在层主机视图上调用setNeedsDisplay：YES不会重绘视图 [英] Calling setNeedsDisplay:YES on layer-hosting view does not redraw the view

问题描述

我在自定义的 NSView 子类中设置了一个层主机视图：

  [self setLayer：rootLayer]; 
 [self setWantsLayer：YES]; 
 

我在调用 setNeedsDisplay 之后将所有子图层添加到图层树中。 code>每个子图层。每一层的内容都是由我的层的委托的 drawLayer：inContext 方法提供的。

这里是我的问题： / p>

初始化我的视图后，视图绘制正确。但是，当模型改变，我调用 [myCustomView setNeedsDisplay：YES]; 从我的视图控制器 drawLayer：inContext

现在我很困惑如何更新视图：

• 我必须在图层树中的每个CALayer上调用 setNeedsDisplay 方法吗？


• $ c> setNeedsDisplay：YES 在层托管视图本身触发整个图层树的重绘？

感谢您的帮助。

编辑

NSView类引用

基于layer的视图是一个由Core Animation层支持的视图。视图执行的任何绘图都在缓存在后台层中。您通过简单地调用setWantsLayer：值为YES来配置基于图层的视图。视图类将自动为您创建一个背景层，并使用视图类的绘图机制。使用分层视图时，您不应该直接与该图层进行交互。

图层托管视图是一个视图，包含您要直接操作的Core Animation图层。您可以通过实例化Core Animation图层类的实例并使用视图的setLayer：方法设置该层来创建层托管视图。在这样做后，然后调用setWantsLayer：值为YES。在使用图层托管视图时，您不应该依赖视图进行绘制，也不应该将图层添加到图层托管视图。

指向文档的链接

在我的例子中，我有一个层主机视图。这是否意味着我必须手动触发重绘？我应该在自定义NSView中实现一个伪drawRect方法来调用在更改的CALayers上的相应setNeedsDisplay？

解决方案

在Apple的示例代码中kiosk样式菜单我发现，如果你使用一个层主机视图，你必须照顾到屏幕更新，这是必要的，由于模型更改自己。调用NSView上的 setNeedsDisplay：YES 将不会做任何事情。

更新一个视图，应该写一个像reloadData这样的方法，并且在每个需要刷新的CALayer上调用 setNeedsDisplay 。我仍然不确定如果在根层调用这个方法将传播通过所有的孩子层，但我不这么认为。

我解决了现在的问题在需要重新缓存的单个CALayers上调用 setNeedsDisplay 。它工作没有问题。

I have a layer-hosting view set up like this in a custom NSView subclass:

[self setLayer:rootLayer];
[self setWantsLayer:YES];

I add all the sublayers to the layer tree after I called setNeedsDisplay on each sublayer. Each layer's content is provided by a drawLayer:inContext method of my layer's delegate.

Here is my problem:

After initializing my view the view gets draw correctly. However, when the model has changed and I call [myCustomView setNeedsDisplay:YES]; from my view controller the drawLayer:inContext is not called.

I am confused now how to update the view:

• Do I have to call the setNeedsDisplay method on each CALayer in the layer tree?
• Should not the call of setNeedsDisplay:YES on the layer-hosting view itself trigger the redraw of the whole layer tree?

Thanks for your help.

Edit

I have found something in the NSView Class reference

A layer-backed view is a view that is backed by a Core Animation layer. Any drawing done by the view is the cached in the backing layer. You configured a layer-backed view by simply invoking setWantsLayer: with a value of YES. The view class will automatically create the a backing layer for you, and you use the view class’s drawing mechanisms. When using layer-backed views you should never interact directly with the layer.

A layer-hosting view is a view that contains a Core Animation layer that you intend to manipulate directly. You create a layer-hosting view by instantiating an instance of a Core Animation layer class and setting that layer using the view’s setLayer: method. After doing so, you then invoke setWantsLayer: with a value of YES. When using a layer-hosting view you should not rely on the view for drawing, nor should you add subviews to the layer-hosting view.

link to documentation

In my case I have a layer-hosting view. So does that indeed mean that I have to trigger the redraw manually? Should I implement a pseudo drawRect method in the custom NSView to call the appropriate setNeedsDisplay on the CALayers that changed?

解决方案

After further research in Apple's sample code of a kiosk-style menu I found out that if you are using a layer-hosting view, you have to take care of the screen updates which are neccessary due to model changes yourself. Calling setNeedsDisplay:YES on the NSView will not do anything.

So what one has to do if one has to update a view one should write a method like reloadData and in it one should call setNeedsDisplayon each CALayer that needs a refresh. I am still not sure if a call to this method on the root layer will propagate through all the children layers but I do not think so.

I solved the problem now by calling setNeedsDisplay on the individual CALayers that needed recaching. It works without problems.

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