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 #include <gui/ISurfaceComposer.h>
29
30 // ----------------------------------------------------------------------------
31
32 namespace android {
33
34 // ----------------------------------------------------------------------------
35
36 class IDisplayEventConnection;
37
38 namespace gui {
39 class BitTube;
40 } // namespace gui
41
fourcc(char c1,char c2,char c3,char c4)42 static inline constexpr uint32_t fourcc(char c1, char c2, char c3, char c4) {
43 return static_cast<uint32_t>(c1) << 24 |
44 static_cast<uint32_t>(c2) << 16 |
45 static_cast<uint32_t>(c3) << 8 |
46 static_cast<uint32_t>(c4);
47 }
48
49 // ----------------------------------------------------------------------------
50 class DisplayEventReceiver {
51 public:
52 enum {
53 DISPLAY_EVENT_VSYNC = fourcc('v', 's', 'y', 'n'),
54 DISPLAY_EVENT_HOTPLUG = fourcc('p', 'l', 'u', 'g'),
55 DISPLAY_EVENT_CONFIG_CHANGED = fourcc('c', 'o', 'n', 'f'),
56 };
57
58 struct Event {
59
60 struct Header {
61 uint32_t type;
62 PhysicalDisplayId displayId;
63 nsecs_t timestamp __attribute__((aligned(8)));
64 };
65
66 struct VSync {
67 uint32_t count;
68 };
69
70 struct Hotplug {
71 bool connected;
72 };
73
74 struct Config {
75 int32_t configId;
76 };
77
78 Header header;
79 union {
80 VSync vsync;
81 Hotplug hotplug;
82 Config config;
83 };
84 };
85
86 public:
87 /*
88 * DisplayEventReceiver creates and registers an event connection with
89 * SurfaceFlinger. VSync events are disabled by default. Call setVSyncRate
90 * or requestNextVsync to receive them.
91 * Other events start being delivered immediately.
92 */
93 explicit DisplayEventReceiver(
94 ISurfaceComposer::VsyncSource vsyncSource = ISurfaceComposer::eVsyncSourceApp);
95
96 /*
97 * ~DisplayEventReceiver severs the connection with SurfaceFlinger, new events
98 * stop being delivered immediately. Note that the queue could have
99 * some events pending. These will be delivered.
100 */
101 ~DisplayEventReceiver();
102
103 /*
104 * initCheck returns the state of DisplayEventReceiver after construction.
105 */
106 status_t initCheck() const;
107
108 /*
109 * getFd returns the file descriptor to use to receive events.
110 * OWNERSHIP IS RETAINED by DisplayEventReceiver. DO NOT CLOSE this
111 * file-descriptor.
112 */
113 int getFd() const;
114
115 /*
116 * getEvents reads events from the queue and returns how many events were
117 * read. Returns 0 if there are no more events or a negative error code.
118 * If NOT_ENOUGH_DATA is returned, the object has become invalid forever, it
119 * should be destroyed and getEvents() shouldn't be called again.
120 */
121 ssize_t getEvents(Event* events, size_t count);
122 static ssize_t getEvents(gui::BitTube* dataChannel, Event* events, size_t count);
123
124 /*
125 * sendEvents write events to the queue and returns how many events were
126 * written.
127 */
128 static ssize_t sendEvents(gui::BitTube* dataChannel, Event const* events, size_t count);
129
130 /*
131 * setVsyncRate() sets the Event::VSync delivery rate. A value of
132 * 1 returns every Event::VSync. A value of 2 returns every other event,
133 * etc... a value of 0 returns no event unless requestNextVsync() has
134 * been called.
135 */
136 status_t setVsyncRate(uint32_t count);
137
138 /*
139 * requestNextVsync() schedules the next Event::VSync. It has no effect
140 * if the vsync rate is > 0.
141 */
142 status_t requestNextVsync();
143
144 private:
145 sp<IDisplayEventConnection> mEventConnection;
146 std::unique_ptr<gui::BitTube> mDataChannel;
147 };
148
149 // ----------------------------------------------------------------------------
150 }; // namespace android
151
152 #endif // ANDROID_GUI_DISPLAY_EVENT_H
153