transparency on uiimageview should show image

Question

Possible Duplicate:
How to draw a transparent stroke (or anyway clear part of an image) on the iPhone

I have a uiimage view on that a transparent layer is there if we make touch on that transparent layer that touched part transparent layer should be erased and should show the image back of it.. how can i do this....? thanks in advance

UIImage * backgroundImage = [UIImage imageNamed:@"images.jpeg"]; CALayer* aLayer = [CALayer layer]; CGFloat nativeWidth = CGImageGetWidth(backgroundImage.CGImage); CGFloat nativeHeight = CGImageGetHeight(backgroundImage.CGImage); CGRect startFrame = CGRectMake(0.0, 0.0, nativeWidth, nativeHeight); aLayer.contents = (id)backgroundImage.CGImage; aLayer.frame = startFrame; [self.view.layer addSublayer:aLayer]; - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { ; — 08442, Sep 08 '12 at 10:07
@pammu do u want to erase the bit of selected image from the source image? — Arun, Sep 08 '12 at 13:39
i have a image on that an overlay image is there when i erse the overlay it should show yha part of the image — 08442, Sep 08 '12 at 14:02

score 0 · Answer 1 · answered Sep 08 '12 at 13:55

For my understanding you want to erase the part of the image by touching... Is that right ?

Try this code for erasing by touches moved part of image....

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    lastTouch = [touch locationInView:canvasView];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    currentTouch = [touch locationInView:canvasView];

    CGFloat brushSize = 35;
    CGColorRef strokeColor = [UIColor whiteColor].CGColor;

    UIGraphicsBeginImageContext(scratchView.frame.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    [canvasView.image drawInRect:CGRectMake(0, 0, canvasView.frame.size.width, canvasView.frame.size.height)];
    CGContextSetLineCap(context, kCGLineCapRound);
    CGContextSetLineWidth(context, brushSize);
    CGContextSetStrokeColorWithColor(context, strokeColor);
    CGContextSetBlendMode(context, kCGBlendModeClear);
    CGContextBeginPath(context);
    CGContextMoveToPoint(context, lastTouch.x, lastTouch.y);
    CGContextAddLineToPoint(context, currentTouch.x, currentTouch.y);
    CGContextStrokePath(context);
    canvasView.image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    lastTouch = [touch locationInView:canvasView];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {

}

I hope this will help you....

transparency on uiimageview should show image

1 Answers1