c# - 设置焦点的wpf问题

Question

嗨我无法将焦点放在控制的父级上。我有一个放在 Canvas 上的控件。如果我单击该控件，我需要将焦点设置在 Canvas 上以处理一些键盘事件。然而，尽管事实上我正试图像那样设置焦点

 protected override void OnPreviewMouseDown(MouseButtonEventArgs e)
        {
            base.OnPreviewMouseDown(e);
           Canvas designer = VisualTreeHelper.GetParent(this) as Canvas;
          designer.Focus() ;//this doesn't work
           Keyboard.Focus(designer); //this also doesn't work


        }

不会触发附加到 Canvas 的键盘事件。

Answer 1

确保 Canvas 有 Focusable和 IsEnabled都设置为真。没有那个，Focus()将失败。来自 Focus()文档:

To be focusable, Focusable and IsEnabled must both be true.

此外，由于您是在 PreviewMouseDown 事件中执行此操作，因此您可能需要按如下方式修改您的方法:

 protected override void OnPreviewMouseDown(MouseButtonEventArgs e)
 {
     Canvas designer = VisualTreeHelper.GetParent(this) as Canvas;
     designer.Focus() ;//this doesn't work
     Keyboard.Focus(designer); //this also doesn't work

     // Just in case something else is changing your focus as a result of a mouse event...
     e.Handled = true;
     base.OnPreviewMouseDown(e);
 }