DisplayEventReceiver.h revision d0566bc26fcf6ca396118701fa11900b627f2c09 
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
31namespace android {
32
33// ----------------------------------------------------------------------------
34
35class BitTube;
36class IDisplayEventConnection;
37
38// ----------------------------------------------------------------------------
39
40class DisplayEventReceiver {
41public:
42    enum {
43        DISPLAY_EVENT_VSYNC = 'vsyn'
44    };
45
46    struct Event {
47
48        struct Header {
49            uint32_t type;
50            nsecs_t timestamp;
51        };
52
53        struct VSync {
54            uint32_t count;
55        };
56
57        Header header;
58        union {
59            VSync vsync;
60        };
61    };
62
63public:
64    /*
65     * DisplayEventReceiver creates and registers an event connection with
66     * SurfaceFlinger. Events start being delivered immediately.
67     */
68    DisplayEventReceiver();
69
70    /*
71     * ~DisplayEventReceiver severs the connection with SurfaceFlinger, new events
72     * stop being delivered immediately. Note that the queue could have
73     * some events pending. These will be delivered.
74     */
75    ~DisplayEventReceiver();
76
77    /*
78     * initCheck returns the state of DisplayEventReceiver after construction.
79     */
80    status_t initCheck() const;
81
82    /*
83     * getFd returns the file descriptor to use to receive events.
84     * OWNERSHIP IS RETAINED by DisplayEventReceiver. DO NOT CLOSE this
85     * file-descriptor.
86     */
87    int getFd() const;
88
89    /*
90     * getEvents reads event from the queue and returns how many events were
91     * read. Returns 0 if there are no more events or a negative error code.
92     * If NOT_ENOUGH_DATA is returned, the object has become invalid forever, it
93     * should be destroyed and getEvents() shouldn't be called again.
94     */
95    ssize_t getEvents(Event* events, size_t count);
96
97private:
98    sp<IDisplayEventConnection> mEventConnection;
99    sp<BitTube> mDataChannel;
100};
101
102// ----------------------------------------------------------------------------
103}; // namespace android
104
105#endif // ANDROID_GUI_DISPLAY_EVENT_H
106