, if a device does not support all device administration policies, 898the device implementation MUST respond to the 899<code>android.app.admin.DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN</code> intent, 900but MUST dislpay a message notifying the user that the device does not support 901device administration.</p> 902 903<a name="section-3.10"></a><h3>3.10 Accessibility</h3> 904<p>Android 4.0 provides an accessibility layer that helps users with disabilities 905to navigate their devices more easily. In addition, Android 4.0 provides 906platform APIs that enable accessibility service implementations to receive 907callbacks for user and system events and generate alternate feedback mechanisms, 908such as text-to-speech, haptic feedback, and trackball/d-pad navigation 909[<a href="#resources29">Resources, 29</a>]. Device implementations MUST provide an 910implementation of the Android accessibility framework consistent with the 911default Android implementation. Specifically, device implementations MUST meet 912the following requirements.</p> 913<ul> 914 <li>Device implementations MUST support third party accessibility service 915 implementations through the <code>android.accessibilityservice</code> 916 APIs [<a href="#resources30">Resources, 30</a>].</li> 917 <li>Device implementations MUST generate <code>AccessibilityEvent</code>s 918 and deliver these events to all registered <code>AccessibilityService 919 </code> implementations in a manner consistent with the default Android 920 implementation.</li> 921 <li>Device implementations MUST provide a user-accessible mechanism to enable 922 and disable accessibility services, and MUST display this interface in 923 response to the 924 <code>android.provider.Settings.ACTION_ACCESSIBILITY_SETTINGS</code> 925 intent.</li> 926</ul> 927<p>Additionally, device implementations SHOULD provide an implementation 928of an accessibility service on the device, and SHOULD provide a mechanism 929for users to enable the accessibility service during device setup. An open 930source implementation of an accessibility service is available from the Eyes 931Free project [<a href="#resources31">Resources, 31</a>].</p> 932 933<a name="section-3.11"></a><h3>3.11 Text-to-Speech</h3> 934<p>Android 4.0 includes APIs that allow applications to make use of 935text-to-speech (TTS) services, and allows service providers to provide 936implementations of TTS services [<a href="#resources32">Resources, 32</a>]. 937Device implementations MUST meet these requirements related to the Android TTS 938framework:</p> 939<ul> 940 <li>Device implementations MUST support the Android TTS framework APIs and 941 SHOULD include a TTS engine supporting the languages available on the 942 device. Note that the upstream Android open source software includes a 943 full-featured TTS engine implementation.</li> 944 <li>Device implementations MUST support installation of third-party TTS 945 engines.</li> 946 <li>Device implementations MUST provide a user-accessible interface that allows 947 users to select a TTS engine for use at the system level.</li> 948</ul> 949 950<a name="section-4"></a><h2>4. Application Packaging Compatibility</h2> 951<p>Device implementations MUST install and run Android ".apk" files as 952generated by the "aapt" tool included in the official Android SDK [<a 953href="#resources33">Resources, 33</a>].</p> 954<p>Devices implementations MUST NOT extend either the .apk [<a 955href="#resources34">Resources, 34</a>], Android Manifest [<a 956href="#resources35">Resources, 35</a>], 957Dalvik bytecode [<a href="#resources17">Resources, 17</a>], or renderscript 958bytecode formats in such a way that would prevent those files from installing 959and running correctly on other compatible devices. Device implementers SHOULD 960use the reference upstream implementation of Dalvik, and the reference 961implementation's package management system.</p> 962 963<a name="section-5"></a><h2>5. Multimedia Compatibility</h2> 964<p>Device implementations MUST include at least one form of audio output, such as 965speakers, headphone jack, external speaker connection, etc.</p> 966<a name="section-5.1"></a><h3>5.1. Media Codecs</h3> 967<p>Device implementations MUST support the core media formats specified 968in the Android SDK documentation [<a href="#resources58">Resources, 58</a>] except 969where explicitly permitted in this document. Specifically, device implementations 970MUST support the media formats, encoders, decoders, file types and container 971formats defined in the tables below. All of these codecs are provided as 972software implementations in the preferred Android implementation from the Android 973Open Source Project.</p> 974 975<p><strong>Please note that neither Google nor the Open Handset Alliance make any 976representation that these codecs are unencumbered by third-party patents. 977Those intending to use this source code in hardware or software products are 978advised that implementations of this code, including in open source software 979or shareware, may require patent licenses from the relevant patent 980holders.</strong></p> 981 982<p>Note that these tables do not list specific bitrate requirements for 983most video codecs because current device hardware does not necessarily support 984bitrates that map exactly to the required bitrates specified by the relevant 985standards. Instead, device implementations SHOULD support the highest bitrate 986practical on the hardware, up to the limits defined by the specifications.</p> 987<div style="page-break-before: always;"></div> 988<table> 989<tbody> 990 991<tr> 992<th>Type</th> 993<th>Format / Codec</th> 994<th>Encoder</th> 995<th>Decoder</th> 996<th>Details</th> 997<th>File Type(s) / Container Formats</th> 998</tr> 999 1000<tr> 1001<td rowspan="10">Audio</td> 1002<td>AAC LC/LTP</td> 1003<td style="text-align: center;">REQUIRED<br/> 1004<small>Required for device implementations that include microphone hardware 1005and define <code>android.hardware.microphone</code>.</small></td> 1006<td style="text-align: center;">REQUIRED</td> 1007<td rowspan="3">Mono/Stereo content in any combination of standard bit 1008rates up to 160 kbps and sampling rates from 8 to 48kHz</td> 1009<td rowspan="3"> 1010 <ul> 1011 <li>3GPP (.3gp)</li> 1012 <li>MPEG-4 (.mp4, .m4a)</li> 1013 <li>ADTS raw AAC (.aac, decode in Android 3.1+, encode in Android 4.0+, ADIF not supported)</li> 1014 <li>MPEG-TS (.ts, not seekable, Android 3.0+)</li> 1015 </ul> 1016</td> 1017</tr> 1018<tr> 1019<td>HE-AACv1 (AAC+)</td> 1020<td> </td> 1021<td style="text-align: center;">REQUIRED</td> 1022</tr> 1023 1024<tr> 1025<td>HE-AACv2 (enhanced AAC+)</td> 1026<td> </td> 1027<td style="text-align: center;">REQUIRED</td> 1028</tr> 1029 1030<tr> 1031<td>AMR-NB</td> 1032<td style="text-align: center;">REQUIRED<br/> 1033<small>Required for device implementations that include microphone hardware 1034and define <code>android.hardware.microphone</code>.</small></td> 1035<td style="text-align: center;">REQUIRED</td> 1036<td>4.75 to 12.2 kbps sampled @ 8kHz</td> 1037<td>3GPP (.3gp) 1038</td> 1039</tr> 1040 1041<tr> 1042<td>AMR-WB</td> 1043<td style="text-align: center;">REQUIRED<br/> 1044<small>Required for device implementations that include microphone hardware 1045and define <code>android.hardware.microphone</code>.</small></td> 1046<td style="text-align: center;">REQUIRED</td> 1047<td>9 rates from 6.60 kbit/s to 23.85 kbit/s sampled @ 16kHz</td> 1048<td>3GPP (.3gp)</td> 1049</tr> 1050 1051<tr> 1052<td>FLAC</td> 1053<td> </td> 1054<td style="text-align: center;">REQUIRED<br/><small>(Android 3.1+)</small></td> 1055<td>Mono/Stereo (no multichannel). Sample rates up to 48 kHz (but up to 44.1 1056kHz is recommended on devices with 44.1 kHz output, as the 48 to 44.1 kHz 1057downsampler does not include a low-pass filter). 16-bit recommended; 1058no dither applied for 24-bit. 1059</td> 1060<td>FLAC (.flac) only</td> 1061</tr> 1062 1063<tr> 1064<td>MP3</td> 1065<td> </td> 1066<td style="text-align: center;">REQUIRED</td> 1067<td>Mono/Stereo 8-320Kbps constant (CBR) or variable bit-rate (VBR) 1068</td> 1069<td>MP3 (.mp3)</td> 1070</tr> 1071 1072<tr> 1073<td>MIDI</td> 1074<td> </td> 1075<td style="text-align: center;">REQUIRED</td> 1076<td>MIDI Type 0 and 1. DLS Version 1 and 2. XMF and Mobile XMF. Support for ringtone formats RTTTL/RTX, OTA, and iMelody </td> 1077<td> 1078 <ul> 1079 <li>Type 0 and 1 (.mid, .xmf, .mxmf)</li> 1080 <li>RTTTL/RTX (.rtttl, .rtx)</li> 1081 <li>OTA (.ota)</li> 1082 <li>iMelody (.imy)</li> 1083 </ul> 1084</td> 1085</tr> 1086 1087<tr> 1088<td>Vorbis</td> 1089<td> </td> 1090<td style="text-align: center;">REQUIRED</td> 1091<td> </td> 1092<td> 1093 <ul> 1094 <li>Ogg (.ogg)</li> 1095 <li>Matroska (.mkv)</li> 1096 </ul> 1097</td> 1098</tr> 1099 1100<tr> 1101<td>PCM/WAVE</td> 1102<td> </td> 1103<td style="text-align: center;">REQUIRED</td> 1104<td>8- and 16-bit linear PCM (rates up to limit of hardware)</td> 1105<td>WAVE (.wav)</td> 1106</tr> 1107 1108<tr> 1109<td rowspan="5">Image</td> 1110<td>JPEG</td> 1111<td style="text-align: center;">REQUIRED</td> 1112<td style="text-align: center;">REQUIRED</td> 1113<td>Base+progressive</td> 1114<td>JPEG (.jpg)</td> 1115</tr> 1116 1117<tr> 1118<td>GIF</td> 1119<td> </td> 1120<td style="text-align: center;">REQUIRED</td> 1121<td> </td> 1122<td>GIF (.gif)</td> 1123</tr> 1124 1125<tr> 1126<td>PNG</td> 1127<td style="text-align: center;">REQUIRED</td> 1128<td style="text-align: center;">REQUIRED</td> 1129<td> </td> 1130<td>PNG (.png)</td> 1131</tr> 1132 1133<tr> 1134<td>BMP</td> 1135<td> </td> 1136<td style="text-align: center;">REQUIRED</td> 1137<td> </td> 1138<td>BMP (.bmp)</td> 1139</tr> 1140 1141 1142<tr> 1143<td>WEBP</td> 1144<td style="text-align: center;">REQUIRED</td> 1145<td style="text-align: center;">REQUIRED</td> 1146<td> </td> 1147<td>WebP (.webp)</td> 1148</tr> 1149 1150<tr> 1151<td rowspan="4">Video</td> 1152<td>H.263</td> 1153<td style="text-align: center;">REQUIRED<br/> 1154<small>Required for device implementations that include camera hardware 1155and define <code>android.hardware.camera</code> or 1156<code>android.hardware.camera.front</code>.</small></td> 1157<td style="text-align: center;">REQUIRED</td> 1158<td> </td> 1159<td> 1160 <ul> 1161 <li>3GPP (.3gp)</li> 1162 <li>MPEG-4 (.mp4)</li> 1163 </ul> 1164</td> 1165</tr> 1166 1167<tr> 1168<td>H.264 AVC</td> 1169<td style="text-align: center;">REQUIRED<br/> 1170<small>Required for device implementations that include camera hardware 1171and define <code>android.hardware.camera</code> or 1172<code>android.hardware.camera.front</code>.