iOS:反向UIBezierPath(bezierPathWithOvalInRect)

Question

我有一个jpg图像与矩形中的圆形对象,并希望使圆形对象的envoirement透明...

(在此示例中删除红色区域)

在这个iOS的帮助下,UIImage透明和"UIBezierPath bezierPathWithOvalInRect"的一部分我已经取得了一些成功,但这会围绕我的对象形成一条路径,我需要将其反转,以使外部而不是内部路径透明..

我不知道在哪里我必须更改我的代码以获得正确的结果..

这是我的代码:

//BezierPath
UIBezierPath *bezierPath = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0, 0, 100, 100)];  

// Create an image context containing the original UIImage.
UIGraphicsBeginImageContext(_imgTemp.image.size);
[_imgTemp.image drawAtPoint:CGPointZero];

// Clip to the bezier path and clear that portion of the image.
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextAddPath(context,bezierPath.CGPath);
CGContextClip(context);
CGContextClearRect(context,CGRectMake(0,0,self._imgTemp.image.size.width,self._imgTemp.image.size.height));

// Build a new UIImage from the image context.
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
self._imgTemp.image = newImage;

有人解决了吗？

Answer 1

要仅在黑色圆圈内绘制,您应该移动[_imgTemp.image drawAtPoint:CGPointZero];到之后CGContextClip(context);,然后CGContextClearRect( ... )完全删除该呼叫:

//BezierPath
UIBezierPath *bezierPath = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0, 0, 100, 100)];  

// Create an image context containing the original UIImage.
UIGraphicsBeginImageContext(_imgTemp.image.size);

// Clip to the bezier path and clear that portion of the image.
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextAddPath(context,bezierPath.CGPath);
CGContextClip(context);

// Draw here when the context is clipped
[_imgTemp.image drawAtPoint:CGPointZero];

// Build a new UIImage from the image context.
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
self._imgTemp.image = newImage;