1 /*
2  * Copyright (C) 2011 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 #ifndef ANDROID_GUI_DISPLAY_EVENT_H
18 #define ANDROID_GUI_DISPLAY_EVENT_H
19 
20 #include <stdint.h>
21 #include <sys/types.h>
22 
23 #include <utils/Errors.h>
24 #include <utils/RefBase.h>
25 #include <utils/Timers.h>
26 
27 #include <binder/IInterface.h>
28 
29 // ----------------------------------------------------------------------------
30 
31 namespace android {
32 
33 // ----------------------------------------------------------------------------
34 
35 class BitTube;
36 class IDisplayEventConnection;
37 
38 // ----------------------------------------------------------------------------
39 
40 class DisplayEventReceiver {
41 public:
42     enum {
43         DISPLAY_EVENT_VSYNC = 'vsyn',
44         DISPLAY_EVENT_HOTPLUG = 'plug'
45     };
46 
47     struct Event {
48 
49         struct Header {
50             uint32_t type;
51             uint32_t id;
52             nsecs_t timestamp __attribute__((aligned(8)));
53         };
54 
55         struct VSync {
56             uint32_t count;
57         };
58 
59         struct Hotplug {
60             bool connected;
61         };
62 
63         Header header;
64         union {
65             VSync vsync;
66             Hotplug hotplug;
67         };
68     };
69 
70 public:
71     /*
72      * DisplayEventReceiver creates and registers an event connection with
73      * SurfaceFlinger. VSync events are disabled by default. Call setVSyncRate
74      * or requestNextVsync to receive them.
75      * Other events start being delivered immediately.
76      */
77     DisplayEventReceiver();
78 
79     /*
80      * ~DisplayEventReceiver severs the connection with SurfaceFlinger, new events
81      * stop being delivered immediately. Note that the queue could have
82      * some events pending. These will be delivered.
83      */
84     ~DisplayEventReceiver();
85 
86     /*
87      * initCheck returns the state of DisplayEventReceiver after construction.
88      */
89     status_t initCheck() const;
90 
91     /*
92      * getFd returns the file descriptor to use to receive events.
93      * OWNERSHIP IS RETAINED by DisplayEventReceiver. DO NOT CLOSE this
94      * file-descriptor.
95      */
96     int getFd() const;
97 
98     /*
99      * getEvents reads events from the queue and returns how many events were
100      * read. Returns 0 if there are no more events or a negative error code.
101      * If NOT_ENOUGH_DATA is returned, the object has become invalid forever, it
102      * should be destroyed and getEvents() shouldn't be called again.
103      */
104     ssize_t getEvents(Event* events, size_t count);
105     static ssize_t getEvents(const sp<BitTube>& dataChannel,
106             Event* events, size_t count);
107 
108     /*
109      * sendEvents write events to the queue and returns how many events were
110      * written.
111      */
112     static ssize_t sendEvents(const sp<BitTube>& dataChannel,
113             Event const* events, size_t count);
114 
115     /*
116      * setVsyncRate() sets the Event::VSync delivery rate. A value of
117      * 1 returns every Event::VSync. A value of 2 returns every other event,
118      * etc... a value of 0 returns no event unless  requestNextVsync() has
119      * been called.
120      */
121     status_t setVsyncRate(uint32_t count);
122 
123     /*
124      * requestNextVsync() schedules the next Event::VSync. It has no effect
125      * if the vsync rate is > 0.
126      */
127     status_t requestNextVsync();
128 
129 private:
130     sp<IDisplayEventConnection> mEventConnection;
131     sp<BitTube> mDataChannel;
132 };
133 
134 // ----------------------------------------------------------------------------
135 }; // namespace android
136 
137 #endif // ANDROID_GUI_DISPLAY_EVENT_H
138