StackOverflow2013

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POHighlighting the PDF - iOS
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copied!<p>I want to implement a Highlight function in my pdf reader app. Unfortunately, my research yielded very few information about this. However, I came to believe that I will have to use an "overlay" where the drawing or "highlighting" must be done. What I plan to do now is add a CALayer into the pdf. I am successful in rendering shapes into the layer (e.g a simple line, circle, and a square), but I can't seem to draw freely into it (like in Draw Something). Here is the code I used:</p> <p>When the user begins highlighting:</p> <pre><code>- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; prevPoint = [touch locationInView:theContentView]; drawImageLayer = [CALayer layer]; drawImageLayer.frame = theContentView.frame; [theContentView.layer addSublayer:drawImageLayer]; } </code></pre> <p>When the user is starting the highlighting:</p> <pre><code>- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; currPoint = [touch locationInView:theContentView]; drawImageLayer.delegate = self; [drawImageLayer setNeedsDisplay]; } </code></pre> <p>This is the code where the drawing happens:</p> <pre><code>- (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx{ NSLog(@"DrawLayer being called.."); CGContextSaveGState(ctx); CGContextSetLineCap(ctx, kCGLineCapRound); CGContextSetLineWidth(ctx, 1.0); CGContextSetRGBStrokeColor(ctx, 1, 0, 0, 1); CGContextBeginPath(ctx); CGContextMoveToPoint(ctx, prevPoint.x, prevPoint.y); CGContextAddLineToPoint(ctx, currPoint.x, currPoint.y); CGContextStrokePath(ctx); prevPoint = currPoint; CGContextRestoreGState(ctx); } </code></pre> <p>What happens is that it draws a point and that point follows the cursor everywhere! Can anyone tell me what's wrong with this code?</p>

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