iphone - 将 CAShapeLayer 蒙版应用于 UIView

Question

我正在使用此代码将图层应用于 UIview:

mask = [[CAShapeLayer alloc] init];
mask.frame = baseView.layer.bounds;
CGRect biggerRect = CGRectMake(mask.frame.origin.x, mask.frame.origin.y, mask.frame.size.width, mask.frame.size.height);
CGRect smallerRect = CGRectMake(0.0f, 0.0f, 0.0f, 0.0f);

UIBezierPath *maskPath = [UIBezierPath bezierPath];
[maskPath moveToPoint:CGPointMake(CGRectGetMinX(biggerRect), CGRectGetMinY(biggerRect))];
[maskPath addLineToPoint:CGPointMake(CGRectGetMinX(biggerRect), CGRectGetMaxY(biggerRect))];
[maskPath addLineToPoint:CGPointMake(CGRectGetMaxX(biggerRect), CGRectGetMaxY(biggerRect))];
[maskPath addLineToPoint:CGPointMake(CGRectGetMaxX(biggerRect), CGRectGetMinY(biggerRect))];
[maskPath addLineToPoint:CGPointMake(CGRectGetMinX(biggerRect), CGRectGetMinY(biggerRect))];

[maskPath moveToPoint:CGPointMake(CGRectGetMinX(smallerRect), CGRectGetMinY(smallerRect))];
[maskPath addLineToPoint:CGPointMake(CGRectGetMinX(smallerRect), CGRectGetMaxY(smallerRect))];
[maskPath addLineToPoint:CGPointMake(CGRectGetMaxX(smallerRect), CGRectGetMaxY(smallerRect))];
[maskPath addLineToPoint:CGPointMake(CGRectGetMaxX(smallerRect), CGRectGetMinY(smallerRect))];
[maskPath addLineToPoint:CGPointMake(CGRectGetMinX(smallerRect), CGRectGetMinY(smallerRect))];

mask.path = maskPath.CGPath;
[mask setFillRule:kCAFillRuleEvenOdd];
mask.fillColor = [[UIColor blackColor] CGColor];
baseView.layer.mask = mask;

由于我要剪切的矩形发生了变化，我想知道是否有一种快速更改蒙版大小的方法，而不是仅仅将其从 UIview 中移除并以不同的尺寸重新应用它:

例如

[mask removeFromSuperlayer];

和...

mask = [[CAShapeLayer alloc] init];
mask.frame = baseView.layer.bounds;
CGRect biggerRect = CGRectMake(mask.frame.origin.x, mask.frame.origin.y, mask.frame.size.width, mask.frame.size.height);
CGRect smallerRect = CGRectMake(0.0f, 100.0f, 200.0f, 200.0f);

UIBezierPath *maskPath = [UIBezierPath bezierPath];
[maskPath moveToPoint:CGPointMake(CGRectGetMinX(biggerRect), CGRectGetMinY(biggerRect))];
[maskPath addLineToPoint:CGPointMake(CGRectGetMinX(biggerRect), CGRectGetMaxY(biggerRect))];
[maskPath addLineToPoint:CGPointMake(CGRectGetMaxX(biggerRect), CGRectGetMaxY(biggerRect))];
[maskPath addLineToPoint:CGPointMake(CGRectGetMaxX(biggerRect), CGRectGetMinY(biggerRect))];
[maskPath addLineToPoint:CGPointMake(CGRectGetMinX(biggerRect), CGRectGetMinY(biggerRect))];

[maskPath moveToPoint:CGPointMake(CGRectGetMinX(smallerRect), CGRectGetMinY(smallerRect))];
[maskPath addLineToPoint:CGPointMake(CGRectGetMinX(smallerRect), CGRectGetMaxY(smallerRect))];
[maskPath addLineToPoint:CGPointMake(CGRectGetMaxX(smallerRect), CGRectGetMaxY(smallerRect))];
[maskPath addLineToPoint:CGPointMake(CGRectGetMaxX(smallerRect), CGRectGetMinY(smallerRect))];
[maskPath addLineToPoint:CGPointMake(CGRectGetMinX(smallerRect), CGRectGetMinY(smallerRect))];

mask.path = maskPath.CGPath;
[mask setFillRule:kCAFillRuleEvenOdd];
mask.fillColor = [[UIColor blackColor] CGColor];
baseView.layer.mask = mask;

Answer 1

如果您问是否可以 reshape 蒙版而不必每次都绘制路径，很遗憾不能。您可以保持蒙版形状不变，并通过设置 transform 对蒙版执行转换。 CAShapeLayer 的属性，但如果您需要蒙版采用不同的形状，则必须通过创建新路径来绘制该形状。 但是 每次需要更改其形状时，无需从 UIView 中移除 mask 并创建一个全新的 mask 。只需设置 path CAShapeLayer 的属性在它仍然屏蔽 UIView 时足以进行更改:

- (void)remask
{
    CAShapeLayer *mask = (CAShapeLayer *)self.view.layer.mask;

    CGRect biggerRect = CGRectMake(mask.frame.origin.x, mask.frame.origin.y, mask.frame.size.width, mask.frame.size.height);
    CGRect smallerRect = CGRectMake(0.0f, 100.0f, 200.0f, 200.0f);

    UIBezierPath *maskPath = [UIBezierPath bezierPath];
    [maskPath moveToPoint:CGPointMake(CGRectGetMinX(biggerRect), CGRectGetMinY(biggerRect))];
    [maskPath addLineToPoint:CGPointMake(CGRectGetMinX(biggerRect), CGRectGetMaxY(biggerRect))];
    [maskPath addLineToPoint:CGPointMake(CGRectGetMaxX(biggerRect), CGRectGetMaxY(biggerRect))];
    [maskPath addLineToPoint:CGPointMake(CGRectGetMaxX(biggerRect), CGRectGetMinY(biggerRect))];
    [maskPath addLineToPoint:CGPointMake(CGRectGetMinX(biggerRect), CGRectGetMinY(biggerRect))];

    [maskPath moveToPoint:CGPointMake(CGRectGetMinX(smallerRect), CGRectGetMinY(smallerRect))];
    [maskPath addLineToPoint:CGPointMake(CGRectGetMinX(smallerRect), CGRectGetMaxY(smallerRect))];
    [maskPath addLineToPoint:CGPointMake(CGRectGetMaxX(smallerRect), CGRectGetMaxY(smallerRect))];
    [maskPath addLineToPoint:CGPointMake(CGRectGetMaxX(smallerRect), CGRectGetMinY(smallerRect))];
    [maskPath addLineToPoint:CGPointMake(CGRectGetMinX(smallerRect), CGRectGetMinY(smallerRect))];

    mask.path = maskPath.CGPath;
}

附带说明一下，您是否知道，您可以使用以下代码创建 mask 路径，而不是手动绘制每个矩形:

mask = [[CAShapeLayer alloc] init];
mask.frame = baseView.layer.bounds;
CGRect biggerRect = CGRectMake(mask.frame.origin.x, mask.frame.origin.y, mask.frame.size.width, mask.frame.size.height);
CGRect smallerRect = CGRectMake(0.0f, 100.0f, 200.0f, 200.0f);

CGMutablePathRef maskPath = CGPathCreateMutable();
CGPathAddRect(maskPath, NULL, biggerRect);
CGPathAddRect(maskPath, NULL, smallerRect);

mask.path = maskPath;
[mask setFillRule:kCAFillRuleEvenOdd];
mask.fillColor = [[UIColor blackColor] CGColor];
baseView.layer.mask = mask;

CGPathRelease(maskPath);

我想我只是指出来，因为它可能在将来对您有帮助。