如何创建一个C＃的WinForms控制徘徊 [英] How to create a C# Winforms Control that hovers

问题描述

您如何创建一个C＃的WinForms控制，超出该地区的边界？比如一个下拉框。有点像，如果你在一个小尺寸面板有一个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窗体不支持这样的窗户很好，这是pretty的与设计师根本不相容的。下面是一些code，让你开始。您无法使用此控件在设计时，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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