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 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 }; 56 57 struct Event { 58 59 struct Header { 60 uint32_t type; 61 uint32_t id; 62 nsecs_t timestamp __attribute__((aligned(8))); 63 }; 64 65 struct VSync { 66 uint32_t count; 67 }; 68 69 struct Hotplug { 70 bool connected; 71 }; 72 73 Header header; 74 union { 75 VSync vsync; 76 Hotplug hotplug; 77 }; 78 }; 79 80 public: 81 /* 82 * DisplayEventReceiver creates and registers an event connection with 83 * SurfaceFlinger. VSync events are disabled by default. Call setVSyncRate 84 * or requestNextVsync to receive them. 85 * Other events start being delivered immediately. 86 */ 87 DisplayEventReceiver( 88 ISurfaceComposer::VsyncSource vsyncSource = ISurfaceComposer::eVsyncSourceApp); 89 90 /* 91 * ~DisplayEventReceiver severs the connection with SurfaceFlinger, new events 92 * stop being delivered immediately. Note that the queue could have 93 * some events pending. These will be delivered. 94 */ 95 ~DisplayEventReceiver(); 96 97 /* 98 * initCheck returns the state of DisplayEventReceiver after construction. 99 */ 100 status_t initCheck() const; 101 102 /* 103 * getFd returns the file descriptor to use to receive events. 104 * OWNERSHIP IS RETAINED by DisplayEventReceiver. DO NOT CLOSE this 105 * file-descriptor. 106 */ 107 int getFd() const; 108 109 /* 110 * getEvents reads events from the queue and returns how many events were 111 * read. Returns 0 if there are no more events or a negative error code. 112 * If NOT_ENOUGH_DATA is returned, the object has become invalid forever, it 113 * should be destroyed and getEvents() shouldn't be called again. 114 */ 115 ssize_t getEvents(Event* events, size_t count); 116 static ssize_t getEvents(gui::BitTube* dataChannel, Event* events, size_t count); 117 118 /* 119 * sendEvents write events to the queue and returns how many events were 120 * written. 121 */ 122 static ssize_t sendEvents(gui::BitTube* dataChannel, Event const* events, size_t count); 123 124 /* 125 * setVsyncRate() sets the Event::VSync delivery rate. A value of 126 * 1 returns every Event::VSync. A value of 2 returns every other event, 127 * etc... a value of 0 returns no event unless requestNextVsync() has 128 * been called. 129 */ 130 status_t setVsyncRate(uint32_t count); 131 132 /* 133 * requestNextVsync() schedules the next Event::VSync. It has no effect 134 * if the vsync rate is > 0. 135 */ 136 status_t requestNextVsync(); 137 138 private: 139 sp<IDisplayEventConnection> mEventConnection; 140 std::unique_ptr<gui::BitTube> mDataChannel; 141 }; 142 143 // ---------------------------------------------------------------------------- 144 }; // namespace android 145 146 #endif // ANDROID_GUI_DISPLAY_EVENT_H 147