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I want to take screen shot of a UIImageView after rotate it through some angle. I use this code,but I get screenshot which is particaly cut from boundries means I am unable to get full screen shot. Here imgDisplayImage is my instance of UIInageVew,lastRotation is total Rotation angle

// 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 = self.imgDisplayImage.frame.size;
if (NULL != UIGraphicsBeginImageContextWithOptions)
    UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0.0);
else
    UIGraphicsBeginImageContext(imageSize);

CGContextRef context = UIGraphicsGetCurrentContext();


CGContextSaveGState(context);

CGContextTranslateCTM(context, [self.imgDisplayImage center].x, [self.imgDisplayImage center].y);
CGContextRotateCTM(context, lastRotation);
CGContextTranslateCTM(context,
                      -self.imgDisplayImage.frame.size.width * [[self.imgDisplayImage layer] anchorPoint].x,
                      -self.imgDisplayImage.frame.size.height * [[self.imgDisplayImage layer] anchorPoint].y);

    [self.imgDisplayImage.layer renderInContext:context];
CGContextRestoreGState(context);

// Retrieve the screenshot image
UIImage *screenshot = UIGraphicsGetImageFromCurrentImageContext();
UIImageWriteToSavedPhotosAlbum(screenshot, nil, nil, nil);
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1 回答 1

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Try using the following code. Here Mailimage is the final screenshot

- (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
    Mailimage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return Mailimage;


}
于 2012-09-11T11:47:16.697 回答