小组没有得到关注

Question

我将继续在我的简单图形程序(使用C#)中编程某种键盘导航.我又一次陷入困境.

我的问题是我想处理键盘输入以移动图层.使用鼠标移动图层已经很好地工作了,但控件没有得到焦点(此控件都没有触发KeyUp/KeyDown/KeyPress和GotFocus/LostFocus).由于我的类派生自Panel(并覆盖了几个事件),我也覆盖了上面提到的事件,但是我无法成功触发这些事件.

我想我可以设法使用Keyboard.GetState()或ProcessCmdWnd之类的东西来实现键盘响应.但是:我仍然必须知道控件何时得到关注.

是否有一种或多或少的优雅方式将此功能添加到用户控件(基于Panel)？

我在这里检查了很多线程,我可能会使用这种方法进行键盘输入.然而,焦点问题仍然存在.

非常感谢您提前获取信息!

伊戈尔.

ps:我使用VS2008在C#.NET v3.5中编程.它是Windows.Forms应用程序,而不是WPF.

Answer 1

Panel类被设计为容器,它避免了焦点,因此子控件将始终获得它.你需要一些手术来解决这个问题.我投入代码以获取KeyDown事件中的光标键击:

using System;
using System.Drawing;
using System.Windows.Forms;

class SelectablePanel : Panel {
    public SelectablePanel() {
        this.SetStyle(ControlStyles.Selectable, true);
        this.TabStop = true;
    }
    protected override void OnMouseDown(MouseEventArgs e) {
        this.Focus();
        base.OnMouseDown(e);
    }
    protected override bool IsInputKey(Keys keyData) {
        if (keyData == Keys.Up || keyData == Keys.Down) return true;
        if (keyData == Keys.Left || keyData == Keys.Right) return true;
        return base.IsInputKey(keyData);
    }
    protected override void OnEnter(EventArgs e) {
        this.Invalidate();
        base.OnEnter(e);
    }
    protected override void OnLeave(EventArgs e) {
        this.Invalidate();
        base.OnLeave(e);
    }
    protected override void OnPaint(PaintEventArgs pe) {
        base.OnPaint(pe);
        if (this.Focused) {
            var rc = this.ClientRectangle;
            rc.Inflate(-2, -2);
            ControlPaint.DrawFocusRectangle(pe.Graphics, rc);
        }
    }
}

Answer 2

VB.NET中的Hans Passant代码相同

Imports System
Imports System.Drawing
Imports System.Windows.Forms

Public Class SelectablePanel
    Inherits Panel

    Public Sub SelectablePanel()
        Me.SetStyle(ControlStyles.Selectable, True)
        Me.TabStop = True
    End Sub

    Protected Overrides Sub OnMouseDown(ByVal e As MouseEventArgs)
        Me.Focus()
        MyBase.OnMouseDown(e)
    End Sub

    Protected Overrides Function IsInputKey(ByVal keydata As Keys) As Boolean
        If (keydata = Keys.Up OrElse keydata = Keys.Down) Then Return True
        If (keydata = Keys.Left OrElse keydata = Keys.Right) Then Return True
        Return MyBase.IsInputKey(keydata)
    End Function

    Protected Overrides Sub OnEnter(ByVal e As EventArgs)
        Me.Invalidate()
        MyBase.OnEnter(e)
    End Sub

    Protected Overrides Sub OnLeave(ByVal e As EventArgs)
        Me.Invalidate()
        MyBase.OnLeave(e)
    End Sub

    Protected Overrides Sub OnPaint(ByVal pe As PaintEventArgs)
        MyBase.OnPaint(pe)
        If (Me.Focused) Then
            Dim rc As Rectangle = Me.ClientRectangle
            rc.Inflate(-2, -2)
            ControlPaint.DrawFocusRectangle(pe.Graphics, rc)
        End If
    End Sub

End Class