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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();
}
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1 回答 1

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如果您在视图的边界上创建一条路径并将其设置为clipping path您的视图会发生什么，我认为一旦设置，什么都不应该再画在外面了。

于 2012-10-01T08:14:21.780 回答