如何在 iOS 中使用视频作为自定义视图控制器转换？

Question

我想使用色度键（绿屏）全屏视频作为 2 个视图控制器之间的自定义过渡。

视频开始时完全是绿色（= 完全透明），显示一些动画效果（将第一个视图控制器隐藏在后面），然后重新变为绿色（显示第二个视图控制器）。 Example transitions

我已经弄清楚了色度键部分（使用GPUImagewith a modified GPUImageChromaKeyFilter）。

如何将视频全屏显示为自定义过渡，同时切换后面的视图控制器？

Answer 1

我不知道我可以在实现UIViewControllerAnimatedTransitioning 的类中将UIViews 添加到transitionContext 中的containerView。

所以我在过渡开始时将filterView 添加到容器中，并在完成块中再次将其删除。

@interface VideoTransitionAnimator() {
    GPUImageOutput<GPUImageInput> *filter;

}

@property(nonatomic, strong) GPUImageMovie * movieFile;
@property(nonatomic, strong) GPUImagePicture * sourcePicture;

@end

@implementation VideoTransitionAnimator


- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext
{
    return 2;
}

- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
    UIViewController* toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    ViewController* fromViewController = (ViewController *) [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    [[transitionContext containerView] addSubview:toViewController.view];
    toViewController.view.alpha = 0;

    NSURL *sampleURL = [[NSBundle mainBundle] URLForResource:@"sample.m4v" withExtension:@"mp4"];

    self.movieFile = [[GPUImageMovie alloc] initWithURL:sampleURL];
    self.movieFile.shouldRepeat = NO;

    filter = [[GPUImageChromaKeyTransparencyFilter alloc] init];
    [(GPUImageChromaKeyTransparencyFilter *)filter setColorToReplaceRed:0.0 green:1.0 blue:0.0];
    [(GPUImageChromaKeyTransparencyFilter *)filter setThresholdSensitivity:0.4];

    [self.movieFile addTarget:filter];

    GPUImageView *filterView = [[GPUImageView alloc] init];
    filterView.frame = fromViewController.view.frame;

    filterView.backgroundColor = [UIColor clearColor];
    [filter addTarget:filterView];

    UIView *containerView = [transitionContext containerView];
    [containerView addSubview:filterView];

    //rfilterView.fillMode = kGPUImageFillModeStretch;

    [self.movieFile startProcessing];

    [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
        toViewController.view.alpha = 1;
    } completion:^(BOOL finished) {
        [transitionContext completeTransition:![transitionContext transitionWasCancelled]];
        [filterView removeFromSuperview];
    }];
}




@end