问题描述

我将继续在我的简单图形程序(使用 C#)中编写某种键盘导航.我又遇到了麻烦.

I am continuing to program some kind of keyboard navigation in my simple graphic program (using C#). And I ran into trouble once again.

我的问题是我想处理键盘输入以移动图层.用鼠标移动图层已经很好用了，但是控件没有获得焦点(KeyUp/KeyDown/KeyPress 和 GotFocus/LostFocus 都没有为此控件触发).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，但我无法成功触发这些事件.

My problem is that I want to process the keyboard input to move a layer around. Moving the layer with the mouse already works quite well, yet the control doesn't get the focus (neither KeyUp/KeyDown/KeyPress nor GotFocus/LostFocus is triggered for this control). Since my class derives from Panel (and overwrites a couple of events), I've also overwritten the events mentioned above, but I can't succeed in getting those events triggered.

我想我可以使用 Keyboard.GetState() 或 ProcessCmdWnd 之类的东西来实现键盘响应.但是:我仍然必须能够判断控件何时获得焦点.

I think I could manage to implement keyboard response either using something like Keyboard.GetState() or ProcessCmdWnd or something. However: I still have to be able to tell when the control got the focus.

是否有或多或少优雅的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 这种方法用于键盘输入.然而，焦点问题仍然存在.

I've checked many threads in here and I might use this approach for keyboard input. The focus problem however still remains.

非常感谢您提前提供信息！

Thank you very much for information in advance!

伊戈尔.

p.s.:我正在使用 VS2008 在 C# .NET v3.5 中编程.这是一个 Windows.Forms 应用程序，不是 WPF.

p.s.: I am programming in C# .NET v3.5, using VS2008. It's a Windows.Forms application, not WPF.

推荐答案

Panel 类被设计为容器，它避免了获取焦点，因此子控件将始终获取它.你需要做一些手术来解决这个问题.我还在 KeyDown 事件中输入了代码以获取光标击键:

The Panel class was designed as container, it avoids taking the focus so a child control will always get it. You'll need some surgery to fix that. I threw in the code to get cursor key strokes in the KeyDown event as well:

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);
        }
    }
}

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