</small></td> 1173<td style="text-align: center;">REQUIRED</td> 1174<td>Baseline Profile (BP)</td> 1175<td> 1176 <ul> 1177 <li>3GPP (.3gp)</li> 1178 <li>MPEG-4 (.mp4)</li> 1179 <li>MPEG-TS (.ts, AAC audio only, not seekable, Android 3.0+)</li> 1180 </ul> 1181</td> 1182</tr> 1183 1184<tr> 1185<td>MPEG-4 SP</td> 1186<td> </td> 1187<td style="text-align: center;">REQUIRED</td> 1188<td> </td> 1189<td>3GPP (.3gp)</td> 1190</tr> 1191 1192<tr> 1193<td>VP8</td> 1194<td> </td> 1195<td style="text-align: center;">REQUIRED<br/><small>(Android 2.3.3+)</small></td> 1196<td> </td> 1197<td><a href="http://www.webmproject.org/">WebM</a> (.webm) and Matroska (.mkv, Android 4.0+)</td> 1198</tr> 1199 1200</tbody></table> 1201 1202<a name="section-5.2"></a><h3>5.2 Video Encoding</h3> 1203<p>Android device implementations that include a rear-facing camera and declare 1204<code>android.hardware.camera</code> SHOULD support the following video encoding 1205profiles.</p> 1206<table> 1207 <thead> 1208 <tr> 1209 <th> </th> 1210 <th>SD (Low quality)</th> 1211 <th>SD (High quality)</th> 1212 <th>HD (When supported by hardware)</th> 1213 </tr> 1214 </thead> 1215 <tbody> 1216 <tr> 1217 <th>Video codec</th> 1218 <td>H.264 Baseline Profile</td> 1219 <td>H.264 Baseline Profile</td> 1220 <td>H.264 Baseline Profile</td> 1221 </tr> 1222 <tr> 1223 <th>Video resolution</th> 1224 <td>176 x 144 px</td> 1225 <td>480 x 360 px</td> 1226 <td>1280 x 720 px</td> 1227 </tr> 1228 <tr> 1229 <th>Video frame rate</th> 1230 <td>12 fps</td> 1231 <td>30 fps</td> 1232 <td>30 fps</td> 1233 </tr> 1234 <tr> 1235 <th>Video bitrate</th> 1236 <td>56 Kbps</td> 1237 <td>500 Kbps or higher</td> 1238 <td>2 Mbps or higher</td> 1239 </tr> 1240 <tr> 1241 <th>Audio codec</th> 1242 <td>AAC-LC</td> 1243 <td>AAC-LC</td> 1244 <td>AAC-LC</td> 1245 </tr> 1246 <tr> 1247 <th>Audio channels</th> 1248 <td>1 (mono)</td> 1249 <td>2 (stereo)</td> 1250 <td>2 (stereo)</td> 1251 </tr> 1252 <tr> 1253 <th>Audio bitrate</th> 1254 <td>24 Kbps</td> 1255 <td>128 Kbps</td> 1256 <td>192 Kbps</td> 1257 </tr> 1258 </tbody> 1259</table> 1260 1261<a name="section-5.3"></a><h3>5.3. Audio Recording</h3> 1262<p>When an application has used the <code>android.media.AudioRecord</code> API to 1263start recording an audio stream, device implementations that include microphone 1264hardware and declare <code>android.hardware.microphone</code> MUST sample and 1265record audio with each of these behaviors:</p> 1266<ul> 1267<li>The device SHOULD exhibit approximately flat amplitude versus frequency 1268 characteristics; specifically, ±3 dB, from 100 Hz to 4000 Hz</li> 1269<li>Audio input sensitivity SHOULD be set such that a 90 dB sound power level 1270 (SPL) source at 1000 Hz yields RMS of 2500 for 16-bit samples.</li> 1271<li>PCM amplitude levels SHOULD linearly track input SPL changes over at least 1272 a 30 dB range from -18 dB to +12 dB re 90 dB SPL at the microphone.</li> 1273<li>Total harmonic distortion SHOULD be less than 1% from 100 Hz to 4000 Hz at 1274 90 dB SPL input level.</li> 1275</ul> 1276<p>In addition to the above recording specifications, when an application has 1277started recording an audio stream using the 1278<code>android.media.MediaRecorder.AudioSource.VOICE_RECOGNITION</code> audio 1279source:</p> 1280<ul> 1281<li>Noise reduction processing, if present, MUST be disabled.</li> 1282<li>Automatic gain control, if present, MUST be disabled.</li> 1283</ul> 1284<p><b>Note:</b> while some of the requirements outlined above are stated as "SHOULD" 1285for Android 4.0, the Compatibility Definition for a future version is planned 1286to change these to "MUST". That is, these requirements are optional in Android 12874.0 but <b>will be required</b> by a future version. Existing and new devices 1288that run Android 4.0 are <b>very strongly encouraged to meet 1289these requirements in Android 4.0</b>, or they will not be able to attain 1290Android compatibility when upgraded to the future version.</p> 1291 1292<a name="section-5.4"></a><h3>5.4. Audio Latency</h3> 1293<p>Audio latency is broadly defined as the interval between when an 1294application requests an audio playback or record operation, and when the 1295device implementation actually begins the operation. Many classes of 1296applications rely on short latencies, to achieve real-time effects such sound 1297effects or VOIP communication. Device implementations that include microphone 1298hardware and declare <code>android.hardware.microphone</code> SHOULD meet all 1299audio latency requirements outlined in this section. See <a href="#section-7"> 1300Section 7</a> for details on the conditions under which microphone hardware may 1301be omitted by device implementations.</p> 1302<p>For the purposes of this section:</p> 1303<ul> 1304<li>"cold output latency" is defined to be the interval between when an 1305 application requests audio playback and when sound begins playing, when 1306 the audio system has been idle and powered down prior to the request</li> 1307<li>"warm output latency" is defined to be the interval between when an 1308 application requests audio playback and when sound begins playing, when 1309 the audio system has been recently used but is currently idle (that is, 1310 silent)</li> 1311<li>"continuous output latency" is defined to be the interval between when an 1312 application issues a sample to be played and when the speaker physically 1313 plays the corresponding sound, while the device is currently playing back 1314 audio</li> 1315<li>"cold input latency" is defined to be the interval between when an 1316 application requests audio recording and when the first sample is 1317 delivered to the application via its callback, when the audio system and 1318 microphone has been idle and powered down prior to the request</li> 1319<li>"continuous input latency" is defined to be when an ambient sound occurs 1320 and when the sample corresponding to that sound is delivered to a 1321 recording application via its callback, while the device is in recording 1322 mode</li> 1323</ul> 1324<p>Using the above definitions, device implementations SHOULD exhibit each of 1325these properties:</p> 1326<ul> 1327<li>cold output latency of 100 milliseconds or less</li> 1328<li>warm output latency of 10 milliseconds or less</li> 1329<li>continuous output latency of 45 milliseconds or less</li> 1330<li>cold input latency of 100 milliseconds or less</li> 1331<li>continuous input latency of 50 milliseconds or less</li> 1332</ul> 1333<p><b>Note:</b> while the requirements outlined above are stated as "SHOULD" 1334for Android 4.0, the Compatibility Definition for a future version is planned 1335to change these to "MUST". That is, these requirements are optional in Android 13364.0 but <b>will be required</b> by a future version. Existing and new devices 1337that run Android 4.0 are <b>very strongly encouraged to meet 1338these requirements in Android 4.0</b>, or they will not be able to attain 1339Android compatibility when upgraded to the future version.</p> 1340<p>If a device implementation meets the requirements of this section, it MAY 1341report support for low-latency audio, by reporting the feature 1342"android.hardware.audio.low-latency" via the 1343<code>android.content.pm.PackageManager</code> class. [<a 1344href="#resources37">Resources, 37</a>] Conversely, if the device 1345implementation does not meet these requirements it MUST NOT report support for 1346low-latency audio.</p> 1347 1348<a name="section-5.5"></a><h3>5.5. Network Protocols</h3> 1349<p>Devices MUST support the media network protocols for audio and video playback 1350as specified in the Android SDK documentation 1351[<a href="#resources58">Resources, 58</a>]. Specifically, devices MUST support 1352the following media network protocols:</p> 1353<ul> 1354<li>RTSP (RTP, SDP)</li> 1355<li>HTTP(S) progressive streaming</li> 1356<li>HTTP(S) Live Streaming draft protocol, Version 3 [<a href="#resources59">Resources, 59</a>]</li> 1357</ul> 1358<a name="section-6"></a><h2>6. Developer Tool Compatibility</h2> 1359<p>Device implementations MUST support the Android Developer Tools provided in 1360the Android SDK. Specifically, Android-compatible devices MUST be compatible 1361with:</p> 1362<ul> 1363<li><b>Android Debug Bridge (known as adb)</b> [<a href="#resources33">Resources, 33</a>]<br/> 1364Device implementations MUST support all <code>adb</code> functions as 1365documented in the Android SDK. The device-side <code>adb</code> daemon MUST 1366be inactive by default, and there MUST be a user-accessible mechanism to turn 1367on the Android Debug Bridge.</li> 1368<li><b>Dalvik Debug Monitor Service (known as ddms)</b> [<a href="#resources33">Resources, 33</a>]<br/> 1369Device implementations MUST support all <code>ddms</code> features as documented in the 1370Android SDK. As <code>ddms</code> uses <code>adb</code>, support for 1371<code>ddms</code> SHOULD be inactive by default, 1372but MUST be supported whenever the user has activated the Android Debug 1373Bridge, as above.</li> 1374<li><b>Monkey</b> [<a href="#resources36">Resources, 36</a>]<br/> 1375Device implementations MUST include the Monkey framework, and make it 1376available for applications to use.</li> 1377</ul> 1378<p>Most Linux-based systems and Apple Macintosh systems recognize Android 1379devices using the standard Android SDK tools, without additional support; 1380however Microsoft Windows systems typically require a driver for new Android 1381devices. (For instance, new vendor IDs and sometimes new device IDs require 1382custom USB drivers for Windows systems.) If a device implementation is 1383unrecognized by the <code>adb</code> tool as provided in the standard Android 1384SDK, device implementers MUST provide Windows drivers allowing developers to 1385connect to the device using the <code>adb</code> protocol. These drivers MUST 1386be provided for Windows XP, Windows Vista, and Windows 7, in both 32-bit and 138764-bit versions.</p> 1388 1389<a name="section-7"></a><h2>7. Hardware Compatibility</h2> 1390<p>If a device includes a particular hardware component that has a 1391corresponding API for third-party developers, the device implementation MUST 1392implement that API as described in the Android SDK documentation. If an API in 1393the SDK interacts with a hardware component that is stated to be optional and 1394the device implementation does not possess that component:</p> 1395<ul> 1396<li>complete class definitions (as documented by the SDK) for the component's 1397APIs MUST still be present</li> 1398<li>the API's behaviors MUST be implemented as no-ops in some reasonable 1399fashion</li> 1400<li>API methods MUST return null values where permitted by the SDK 1401documentation</li> 1402<li>API methods MUST return no-op implementations of classes where null 1403values are not permitted by the SDK documentation</li> 1404<li>API methods MUST NOT throw exceptions not documented by the SDK 1405documentation</li> 1406</ul> 1407<p>A typical example of a scenario where these requirements apply is the 1408telephony API: even on non-phone devices, these APIs must be implemented as 1409reasonable no-ops.