如何以编程方式捕获正在播放的视频的屏幕截图? [英] How can I programmatically capture a screenshot of a playing video?

问题描述

我想在 xcode 中捕获正在播放的视频的屏幕截图.我怎样才能以编程方式做到这一点?我在苹果文档中找到了一个截图方法如下.如果我只想截取视图的屏幕截图，该方法工作正常.但是，它无法与正在播放的视频一起使用.

I want to capture a screenshot of a playing video in xcode. How can I do it programmatically? I found a screenshot method in apple document as following. The method works fine if I just want to take a screenshot of a view. However, it fails to work with a playing video.

- (UIImage*)screenshot 
{
    // Create a graphics context with the target size
    // On iOS 4 and later, use UIGraphicsBeginImageContextWithOptions to take the scale into consideration
    // On iOS prior to 4, fall back to use UIGraphicsBeginImageContext
    CGSize imageSize = [[UIScreen mainScreen] bounds].size;
    if (NULL != UIGraphicsBeginImageContextWithOptions)
        UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);
    else
        UIGraphicsBeginImageContext(imageSize);

    CGContextRef context = UIGraphicsGetCurrentContext();

    // Iterate over every window from back to front
    for (UIWindow *window in [[UIApplication sharedApplication] windows]) 
    {
        if (![window respondsToSelector:@selector(screen)] || [window screen] == [UIScreen mainScreen])
        {
            // -renderInContext: renders in the coordinate space of the layer,
            // so we must first apply the layer's geometry to the graphics context
            CGContextSaveGState(context);
            // Center the context around the window's anchor point
            CGContextTranslateCTM(context, [window center].x, [window center].y);
            // Apply the window's transform about the anchor point
            CGContextConcatCTM(context, [window transform]);
            // Offset by the portion of the bounds left of and above the anchor point
            CGContextTranslateCTM(context,
                                  -[window bounds].size.width * [[window layer] anchorPoint].x,
                                  -[window bounds].size.height * [[window layer] anchorPoint].y);

            // Render the layer hierarchy to the current context
            [[window layer] renderInContext:context];

            // Restore the context
            CGContextRestoreGState(context);
        }
    }

    // Retrieve the screenshot image
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return image;
}

我需要截取正在播放的视频的屏幕截图.有什么想法吗?

I need to capture a screenshot of a playing video. Any idea?

推荐答案

希望这段代码能有所帮助

- (void)setupVideoPlayerView
{
videoPlayerVC = [[AVPlayerViewController alloc] init];
videoPlayerVC.view.frame = self.videoPlayerView.bounds;
videoPlayerVC.videoGravity = AVLayerVideoGravityResizeAspectFill
[videoPlayerView addSubview:_videoPlayerVC.view];
[videoPlayerVC setShowsPlaybackControls:NO];
videoPlayerVC.player = [AVPlayer playerWithURL:[NSURL URLWithString:kVideoURL];
[videoPlayerVC.player play];
}

- (UIImage *)snapImageFromRuningVideo
{
AVAsset *assest = [self.videoPlayerVC.player.currentItem asset];
AVAssetImageGenerator *imageGenerator = [AVAssetImageGenerator assetImageGeneratorWithAsset:assest];
CGImageRef imageRef = [imageGenerator copyCGImageAtTime:self.videoPlayerVC.player.currentItem.currentTime actualTime:nil error:nil];
UIImage *screengrab = [UIImage imageWithCGImage:imageRef];
return screengrab;
}

如果你想要控制器栏，这里只创建 AVPlayerViewController 或者只是实例化 AVPlayer 并绑定视频的 URL 并播放.

here just create AVPlayerViewController if you want controller bar or just instantiate AVPlayer and bind the URL of the Video and play.

每当您想在点击快照按钮时捕获当时正在运行的视频的快照时，您都可以调用方法snapImageFromRuningVideo"，该方法将返回 UIImage 对象引用.

whenever you want to capture a snapshot of the running video at that time on button click of Snapshot you can call method "snapImageFromRuningVideo" which will return UIImage object reference.

AVPlayer 在内部创建 AVPlayerItem 和 AVAsset 对象.现在只需使用 AVAsset 对象创建 AVAssetImageGenerator 对象，然后通过调用从您想要拍摄快照的时间复制图像"CGImageRef imageRef = [imageGenerator copyCGImageAtTime:self.videoPlayerVC.player.currentItem.currentTime actualTime:nil error:nil];"

AVPlayer internally create AVPlayerItem and AVAsset object. now create AVAssetImageGenerator object just by using AVAsset object then copy the image at a time from when you want to take the snapshot by calling "CGImageRef imageRef = [imageGenerator copyCGImageAtTime:self.videoPlayerVC.player.currentItem.currentTime actualTime:nil error:nil];"

这里我们必须在拍摄快照的瞬间传递玩家当前时间

here we have to pass player current time at the instant of taking the snapshot

这篇关于如何以编程方式捕获正在播放的视频的屏幕截图?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！