Her er et eksempel til .NET 2.0, det skal måske tilpasses lidt hvis du skal bruge det i ver 1.1.
using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;
using System.Drawing;
namespace ComboTest
{
/// <summary>
/// An extended combobox with a working paint event
/// </summary>
class ComboBoxEx : ComboBox
{
/// <summary>
/// Constructor
/// </summary>
public ComboBoxEx()
{
this.DrawMode = DrawMode.OwnerDrawFixed;
this.DrawItem += new DrawItemEventHandler(ComboBoxEx_DrawItem);
this.Paint += new PaintEventHandler(ComboBoxEx_Paint);
}
/// <summary>
/// Handles the paint event
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void ComboBoxEx_Paint(object sender, PaintEventArgs e)
{
Graphics g = e.Graphics;
Rectangle rect = ClientRectangle;
rect.X = rect.Right - 25;
g.FillRectangle(Brushes.Navy, rect);
}
/// <summary>
/// Draw one item in the drop-down
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void ComboBoxEx_DrawItem(object sender, DrawItemEventArgs e)
{
Graphics g = e.Graphics;
e.DrawBackground();
float w = 2;
if (e.State == DrawItemState.Selected)
w += 3;
Pen p = new Pen(e.ForeColor,w);
g.DrawRectangle(p, e.Bounds);
PointF pos = new PointF(e.Bounds.X + w + 1, e.Bounds.Y + w);
g.DrawString(Items[e.Index].ToString(), e.Font, new SolidBrush(e.ForeColor), pos);
}
/// <summary>
/// Overrides WndProc to provide a functioning Paint event in ComboBox
/// </summary>
/// <param name="m"></param>
protected override void WndProc(ref Message m)
{
base.WndProc(ref m);
if (m.Msg == WM_PAINT)
{
// fake a Paint event
using (Graphics g = this.CreateGraphics())
{
PaintEventArgs pea = new PaintEventArgs(this.CreateGraphics(), this.ClientRectangle);
OnPaint(pea);
}
}
}
/// <summary>
/// Message WM_PAINT
/// </summary>
private const int WM_PAINT = 15;
}
}
