iOS 在 drawRect 中反转遮罩 [英] iOS invert mask in drawRect

问题描述

使用下面的代码，我成功地掩盖了我的绘图的一部分，但这与我想要掩盖的相反.这掩盖了绘图的内部部分，我想掩盖外部部分.有没有简单的方法可以反转这个掩码?

With the code below, I am successfully masking part of my drawing, but it's the inverse of what I want masked. This masks the inner portion of the drawing, where I would like to mask the outer portion. Is there a simple way to invert this mask?

myPath 下面是一个 UIBezierPath.

CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
CGMutablePathRef maskPath = CGPathCreateMutable();
CGPathAddPath(maskPath, nil, myPath.CGPath);
[maskLayer setPath:maskPath];
CGPathRelease(maskPath);
self.layer.mask = maskLayer;

推荐答案

在形状图层上使用偶数奇数填充 (maskLayer.fillRule = kCAFillRuleEvenOdd;) 你可以添加一个覆盖整个的大矩形框，然后添加您要遮罩的形状.这实际上将反转掩码.

With even odd filling on the shape layer (maskLayer.fillRule = kCAFillRuleEvenOdd;) you can add a big rectangle that covers the entire frame and then add the shape you are masking out. This will in effect invert the mask.

CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
CGMutablePathRef maskPath = CGPathCreateMutable();
CGPathAddRect(maskPath, NULL, someBigRectangle); // this line is new
CGPathAddPath(maskPath, nil, myPath.CGPath);
[maskLayer setPath:maskPath];
maskLayer.fillRule = kCAFillRuleEvenOdd;         // this line is new
CGPathRelease(maskPath);
self.layer.mask = maskLayer;

这篇关于iOS 在 drawRect 中反转遮罩的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！