为什么我的 CGContext 被剪裁到边界？
我是否应该能够重写 drawInContext() 并在 CALayer 的边界之外进行绘制？即使我的图层的 maskToBounds 设置为 NO（默认值），我的 drawInContext() 也会被调用，并将剪辑设置为我的图层边界，但我无法在其外部进行绘制。
我的测试层做了类似的事情：
-(void)drawInContext:(CGContextRef)context
{
[super drawInContext:context];
NSLog(@"mask to bounds=%d", self.masksToBounds); // NO
CGRect clip = CGContextGetClipBoundingBox(context);
NSLog(@"clip=%f,%f,%f,%f", clip.origin.x, clip.origin.y, clip.size.width, clip.size.height); // reports the bounds
CGContextSetStrokeColorWithColor(context, [[UIColor whiteColor] CGColor]);
CGContextBeginPath(context);
CGContextSetLineWidth(context, 5.0);
CGContextMoveToPoint(context, 0, 0);
CGContextAddLineToPoint(context, 500, 0.0); // wider than my layer...
CGContextStrokePath(context);
}
这是我的设置方式：
- (void)viewDidLoad
{
[super viewDidLoad];
CALayer *layer = [[MyLayer alloc] init];
layer.needsDisplayOnBoundsChange=YES;
layer.frame = CGRectMake(50, 50, 200, 200);
[self.view.layer addSublayer:layer];
}
这只是核心动画层的限制吗？ （我需要在这层之上的图层中绘制吗？）
谢谢。
Should I be able to override drawInContext() and draw outside the bounds of my CALayer? Even though my layer has maskToBounds set to NO (the default) my drawInContext() is called with a clip set to the bounds of my layer and I am unable to draw outside of it.
My test layer does something like this:
-(void)drawInContext:(CGContextRef)context
{
[super drawInContext:context];
NSLog(@"mask to bounds=%d", self.masksToBounds); // NO
CGRect clip = CGContextGetClipBoundingBox(context);
NSLog(@"clip=%f,%f,%f,%f", clip.origin.x, clip.origin.y, clip.size.width, clip.size.height); // reports the bounds
CGContextSetStrokeColorWithColor(context, [[UIColor whiteColor] CGColor]);
CGContextBeginPath(context);
CGContextSetLineWidth(context, 5.0);
CGContextMoveToPoint(context, 0, 0);
CGContextAddLineToPoint(context, 500, 0.0); // wider than my layer...
CGContextStrokePath(context);
}
and here is how I set it up:
- (void)viewDidLoad
{
[super viewDidLoad];
CALayer *layer = [[MyLayer alloc] init];
layer.needsDisplayOnBoundsChange=YES;
layer.frame = CGRectMake(50, 50, 200, 200);
[self.view.layer addSublayer:layer];
}
Is this just a limitation of core animation layers? (Do I need to draw in the layer above this layer?)
thanks.
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图层的内容不可能溢出其边界；但是，您可以通过指定延伸到边界之外的框架并将
masksToBounds属性设置为NO（默认值）来添加溢出的子图层。There is no way for a layer's contents to overflow its bounds; however, you can add a sublayer that overflows by specifying a frame that stretches outside the bounds and setting the
masksToBoundsproperty toNO(the default).