确定是否绘制NSView的正确方法

问题描述：

是否有正确的方法来确定 NSView 是否实际绘制在当前视图层次结构中，考虑以下情况：

Is there a proper way to determine if a NSView is actually drawn in the current view hierarchy or not, considering cases like:

视图完全在屏幕外（不是强制性的）

视图不在视图层次结构顶部

不幸的是， -isHidden 和 -isHiddenOrHasHiddenAncestor 不设置时一个视图消失，因为一个标签视图切换到另一个标签。

The -isHidden and -isHiddenOrHasHiddenAncestor are unfortunately not set when e.g. a view disappears because a tab view switches to another tab.

这是因为我有一个附加的子窗口，我想能够隐藏它

The reason for this is that I have an attached child window and I would like to be able to hide it as well when the view that it is attached to is not drawn.

答

我发现了一个技巧来判断它是否可见，但它需要子类化。它通过在2个事件上切换一个ivar来工作。

I have found a trick to tell if it is visible, but it requires subclassing. It works by toggling an ivar on 2 events.

- (void)discardCursorRects {
  isDrawn_ = NO;
  [super discardCursorRects];
}

- (void)resetCursorRects {
  isDrawn_ = YES;
  [super resetCursorRects];
}

确定是否绘制NSView的正确方法

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