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      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         DISPLAY_EVENT_HOTPLUG = 'plug'
     45     };
     46 
     47     struct Event {
     48 
     49         struct Header {
     50             uint32_t type;
     51             uint32_t id;
     52             nsecs_t timestamp __attribute__((aligned(8)));
     53         };
     54 
     55         struct VSync {
     56             uint32_t count;
     57         };
     58 
     59         struct Hotplug {
     60             bool connected;
     61         };
     62 
     63         Header header;
     64         union {
     65             VSync vsync;
     66             Hotplug hotplug;
     67         };
     68     };
     69 
     70 public:
     71     /*
     72      * DisplayEventReceiver creates and registers an event connection with
     73      * SurfaceFlinger. VSync events are disabled by default. Call setVSyncRate
     74      * or requestNextVsync to receive them.
     75      * Other events start being delivered immediately.
     76      */
     77     DisplayEventReceiver();
     78 
     79     /*
     80      * ~DisplayEventReceiver severs the connection with SurfaceFlinger, new events
     81      * stop being delivered immediately. Note that the queue could have
     82      * some events pending. These will be delivered.
     83      */
     84     ~DisplayEventReceiver();
     85 
     86     /*
     87      * initCheck returns the state of DisplayEventReceiver after construction.
     88      */
     89     status_t initCheck() const;
     90 
     91     /*
     92      * getFd returns the file descriptor to use to receive events.
     93      * OWNERSHIP IS RETAINED by DisplayEventReceiver. DO NOT CLOSE this
     94      * file-descriptor.
     95      */
     96     int getFd() const;
     97 
     98     /*
     99      * getEvents reads events from the queue and returns how many events were
    100      * read. Returns 0 if there are no more events or a negative error code.
    101      * If NOT_ENOUGH_DATA is returned, the object has become invalid forever, it
    102      * should be destroyed and getEvents() shouldn't be called again.
    103      */
    104     ssize_t getEvents(Event* events, size_t count);
    105     static ssize_t getEvents(const sp<BitTube>& dataChannel,
    106             Event* events, size_t count);
    107 
    108     /*
    109      * sendEvents write events to the queue and returns how many events were
    110      * written.
    111      */
    112     static ssize_t sendEvents(const sp<BitTube>& dataChannel,
    113             Event const* events, size_t count);
    114 
    115     /*
    116      * setVsyncRate() sets the Event::VSync delivery rate. A value of
    117      * 1 returns every Event::VSync. A value of 2 returns every other event,
    118      * etc... a value of 0 returns no event unless  requestNextVsync() has
    119      * been called.
    120      */
    121     status_t setVsyncRate(uint32_t count);
    122 
    123     /*
    124      * requestNextVsync() schedules the next Event::VSync. It has no effect
    125      * if the vsync rate is > 0.
    126      */
    127     status_t requestNextVsync();
    128 
    129 private:
    130     sp<IDisplayEventConnection> mEventConnection;
    131     sp<BitTube> mDataChannel;
    132 };
    133 
    134 // ----------------------------------------------------------------------------
    135 }; // namespace android
    136 
    137 #endif // ANDROID_GUI_DISPLAY_EVENT_H
    138