Problem draw line by Quartz 2D with alpha property < 1.0 on iPhone
- by The Khanh
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.
