[英]CALayer renderInContext: Position of Drawing
I have a UIView
with a custom shape drawn in drawRect:
. 我有一个
UIView
其中包含在drawRect:
绘制的自定义形状drawRect:
。 The frame
property is set to: frame
属性设置为:
{5.f, 6.f, 50.f, 50.f}
Now, I render the view in an Image Context, but it is ignoring the frame property of the UIView
, and always drawing the UIView
in the top left. 现在,我在图像上下文中渲染视图,但它忽略了
UIView
的frame属性,并且始终在左上角绘制UIView
。
[_shapeView.layer renderInContext:UIGraphicsGetCurrentContext()];
I tried to change the frame
of the CALayer
, but nothing changed. 我试图更改
CALayer
的frame
,但没有任何改变。 Modifying the bounds
property made things worse. 修改
bounds
属性会让事情变得更糟。 The only work around I found useful was: 我发现有用的唯一工作是:
CGRect frame = _shapeView.frame;
CGContextTranslateCTM(context, frame.origin.x, frame.origin.y);
[_shapeView.layer renderInContext:context];
But, this is impractical when I am dealing with many shapes, I want to just use the frame property. 但是,当我处理许多形状时,这是不切实际的,我想只使用frame属性。
Using CGContextTranslateCTM
is the proper way to go. 使用
CGContextTranslateCTM
是正确的方法。 As renderInContext:
documentation states : "Renders in the coordinate space of the layer." 作为
renderInContext:
documentation说明:“在图层的坐标空间中渲染”。 This means the frame origin of your layer/view is ignored. 这意味着将忽略图层/视图的框架原点。
Regarding CGContextDrawLayer
, it is not made to be used with CALayer
, but with CGLayer
. 关于
CGContextDrawLayer
,它不能与CALayer
一起使用,而是与CGLayer
一起CGLayer
。 These are two very different things, and explains your crash. 这是两个截然不同的事情,并解释了你的崩溃。
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