</p> 1410<p>Device implementations MUST accurately report accurate hardware configuration 1411information via the <code>getSystemAvailableFeatures()</code> and 1412<code>hasSystemFeature(String)</code> methods on the 1413<code>android.content.pm.PackageManager</code> class. [<a 1414href="#resources37">Resources, 37</a>]</p> 1415 1416<a name="section-7.1"></a><h3>7.1. Display and Graphics</h3> 1417<p>Android 4.0 includes facilities that automatically adjust application 1418assets and UI layouts appropriately for the device, to ensure that third-party 1419applications run well on a variety of hardware configurations [<a 1420href="#resources38">Resources, 38</a>]. Devices MUST properly implement these 1421APIs and behaviors, as detailed in this section.</p> 1422 1423<p>The units referenced by the requirements in this section are defined as follows:</p> 1424<ul> 1425<li>"Physical diagonal size" is the distance in inches between two opposing 1426corners of the illuminated portion of the display.</li> 1427<li>"dpi" (meaning "dots per inch") is the number of pixels encompassed by a 1428linear horizontal or vertical span of 1". Where dpi values are listed, both 1429horizontal and vertical dpi must fall within the range.</li> 1430<li>"Aspect ratio" is the ratio of the longer dimension of the screen to the 1431shorter dimension. For example, a display of 480x854 pixels would be 854 / 480 1432= 1.779, or roughly "16:9".</li> 1433<li>A "density-independent pixel" or ("dp") is the virtual pixel unit normalized to a 1434160 dpi screen, calculated as: 1435<code>pixels = dps * (density / 160)</code>.</li> 1436</ul> 1437 1438 1439<a name="section-7.1.1"></a><h4>7.1.1. Screen Configuration</h4> 1440 1441<p style="font-weight:bold;">Screen Size</p> 1442<p>The Android UI framework supports a variety of different screen sizes, and 1443allows applications to query the device screen size (aka "screen layout") via 1444<code>android.content.res.Configuration.screenLayout</code> with the 1445<code>SCREENLAYOUT_SIZE_MASK</code>. Device implementations MUST report the 1446correct screen size as defined in the Android SDK documentation 1447[<a href="#resources38">Resources, 38</a>] and determined by the upstream 1448Android platform. Specifically, device implementations must report the correct 1449screen size according to the following logical density-independent pixel (dp) 1450screen dimensions.</p> 1451<ul> 1452<li>Devices MUST have screen sizes of at least 426 dp x 320 dp ('small')</li> 1453<li>Devices that report screen size 'normal' MUST have screen sizes of at least 1454470 dp x 320 dp</li> 1455<li>Devices that report screen size 'large' MUST have screen sizes of at least 1456640 dp x 480 dp</li> 1457<li>Devices that report screen size 'xlarge' MUST have screen sizes of at least 1458960 dp x 720 dp</li> 1459</ul> 1460<p>In addition, devices MUST have screen sizes of at least 2.5 inches in 1461physical diagonal size.</p> 1462 1463<p>Devices MUST NOT change their reported screen size at any time.</p> 1464<p>Applications optionally indicate which screen sizes they support via the 1465<code><supports-screens></code> attribute in the AndroidManifest.xml 1466file. Device implementations MUST correctly honor applications' stated support 1467for small, normal, large, and xlarge screens, as described in the Android 1468SDK documentation.</p> 1469 1470<p style="font-weight:bold;">Screen Aspect Ratio</p> 1471<p>The aspect ratio MUST be between 1.3333 (4:3) and 1.85 (16:9).</p> 1472 1473<p style="font-weight:bold;">Screen Density</p> 1474<p>The Android UI framework defines a set of standard logical densities to 1475help application developers target application resources. Device 1476implementations MUST report one of the following logical Android framework 1477densities through the <code>android.util.DisplayMetrics</code> APIs, and MUST 1478execute applications at this standard density. 1479<ul> 1480<li>120 dpi, known as 'ldpi'</li> 1481<li>160 dpi, known as 'mdpi'</li> 1482<li>213 dpi, known as 'tvdpi'</li> 1483<li>240 dpi, known as 'hdpi'</li> 1484<li>320 dpi, known as 'xhdpi'</li> 1485</ul> 1486Device implementations SHOULD define the standard Android framework density 1487that is numerically closest to the physical density of the screen, unless that 1488logical density pushes the reported screen size below the minimum supported. 1489If the standard Android framework density that is numerically closest to the 1490physical density results in a screen size that is smaller than the smallest 1491supported compatible screen size (320 dp width), device implementations SHOULD 1492report the next lowest standard Android framework density.</p> 1493 1494<a name="section-7.1.2"></a><h4>7.1.2. Display Metrics</h4> 1495<p>Device implementations MUST report correct values for all display metrics 1496defined in <code>android.util.DisplayMetrics</code> [<a 1497href="#resources39">Resources, 39</a>].</p> 1498 1499<a name="section-7.1.3"></a><h4>7.1.3. Screen Orientation</h4> 1500<p>Devices MUST support dynamic orientation by applications to 1501either portrait or landscape screen orientation. That is, the device must 1502respect the application's request for a specific screen orientation. Device 1503implementations MAY select either portrait or landscape orientation as the 1504default.</p> 1505<p>Devices MUST report the correct value for the device's current orientation, 1506whenever queried via the android.content.res.Configuration.orientation, 1507android.view.Display.getOrientation(), or other APIs.</p> 1508<p>Devices MUST NOT change the reported screen size or density when changing 1509orientation.</p> 1510<p>Devices MUST report which screen orientations they support ( 1511<code>android.hardware.screen.portrait</code> and/or 1512<code>android.hardware.screen.landscape</code>) and MUST report at least one 1513supported orientation. For example, a device with a fixed-orientation 1514landscape screen, such as a television or laptop, MUST only report 1515<code>android.hardware.screen.landscape</code>.</p> 1516 1517<a name="section-7.1.4"></a><h4>7.1.4. 2D and 3D Graphics Acceleration</h4> 1518<p>Device implementations MUST support both OpenGL ES 1.0 and 2.0, as embodied 1519and detailed in the Android SDK documentations. Device implementations MUST 1520also support Android Renderscript, as detailed in the Android SDK 1521documentation [<a href="#resources08">Resources, 8</a>].</p> 1522<p>Device implementations MUST also correctly identify themselves as 1523supporting OpenGL ES 1.0 and 2.0. That is:</p> 1524<ul> 1525<li>The managed APIs (such as via the <code>GLES10.getString()</code> method) 1526MUST report support for OpenGL ES 1.0 and 2.0</li> 1527<li>The native C/C++ OpenGL APIs (that is, those available to apps via 1528libGLES_v1CM.so, libGLES_v2.so, or libEGL.so) MUST report support for 1529OpenGL ES 1.0 and 2.0.</li> 1530</ul> 1531<p>Device implementations MAY implement any desired OpenGL ES extensions. 1532However, device implementations MUST report via the OpenGL ES managed and 1533native APIs all extension strings that they do support, and conversely MUST 1534NOT report extension strings that they do not support.</p> 1535<p>Note that Android 4.0 includes support for applications to optionally 1536specify that they require specific OpenGL texture compression formats. These 1537formats are typically vendor-specific. Device implementations are not required 1538by Android 4.0 to implement any specific texture compression format. However, 1539they SHOULD accurately report any texture compression formats that they do 1540support, via the <code>getString()</code> method in the OpenGL API.</p> 1541 1542<p>Android 3.0 introduced a mechanism for applications to declare that they 1543wanted to enable hardware acceleration for 2D graphics at the Application, 1544Activity, Window or View level through the use of a manifest tag 1545<code>android:hardwareAccelerated</code> or direct API calls 1546[<a href="#resources09">Resources, 9</a>].</p> 1547<p>In Android 4.0, device implementations MUST enable hardware acceleration by 1548default, and MUST disable hardware acceleration if the developer so requests 1549by setting <code>android:hardwareAccelerated="false"</code> or disabling 1550hardware acceleration directly through the Android View APIs.</p> 1551<p>In addition, device implementations MUST exhibit behavior consistent with the 1552Android SDK documentation on hardware acceleration 1553[<a href="#resources09">Resources, 9</a>].</p> 1554<p>Android 4.0 includes a <code>TextureView</code> object that lets developers 1555directly integrate hardware-accelerated OpenGL ES textures as rendering targets 1556in a UI hierarchy. Device implementations MUST support the <code>TextureView 1557</code> API, and MUST exhibit consistent behavior with the upstream Android 1558implementation.</p> 1559 1560<a name="section-7.1.5"></a><h4>7.1.5. Legacy Application Compatibility Mode</h4> 1561<p>Android 4.0 specifies a "compatibility mode" in which the framework 1562operates in an 'normal' screen size equivalent (320dp width) mode for the benefit 1563of legacy applications not developed for old versions of Android that pre-date 1564screen-size independence. Device implementations MUST include support for legacy 1565application compatibility mode as implemented by the upstream Android open source 1566code. That is, device implementations MUST NOT alter the triggers or thresholds at 1567which compatibility mode is activated, and MUST NOT alter the behavior of the 1568compatibility mode itself.</p> 1569 1570<a name="section-7.1.6"></a><h4>7.1.6. Screen Types</h4> 1571<p>Device implementation screens are classified as one of two types:</p> 1572<ul> 1573<li>Fixed-pixel display implementations: the screen is a single panel that supports only a 1574single pixel width and height. Typically the screen is physically integrated with 1575the device. Examples include mobile phones, tablets, and so on.</li> 1576<li>Variable-pixel display implementations: the device implementation either has no 1577embedded screen and includes a video output port such as VGA or HDMI for 1578display, or has an embedded screen that can change pixel dimensions. Examples 1579include televisions, set-top boxes, and so on.</li> 1580</ul> 1581<p style="font-weight: bold;">Fixed-Pixel Device Implementations</p> 1582<p>Fixed-pixel device implementations MAY use screens of any pixel dimensions, provided 1583that they meet the requirements defined this Compatibility Definition.