Sibling NSView在可可中的z顺序 [英] Sibling NSView z-ordering in Cocoa

问题描述

z-ordering如何在Cocoa中使用sibling NSViews？我很困惑，因为我在Apple的文档和API中发现了冲突的信息来源。 （注意：子视图显然是在其父视图之上显示的，我在这里明确谈到兄弟视图。）

How does z-ordering work with sibling NSViews in Cocoa? I'm confused because I'm finding conflicting sources of information in Apple's docs and APIs. (Note: Subviews are obviously rendered on top of its parent view, I am talking explicitly about sibling views here).

假设A ：是，您可以定义同级的z顺序 NSViews

• 在 IB 中，您可以将视图叠加在一起，而且它们将始终以您期望的方式进行合成。


• Xcode中的编辑器菜单中有一些按钮，名为发送回，发送转发等。


• NSView 也有一个名为 - （void）addSubview：（NSView *）aView的方法：（NSWindowOrderingMode）place relativeTo：（NSView *）otherView; 这似乎暗示着有一个明确的排序。

• In IB you can place views on top of each other and they will always be composited in the way you'd expect.
• There's buttons in Xcode under the Editor menu named "Send to Back", "Send Forward" etc.
• The NSView also has a method named - (void)addSubview:(NSView *)aView positioned:(NSWindowOrderingMode)place relativeTo:(NSView *)otherView; which seems to imply that there is a well defined ordering.

假设B ：没有办法，兄弟的z顺序 NSViews 在运行时是未定义的，有时它工作，有时它不工作，不信任它！

Hypothesis B: "No way, z-order of sibling NSViews is undefined at runtime. Sometimes it works, sometimes it doesn't. Don't trust it!"

• Apple的文档（查看编程指南）state：出于性能原因，Cocoa不会强制在同级视图中进行剪裁，或者在同级视图重叠时保证正确的无效和绘制行为。如果您想在另一个视图前绘制视图，则应该将前视图设置为后视图的子视图（或后代）。

• Apple's Docs (View Programming guide) state: For performance reasons, Cocoa does not enforce clipping among sibling views or guarantee correct invalidation and drawing behavior when sibling views overlap. If you want a view to be drawn in front of another view, you should make the front view a subview (or descendant) of the rear view.

那么这是什么呢？

推荐答案

是的，NSView兄弟 允许重叠，Apple文档已过期：

Yes, NSView siblings are allowed to overlap, the Apple docs are out of date: Are layer-backed NSView siblings allowed to overlap?

此外，z顺序取决于子视图在父视图的<$ c $中的顺序c> subviews 数组。

Also, the z-order depends on the order of the subviews in the parent view's subviews array.

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