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我正在截取一些 UIButtons 的屏幕截图，它们是大约 500 宽和 500 高的圆圈。由于屏幕截图只能以正方形形式制作，并且我不想在图像周围出现白色角落，因此我使用了以下代码：

UIGraphicsBeginImageContext(self.Button3.layer.bounds.size);
[self.Button3.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage* image2 = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

    NSData* data = UIImagePNGRepresentation(image);
    [data writeToFile:BusinessCardPath atomically:YES];

这非常有效，它返回给我一张只有没有白角的圆圈的照片。但它不能被放大，因为它会丢失像素，并且它不包括在镜头中的所有元素，例如 UIButton 上的 UILabel，但不包括 UIButton 的子视图。

如果我使用此代码：

CGSize imageSize = CGSizeMake(310, 310);

UIGraphicsBeginImageContext(self.Button3.layer.bounds.size);

CGContextRef context = UIGraphicsGetCurrentContext();
/*CGContextTranslateCTM(context, -5, -50);*/
// 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();

...我得到相反的效果。上面的元素包含在屏幕截图中，高分辨率，但图像周围的白色角落在那里。

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1 回答 1

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您可以使用 CAShapeLayer 来遮盖图像的某些部分。.path 属性用于定义将被渲染的区域。

UIImageView *myImageView = [UIImageView alloc] init];
myImageView.image = [UIImage imageNamed:@"anImage.gif"];
[myImageView setClipsToBounds:YES];

UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:myImageView.bounds byRoundingCorners:UIRectCornerAllCorners cornerRadii:CGSizeMake(48, 48)];
CAShapeLayer *maskLayer = [CAShapeLayer layer];
maskLayer.frame = myImageView.bounds;
maskLayer.path = maskPath.CGPath;

myImageView.layer.mask = maskLayer;

那应该给你一个圆形图像。您可能需要使用半径。

于 2013-08-29T15:57:19.237 回答