</p> 1584<p>Fixed-pixel implementations MAY include a video output port for use with an 1585external display. However, if that display is ever used for running apps, the 1586device MUST meet the following requirements:</p> 1587<ul> 1588<li>The device MUST report the same screen configuration and display metrics, as detailed 1589in Sections 7.1.1 and 7.1.2, as the fixed-pixel display.</li> 1590<li>The device MUST report the same logical density as the fixed-pixel display.</li> 1591<li>The device MUST report screen dimensions that are the same as, or very close to, 1592the fixed-pixel display.</li> 1593</ul> 1594<p>For example, a tablet that is 7" diagonal size with a 1024x600 pixel resolution is 1595considered a fixed-pixel large mdpi display implementation. If it contains a video 1596output port that displays at 720p or 1080p, the device implementation MUST scale the output so that 1597applications are only executed in a large mdpi window, regardless of whether the fixed-pixel display 1598or video output port is in use.</p> 1599 1600<p style="font-weight: bold;">Variable-Pixel Device Implementations</p> 1601<p>Variable-pixel device implementations MUST support one or both of 1280x720, 1602or 1920x1080 (that is, 720p or 1080p). Device implementations with 1603variable-pixel displays MUST NOT support any other screen configuration or 1604mode. Device implementations with variable-pixel screens MAY change screen 1605configuration or mode at runtime or boot-time. For example, a user of a 1606set-top box may replace a 720p display with a 1080p display, and the device 1607implementation may adjust accordingly.</p> 1608 1609<p>Additionally, variable-pixel device implementations MUST report the following 1610configuration buckets for these pixel dimensions:</p> 1611<ul> 1612<li>1280x720 (also known as 720p): 'large' screen size, 'tvdpi' (213 dpi) 1613density</li> 1614<li>1920x1080 (also known as 1080p): 'large' screen size, 'xhdpi' (320 dpi) 1615density</li> 1616</ul> 1617<p>For clarity, device implementations with variable pixel dimensions are 1618restricted to 720p or 1080p in Android 4.0, and MUST be configured to report 1619screen size and density buckets as noted above.</p> 1620 1621<a name="section-7.1.7"></a><h4>7.1.7. Screen Technology</h4> 1622<p>The Android platform includes APIs that allow applications to render rich 1623graphics to the display. Devices MUST support all of these APIs as defined by 1624the Android SDK unless specifically allowed in this document. Specifically:</p> 1625<ul> 1626<li>Devices MUST support displays capable of rendering 16-bit color graphics and 1627SHOULD support displays capable of 24-bit color graphics.</li> 1628<li>Devices MUST support displays capable of rendering animations.</li> 1629<li>The display technology used MUST have a pixel aspect ratio (PAR) between 1630 0.9 and 1.1. That is, the pixel aspect ratio MUST be near square (1.0) with 1631 a 10% tolerance.</li> 1632</ul> 1633 1634<a name="section-7.2"></a><h3>7.2. Input Devices</h3> 1635<a name="section-7.2.1"></a><h4>7.2.1. Keyboard</h4> 1636<p>Device implementations:</p> 1637<ul> 1638<li>MUST include support for the Input Management Framework (which allows third 1639party developers to create Input Management Engines - i.e. soft keyboard) as 1640detailed at <a href="http://developer.android.com">http://developer.android.com</a> 1641</li> 1642<li>MUST provide at least one soft keyboard implementation (regardless of whether 1643a hard keyboard is present)</li> 1644<li>MAY include additional soft keyboard implementations</li> 1645<li>MAY include a hardware keyboard</li> 1646<li>MUST NOT include a hardware keyboard that does not match one of the 1647formats specified in <code>android.content.res.Configuration.keyboard</code> 1648[<a href="#resources40">Resources, 40</a>] (that is, QWERTY, or 12-key)</li> 1649</ul> 1650<a name="section-7.2.2"></a><h4>7.2.2. Non-touch Navigation</h4> 1651<p>Device implementations:</p> 1652<ul> 1653<li>MAY omit a non-touch navigation option (that is, may omit a trackball, d-pad, 1654or wheel)</li> 1655<li>MUST report the correct value for 1656<code>android.content.res.Configuration.navigation</code> 1657[<a href="#resources40">Resources, 40</a>]</li> 1658<li>MUST provide a reasonable alternative user interface mechanism for the 1659selection and editing of text, compatible with Input Management Engines. The 1660upstream Android open source software includes a selection mechanism suitable 1661for use with devices that lack non-touch navigation inputs.</li> 1662</ul> 1663<a name="section-7.2.3"></a><h4>7.2.3. Navigation keys</h4> 1664<p>The Home, Menu and Back functions are essential to the Android navigation 1665paradigm. Device implementations MUST make these functions available to the 1666user at all times when running applications. These functions MAY be implemented 1667via dedicated physical buttons (such as mechanical or capacitive touch buttons), 1668or MAY be implemented using dedicated software keys, gestures, touch panel, etc. 1669Android 4.0 supports both implementations.</p> 1670 1671<p>Device implementations MAY use a distinct portion of the screen to display 1672the navigation keys, but if so, MUST meet these requirements:</p> 1673 1674<ul> 1675 <li>Device implementation navigation keys MUST use a distinct portion of the 1676 screen, not available to applications, and MUST NOT obscure or otherwise 1677 interfere with the portion of the screen available to applications.</li> 1678 <li>Device implementations MUST make available a portion of the display to 1679 applications that meets the requirements defined in 1680 <a href="section-7.1.1">Section 7.1.1</a>.</li> 1681 <li>Device implementations MUST display the navigation keys when applications 1682 do not specify a system UI mode, or specify 1683 <code>SYSTEM_UI_FLAG_VISIBLE</code>.</li> 1684 <li>Device implementations MUST present the navigation keys in an unobtrusive 1685 "low profile" (eg. dimmed) mode when applications specify 1686 <code>SYSTEM_UI_FLAG_LOW_PROFILE</code>.</li> 1687 <li>Device implementations MUST hide the navigation keys when applications 1688 specify <code>SYSTEM_UI_FLAG_HIDE_NAVIGATION</code>.</li> 1689 <li>Device implementation MUST present a Menu key to applications when 1690 targetSdkVersion <= 10 and SHOULD NOT present a Menu key when the 1691 targetSdkVersion > 10.</li> 1692</ul> 1693 1694<a name="section-7.2.4"></a><h4>7.2.4. Touchscreen input</h4> 1695<p>Device implementations:</p> 1696<ul> 1697<li>MUST have a pointer input system of some kind (either mouse-like, or touch)</li> 1698<li>MAY have a touchscreen of any modality (such as capacitive or resistive)</li> 1699<li>SHOULD support fully independently tracked pointers, if a touchscreen supports multiple pointers</li> 1700<li>MUST report the value of <code>android.content.res.Configuration.touchscreen</code> [<a href="#resources40">Resources, 40</a>] 1701corresponding to the type of the specific touchscreen on the device</li> 1702</ul> 1703 1704<p>Android 4.0 includes support for a variety of touch screens, touch pads, and fake touch input devices. 1705Touch screen based device implementations are associated with a display [<a href="#resources61">Resources, 61</a>] 1706such that the user has the impression of directly manipulating items on screen. Since the user is directly touching the screen, 1707the system does not require any additional affordances to indicate the objects being manipulated. 1708In contrast, a fake touch interface provides a user input system that approximates a subset of touchscreen capabilities. 1709For example, a mouse or remote control that drives an on-screen cursor approximates touch, but requires the user to first 1710point or focus then click. Numerous input devices like the mouse, trackpad, gyro-based air mouse, gyro-pointer, joystick, 1711and multi-touch trackpad can support fake touch interactions. Android 4.0 includes the feature constant <code>android.hardware.faketouch</code>, 1712which corresponds to a high-fidelity non-touch (that is, pointer-based) input device such as a mouse or trackpad that can adequately emulate touch-based 1713input (including basic gesture support), and indicates that the device supports an emulated subset of touchscreen 1714functionality. Device implementations that declare the fake touch feature MUST meet the fake touch requirements in <a href="section 7.2.5">Section 7.2.5</a>.</p> 1715 1716<p>Device implementations MUST report the correct feature corresponding to the type of input used. Device implementations that 1717include a touchscreen (single-touch or better) MUST also report the platform feature constant <code>android.hardware.faketouch</code>. 1718Device implementations that do not include a touchscreen (and rely on a pointer device only) MUST NOT report any touchscreen feature, and MUST report only 1719<code>android.hardware.faketouch</code> if they meet the fake touch requirements in <a href="section 7.2.5">Section 7.2.5</a>.</p> 1720 1721<a name="section-7.2.5"></a><h4>7.2.5. Fake touch input</h4> 1722<p>Device implementations that declare support for <code>android.hardware.faketouch</code></p> 1723<ul> 1724<li> MUST report the absolute X and Y screen positions of the pointer location and display a visual pointer on the screen[<a href="#resources60">Resources, 60</a>] </li> 1725<li> MUST report touch event with the action code [<a href="#resources60">Resources, 60</a>] that specifies the state change 1726that occurs on the pointer going <code>down</code> or <code>up</code> on the screen [<a href="#resources60">Resources, 60</a>] </li> 1727<li> MUST support pointer <code>down</code> and <code>up</code> on an object on the screen, which allows users to emulate tap on an object on the screen</li> 1728<li> MUST support pointer <code>down</code>, pointer <code>up</code>, pointer <code>down</code> then pointer <code>up</code> in the same place on an object on the screen 1729within a time threshold, which allows users to emulate double tap on an object on the screen [<a href="#resources60">Resources, 60</a>]</li> 1730<li>MUST support pointer <code>down</code> on an arbitrary point on the screen, pointer move to any other arbitrary point on the screen, 1731followed by a pointer <code>up</code>, which allows users to emulate a touch drag</li> 1732<li> MUST support pointer <code>down</code> then allow users to quickly move the object to a different position on the screen 1733and then pointer <code>up</code> on the screen, which allows users to fling an object on the screen</li> 1734</ul> 1735 1736<p>Devices that declare support for <code>android.hardware.faketouch.multitouch.distinct</code> MUST meet the requirements for 1737faketouch above, and MUST also support distinct tracking of two or more independent pointer inputs.