DisplayEventReceiver.cpp revision 90ac799241f077a7b7e6c1875fd933864c8dd2a7
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#include <string.h>
18
19#include <utils/Errors.h>
20
21#include <gui/BitTube.h>
22#include <gui/DisplayEventReceiver.h>
23#include <gui/IDisplayEventConnection.h>
24#include <gui/ISurfaceComposer.h>
25
26#include <private/gui/ComposerService.h>
27
28// ---------------------------------------------------------------------------
29
30namespace android {
31
32// ---------------------------------------------------------------------------
33
34DisplayEventReceiver::DisplayEventReceiver() {
35    sp<ISurfaceComposer> sf(ComposerService::getComposerService());
36    if (sf != NULL) {
37        mEventConnection = sf->createDisplayEventConnection();
38        if (mEventConnection != NULL) {
39            mDataChannel = mEventConnection->getDataChannel();
40        }
41    }
42}
43
44DisplayEventReceiver::~DisplayEventReceiver() {
45}
46
47status_t DisplayEventReceiver::initCheck() const {
48    if (mDataChannel != NULL)
49        return NO_ERROR;
50    return NO_INIT;
51}
52
53int DisplayEventReceiver::getFd() const {
54    if (mDataChannel == NULL)
55        return NO_INIT;
56
57    return mDataChannel->getFd();
58}
59
60status_t DisplayEventReceiver::setVsyncRate(uint32_t count) {
61    if (int32_t(count) < 0)
62        return BAD_VALUE;
63
64    if (mEventConnection != NULL) {
65        mEventConnection->setVsyncRate(count);
66        return NO_ERROR;
67    }
68    return NO_INIT;
69}
70
71status_t DisplayEventReceiver::requestNextVsync() {
72    if (mEventConnection != NULL) {
73        mEventConnection->requestNextVsync();
74        return NO_ERROR;
75    }
76    return NO_INIT;
77}
78
79
80ssize_t DisplayEventReceiver::getEvents(DisplayEventReceiver::Event* events,
81        size_t count) {
82    return DisplayEventReceiver::getEvents(mDataChannel, events, count);
83}
84
85ssize_t DisplayEventReceiver::getEvents(const sp<BitTube>& dataChannel,
86        Event* events, size_t count)
87{
88    ssize_t size = dataChannel->read(events, sizeof(events[0])*count);
89    ALOGE_IF(size<0,
90            "DisplayEventReceiver::getEvents error (%s)",
91            strerror(-size));
92    if (size >= 0) {
93        // Note: if (size % sizeof(events[0])) != 0, we've got a
94        // partial read. This can happen if the queue filed up (ie: if we
95        // didn't pull from it fast enough).
96        // We discard the partial event and rely on the sender to
97        // re-send the event if appropriate (some events, like VSYNC
98        // can be lost forever).
99
100        // returns number of events read
101        size /= sizeof(events[0]);
102    }
103    return size;
104}
105
106// ---------------------------------------------------------------------------
107
108}; // namespace android
109