效果如下图，本人网上搜索资料加上自己的研究终于实现了在combobox子项中加上删除按钮。
一、窗体中的代码：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Drawing.Drawing2D; namespace ComboBoxEx
{
public partial class Form1 : Form
{
[DllImport("user32")]
private static extern int GetComboBoxInfo(IntPtr hwnd, out COMBOBOXINFO comboInfo);
struct RECT
{
public int left, top, right, bottom;
}
struct COMBOBOXINFO
{
public int cbSize;
public RECT rcItem;
public RECT rcButton;
public int stateButton;
public IntPtr hwndCombo;
public IntPtr hwndItem;
public IntPtr hwndList;
}
private void Form1_Load(object sender, EventArgs e)
{
comboBox1.DrawMode = DrawMode.OwnerDrawFixed;
comboBox1.Items.Add(new comboItem("sgset", pictureBox1.Image));
comboBox1.Items.Add(new comboItem("sdgsdg", pictureBox1.Image));
comboBox1.Items.Add(new comboItem("sdgsdg", pictureBox1.Image));
}
public Form1()
{
InitializeComponent();
comboBox1.HandleCreated += (s, e) =>
{
COMBOBOXINFO combo = new COMBOBOXINFO();
combo.cbSize = Marshal.SizeOf(combo);
GetComboBoxInfo(comboBox1.Handle, out combo);
hwnd = combo.hwndList;
init = false;
};
}
bool init;
IntPtr hwnd;
NativeCombo nativeCombo = new NativeCombo();
//This is to store the Rectangle info of your Icons
//Key: the Item index
//Value: the Rectangle of the Icon of the item (not the Rectangle of the item)
Dictionary<int, Rectangle> dict = new Dictionary<int, Rectangle>();
public class NativeCombo : NativeWindow
{
//this is custom MouseDown event to hook into later
public event MouseEventHandler MouseDown;
protected override void WndProc(ref Message m)
{
if (m.Msg == 0x201)//WM_LBUTTONDOWN = 0x201
{
int x = m.LParam.ToInt32() & 0x00ff;
int y = m.LParam.ToInt32() >> ;
if (MouseDown != null) MouseDown(null, new MouseEventArgs(MouseButtons.Left, , x, y, ));
}
base.WndProc(ref m);
}
}
private void comboBox1_DrawItem(object sender, DrawItemEventArgs e)
{ if ((e.State & DrawItemState.Selected) != )//鼠标选中在这个项上
{
//渐变画刷
LinearGradientBrush brush = new LinearGradientBrush(e.Bounds, Color.FromArgb(, , ),
Color.FromArgb(, , ), LinearGradientMode.Vertical);
//填充区域
Rectangle borderRect = new Rectangle(, e.Bounds.Y, e.Bounds.Width, e.Bounds.Height - );
e.Graphics.FillRectangle(brush, borderRect);
//画边框
Pen pen = new Pen(Color.FromArgb(, , ));
e.Graphics.DrawRectangle(pen, borderRect);
}
else
{
SolidBrush brush = new SolidBrush(Color.FromArgb(, , ));
e.Graphics.FillRectangle(brush, e.Bounds);
}
//获得项图片,绘制图片
comboItem item = (comboItem)comboBox1.Items[e.Index];
Image img = item.Img; //图片绘制的区域
Rectangle imgRect = new Rectangle(e.Bounds.Width - , e.Bounds.Y, , );
dict[e.Index] = imgRect;
if (img != null && (e.State & DrawItemState.Selected) != )
{
e.Graphics.DrawImage(img, imgRect);
}
Rectangle textRect =
new Rectangle(, imgRect.Y, e.Bounds.Width - imgRect.Width, e.Bounds.Height + );
string itemText = comboBox1.Items[e.Index].ToString();
StringFormat strFormat = new StringFormat();
strFormat.LineAlignment = StringAlignment.Center;
e.Graphics.DrawString(itemText, new Font("宋体", ), Brushes.Black, textRect, strFormat); } private void comboBox1_DropDown(object sender, EventArgs e)
{
if (!init)
{
//Register the MouseDown event handler <--- THIS is WHAT you want.
nativeCombo.MouseDown += comboListMouseDown;
nativeCombo.AssignHandle(hwnd);
init = true;
}
} //This is the MouseDown event handler to handle the clicked icon
private void comboListMouseDown(object sender, MouseEventArgs e)
{
foreach (var kv in dict)
{
if (kv.Value.Contains(e.Location))
{
//Show the item index whose the corresponding icon was held down
MessageBox.Show(kv.Key.ToString());
return;
}
}
}
}
}
二、子项辅助类
using System;
using System.Collections.Generic;
using System.Text;
using System.Drawing; namespace ComboBoxEx
{
public class comboItem : object
{
private Image img = null;
private string text = null; public comboItem()
{ } public comboItem(string text)
{
Text = text;
} public comboItem(string text,Image img)
{
Text = text;
Img = img;
} // item Img
public Image Img
{
get
{
return img;
}
set
{
img = value;
}
} // item text
public string Text
{
get
{
return text;
}
set
{
text = value;
}
} // ToString() should return item text
public override string ToString()
{
return text;
}
}
}