</p> 1738 1739<a name="section-7.2.6"></a><h4>7.2.6. Microphone</h4> 1740<p>Device implementations MAY omit a microphone. However, if a device 1741implementation omits a microphone, it MUST NOT report the 1742<code>android.hardware.microphone</code> feature constant, and must implement 1743the audio recording API as no-ops, per <a href="section-7">Section 7</a>. 1744Conversely, device implementations that do possess a microphone:</p> 1745<ul> 1746<li>MUST report the <code>android.hardware.microphone</code> feature 1747constant</li> 1748<li>SHOULD meet the audio quality requirements in <a 1749href="section-5.3">Section 5.3</a></li> 1750<li>SHOULD meet the audio latency requirements in <a 1751href="section-5.4">Section 5.4</a></li> 1752</ul> 1753 1754<a name="section-7.3"></a><h3>7.3. Sensors</h3> 1755<p>Android 4.0 includes APIs for accessing a variety of sensor types. Devices 1756implementations generally MAY omit these sensors, as provided for in the 1757following subsections. If a device includes a particular sensor type that has a 1758corresponding API for third-party developers, the device implementation MUST 1759implement that API as described in the Android SDK documentation. For example, 1760device implementations:</p> 1761<ul> 1762<li>MUST accurately report the presence or absence of sensors per the 1763<code>android.content.pm.PackageManager</code> class. [<a 1764href="#resources37">Resources, 37</a>]</li> 1765<li>MUST return an accurate list of supported sensors via the 1766<code>SensorManager.getSensorList()</code> and similar methods</li> 1767<li>MUST behave reasonably for all other sensor APIs (for example, by 1768returning true or false as appropriate when applications attempt to register 1769listeners, not calling sensor listeners when the corresponding sensors are not 1770present; etc.)</li> 1771<li>MUST report all sensor measurements using the relevant International System 1772of Units (i.e. metric) values for each sensor type as defined in the Android SDK 1773documentation [<a href="#resources41">Resources, 41</a>]</li> 1774</ul> 1775<p>The list above is not comprehensive; the documented behavior of the Android 1776SDK is to be considered authoritative.</p> 1777<p>Some sensor types are synthetic, meaning they can be derived from data 1778provided by one or more other sensors. (Examples include the orientation 1779sensor, and the linear acceleration sensor.) Device implementations SHOULD 1780implement these sensor types, when they include the prerequisite physical 1781sensors.</p> 1782<p>The Android 4.0 APIs introduce a notion of a "streaming" sensor, which is 1783one that returns data continuously, rather than only when the data changes. 1784Device implementations MUST continuously provide periodic data samples for any 1785API indicated by the Android 4.0 SDK documentation to be a streaming 1786sensor.</p> 1787<a name="section-7.3.1"></a><h4>7.3.1. Accelerometer</h4> 1788<p>Device implementations SHOULD include a 3-axis accelerometer. If a device 1789implementation does include a 3-axis accelerometer, it:</p> 1790<ul> 1791<li>MUST be able to deliver events at 50 Hz or greater</li> 1792<li>MUST comply with the Android sensor coordinate system as detailed 1793in the Android APIs (see [<a href="#resources41">Resources, 41</a>])</li> 1794<li>MUST be capable of measuring from freefall up to twice gravity (2g) or 1795more on any three-dimensional vector</li> 1796<li>MUST have 8-bits of accuracy or more</li> 1797<li>MUST have a standard deviation no greater than 0.05 m/s^2</li> 1798</ul> 1799<a name="section-7.3.2"></a><h4>7.3.2. Magnetometer</h4> 1800<p>Device implementations SHOULD include a 3-axis magnetometer (i.e. compass.) 1801If a device does include a 3-axis magnetometer, it:</p> 1802<ul> 1803<li>MUST be able to deliver events at 10 Hz or greater</li> 1804<li>MUST comply with the Android sensor coordinate system as detailed 1805in the Android APIs (see [<a href="#resources41">Resources, 41</a>]).</li> 1806<li>MUST be capable of sampling a range of field strengths adequate to cover the 1807geomagnetic field</li> 1808<li>MUST have 8-bits of accuracy or more</li> 1809<li>MUST have a standard deviation no greater than 0.5 µT</li> 1810</ul> 1811<a name="section-7.3.3"></a><h4>7.3.3. GPS</h4> 1812<p>Device implementations SHOULD include a GPS receiver. If a device 1813implementation does include a GPS receiver, it SHOULD include 1814some form of "assisted GPS" technique to minimize GPS lock-on time.</p> 1815<a name="section-7.3.4"></a><h4>7.3.4. Gyroscope</h4> 1816<p>Device implementations SHOULD include a gyroscope (i.e. angular change 1817sensor.) Devices SHOULD NOT include a gyroscope sensor unless a 3-axis 1818accelerometer is also included. If a device implementation includes a 1819gyroscope, it:</p> 1820<ul> 1821<li>MUST be temperature compensated</li> 1822<li>MUST be capable of measuring orientation changes up to 5.5*Pi 1823radians/second (that is, approximately 1,000 degrees per second)</li> 1824<li>MUST be able to deliver events at 100 Hz or greater</li> 1825<li>MUST have 12-bits of accuracy or more</li> 1826<li>MUST have a variance no greater than 1e-7 rad^2 / s^2 per Hz (variance per Hz, or rad^2 / s). 1827The variance is allowed to vary with the sampling rate, but must be constrained by this value. 1828In other words, if you measure the variance of the gyro at 1 Hz sampling rate it should be no 1829greater than 1e-7 rad^2/s^2. </li> 1830<li>MUST have timestamps as close to when the hardware event happened as possible. The constant latency must be removed.</li> 1831</ul> 1832<a name="section-7.3.5"></a><h4>7.3.5. Barometer</h4> 1833<p>Device implementations MAY include a barometer (i.e. ambient air pressure 1834sensor.) If a device implementation includes a barometer, it:</p> 1835<ul> 1836<li>MUST be able to deliver events at 5 Hz or greater</li> 1837<li>MUST have adequate precision to enable estimating altitude</li> 1838</ul> 1839<a name="section-7.3.6"></a><h4>7.3.7. Thermometer</h4> 1840<p>Device implementations MAY but SHOULD NOT include a thermometer (i.e. 1841temperature sensor.) If a device implementation does include a thermometer, it 1842MUST measure the temperature of the device CPU. It MUST NOT measure any other 1843temperature. (Note that this sensor type is deprecated in the Android 4.0 1844APIs.)</p> 1845<a name="section-7.3.7"></a><h4>7.3.7. Photometer</h4> 1846<p>Device implementations MAY include a photometer (i.e. ambient light 1847sensor.)</p> 1848<a name="section-7.3.8"></a><h4>7.3.8. Proximity Sensor</h4> 1849<p>Device implementations MAY include a proximity sensor. If a device 1850implementation does include a proximity sensor, it MUST measure the proximity 1851of an object in the same direction as the screen. That is, the proximity 1852sensor MUST be oriented to detect objects close to the screen, as the 1853primary intent of this sensor type is to detect a phone in use by the 1854user. If a device implementation includes a proximity sensor with any other 1855orientation, it MUST NOT be accessible through this API. If a device 1856implementation has a proximity sensor, it MUST be have 1-bit of accuracy or 1857more.</p> 1858 1859<a name="section-7.4"></a><h3>7.4. Data Connectivity</h3> 1860<a name="section-7.4.1"></a><h4>7.4.1. Telephony</h4> 1861<p>"Telephony" as used by the Android 4.0 APIs and this document refers 1862specifically to hardware related to placing voice calls and sending SMS 1863messages via a GSM or CDMA network. While these voice calls may or may not be 1864packet-switched, they are for the purposes of Android 4.0 considered 1865independent of any data connectivity that may be implemented using the same 1866network. In other words, the Android "telephony" functionality and APIs refer 1867specifically to voice calls and SMS; for instance, device implementations that 1868cannot place calls or send/receive SMS messages MUST NOT report the 1869"android.hardware.telephony" feature or any sub-features, regardless of 1870whether they use a cellular network for data connectivity.</p> 1871<p>Android 4.0 MAY be used on devices that do not include telephony hardware. 1872That is, Android 4.0 is compatible with devices that are not phones. 1873However, if a device implementation does include GSM or CDMA telephony, it 1874MUST implement full support for the API for that technology. Device 1875implementations that do not include telephony hardware MUST implement the full 1876APIs as no-ops.</p> 1877<a name="section-7.4.2"></a><h4>7.4.2. IEEE 802.11 (WiFi)</h4> 1878<p>Android 4.0 device implementations SHOULD include support for one or more 1879forms of 802.11 (b/g/a/n, etc.) If a device implementation does include 1880support for 802.11, it MUST implement the corresponding Android API.</p> 1881<a name="section-7.4.3"></a><h4>7.4.3. Bluetooth</h4> 1882<p>Device implementations SHOULD include a Bluetooth transceiver. Device 1883implementations that do include a Bluetooth transceiver MUST enable the 1884RFCOMM-based Bluetooth API as described in the SDK documentation [<a 1885href="#resources42">Resources, 42</a>]. Device implementations SHOULD 1886implement relevant Bluetooth profiles, such as A2DP, AVRCP, OBEX, etc. as 1887appropriate for the device.</p> 1888<p>The Compatibility Test Suite includes cases that cover basic operation of 1889the Android RFCOMM Bluetooth API. However, since Bluetooth is a communications 1890protocol between devices, it cannot be fully tested by unit tests running on a 1891single device. Consequently, device implementations MUST also pass the 1892human-driven Bluetooth test procedure described in Appendix A.</p> 1893<a name="section-7.4.4"></a><h4>7.4.4. Near-Field Communications</h4> 1894<p>Device implementations SHOULD include a transceiver and related hardware 1895for Near-Field Communications (NFC). If a device implementation does include 1896NFC hardware, then it:</p> 1897<ul> 1898 <li>MUST report the android.hardware.nfc feature from the 1899 <code>android.content.pm.PackageManager.hasSystemFeature()</code> method. 1900 [<a href="#resources37">Resources, 37</a>]</li> 1901 <li>MUST be capable of reading and writing NDEF messages via the following NFC 1902 standards: 1903 <ul> 1904 <li>MUST be capable of acting as an NFC Forum reader/writer 1905 (as defined by the NFC Forum technical specification 1906 NFCForum-TS-DigitalProtocol-1.0) via the following NFC standards: 1907 <ul> 1908 <li>NfcA (ISO14443-3A)</li> 1909 <li>NfcB (ISO14443-3B) </li> 1910 <li>NfcF (JIS 6319-4)</li> 1911 <li>IsoDep (ISO 14443-4)</li> 1912 <li>NFC Forum Tag Types 1, 2, 3, 4 (defined by the NFC Forum)</li> 1913 </ul> 1914 </li> 1915 </ul> 1916 </li> 1917 <li>SHOULD be capable of reading and writing NDEF messages via the following 1918 NFC standards. Note that while the NFC standards below are stated as 1919 "SHOULD" for Android 4.0, the Compatibility Definition for a future 1920 version is planned to change these to "MUST". That is, these stanards are 1921 optional in Android 4.0 but <b>will be required</b> in future versions. 