如何在面具周围绘制CALayer边框？ [英] How to draw CALayer border around its mask?

问题描述

所以，我有一个 CALayer ，它有一个掩码&我想在这个图层的蒙版周围添加边框。例如，我已经为图层设置了三角形蒙版，我希望在该图层周围设置边框。

So, I have a CALayer, which has a mask & I want to add border around this layer's mask. For example, I have set triangle mask to the layer and I want to have border around that layer.

有谁可以帮我解决这个问题？

Can anyone please help me to solve this problem?

推荐答案

考虑以下示例代码：

- (void)drawRect:(CGRect)rect {
    CAShapeLayer *maskLayer = [CAShapeLayer layer];

    //Modify to your needs
    CGFloat maskInsetWidth = 5.0f;
    CGFloat maskInsetHeight = 5.0f;
    CGFloat maskCornerRadius = 5.0f;
    CGFloat borderWidth = 2.0f;
    UIColor *borderColor = [UIColor blackColor];

    CGRect insetRect = CGRectInset(self.bounds, maskInsetWidth, maskInsetHeight);
    insetRect.size.width = MAX(insetRect.size.width, 0);
    insetRect.size.height = MAX(insetRect.size.height, 0);

    CGPathRef path = [UIBezierPath bezierPathWithRoundedRect:insetRect cornerRadius:maskCornerRadius].CGPath;

    if (borderWidth > 0.0f && borderColor != nil) {
        CAShapeLayer *borderLayer = [CAShapeLayer layer];

        [borderLayer setPath:path];
        [borderLayer setLineWidth:borderWidth * 2.0f];
        [borderLayer setStrokeColor:borderColor.CGColor];
        [borderLayer setFillColor:[UIColor clearColor].CGColor];

        borderLayer.frame = self.bounds;
        [self.layer addSublayer:borderLayer];
    }
    [maskLayer setPath:path];
    [maskLayer setFillRule:kCAFillRuleEvenOdd];
    maskLayer.frame = self.bounds;
    [self.layer setMask:maskLayer];
}

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