combox系统颜色和刷子的下拉条 洋

先让我们看看效果图吧,
 
 

首先必须把combox的两个属性Drowmode=OwnerDrawFixed，Dorwdownstyle=DropDownList，则具体的代码如下：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Drawing2D;
using System.Collections;

namespace color_brush
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            //获取系统的刷子
            Array brush = System.Enum.GetValues(typeof(HatchStyle));
            foreach (object hs in brush)
            {
                string st = hs.ToString();
                this.comboBox2.Items.AddRange(new object[] { st });
            }
            this.comboBox2.SelectedIndex = 1;
            this.comboBox2.DropDownHeight = 150;
            this.comboBox2.DrawItem += new DrawItemEventHandler(comboBox2_DrawItem);
            //获取系统的颜色
            Array allcol = System.Enum.GetValues(typeof(KnownColor));
            foreach (object hs in allcol)
            {
                string st = hs.ToString();
                this.comboBox1.Items.AddRange(new object[] { st });
            }
            comboBox1.DropDownHeight = 170;
            comboBox1.SelectedIndex = 0;
            this.Cursor = Cursors.Hand;
        }

        /// <summary>
        /// 转换画刷的枚举对象
        /// </summary>
        /// <param name="s"></param>
        /// <returns></returns>
        private HatchStyle getHatchStyle(String s)
        {
            return (HatchStyle)Enum.Parse(typeof(HatchStyle), s, true);
        }

        /// <summary>
        /// combox2上绘制系统的画刷下拉条
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void comboBox2_DrawItem(object sender, DrawItemEventArgs e)
        {
            Rectangle r = e.Bounds;
            if (e.Index==-1)
            {
                return;
            }
            if (sender==null)
            {
                 return;
            }
         
            string displayText = this.comboBox2.Items[e.Index].ToString();           
            HatchStyle hs = this.getHatchStyle(displayText);         
            using (HatchBrush b = new HatchBrush(hs, e.ForeColor, e.BackColor))
            {
                e.Graphics.FillRectangle(b, r);
            }
          
            e.DrawFocusRectangle();
        }
         

      
        /// <summary>
        /// combox1上绘制系统颜色条
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void comboBox1_DrawItem(object sender, DrawItemEventArgs e)
        {        

            Rectangle r = e.Bounds;
         
            if (e.Index==-1)
            {
                return;
            }
            if (sender==null)
            {
                return;
            }        

            string ColorName = this.comboBox1.Items[e.Index].ToString();          
            using (SolidBrush myBrush = new SolidBrush(Color.FromName(ColorName)))
            {
                   e.Graphics.FillRectangle(myBrush, r);
                  e.Graphics.DrawString(ColorName, this.Font, new SolidBrush(this.ForeColor), e.Bounds.X , e.Bounds.Y);
                  Pen p=new Pen(Brushes.WhiteSmoke);
                  e.Graphics.DrawRectangle(p, e.Bounds);
            }

            e.DrawFocusRectangle();   
        }
                
        /// <summary>
        /// combox1选择后pannel1的变化
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            string text = comboBox1.SelectedItem.ToString();
            Color fcol = Color.FromName(text);
            string comb2 = comboBox2.SelectedItem.ToString();
            HatchStyle hs = this.getHatchStyle(comb2);
            using (HatchBrush b = new HatchBrush(hs, fcol, Color.WhiteSmoke))
            {
                Graphics g = this.panel1.CreateGraphics();
                g.FillRectangle(b, 0, 0, panel1.Width, panel1.Height);
            }
        }

        /// <summary>
        /// combox2选择后pannel1变化
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
        {
            Color fcol=new Color();

           //combox1没选择的时候
            if (comboBox1.SelectedIndex == 0)
            {
                string comb1text = comboBox1.Items[0].ToString();
                fcol = Color.FromName(comb1text);

            }
            else if(comboBox1.SelectedIndex>0)
            {
                string comb1text = comboBox1.SelectedItem.ToString();
                fcol = Color.FromName(comb1text);
            }
            string distent = comboBox2.SelectedItem.ToString();
            HatchStyle hs = this.getHatchStyle(distent);
            using (HatchBrush b = new HatchBrush(hs,fcol,Color.WhiteSmoke))
            {
                Graphics g = this.panel1.CreateGraphics();
                g.FillRectangle(b, 0, 0, panel1.Width, panel1.Height);
            }
        }     
    }
}

 前几天发了这个很烂的文章，这两天感觉不是很理想，又打开添几句。有一个问题：就是重绘的问题，当拖动窗口到屏幕外一部分的话，pannel中被遮盖的地方不见了。而这个问题的解决平时都是在控件的onpaint事件上操作的。同时这个程序还可以在改进，定义两个属性，一个颜色，一个刷子，这样的的话两个combox中只选择改变节点就ok了，促发pannel的onpaint交给属性了，当属性改变在重绘，这样才商业化些。如果你认为说的有理，你可以演练一下吧，怎么样，你一定比我做的好！