我正在制作一个应用程序，用户可以在其中通过触摸在图像视图中填充和描边颜色。但是我希望当用户在图像视图范围内填充颜色时，如果不小心触摸到图像视图之外，他/她不应该将颜色溢出该图像视图。到目前为止，我已经实现了这一点。有什么建议么？
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
mouseSwiped = NO;
UITouch *touch = [touches anyObject];
lastPoint = [touch locationInView:self.view];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
// mouseSwiped = YES;
// UITouch *touch = [touches anyObject];
// CGPoint currentPoint = [touch locationInView:self.view];
//
// UIGraphicsBeginImageContext(self.view.frame.size);
// [self.tempDrawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
// CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
// CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
// CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
// CGContextSetLineWidth(UIGraphicsGetCurrentContext(), brush );
// CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), red, green, blue, 1.0);
// CGContextSetBlendMode(UIGraphicsGetCurrentContext(),kCGBlendModeNormal);
//
// CGContextStrokePath(UIGraphicsGetCurrentContext());
// self.tempDrawImage.image = UIGraphicsGetImageFromCurrentImageContext();
// [self.tempDrawImage setAlpha:opacity];
// UIGraphicsEndImageContext();
//
// lastPoint = currentPoint;
if(CGRectContainsPoint([testImage bounds], lastPoint))
{
mouseSwiped = YES;
UITouch *touch = [touches anyObject];
CGPoint currentPoint = [touch locationInView:self.view];
UIGraphicsBeginImageContext(self.view.frame.size);
[self.testImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), brush );
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), red, green, blue, 1.0);
CGContextSetBlendMode(UIGraphicsGetCurrentContext(),kCGBlendModeNormal);
CGContextStrokePath(UIGraphicsGetCurrentContext());
self.testImage.image = UIGraphicsGetImageFromCurrentImageContext();
[self.testImage setAlpha:opacity];
UIGraphicsEndImageContext();
lastPoint = currentPoint;
}
else
{
// CGRectContainsPoint(testImage.frame, lastPoint) = ;
}
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
if(!mouseSwiped) {
UIGraphicsBeginImageContext(self.view.frame.size);
[self.testImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), brush);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), red, green, blue, opacity);
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
CGContextFlush(UIGraphicsGetCurrentContext());
self.tempDrawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
UIGraphicsBeginImageContext(self.mainImage.frame.size);
[self.mainImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height) blendMode:kCGBlendModeNormal alpha:1.0];
[self.tempDrawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height) blendMode:kCGBlendModeNormal alpha:opacity];
self.mainImage.image = UIGraphicsGetImageFromCurrentImageContext();
self.tempDrawImage.image = nil;
UIGraphicsEndImageContext();
}