對C# 中Combox控制元件的一些簡單的操作，改變其顯示特性，主要是改變其中的項的屬性

我們需要注意的是：每次為Combox新增項的時候，就會觸發DrawItem事件，而我們正是通過DrawItem來改變Combox的顯示特性的

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.Collections; namespace Combox_Image { public partial class Form1 : Form { ArrayList brushArray = new ArrayList() ; ArrayList fontArray = new ArrayList() ; public Form1() { InitializeComponent(); } private void comboBox1_DrawItem(object sender, DrawItemEventArgs e) { //確定畫布 Graphics g = e.Graphics; //繪製區域 Rectangle r = e.Bounds; Font fn = null; if (e.Index >= 0) { //設定字型、字串格式、對齊方式 fn = (Font)fontArray[e.Index]; string s = (string)comboBox1.Items[e.Index]; StringFormat sf = new StringFormat(); sf.Alignment = StringAlignment.Near; //根據不同的狀態用不同的顏色表示 if (e.State == (DrawItemState.NoAccelerator | DrawItemState.NoFocusRect)) { e.Graphics.FillRectangle(new SolidBrush(Color.Red), r); e.Graphics.DrawString(s, fn, new SolidBrush(Color.Black), r, sf); e.DrawFocusRectangle(); } else { e.Graphics.FillRectangle(new SolidBrush(Color.LightBlue), r); e.Graphics.DrawString(s, fn, new SolidBrush(Color.Red), r, sf); e.DrawFocusRectangle(); } } } private void Form1_Load(object sender, EventArgs e) { fontArray.Add(new Font("Ariel", 8, FontStyle.Bold)); fontArray.Add(new Font("Courier", 8, FontStyle.Italic)); fontArray.Add(new Font("Veranda", 8, FontStyle.Bold)); fontArray.Add(new Font("System", 8, FontStyle.Strikeout)); fontArray.Add(new Font("Century SchoolBook", 8, FontStyle.Underline)); fontArray.Add(new Font("Helevctia", 8, FontStyle.Italic)); //建立畫刷 brushArray.Add(new SolidBrush(Color.Red)); brushArray.Add(new SolidBrush(Color.Blue)); brushArray.Add(new SolidBrush(Color.Green)); brushArray.Add(new SolidBrush(Color.Yellow)); brushArray.Add(new SolidBrush(Color.Black)); brushArray.Add(new SolidBrush(Color.Azure)); brushArray.Add(new SolidBrush(Color.Firebrick)); brushArray.Add(new SolidBrush(Color.DarkMagenta)); brushArray.Add(new SolidBrush(Color.DarkTurquoise)); brushArray.Add(new SolidBrush(Color.Khaki)); //畫comboBox1，注意它要呼叫comboBox1_DrawItem來畫 comboBox1.Items.Add("中國"); comboBox1.Items.Add("巴西"); comboBox1.Items.Add("哥斯大黎加"); comboBox1.Items.Add("土耳其"); comboBox1.Items.Add("韓國"); comboBox1.Items.Add("日本"); //畫comboBox2，注意它要呼叫comboBox2_DrawItem來畫 comboBox2.Items.Add(""); comboBox2.Items.Add(""); comboBox2.Items.Add(""); comboBox2.Items.Add(""); comboBox2.Items.Add(""); comboBox2.Items.Add(""); comboBox2.Items.Add(""); comboBox2.Items.Add(""); comboBox2.Items.Add(""); comboBox2.Items.Add(""); //畫comboBox3，注意它要呼叫comboBox3_DrawItem來畫 comboBox3.Items.Add("趙微"); comboBox3.Items.Add("舒淇"); comboBox3.Items.Add("諶豹"); comboBox3.Items.Add("鄭巧玲"); } private void comboBox2_DrawItem(object sender, DrawItemEventArgs e) { Graphics g = e.Graphics; Rectangle r = e.Bounds; if (e.Index >= 0) { //設定字串前矩形塊rd的大小 Rectangle rd = r; rd.Width = rd.Left + 20; Rectangle rt = r; r.X = rd.Right; //用不同的顏色畫矩形塊 SolidBrush b = (SolidBrush)brushArray[e.Index]; g.FillRectangle(b, rd); //設定字串的格式 StringFormat sf = new StringFormat(); sf.Alignment = StringAlignment.Near; if (e.State == (DrawItemState.NoAccelerator | DrawItemState.NoFocusRect)) { //字串背景 e.Graphics.FillRectangle(new SolidBrush(Color.White), r); //顯示字串 e.Graphics.DrawString(b.Color.Name, new Font("Ariel", 8, FontStyle.Bold), new SolidBrush(Color.Black), r, sf); //繪製取得焦點時的虛線框 e.DrawFocusRectangle(); } else { e.Graphics.FillRectangle(new SolidBrush(Color.LightBlue), r); e.Graphics.DrawString(b.Color.Name, new Font("Veranda", 8, FontStyle.Bold), new SolidBrush(Color.Red), r, sf); e.DrawFocusRectangle(); } } } private void comboBox3_DrawItem(object sender, DrawItemEventArgs e) { Graphics g = e.Graphics; Rectangle r = e.Bounds; Size imageSize = imageList1.ImageSize; Font fn = null; if (e.Index >= 0) { fn = (Font)fontArray[0]; string s = (string)comboBox3.Items[e.Index]; StringFormat sf = new StringFormat(); sf.Alignment = StringAlignment.Near; if (e.State == (DrawItemState.NoAccelerator | DrawItemState.NoFocusRect)) { //畫條目背景 e.Graphics.FillRectangle(new SolidBrush(Color.Red), r); //繪製圖像 imageList1.Draw(e.Graphics, r.Left, r.Top, e.Index); //顯示字串 e.Graphics.DrawString(s, fn, new SolidBrush(Color.Black), r.Left + imageSize.Width, r.Top); //顯示取得焦點時的虛線框 e.DrawFocusRectangle(); } else { e.Graphics.FillRectangle(new SolidBrush(Color.LightBlue), r); imageList1.Draw(e.Graphics, r.Left, r.Top, e.Index); e.Graphics.DrawString(s, fn, new SolidBrush(Color.Black), r.Left + imageSize.Width, r.Top); e.DrawFocusRectangle(); } } } } }

 三個Combox的效果如下圖所示：