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我想为路径添加发光效果，例如（OS X）界面元素具有焦点时周围的蓝色发光。

我使用了带有（矩形）路径的 CAShapeLayer：

self.borderLayer = [CAShapeLayer layer];
CGPathRef path = CGPathCreateWithRect(self.bounds, NULL);
[self.borderLayer setPath:path];
CGPathRelease(path);

最后，这给了我一个透明的 UIView，周围有一个边框。（在我的具体情况下，它是一条带有附加动画的虚线，但这对于这个特定问题并不重要）

我玩过 CALayer 的阴影属性，但它们总是会填满整个图层。

self.borderLayer.shadowPath = self.borderLayer.path;
self.borderLayer.shouldRasterize = YES;

我想要的是只有 UIViews 周围的线会投下阴影，以便 UIView 的内部保持透明。

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2 回答 2

3

我在看到我想要的阴影而不是发光的地方时遇到了类似的问题。我通过使用两个 CALayers 解决了它。一，在代码中，“_bg”作为背景（在我的例子中为黑色，不透明度为 0.55）和白色边框。代码“_shadow”中的另一层具有清晰的背景并添加了发光效果。_bg 是 _shadow 层的子视图。以下是相关代码：

_bg = [CALayer layer];
_shadow = [CALayer layer];

[self.layer insertSublayer:_shadow atIndex:0];
[_shadow addSublayer:_bg];

_bg.frame = self.bounds;
_bg.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:.55].CGColor;
_bg.cornerRadius=20.0;
_bg.borderColor=[UIColor whiteColor].CGColor;
_bg.borderWidth=2.0;

_shadow.frame=self.bounds;
_shadow.masksToBounds=NO;
_shadow.backgroundColor = [UIColor clearColor].CGColor;
_shadow.cornerRadius=3.0;
_shadow.shadowRadius=3.0;
_shadow.shadowColor=[UIColor whiteColor].CGColor;
_shadow.shadowOpacity=0.6;
_shadow.shadowOffset=CGSizeMake(0.0, 0.0);
于 2013-05-08T16:18:33.310 回答
2

你可以试试这样：</p> 

    //background layer of the shadow layer
    contentViewBackgroundLayer = [CALayer layer];
    contentViewBackgroundLayer.frame = contentView.bounds;
    contentViewBackgroundLayer.backgroundColor = someColor.CGColor;
    //shadow layer
    contentViewShadowLayer = [CALayer layer];
    [contentViewShadowLayer addSublayer:contentViewBackgroundLayer];
    contentViewShadowLayer.backgroundColor = [UIColor clearColor].CGColor;
    //shadowRadius
    contentViewShadowLayer.shadowRadius = 10.0;
    contentViewShadowLayer.shadowColor = [UIColor blackColor].CGColor;
    contentViewShadowLayer.shadowOpacity = 0.5;
    contentViewShadowLayer.shadowOffset = CGSizeMake(0.0, 0.0);
    //Important!!!!  add mask to shadowLayer
    contentViewBackgroundLayer.frame = contentView.bounds;
    contentViewShadowLayer.frame = contentView.bounds;
    CGRect rect = CGRectMake(contentViewShadowLayer.bounds.origin.x - 20, contentViewShadowLayer.bounds.origin.y - 20, contentViewShadowLayer.bounds.size.width + 40, contentViewShadowLayer.bounds.size.height + 40);
    UIBezierPath *path = [UIBezierPath bezierPathWithRect:rect];
    [path appendPath:[UIBezierPath bezierPathWithRect:CGRectMake(0, 0, contentView.bounds.size.width, contentView.bounds.size.height)]];
    //a rectangle which is transparent surrounded by a bigger rectangle
    CAShapeLayer *shapeLayer = [CAShapeLayer layer];
    shapeLayer.fillRule = kCAFillRuleEvenOdd;
    shapeLayer.path = [path CGPath];
    contentViewShadowLayer.mask = shapeLayer;
    [contentView.layer insertSublayer:contentViewShadowLayer atIndex:0];
于 2015-02-04T13:05:32.557 回答