如何创建悬停的 C# Winforms 控件 [英] How to create a C# Winforms Control that hovers

问题描述

如何创建超出其区域边界的 C# Winforms 控件?比如下拉框.有点像你在小面板中有一个 DropDownBox.

How can you create a C# Winforms control which goes out of the bounds of its region? Such as a drop down box. Kind of like if you had a DropDownBox in a Small Sized Panel.

推荐答案

Windows Forms 不能很好地支持 Windows，它与设计器从根本上不兼容.这里有一些代码可以帮助您入门.您不能在设计器中使用此控件，它必须在运行时创建.您还必须自己调用它的 Dispose() 方法.

Windows Forms doesn't support windows like that well, it is pretty fundamentally incompatible with the designer. Here's some code to get you started. You can't use this control in the designer, it must be created at run-time. You also must call its Dispose() method yourself.

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

public class MyListBox : ListBox {
  private Control mParent;
  private Point mPos;
  private bool mInitialized;

  public MyListBox(Control parent) {
    mParent = parent;
    mInitialized = true;
    this.SetTopLevel(true);
    parent.LocationChanged += new EventHandler(parent_LocationChanged);
    mPos = mParent.Location;
  }

  public new Point Location {
    get { return mParent.PointToClient(this.Location); }
    set { 
      Point zero = mParent.PointToScreen(Point.Empty);
      base.Location = new Point(zero.X + value.X, zero.Y + value.Y);
    }
  }

  protected override Size DefaultSize {
    get {
      return mInitialized ? base.DefaultSize : Size.Empty;
    }
  }

  protected override void SetBoundsCore(int x, int y, int width, int height, BoundsSpecified specified) {
    if (this.mInitialized)
      base.SetBoundsCore(x, y, width, height, specified);
  }

  void parent_LocationChanged(object sender, EventArgs e) {
    base.Location = new Point(base.Left + mParent.Left - mPos.X, base.Top + mParent.Top - mPos.Y);
    mPos = mParent.Location;
  }

  protected override CreateParams CreateParams {
    get {
      CreateParams cp = base.CreateParams;
      if (mParent != null && !DesignMode) {
        cp.Style = (int)(((long)cp.Style & 0xffff) | 0x90200000);
        cp.Parent = mParent.Handle;
        Point pos = mParent.PointToScreen(Point.Empty);
        cp.X = pos.X;
        cp.Y = pos.Y;
        cp.Width = base.DefaultSize.Width;
        cp.Height = base.DefaultSize.Height;
      }
      return cp;
    }
  }
}

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