1922 Existing and new devices that run Android 4.0 are <b>very strongly 1923 encouraged to meet these requirements in Android 4.0</b> so they will be 1924 able to upgrade to the future platform releases. 1925 <ul> 1926 <li>NfcV (ISO 15693)</li> 1927 </ul> 1928 </li> 1929 <li>MUST be capable of transmitting and receiving data via the following 1930 peer-to-peer standards and protocols: 1931 <ul> 1932 <li>ISO 18092</li> 1933 <li>LLCP 1.0 (defined by the NFC Forum)</li> 1934 <li>SDP 1.0 (defined by the NFC Forum)</li> 1935 <li>NDEF Push Protocol [<a href="#resources43">Resources, 43</a>]</li> 1936 <li>SNEP 1.0 (defined by the NFC Forum)</li> 1937 </ul> 1938 </li> 1939 <li>MUST include support for Android Beam: 1940 <ul> 1941 <li>MUST implement the SNEP default server. Valid NDEF messages received 1942 by the default SNEP server MUST be dispatched to applications using 1943 the android.nfc.ACTION_NDEF_DISCOVERED intent. Disabling Android Beam 1944 in settings MUST NOT disable dispatch of incoming NDEF message.</li> 1945 <li>MUST implement the NPP server. Messages received by the NPP server MUST 1946 be processed the same way as the SNEP default server.</li> 1947 <li>MUST implement a SNEP client and attempt to send outbound P2P NDEF to 1948 the default SNEP server when Android Beam is enabled. If no default 1949 SNEP server is found then the client MUST attempt to send to an NPP 1950 server.</li> 1951 <li>MUST allow foreground activities to set the outbound P2P NDEF message 1952 using android.nfc.NfcAdapter.setNdefPushMessage, and 1953 android.nfc.NfcAdapter.setNdefPushMessageCallback, and 1954 android.nfc.NfcAdapter.enableForegroundNdefPush.</li> 1955 <li>SHOULD use a gesture or on-screen confirmation, such as 'Touch to Beam', 1956 before sending outbound P2P NDEF messages.</li> 1957 <li>SHOULD enable Android Beam by default</li> 1958 </ul> 1959 </li> 1960 <li>MUST poll for all supported technologies while in NFC discovery mode.</li> 1961 <li>SHOULD be in NFC discovery mode while the device is awake with the screen active 1962 and the lock-screen unlocked.</li> 1963</ul> 1964 1965<p>(Note that publicly available links are not available for the JIS, ISO, and 1966NFC Forum specifications cited above.)</p> 1967<p>Additionally, device implementations MAY include reader/writer support for 1968the following MIFARE technologies.</p> 1969<ul> 1970 <li>MIFARE Classic (NXP MF1S503x [<a href="#resources44">Resources, 44</a>], 1971 MF1S703x [<a href="#resources44">Resources, 44</a>])</li> 1972 <li>MIFARE Ultralight (NXP MF0ICU1 [<a href="#resources46">Resources, 46</a>], 1973 MF0ICU2 [<a href="#resources46">Resources, 46</a>])</li> 1974 <li>NDEF on MIFARE Classic (NXP AN130511 [<a href="#resources48">Resources, 48</a>], 1975 AN130411 [<a href="#resources49">Resources, 49</a>])</li> 1976</ul> 1977<p>Note that Android 4.0 includes APIs for these MIFARE types. If a 1978device implementation supports MIFARE in the reader/writer role, it:</p> 1979<ul> 1980 <li>MUST implement the corresponding Android APIs as documented by the 1981 Android SDK</li> 1982 <li>MUST report the feature com.nxp.mifare from the 1983 <code>android.content.pm.PackageManager.hasSystemFeature()</code> method. 1984 [<a href="#resources37">Resources, 37</a>] Note that this is not a standard 1985 Android feature, and as such does not appear as a constant on the 1986 <code>PackageManager</code> class.</li> 1987 <li>MUST NOT implement the corresponding Android APIs nor report the 1988 com.nxp.mifare feature unless it also implements general NFC support as 1989 described in this section</li> 1990</ul> 1991<p>If a device implementation does not include NFC hardware, it MUST NOT 1992declare the android.hardware.nfc feature from the 1993<code>android.content.pm.PackageManager.hasSystemFeature()</code> method [<a 1994href="#resources37">Resources, 37</a>], and MUST implement the Android 4.0 NFC 1995API as a no-op.</p> 1996<p>As the classes <code>android.nfc.NdefMessage</code> and 1997<code>android.nfc.NdefRecord</code> represent a protocol-independent data 1998representation format, device implementations MUST implement these APIs even 1999if they do not include support for NFC or declare the android.hardware.nfc 2000feature.</p> 2001<a name="section-7.4.5"></a><h4>7.4.5. Minimum Network Capability</h4> 2002<p>Device implementations MUST include support for one or more forms of data 2003networking. Specifically, device implementations MUST include support for at 2004least one data standard capable of 200Kbit/sec or greater. Examples of 2005technologies that satisfy this requirement include EDGE, HSPA, EV-DO, 802.11g, 2006Ethernet, etc.</p> 2007<p>Device implementations where a physical networking standard (such as 2008Ethernet) is the primary data connection SHOULD also include support for at 2009least one common wireless data standard, such as 802.11 (WiFi).</p> 2010<p>Devices MAY implement more than one form of data connectivity.</p> 2011 2012 2013<a name="section-7.5"></a><h3>7.5. Cameras</h3> 2014<p>Device implementations SHOULD include a rear-facing camera, and MAY include 2015a front-facing camera. A rear-facing camera is a camera located on the side of 2016the device opposite the display; that is, it images scenes on the far side of 2017the device, like a traditional camera. A front-facing camera is a camera 2018located on the same side of the device as the display; that is, a camera 2019typically used to image the user, such as for video conferencing and similar 2020applications.</p> 2021<a name="section-7.5.1"></a><h4>7.5.1. Rear-Facing Camera</h4> 2022<p>Device implementations SHOULD include a rear-facing camera. If a device 2023implementation includes a rear-facing camera, it:</p> 2024<ul> 2025<li>MUST have a resolution of at least 2 megapixels</li> 2026<li>SHOULD have either hardware auto-focus, or software auto-focus implemented 2027in the camera driver (transparent to application software)</li> 2028<li>MAY have fixed-focus or EDOF (extended depth of field) hardware</li> 2029<li>MAY include a flash. If the Camera includes a flash, the flash lamp MUST 2030NOT be lit while an android.hardware.Camera.PreviewCallback instance has been 2031registered on a Camera preview surface, unless the application has explicitly 2032enabled the flash by enabling the <code>FLASH_MODE_AUTO</code> or 2033<code>FLASH_MODE_ON</code> attributes of a <code>Camera.Parameters</code> 2034object. Note that this constraint does not apply to the device's built-in 2035system camera application, but only to third-party applications using 2036<code>Camera.PreviewCallback</code>.</li> 2037</ul> 2038<a name="section-7.5.2"></a><h4>7.5.2. Front-Facing Camera</h4> 2039<p>Device implementations MAY include a front-facing camera. If a device 2040implementation includes a front-facing camera, it:</p> 2041<ul> 2042<li>MUST have a resolution of at least VGA (that is, 640x480 pixels)</li> 2043<li>MUST NOT use a front-facing camera as the default for the Camera API. 2044That is, the camera API in Android 4.0 has specific support for front-facing 2045cameras, and device implementations MUST NOT configure the API to to treat a 2046front-facing camera as the default rear-facing camera, even if it is the only 2047camera on the device.</li> 2048<li>MAY include features (such as auto-focus, flash, etc.) 2049available to rear-facing cameras as described in Section 7.5.1.</li> 2050<li>MUST horizontally reflect (i.e. mirror) the stream displayed by an app in a 2051CameraPreview, as follows:</li> 2052<ul> 2053<li>If the device implementation is capable of being rotated by user (such as 2054automatically via an accelerometer or manually via user input), the camera 2055preview MUST be mirrored horizontally relative to the device's current 2056orientation.</li> 2057<li>If the current application has explicitly requested that the Camera 2058display be rotated via a call to the 2059<code>android.hardware.Camera.setDisplayOrientation()</code> [<a 2060href="#resources50">Resources, 50</a>] method, the camera preview MUST be 2061mirrored horizontally relative to the orientation specified by the 2062application.</li> 2063<li>Otherwise, the preview MUST be mirrored along the device's default horizontal axis.</li> 2064</ul> 2065<li>MUST mirror the image displayed by the postview in the same manner as 2066the camera preview image stream. (If the device implementation does not 2067support postview, this requirement obviously does not apply.)</li> 2068<li>MUST NOT mirror the final captured still image or video streams returned 2069to application callbacks or committed to media storage</li> 2070</ul> 2071<a name="section-7.5.3"></a><h4>7.5.3. Camera API Behavior</h4> 2072<p>Device implementations MUST implement the following behaviors for the 2073camera-related APIs, for both front- and rear-facing cameras:</p> 2074<ol> 2075<li>If an application has never called 2076<code>android.hardware.Camera.Parameters.setPreviewFormat(int)</code>, then the 2077device MUST use <code>android.hardware.PixelFormat.YCbCr_420_SP</code> for 2078preview data provided to application callbacks.</li> 2079<li>If an application registers an <code>android.hardware.Camera.PreviewCallback 2080</code> instance and the system calls the <code>onPreviewFrame()</code> method 2081when the preview format is YCbCr_420_SP, the data in the <code>byte[]</code> 2082passed into <code>onPreviewFrame()</code> must further be in the NV21 encoding 2083format. That is, NV21 MUST be the default.</li> 2084<li>Device implementations MUST support the YV12 format (as denoted by the 2085<code>android.graphics.ImageFormat.YV12</code> constant) for camera previews 2086for both front- and rear-facing cameras. (The hardware video decoder and camera 2087may use any native pixel format, but the device implementation MUST support conversion 2088to YV12.)</li> 2089</ol> 2090<p>Device implementations MUST implement the full Camera API included in the 2091Android 4.0 SDK documentation [<a href="#resources51">Resources, 51</a>]), 2092regardless of whether the device includes hardware autofocus or other 2093capabilities. For instance, cameras that lack autofocus MUST still call any 2094registered <code>android.hardware.Camera.AutoFocusCallback</code> instances (even though 2095this has no relevance to a non-autofocus camera.) Note that this does apply 2096to front-facing cameras; for instance, even though most front-facing cameras 2097do not support autofocus, the API callbacks must still be "faked" as 2098described.