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