Problem draw line by Quartz 2D with alpha property < 1.0 on iPhone
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by The Khanh
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Published on 2010-05-14T02:38:11Z
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2010/05/14
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Hello Everybody !
This code i use to draw in my app. So i have problem, if i draw with alpha property = 1. It is very good but if i change alpha property = 0.2 then my paint is not good. How do i make for better with alpha property = 0.2.
http://www.flickr.com/photos/9601621@N05/page1/
Draw with alpha = 1: It is good Draw with alpha = 0.2: It is bad
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
if ([self.view superview] && (headerView.frame.origin.y == -30)) { mouseSwiped = YES;
UITouch *touch = [touches anyObject]; CGPoint currentPoint = [touch locationInView:self.view]; currentPoint.y -= 20;
UIGraphicsBeginImageContext(self.view.frame.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[drawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)]; CGContextSetLineCap(context, kCGLineCapRound); CGContextSetLineWidth(context, currentBrushProperty.brushSize); CGContextSetRGBStrokeColor(context, [self red], [self green], [self blue], currentBrushProperty.brushTransparency); CGContextSetRGBStrokeColor(context, 1.0, 0.0, 0.0, 1.0);
CGContextBeginPath(context); CGContextMoveToPoint(context, lastPoint.x, lastPoint.y); CGContextAddLineToPoint(context, currentPoint.x, currentPoint.y);
CGContextStrokePath(context); drawImage.image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext();
lastPoint = currentPoint;
}}
Help me, please.
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