Erase and Unerase Image

Question

I am having two overlapping images. If I erase a portion of the above image, that specific portion gets erased and the underlying image should appear. But if I unerase that particular portion it should give me back the erased part of that image.

I don't require undo functionality but only the erased portion should appear.

Here is the code which I am using to erase the above image:

On touchesMoved event:

UIGraphicsBeginImageContext(frontImage.frame.size);
[frontImage.image drawInRect:CGRectMake(0, 0, frontImage.frame.size.width, frontImage.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(),kCGImageAlphaNone); //kCGImageAlphaPremultipliedLast);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 10);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1, 0, 0, 10);
CGContextBeginPath(UIGraphicsGetCurrentContext());
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
//this line code for erasing select the part of the image
CGContextClearRect (UIGraphicsGetCurrentContext(), CGRectMake(lastPoint.x, lastPoint.y, 10, 10)); 
//End the code
CGContextStrokePath(UIGraphicsGetCurrentContext());
frontImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

Kindly help me regarding the problem.

Thank you all in advance

Answer 1

Instead of erasing, why don't you modify the alpha for that part of the image. Then when you want it back, you modify the alpha back.

Otherwise you should restore the entire upper image when the bottom one is erased.

Answer 2

modifying alpha of that part of image is good idea but how can we modify alpha value of selected or touched part of image? do know how to do it? kindly help me.

Answer 3

anyone kindly help me above the question.

Thank you,