将焦点放在 WPF 中的自定义（用户）控件上

Question

比如说，我需要使用键盘在表单中移动自定义（用户）控件。

行为很简单：用户单击控件，然后可以使用键盘移动它（向上/d/l/r）。

在此示例中，我将使用 Canvas，而不是 UserControl。

问题是，当我“聚焦”我的控件时，或者在文本框的一系列“步骤”之后我失去了它，或者我根本没有收到它......

XAML：

<Window x:Class="WpfApplication14.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525"
        PreviewKeyDown="Window_PreviewKeyDown">
    <Grid>
        <TextBox Name="textBox1" 
                 Margin="91,66,292,223" Width="120" 
                 Text="Good morning, miss Hilton!"/>
        <Canvas Name="canvas1" Focusable="True"
                Margin="124,112,179,99" Width="200"
                Background="AliceBlue"
                MouseDown="canvas1_MouseDown"
                PreviewKeyDown="canvas1_PreviewKeyDown"  />
    </Grid>
</Window>

CS：

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void canvas1_MouseDown(object sender, MouseButtonEventArgs e)
    {
        Console.WriteLine("canvas_MouseDown 0, canvas1.IsFocused? {0}",
            canvas1.IsFocused);

        canvas1.Focus();

        Console.WriteLine("canvas_MouseDown 1, canvas1.IsFocused? {0}",
            canvas1.IsFocused);
    }

    private void canvas1_PreviewKeyDown(object sender, KeyEventArgs e)
    {
        Console.WriteLine("canvas_PreviewKeyDown, canvas1.IsFocused? {0}",
            canvas1.IsFocused);

        if (canvas1.IsFocused)
            MoveCanvas(e.Key);
    }

    private void Window_PreviewKeyDown(object sender, KeyEventArgs e)
    {
        //Console.WriteLine("Window_PreviewKeyDown, canvas1.IsFocused? {0}",
        //    canvas1.IsFocused);

        //if (canvas1.IsFocused)
        //    MoveCanvas(e.Key);
    }

    void MoveCanvas(Key key)
    {
        int delta = 10;
        switch (key)
        {
            case Key.Left: canvas1.Margin = new Thickness(
                canvas1.Margin.Left - delta,
                canvas1.Margin.Top,
                canvas1.Margin.Right,
                canvas1.Margin.Bottom);
                break;
            case Key.Up: canvas1.Margin = new Thickness(
                canvas1.Margin.Left,
                canvas1.Margin.Top - delta,
                canvas1.Margin.Right,
                canvas1.Margin.Bottom + delta);
                break;
            case Key.Right: canvas1.Margin = new Thickness(
                canvas1.Margin.Left,
                canvas1.Margin.Top,
                canvas1.Margin.Right - delta,
                canvas1.Margin.Bottom);
                break;
            case Key.Down: canvas1.Margin = new Thickness(
                canvas1.Margin.Left,
                canvas1.Margin.Top + delta,
                canvas1.Margin.Right,
                canvas1.Margin.Bottom - delta);
                break;
            default:
                break;
        }
    }
}

贝娄是鼠标后的执行日志按下控件和三个“keyUp”：

   canvas_MouseDown 0, canvas1.IsFocused? False ' before click '
   canvas_MouseDown 1, canvas1.IsFocused? True  ' after click ' 
Window_PreviewKeyDown, canvas1.IsFocused? True  ' up 1 '
canvas_PreviewKeyDown, canvas1.IsFocused? True  ' up 1 '
Window_PreviewKeyDown, canvas1.IsFocused? False ' up 2 '
Window_PreviewKeyDown, canvas1.IsFocused? False ' up 3 '

Answer 1

您可以尝试以下两件事：

1. 如果您正在处理事件，请将 e.Handled 设置为 true。这应该可以防止其他事件对击键做出反应。

2. 您可能需要使用 所有祖先控件上的 KeyboardNavigation.DirectionalNavigation 设置。默认情况下，箭头键将移动键盘焦点，但这基于 DirectionalNavigation 设置。您希望将其设置为“无”，但这假设#1 无法解决问题。