1 /* 2 * Copyright (C) 2007 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.widget; 18 19 import android.content.Context; 20 import android.util.AttributeSet; 21 import android.view.MotionEvent; 22 import android.view.PointerIcon; 23 import android.widget.RemoteViews.RemoteView; 24 25 /** 26 * <p> 27 * Displays a button with an image (instead of text) that can be pressed 28 * or clicked by the user. By default, an ImageButton looks like a regular 29 * {@link android.widget.Button}, with the standard button background 30 * that changes color during different button states. The image on the surface 31 * of the button is defined either by the {@code android:src} attribute in the 32 * {@code <ImageButton>} XML element or by the 33 * {@link #setImageResource(int)} method.</p> 34 * 35 * <p>To remove the standard button background image, define your own 36 * background image or set the background color to be transparent.</p> 37 * <p>To indicate the different button states (focused, selected, etc.), you can 38 * define a different image for each state. E.g., a blue image by default, an 39 * orange one for when focused, and a yellow one for when pressed. An easy way to 40 * do this is with an XML drawable "selector." For example:</p> 41 * <pre> 42 * <?xml version="1.0" encoding="utf-8"?> 43 * <selector xmlns:android="http://schemas.android.com/apk/res/android"> 44 * <item android:state_pressed="true" 45 * android:drawable="@drawable/button_pressed" /> <!-- pressed --> 46 * <item android:state_focused="true" 47 * android:drawable="@drawable/button_focused" /> <!-- focused --> 48 * <item android:drawable="@drawable/button_normal" /> <!-- default --> 49 * </selector></pre> 50 * 51 * <p>Save the XML file in your project {@code res/drawable/} folder and then 52 * reference it as a drawable for the source of your ImageButton (in the 53 * {@code android:src} attribute). Android will automatically change the image 54 * based on the state of the button and the corresponding images 55 * defined in the XML.</p> 56 * 57 * <p>The order of the {@code <item>} elements is important because they are 58 * evaluated in order. This is why the "normal" button image comes last, because 59 * it will only be applied after {@code android:state_pressed} and {@code 60 * android:state_focused} have both evaluated false.</p> 61 * 62 * <p>See the <a href="{@docRoot}guide/topics/ui/controls/button.html">Buttons</a> 63 * guide.</p> 64 * 65 * <p><strong>XML attributes</strong></p> 66 * <p> 67 * See {@link android.R.styleable#ImageView Button Attributes}, 68 * {@link android.R.styleable#View View Attributes} 69 * </p> 70 */ 71 @RemoteView 72 public class ImageButton extends ImageView { ImageButton(Context context)73 public ImageButton(Context context) { 74 this(context, null); 75 } 76 ImageButton(Context context, AttributeSet attrs)77 public ImageButton(Context context, AttributeSet attrs) { 78 this(context, attrs, com.android.internal.R.attr.imageButtonStyle); 79 } 80 ImageButton(Context context, AttributeSet attrs, int defStyleAttr)81 public ImageButton(Context context, AttributeSet attrs, int defStyleAttr) { 82 this(context, attrs, defStyleAttr, 0); 83 } 84 ImageButton(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes)85 public ImageButton(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { 86 super(context, attrs, defStyleAttr, defStyleRes); 87 setFocusable(true); 88 } 89 90 @Override onSetAlpha(int alpha)91 protected boolean onSetAlpha(int alpha) { 92 return false; 93 } 94 95 @Override getAccessibilityClassName()96 public CharSequence getAccessibilityClassName() { 97 return ImageButton.class.getName(); 98 } 99 100 @Override onResolvePointerIcon(MotionEvent event, int pointerIndex)101 public PointerIcon onResolvePointerIcon(MotionEvent event, int pointerIndex) { 102 if (getPointerIcon() == null && isClickable() && isEnabled()) { 103 return PointerIcon.getSystemIcon(getContext(), PointerIcon.TYPE_HAND); 104 } 105 return super.onResolvePointerIcon(event, pointerIndex); 106 } 107 } 108