How to take screenshot of a user defined rectangular area in cocos2d

Question

I need to take the screenshot in my cocos2d application. I've searched a lot, even in stack overflow. Then I found the following code:

+(UIImage*) screenshotWithStartNode:(CCNode*)stNode
{
    [CCDirector sharedDirector].nextDeltaTimeZero = YES;

    CGSize winSize = [[CCDirector sharedDirector] winSize];
    CCRenderTexture* renTxture = 
    [CCRenderTexture renderTextureWithWidth:winSize.width 
                                 height:winSize.height];
    [renTxture begin];
    [stNode visit];
    [renTxture end];

    return [renTxture getUIImage];
}

Now,

Problem: The above code gives me the entire screenshot. But I am in need of the screenshot of a custom are, such as, within a CGRect(50,50,100,200).

Can anyone please help me..? Thanks...

Answer 1

Wow... found out what I need. I've changed the above method like:

-(UIImage*) screenshotWithStartNode:(CCNode*)startNode
{
    [CCDirector sharedDirector].nextDeltaTimeZero = YES;

    CGSize winSize = [CCDirector sharedDirector].winSize;
    CCRenderTexture* rtx =
    [CCRenderTexture renderTextureWithWidth:winSize.width
                                     height:winSize.height];

    [rtx begin];
    [startNode visit];
    [rtx end];

    UIImage *tempImage = [rtx getUIImage];
    CGRect imageBoundary = CGRectMake(100, 100, 300, 300);

    UIGraphicsBeginImageContext(imageBoundary.size);
    CGContextRef context = UIGraphicsGetCurrentContext();

    // translated rectangle for drawing sub image
    CGRect drawRect = CGRectMake(-imageBoundary.origin.x, -imageBoundary.origin.y, tempImage.size.width, tempImage.size.height);

    // clip to the bounds of the image context
    CGContextClipToRect(context, CGRectMake(0, 0, imageBoundary.size.width, imageBoundary.size.height));

    // draw image
    [tempImage drawInRect:drawRect];

    // grab image
    UIImage* subImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return subImage;

}