问题描述

我在我的 WinForms 应用程序中使用 OwnerDrawFixed 作为自定义 ListBox 控件的 DrawMode.

I'm using OwnerDrawFixed as a DrawMode for the custom ListBox control in my WinForms app.

当用户将鼠标悬停在列表框项目上时，我想重新绘制 ListBoxItem 的背景(或执行一些其他操作)，即在 MouseMove...

I want to repaint the background (or do some other action) of the ListBoxItem when the user hovers over the listbox item, that is, at the MouseMove...

DrawItemState.HotLight 从不适用于 ListBox，所以我想知道如何模拟它，如何解决这个问题.

DrawItemState.HotLight never works for the ListBox, so i wonder how to emulate it, how to workaround this problem.

推荐答案

我只用了两年的时间才为你找到答案，但这里是:

It took me only two years to find the answer for you, but here it is:

DrawItemState.HotLight 仅适用于所有者绘制的菜单，而不适用于列表框.对于 ListBox，您必须自己跟踪项目:

The DrawItemState.HotLight only applies to owner drawn menus, not the listbox. For the ListBox, you have to keep track of the item yourself:

public partial class Form1 : Form
{
  private int _MouseIndex = -1;

  public Form1()
  { InitializeComponent(); }

  private void listBox1_DrawItem(object sender, DrawItemEventArgs e)
  {
    Brush textBrush = SystemBrushes.WindowText;

    if (e.Index > -1)
    {
      if (e.Index == _MouseIndex)
      {
        e.Graphics.FillRectangle(SystemBrushes.HotTrack, e.Bounds);
        textBrush = SystemBrushes.HighlightText;
      }
      else
      {
        if ((e.State & DrawItemState.Selected) == DrawItemState.Selected)
        {
          e.Graphics.FillRectangle(SystemBrushes.Highlight, e.Bounds);
          textBrush = SystemBrushes.HighlightText;
        }
        else
          e.Graphics.FillRectangle(SystemBrushes.Window, e.Bounds);
      }
      e.Graphics.DrawString(listBox1.Items[e.Index].ToString(), e.Font, textBrush, e.Bounds.Left + 2, e.Bounds.Top);
    }
  }

  private void listBox1_MouseMove(object sender, MouseEventArgs e)
  {
    int index = listBox1.IndexFromPoint(e.Location);
    if (index != _MouseIndex)
    {
      _MouseIndex = index;
      listBox1.Invalidate();
    }
  }

  private void listBox1_MouseLeave(object sender, EventArgs e)
  {
    if (_MouseIndex > -1)
    {
      _MouseIndex = -1;
      listBox1.Invalidate();
    }
  }
}

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