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此代碼用於在我的應用程序中繪製。所以我有問題,如果我用alpha屬性= 1繪製。這是非常好的,但如果我改變alpha屬性= 0.2,那麼我的油漆不好。如何使alpha屬性= 0.2更好。在iPhone上使用alpha屬性<1.0的Quartz 2D繪製線條時發生的問題
http://www.flickr.com/photos/[email protected]/page1/
戰平的α= 1:這是很好 戰平阿爾法= 0.2:這是不好的
- (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;
}}