2

在 Apples Technical notes 网站上，他们将代码发布到屏幕截图。一切正常，除了它不捕获在 iOS 6 下使用 QLPreviewController 预览的文件。

我想知道他们是否正在使用一些新的 OpenGL ES 来渲染文件预览以使其无法捕获？理论上，这段代码应该可以捕捉到屏幕上的任何东西吧？？

来自http://developer.apple.com/library/ios/#qa/qa1703/_index.html

- (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;
}
4

1 回答 1

0

这听起来并不相似，但这实际上不起作用，原因与它不起作用的原因相同：iOS 6 UIGestures (Tap) stop working with QLPreviewController

由于 ios 6 QLPreviewController 实际上是一个完全独立的应用程序（独立的进程和一切）

=> 所以当你按下它时，你的整个应用程序都会移动到 bg，包括它的窗口。

=> QlController 从来都不是你窗口的一部分

于 2012-11-11T15:34:40.003 回答