</p> 2099<p>Device implementations MUST recognize and honor each parameter name defined 2100as a constant on the <code>android.hardware.Camera.Parameters</code> class, if the 2101underlying hardware supports the feature. If the device hardware does not 2102support a feature, the API must behave as documented. Conversely, Device 2103implementations MUST NOT honor or recognize string constants passed 2104to the <code>android.hardware.Camera.setParameters()</code> method other than 2105those documented as constants on the 2106<code>android.hardware.Camera.Parameters</code>. That is, 2107device implementations MUST support all standard Camera parameters if the 2108hardware allows, and MUST NOT support custom Camera parameter types.</p> 2109<p>Device implementations MUST broadcast the <code>Camera.ACTION_NEW_PICTURE</code> 2110intent whenever a new picture is taken by the camera and the entry of the picture 2111has been added to the media store.</p> 2112<p>Device implementations MUST broadcast the <code>Camera.ACTION_NEW_VIDEO</code> 2113intent whenever a new video is recorded by the camera and the entry of the picture 2114has been added to the media store.</p> 2115<a name="section-7.5.4"></a><h4>7.5.4. Camera Orientation</h4> 2116<p>Both front- and rear-facing cameras, if present, MUST be oriented so that 2117the long dimension of the camera aligns with the screen's long dimention. That 2118is, when the device is held in the landscape orientation, cameras MUST 2119capture images in the landscape orientation. This applies regardless of the 2120device's natural orientation; that is, it applies to landscape-primary devices 2121as well as portrait-primary devices.</p> 2122 2123 2124<a name="section-7.6"></a><h3>7.6. Memory and Storage</h3> 2125<a name="section-7.6.1"></a><h4>7.6.1. Minimum Memory and Storage</h4> 2126<p>Device implementations MUST have at least 340MB of memory available to the 2127kernel and userspace. The 340MB MUST be in addition to any memory dedicated to 2128hardware components such as radio, video, and so on that is not under the 2129kernel's control.</p> 2130<p>Device implementations MUST have at least 350MB of non-volatile storage 2131available for application private data. That is, the <code>/data</code> partition MUST be at 2132least 350MB.</p> 2133<p>The Android APIs include a Download Manager that applications may use to 2134download data files [<a href="#resources56">Resources, 56</a>]. The device 2135implementation of the Download Manager MUST be capable of downloading individual 2136files of at least 100MB in size to the default "cache" location.</p> 2137<a name="section-7.6.2"></a><h4>7.6.2. Application Shared Storage</h4> 2138<p>Device implementations MUST offer shared storage for applications. The 2139shared storage provided MUST be at least 1GB in size.</p> 2140<p>Device implementations MUST be configured with shared storage mounted by 2141default, "out of the box". If the shared storage is not mounted on the Linux 2142path <code>/sdcard</code>, then the device MUST include a Linux symbolic link 2143from <code>/sdcard</code> to the actual mount point.</p> 2144<p>Device implementations MUST enforce as documented the 2145<code>android.permission.WRITE_EXTERNAL_STORAGE</code> permission on this 2146shared storage. Shared storage MUST otherwise be writable by any application 2147that obtains that permission.</p> 2148<p>Device implementations MAY have hardware for user-accessible removable 2149storage, such as a Secure Digital card. Alternatively, device implementations 2150MAY allocate internal (non-removable) storage as shared storage for apps.</p> 2151<p>Regardless of the form of shared storage used, device implementations MUST 2152provide some mechanism to access the contents of shared storage from a host 2153computer, such as USB mass storage (UMS) or Media Transfer Protocol (MTP). Device 2154implementations MAY use USB mass storage, but SHOULD use Media Transfer 2155Protocol. If the device implementation supports Media Transfer Protocol:</p> 2156<ul> 2157<li>The device implementation SHOULD be compatible with the reference Android 2158MTP host, Android File Transfer [<a href="#resources57">Resources, 57</a>].</li> 2159<li>The device implementation SHOULD report a USB device class of <code>0x00</code>.</li> 2160<li>The device implementation SHOULD report a USB interface name of 'MTP'.</li> 2161</ul> 2162<p>If the device implementation lacks USB ports, it MUST provide a host 2163computer with access to the contents of shared storage by some other means, 2164such as a network file system.</p> 2165<p>It is illustrative to consider two common examples. If a device 2166implementation includes an SD card slot to satisfy the shared storage 2167requirement, a FAT-formatted SD card 1GB in size or larger MUST be included 2168with the device as sold to users, and MUST be mounted by default. 2169Alternatively, if a device implementation uses internal fixed storage to 2170satisfy this requirement, that storage MUST be 1GB in size or larger 2171and mounted on <code>/sdcard</code> (or <code>/sdcard</code> 2172MUST be a symbolic link to the physical location if it is mounted elsewhere.)</p> 2173<p>Device implementations that include multiple shared storage paths (such as 2174both an SD card slot and shared internal storage) SHOULD modify the core 2175applications such as the media scanner and ContentProvider to transparently 2176support files placed in both locations.</p> 2177 2178<a name="section-7.7"></a><h3>7.7. USB</h3> 2179<p>Device implementations SHOULD include a USB client port, and SHOULD include 2180a USB host port.</p> 2181<p>If a device implementation includes a USB client port:</p> 2182<ul> 2183<li>the port MUST be connectable to a USB host with a standard USB-A port</li> 2184<li>the port SHOULD use the micro USB form factor on the device side</li> 2185<li>it MUST allow a host connected to the device to access the contents of the 2186shared storage volume using either USB mass storage or Media Transfer 2187Protocol</li> 2188<li>it MUST implement the Android Open Accessory API and specification as documented 2189in the Android SDK documentation, and MUST declare support for the hardware 2190feature <code>android.hardware.usb.accessory</code> [<a href="#resources52">Resources, 219151</a>]</li> 2192</ul> 2193 2194<p>If a device implementation includes a USB host port:</p> 2195<ul> 2196<li>it MAY use a non-standard port form factor, but if so MUST ship with a 2197cable or cables adapting the port to standard USB-A</li> 2198<li>it MUST implement the Android USB host API as documented in the Android 2199SDK, and MUST declare support for the hardware feature 2200<code>android.hardware.usb.host</code> [<a href="#resources53">Resources, 220152</a>]</li> 2202</ul> 2203<p>Device implementations MUST implement the Android Debug Bridge. If a device 2204implementation omits a USB client port, it MUST implement the Android Debug 2205Bridge via local-area network (such as Ethernet or 802.11)</p> 2206 2207<a name="section-8"></a><h2>8. Performance Compatibility</h2> 2208<p>Device implementations MUST meet the key performance metrics of an Android 22094.0 compatible device defined in the table below:</p> 2210<table><tbody><tr> 2211<td><b>Metric</b></td> 2212<td><b>Performance Threshold</b></td> 2213<td><b>Comments</b></td> 2214</tr> 2215<tr> 2216<td>Application Launch Time</td> 2217<td>The following applications should launch within the specified time.<ul> 2218<li>Browser: less than 1300ms</li> 2219<li>Contacts: less than 700ms</li> 2220<li>Settings: less than 700ms</li> 2221</ul></td> 2222<td>The launch time is measured as the total time to 2223complete loading the default activity for the application, including the time 2224it takes to start the Linux process, load the Android package into the Dalvik 2225VM, and call onCreate.</td> 2226</tr> 2227<tr> 2228<td>Simultaneous Applications</td> 2229<td>When multiple applications have been launched, re-launching an 2230already-running application after it has been launched must take less than the 2231original launch time.</td> 2232<td> </td> 2233</tr> 2234</tbody> 2235</table> 2236 2237<a name="section-9"></a><h2>9. Security Model Compatibility</h2> 2238<p>Device implementations MUST implement a security model consistent with the 2239Android platform security model as defined in Security and Permissions 2240reference document in the APIs [<a href="#resources54">Resources, 54</a>] in the 2241Android developer documentation. Device implementations MUST support 2242installation of self-signed applications without requiring any additional 2243permissions/certificates from any third parties/authorities. Specifically, 2244compatible devices MUST support the security mechanisms described in the 2245follow sub-sections.</p> 2246<a name="section-9.1"></a><h3>9.1. Permissions</h3> 2247<p>Device implementations MUST support the Android permissions model as 2248defined in the Android developer documentation [<a 2249href="#resources54">Resources, 54</a>]. Specifically, 2250implementations MUST enforce each permission defined as described in the SDK 2251documentation; no permissions may be omitted, altered, or ignored. 2252Implementations MAY add additional permissions, provided the new permission ID 2253strings are not in the android.* namespace.</p> 2254<a name="section-9.2"></a><h3>9.2. UID and Process Isolation</h3> 2255<p>Device implementations MUST support the Android application sandbox model, 2256in which each application runs as a unique Unix-style UID and in a separate 2257process. Device implementations MUST support running multiple applications as 2258the same Linux user ID, provided that the applications are properly signed and 2259constructed, as defined in the Security and Permissions reference [<a 2260href="#resources54">Resources, 54</a>].</p> 2261<a name="section-9.3"></a><h3>9.3. Filesystem Permissions</h3> 2262<p>Device implementations MUST support the Android file access permissions 2263model as defined in as defined in the Security and Permissions reference [<a 2264href="#resources54">Resources, 54</a>].</p> 2265<a name="section-9.4"></a><h3>9.4. Alternate Execution Environments</h3> 2266<p>Device implementations MAY include runtime environments that execute 2267applications using some other software or technology than the Dalvik virtual 2268machine or native code. However, such alternate execution environments MUST 2269NOT compromise the Android security model or the security of installed Android 2270applications, as described in this section.</p> 2271<p>Alternate runtimes MUST themselves be Android applications, and abide by 2272 the standard Android security model, as described elsewhere in Section 9.</p> 2273<p>Alternate runtimes MUST NOT be granted access to resources protected by 2274 permissions not requested in the runtime's AndroidManifest.xml file via the 2275 <code><uses-permission></code> mechanism.