我知道如何拍摄iPhone/iPad屏幕的常规矩形截图(代码如下)。然而,我正在寻找一种方法来获取一个任意角度旋转的截图
如何使用任意角度旋转的矩形拍摄UIView
的截图?
//this is the rotation of the rectangle
NSNumber* savedRotation = [NSNumber numberWithFloat: 0.35]; //radians, get the real number from a gesture recognizer
//create a screenshot
CGSize screenshotSize;
//screenshot size has to be adjusted for the rotation, or multiplied by the square root of 2
if( UIDeviceOrientationIsLandscape([[UIApplication sharedApplication]statusBarOrientation]))
{
screenshotSize = CGSizeMake(1024,768);
}else
{
screenshotSize = CGSizeMake(768, 1024);
}
if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)])
UIGraphicsBeginImageContextWithOptions(screenshotSize, NO, [UIScreen mainScreen].scale);
else
UIGraphicsBeginImageContext(screenshotSize);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSaveGState(context);
//this does the proper rotation, but there's some kind of extra translation required to make it capture what's under the rectangle
CGContextRotateCTM(context, -savedRotation.floatValue);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *screenshot = UIGraphicsGetImageFromCurrentImageContext();
CGContextRestoreGState(context);
这是上面代码的结果,看起来部分工作已经完成,但需要对CTM进行一些额外的转换才能完全匹配捕获矩形。此外,我需要将上下文的边界扩大(可能是1024 * sqrt(2)宽度和高度),以允许任何旋转而不会裁剪。