將CAShapeLayer蒙版應用於UIView

Question

我正在使用此代碼將圖層應用於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;

由於我要剪切的矩形發生了變化，我很想知道是否有一種快速的方法來改變蒙版的大小，而不是僅僅從UIview中刪除它並重新應用它的不同尺寸：

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

如果您詢問是否可以重塑面罩而不必每次都畫路徑，不幸的是沒有。 您可以通過設置CAShapeLayer的transform屬性來保持蒙版形狀相同並對蒙版執行變換，但如果需要蒙版采用不同的形狀，則必須通過創建新路徑來繪制該形狀。 但是 ，無需從UIView移除遮罩，並在每次需要更改形狀時創建一個全新的遮罩。 簡單地設置CAShapeLayer的路徑屬性，同時仍然屏蔽UIView就足以進行更改：

- (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;
}

另外，您是否知道不是手動繪制每個矩形，而是使用以下代碼創建蒙版路徑：

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);

我以為我只是指出它，因為它可能對你將來很方便。