talk/app/webrtc/objc/RTCEAGLVideoView.m

/*
 * libjingle
 * Copyright 2014, Google Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  1. Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright notice,
 *     this list of conditions and the following disclaimer in the documentation
 *     and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#if !defined(__has_feature) || !__has_feature(objc_arc)
#error "This file requires ARC support."
#endif

#import "RTCEAGLVideoView+Internal.h"

#import <GLKit/GLKit.h>
#import <QuartzCore/QuartzCore.h>

#import "RTCEAGLVideoRenderer.h"
#import "RTCVideoRenderer.h"
#import "RTCVideoTrack.h"

@interface RTCEAGLVideoView () <GLKViewDelegate>
@property(atomic, strong) RTCI420Frame* i420Frame;
@end

@implementation RTCEAGLVideoView {
  CADisplayLink* _displayLink;
  GLKView* _glkView;
  RTCEAGLVideoRenderer* _glRenderer;
  RTCVideoRenderer* _videoRenderer;
}

- (instancetype)initWithFrame:(CGRect)frame {
  if (self = [super initWithFrame:frame]) {
    EAGLContext* glContext =
        [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];
    _glRenderer = [[RTCEAGLVideoRenderer alloc] initWithContext:glContext];

    // GLKView manages a framebuffer for us.
    _glkView = [[GLKView alloc] initWithFrame:CGRectZero
                                      context:glContext];
    _glkView.drawableColorFormat = GLKViewDrawableColorFormatRGBA8888;
    _glkView.drawableDepthFormat = GLKViewDrawableDepthFormatNone;
    _glkView.drawableStencilFormat = GLKViewDrawableStencilFormatNone;
    _glkView.drawableMultisample = GLKViewDrawableMultisampleNone;
    _glkView.delegate = self;
    _glkView.layer.masksToBounds = YES;
    [self addSubview:_glkView];

    // Listen to application state in order to clean up OpenGL before app goes
    // away.
    NSNotificationCenter* notificationCenter =
        [NSNotificationCenter defaultCenter];
    [notificationCenter addObserver:self
                           selector:@selector(willResignActive)
                               name:UIApplicationWillResignActiveNotification
                             object:nil];
    [notificationCenter addObserver:self
                           selector:@selector(didBecomeActive)
                               name:UIApplicationDidBecomeActiveNotification
                             object:nil];
    _displayLink =
        [CADisplayLink displayLinkWithTarget:self
                                    selector:@selector(displayLinkDidFire:)];
    _displayLink.paused = YES;
    // Set to half of screen refresh, which should be 30fps.
    [_displayLink setFrameInterval:2];
    [_displayLink addToRunLoop:[NSRunLoop currentRunLoop]
                       forMode:NSRunLoopCommonModes];
    _videoRenderer = [[RTCVideoRenderer alloc] initWithDelegate:self];
    [self setupGL];
  }
  return self;
}

- (void)dealloc {
  [[NSNotificationCenter defaultCenter] removeObserver:self];
  UIApplicationState appState =
      [UIApplication sharedApplication].applicationState;
  if (appState == UIApplicationStateActive) {
    [self teardownGL];
  }
}

- (void)setVideoTrack:(RTCVideoTrack*)videoTrack {
  if (_videoTrack == videoTrack) {
    return;
  }
  [_videoTrack removeRenderer:_videoRenderer];
  _videoTrack = videoTrack;
  [_videoTrack addRenderer:_videoRenderer];
  // TODO(tkchin): potentially handle changes in track state - e.g. render
  // black if track fails.
}

#pragma mark - UIView

- (void)layoutSubviews {
  [super layoutSubviews];
  _glkView.frame = self.bounds;
}

#pragma mark - GLKViewDelegate

// This method is called when the GLKView's content is dirty and needs to be
// redrawn. This occurs on main thread.
- (void)glkView:(GLKView*)view drawInRect:(CGRect)rect {
  if (self.i420Frame) {
    // The renderer will draw the frame to the framebuffer corresponding to the
    // one used by |view|.
    [_glRenderer drawFrame:self.i420Frame];
  }
}

#pragma mark - Private

// Frames are received on a separate thread, so we poll for current frame
// using a refresh rate proportional to screen refresh frequency. This occurs
// on main thread.
- (void)displayLinkDidFire:(CADisplayLink*)displayLink {
  // Don't render if frame hasn't changed.
  if (_glRenderer.lastDrawnFrame == self.i420Frame) {
    return;
  }
  // This tells the GLKView that it's dirty, which will then call the the
  // GLKViewDelegate method implemented above.
  [_glkView setNeedsDisplay];
}

- (void)setupGL {
  [_glRenderer setupGL];
  _displayLink.paused = NO;
}

- (void)teardownGL {
  _displayLink.paused = YES;
  [_glkView deleteDrawable];
  [_glRenderer teardownGL];
}

- (void)didBecomeActive {
  [self setupGL];
}

- (void)willResignActive {
  [self teardownGL];
}

@end

@implementation RTCEAGLVideoView (Internal)

#pragma mark - RTCVideoRendererDelegate

// These methods are called when the video track has frame information to
// provide. This occurs on non-main thread.
- (void)renderer:(RTCVideoRenderer*)renderer
      didSetSize:(CGSize)size {
  // Size is checked in renderer as frames arrive, no need to do anything here.
}

- (void)renderer:(RTCVideoRenderer*)renderer
    didReceiveFrame:(RTCI420Frame*)frame {
  self.i420Frame = frame;
}

@end