如何确定一个控制的知名度？ [英] How do I determine visibility of a control?

问题描述

我有一个<一个href="http://msdn.microsoft.com/en-us/library/system.windows.forms.tabcontrol.aspx"><$c$c>TabControl包含几个选项卡。每个标签都有一个<一个href="http://msdn.microsoft.com/en-us/library/system.windows.forms.usercontrol.aspx"><$c$c>UserControl在上面。我想检查的控制 X 在用户控件 A 从用户控件 B 。我想，做 x.Visible 从用户控件 B 会不够好。事实证明，这是展示假中，即使我明确地将它设置为调试器真，这是从来没有改变。然后我读MSDN上的<一个href="http://msdn.microsoft.com/en-us/library/system.windows.forms.control.visible.aspx">Control.Visible即：

I have a TabControl that contains several tabs. Each tab has one UserControl on it. I would like to check the visibility of a control x on UserControl A from UserControl B. I figured that doing x.Visible from UserControl B would be good enough. As it turns out, it was displaying false in the debugger even though I set it explicitly to true and it was never changed. Then I read on MSDN for Control.Visible that:

即使可见被设置为true，控制可能是不可见的用户，如果它是模糊其他控件的后面。

Even if Visible is set to true, the control might not be visible to the user if it is obscured behind other controls.

所以，出乎我的意料，这是行不通的。现在我想知道我怎么能告诉如果控制 X 可见从不同的用户控件。我想避免使用布尔如果可能的话。有没有人遇到这个，发现一个解决办法？

So much to my surprise, that will not work. Now I'm wondering how I can tell if the control x is visible from a different UserControl. I would like to avoid using a boolean if possible. Has anyone run into this and found a solution?

请注意：它也出现了 Control.IsAccessible 为假在这种情况下

Note: It also appears that Control.IsAccessible is false in this situation.

推荐答案

不幸的是，控制不提供任何市民，可以让你检查一下。

Unfortunately the control doesn't provide anything public that will allow you to check this.

一种可能性是设置一些在控制标签属性。标签的用途是将用户数据与控制关联。因此，它可以是任何东西不仅仅是一个布尔值。

One possibility would be to set something in the controls 'Tag' property. The tag’s purpose is to associate user data with the control. So it can be anything not just a boolean.

这里是标记属性DOC

如果你真的想要的强制方法，您可以使用反射，基本要求GETSTATE（2）：

If you really want the brute force way, you can use Reflection, basically calling GetState(2):

public static bool WouldBeVisible(Control ctl) 
{
      // Returns true if the control would be visible if container is visible
      MethodInfo mi = ctl.GetType().GetMethod("GetState", BindingFlags.Instance | BindingFlags.NonPublic);
      if (mi == null) return ctl.Visible;
      return (bool)(mi.Invoke(ctl, new object[] { 2 }));
}

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