I have some CGPath
(a poly with two circle) carried out on a CAShapeLayer
.
Can I trim/subtract paths like this?
Instead of do the math, the result can be achieved at drawing time using kCGBlendModeClear
.
// Create the poly.
CGContextBeginPath(context);
CGContextMoveToPoint (context, a_.x, a_.y);
CGContextAddLineToPoint (context, b_.x, b_.y);
CGContextAddLineToPoint (context, c_.x, c_.y);
CGContextAddLineToPoint (context, d_.x, d_.y);
CGContextClosePath(context);
// Draw with the desired color.
CGContextSetFillColorWithColor(context, self.color.CGColor);
CGContextFillPath(context);
// Create a circle.
CGContextBeginPath(context);
CGContextAddEllipseInRect(context, (CGRect){
b_.x - self.radius,
b_.y - self.radius,
self.radius * 2.0,
self.radius * 2.0 });
CGContextClosePath(context);
// Draw with Clear (!) blend mode.
CGContextSetBlendMode(context, kCGBlendModeClear);
CGContextSetFillColorWithColor(context, self.color.CGColor);
CGContextFillPath(context);
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