</p> 2276<p>Alternate runtimes MUST NOT permit applications to make use of features 2277 protected by Android permissions restricted to system applications.</p> 2278<p>Alternate runtimes MUST abide by the Android sandbox model. Specifically:</p> 2279<ul> 2280<li>Alternate runtimes SHOULD install apps via the PackageManager into 2281 separate Android sandboxes (that is, Linux user IDs, etc.)</li> 2282<li>Alternate runtimes MAY provide a single Android sandbox shared by all 2283 applications using the alternate runtime.</li> 2284<li>Alternate runtimes and installed applications using an alternate runtime 2285 MUST NOT reuse the sandbox of any other app installed on the device, except 2286 through the standard Android mechanisms of shared user ID and signing 2287 certificate</li> 2288<li>Alternate runtimes MUST NOT launch with, grant, or be granted access to 2289 the sandboxes corresponding to other Android applications.</li> 2290</ul> 2291<p>Alternate runtimes MUST NOT be launched with, be granted, or grant to other 2292 applications any privileges of the superuser (root), or of any other user ID.</p> 2293<p>The .apk files of alternate runtimes MAY be included in the system image of 2294 a device implementation, but MUST be signed with a key distinct 2295 from the key used to sign other applications included with the device 2296 implementation.</p> 2297<p>When installing applications, alternate runtimes MUST obtain user consent 2298 for the Android permissions used by the application. That is, if an 2299 application needs to make use of a device resource for which there is a 2300 corresponding Android permission (such as Camera, GPS, etc.), the alternate 2301 runtime MUST inform the user that the application will be able to access 2302 that resource. If the runtime environment does not record application 2303 capabilities in this manner, the runtime environment MUST list all 2304 permissions held by the runtime itself when installing any application 2305 using that runtime.</p> 2306 2307<a name="section-10"></a><h2>10. Software Compatibility Testing</h2> 2308<p>Device implementations MUST pass all tests described in this section.</p> 2309<p>However, note that no software test package is fully comprehensive. For 2310this reason, device implementers are very strongly encouraged to make the 2311minimum number of changes as possible to the reference and preferred 2312implementation of Android 4.0 available from the Android Open Source Project. 2313This will minimize the risk of introducing bugs that create incompatibilities 2314requiring rework and potential device updates.</p> 2315<a name="section-10.1"></a><h3>10.1. Compatibility Test Suite</h3> 2316<p>Device implementations MUST pass the Android Compatibility Test Suite (CTS) 2317[<a href="#resources02">Resources, 2</a>] available from the Android Open Source 2318Project, using the final shipping software on the device. Additionally, device 2319implementers SHOULD use the reference implementation in the Android Open 2320Source tree as much as possible, and MUST ensure compatibility in cases of 2321ambiguity in CTS and for any reimplementations of parts of the reference 2322source code.</p> 2323<p>The CTS is designed to be run on an actual device. Like any software, the 2324CTS may itself contain bugs. The CTS will be versioned independently of this 2325Compatibility Definition, and multiple revisions of the CTS may be released 2326for Android 4.0. Device implementations MUST pass the latest CTS version 2327available at the time the device software is completed.</p> 2328<a name="section-10.2"></a><h3>10.2. CTS Verifier</h3> 2329<p>Device implementations MUST correctly execute all applicable cases in the 2330CTS Verifier. The CTS Verifier is included with the Compatibility Test Suite, 2331and is intended to be run by a human operator to test functionality that 2332cannot be tested by an automated system, such as correct functioning of a 2333camera and sensors.</p> 2334<p>The CTS Verifier has tests for many kinds of hardware, including some 2335hardware that is optional. Device implementations MUST pass all tests for 2336hardware which they possess; for instance, if a device possesses an 2337accelerometer, it MUST correctly execute the Accelerometer test case in the 2338CTS Verifier. Test cases for features noted as optional by this Compatibility 2339Definition Document MAY be skipped or omitted.</p> 2340<p>Every device and every build MUST correctly run the CTS Verifier, as noted 2341above. However, since many builds are very similar, device implementers are 2342not expected to explicitly run the CTS Verifier on builds that differ only in 2343trivial ways. Specifically, device implementations that differ from an 2344implementation that has passed the CTS Verfier only by the set of included 2345locales, branding, etc. MAY omit the CTS Verifier test.</p> 2346<a name="section-10.3"></a><h3>10.3. Reference Applications</h3> 2347<p>Device implementers MUST test implementation compatibility using the 2348following open source applications:</p> 2349<ul> 2350<li>The "Apps for Android" applications [<a href="#resources55">Resources, 55</a>].</li> 2351<li>Replica Island (available in Android Market)</li> 2352</ul> 2353<p>Each app above MUST launch and behave correctly on the implementation, for 2354the implementation to be considered compatible.</p> 2355 2356 2357<a name="section-11"></a><h2>11. Updatable Software</h2> 2358<p>Device implementations MUST include a mechanism to replace the entirety of 2359the system software. The mechanism need not perform "live" upgrades - that 2360is, a device restart MAY be required.</p> 2361<p>Any method can be used, provided that it can replace the entirety of the 2362software preinstalled on the device. For instance, any of the following 2363approaches will satisfy this requirement:</p> 2364<ul> 2365<li>Over-the-air (OTA) downloads with offline update via reboot</li> 2366<li>"Tethered" updates over USB from a host PC</li> 2367<li>"Offline" updates via a reboot and update from a file on removable 2368storage</li> 2369</ul> 2370<p>The update mechanism used MUST support updates without wiping user data. 2371That is, the update mechanism MUST preserve application private data 2372and application shared data. Note that the upstream Android software includes 2373an update mechanism that satisfies this requirement.</p> 2374<p>If an error is found in a device implementation after it has been released 2375but within its reasonable product lifetime that is determined in consultation 2376with the Android Compatibility Team to affect the compatibility of third-party 2377applications, the device implementer MUST correct the error via a software 2378update available that can be applied per the mechanism just described.</p> 2379 2380<a name="section-12"></a><h2>12. Contact Us</h2> 2381<p>You can contact the document authors at <a 2382href="mailto:compatibility@android.com">compatibility@android.com</a> for 2383clarifications and to bring up any issues that you think the document does not 2384cover.</p> 2385 2386<div style="page-break-before: always;"></div> 2387 2388<a name="appendix-A"></a><h2>Appendix A - Bluetooth Test Procedure</h2> 2389<p>The Compatibility Test Suite includes cases that cover basic operation of 2390the Android RFCOMM Bluetooth API. However, since Bluetooth is a communications 2391protocol between devices, it cannot be fully tested by unit tests running on a 2392single device. Consequently, device implementations MUST also pass the 2393human-operated Bluetooth test procedure described below.</p> 2394<p>The test procedure is based on the BluetoothChat sample app included in the 2395Android open source project tree. The procedure requires two devices:</p> 2396<ul> 2397<li>a candidate device implementation running the software build to be tested</li> 2398<li>a separate device implementation already known to be compatible, and of a 2399 model from the device implementation being tested - that is, a "known 2400 good" device implementation</li> 2401</ul> 2402<p>The test procedure below refers to these devices as the "candidate" and "known 2403good" devices, respectively.</p> 2404<h3>Setup and Installation</h3> 2405<ol> 2406<li>Build BluetoothChat.apk via 'make samples' from an Android source code tree.</li> 2407<li>Install BluetoothChat.apk on the known-good device.</li> 2408<li>Install BluetoothChat.apk on the candidate device.</li> 2409</ol> 2410<h3>Test Bluetooth Control by Apps</h3> 2411<ol> 2412<li>Launch BluetoothChat on the candidate device, while Bluetooth is disabled.</li> 2413<li>Verify that the candidate device either turns on Bluetooth, or prompts the user with a dialog to turn on Bluetooth.</li> 2414</ol> 2415<h3>Test Pairing and Communication</h3> 2416<ol> 2417<li>Launch the Bluetooth Chat app on both devices.</li> 2418<li>Make the known-good device discoverable from within BluetoothChat (using the Menu).</li> 2419<li>On the candidate device, scan for Bluetooth devices from within BluetoothChat (using the Menu) and pair with the known-good device.</li> 2420<li>Send 10 or more messages from each device, and verify that the other device receives them correctly.</li> 2421<li>Close the BluetoothChat app on both devices by pressing <b>Home</b>.</li> 2422<li>Unpair each device from the other, using the device Settings app.</li> 2423</ol> 2424<h3>Test Pairing and Communication in the Reverse Direction</h3> 2425<ol> 2426<li>Launch the Bluetooth Chat app on both devices.</li> 2427<li>Make the candidate device discoverable from within BluetoothChat (using the Menu).</li> 2428<li>On the known-good device, scan for Bluetooth devices from within BluetoothChat (using the Menu) and pair with the candidate device.</li> 2429<li>Send 10 or messages from each device, and verify that the other device receives them correctly.</li> 2430<li>Close the Bluetooth Chat app on both devices by pressing Back repeatedly to get to the Launcher.</li> 2431</ol> 2432<h3>Test Re-Launches</h3> 2433<ol> 2434<li>Re-launch the Bluetooth Chat app on both devices.</li> 2435<li>Send 10 or messages from each device, and verify that the other device receives them correctly.</li> 2436</ol> 2437<p>Note: the above tests have some cases which end a test section by using 2438Home, and some using Back. These tests are not redundant and are not optional: 2439the objective is to verify that the Bluetooth API and stack works correctly 2440both when Activities are explicitly terminated (via the user pressing Back, 2441which calls finish()), and implicitly sent to background (via the user 2442pressing Home.) Each test sequence MUST be performed as described.</p> 2443 2444<div id="footerContent" xmlns:pdf="http://whatever"> 2445<pdf:pagenumber/> 2446</div> 2447</body> 2448</html> 2449
