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 #include <gui/VsyncEventData.h>
30
31 // ----------------------------------------------------------------------------
32
33 namespace android {
34
35 // ----------------------------------------------------------------------------
36
37 using gui::IDisplayEventConnection;
38 using gui::ParcelableVsyncEventData;
39 using gui::VsyncEventData;
40
41 namespace gui {
42 class BitTube;
43 } // namespace gui
44
fourcc(char c1,char c2,char c3,char c4)45 static inline constexpr uint32_t fourcc(char c1, char c2, char c3, char c4) {
46 return static_cast<uint32_t>(c1) << 24 |
47 static_cast<uint32_t>(c2) << 16 |
48 static_cast<uint32_t>(c3) << 8 |
49 static_cast<uint32_t>(c4);
50 }
51
52 // ----------------------------------------------------------------------------
53 class DisplayEventReceiver {
54 public:
55
56 enum {
57 DISPLAY_EVENT_VSYNC = fourcc('v', 's', 'y', 'n'),
58 DISPLAY_EVENT_HOTPLUG = fourcc('p', 'l', 'u', 'g'),
59 DISPLAY_EVENT_MODE_CHANGE = fourcc('m', 'o', 'd', 'e'),
60 DISPLAY_EVENT_NULL = fourcc('n', 'u', 'l', 'l'),
61 DISPLAY_EVENT_FRAME_RATE_OVERRIDE = fourcc('r', 'a', 't', 'e'),
62 DISPLAY_EVENT_FRAME_RATE_OVERRIDE_FLUSH = fourcc('f', 'l', 's', 'h'),
63 };
64
65 struct Event {
66 // We add __attribute__((aligned(8))) for nsecs_t fields because
67 // we need to make sure all fields are aligned the same with x86
68 // and x64 (long long has different default alignment):
69 //
70 // https://en.wikipedia.org/wiki/Data_structure_alignment
71
72 struct Header {
73 uint32_t type;
74 PhysicalDisplayId displayId __attribute__((aligned(8)));
75 nsecs_t timestamp __attribute__((aligned(8)));
76 };
77
78 struct VSync {
79 uint32_t count;
80 VsyncEventData vsyncData;
81 };
82
83 struct Hotplug {
84 bool connected;
85 };
86
87 struct ModeChange {
88 int32_t modeId;
89 nsecs_t vsyncPeriod __attribute__((aligned(8)));
90 };
91
92 struct FrameRateOverride {
93 uid_t uid __attribute__((aligned(8)));
94 float frameRateHz __attribute__((aligned(8)));
95 };
96
97 Header header;
98 union {
99 VSync vsync;
100 Hotplug hotplug;
101 ModeChange modeChange;
102 FrameRateOverride frameRateOverride;
103 };
104 };
105
106 public:
107 /*
108 * DisplayEventReceiver creates and registers an event connection with
109 * SurfaceFlinger. VSync events are disabled by default. Call setVSyncRate
110 * or requestNextVsync to receive them.
111 * To receive ModeChanged and/or FrameRateOverrides events specify this in
112 * the constructor. Other events start being delivered immediately.
113 */
114 explicit DisplayEventReceiver(
115 ISurfaceComposer::VsyncSource vsyncSource = ISurfaceComposer::eVsyncSourceApp,
116 ISurfaceComposer::EventRegistrationFlags eventRegistration = {});
117
118 /*
119 * ~DisplayEventReceiver severs the connection with SurfaceFlinger, new events
120 * stop being delivered immediately. Note that the queue could have
121 * some events pending. These will be delivered.
122 */
123 ~DisplayEventReceiver();
124
125 /*
126 * initCheck returns the state of DisplayEventReceiver after construction.
127 */
128 status_t initCheck() const;
129
130 /*
131 * getFd returns the file descriptor to use to receive events.
132 * OWNERSHIP IS RETAINED by DisplayEventReceiver. DO NOT CLOSE this
133 * file-descriptor.
134 */
135 int getFd() const;
136
137 /*
138 * getEvents reads events from the queue and returns how many events were
139 * read. Returns 0 if there are no more events or a negative error code.
140 * If NOT_ENOUGH_DATA is returned, the object has become invalid forever, it
141 * should be destroyed and getEvents() shouldn't be called again.
142 */
143 ssize_t getEvents(Event* events, size_t count);
144 static ssize_t getEvents(gui::BitTube* dataChannel, Event* events, size_t count);
145
146 /*
147 * sendEvents write events to the queue and returns how many events were
148 * written.
149 */
150 ssize_t sendEvents(Event const* events, size_t count);
151 static ssize_t sendEvents(gui::BitTube* dataChannel, Event const* events, size_t count);
152
153 /*
154 * setVsyncRate() sets the Event::VSync delivery rate. A value of
155 * 1 returns every Event::VSync. A value of 2 returns every other event,
156 * etc... a value of 0 returns no event unless requestNextVsync() has
157 * been called.
158 */
159 status_t setVsyncRate(uint32_t count);
160
161 /*
162 * requestNextVsync() schedules the next Event::VSync. It has no effect
163 * if the vsync rate is > 0.
164 */
165 status_t requestNextVsync();
166
167 /**
168 * getLatestVsyncEventData() gets the latest vsync event data.
169 */
170 status_t getLatestVsyncEventData(ParcelableVsyncEventData* outVsyncEventData) const;
171
172 private:
173 sp<IDisplayEventConnection> mEventConnection;
174 std::unique_ptr<gui::BitTube> mDataChannel;
175 std::optional<status_t> mInitError;
176 };
177
178 inline bool operator==(DisplayEventReceiver::Event::FrameRateOverride lhs,
179 DisplayEventReceiver::Event::FrameRateOverride rhs) {
180 return (lhs.uid == rhs.uid) && std::abs(lhs.frameRateHz - rhs.frameRateHz) < 0.001f;
181 }
182
183 // ----------------------------------------------------------------------------
184 }; // namespace android
185
186 #endif // ANDROID_GUI_DISPLAY_EVENT_H
187