项目中遇到需要下拉框列表内容为线类型或点类型图形的需求，想到可以使用手绘线条和图形的方式来实现下拉列表内容自定义，记录下来供大家参考学习之用。
在项目中添加一个组件
添加完之后会显示如下设计界面
这里直接点击切换到代码视图即可
注意：新建的组件默认继承Component，我们这里是要自定义一个ComboBox下拉框，所以要继承自ComboBox，此类位于using System.Windows.Forms命名空间下
线的类型列表
using System;using System.Collections.Generic;using ponentModel;using System.Diagnostics;using System.Drawing;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;namespace CustomComponents{/// <summary>/// 填充线型/// </summary>public partial class FillLineTypeCbo : ComboBox{public FillLineTypeCbo(){//初始化组件InitializeComponent();}public FillLineTypeCbo(IContainer container){container.Add(this);InitializeComponent();InitItems();}private void InitItems(){this.DrawMode = DrawMode.OwnerDrawFixed;//手动绘制所有元素this.DropDownStyle = ComboBoxStyle.DropDownList;//下拉框样式设置为不能编辑this.Items.Clear();//清空原有项 }public enum LineType{DoubleHorizontalLine = 0,//双横线VerticalLine,//垂直线LeftSlash,//左斜线RightSlash,//右斜线VerticalGridlines,//垂直网格线CrossGridlines,//交叉网格线SolidBrush,//实心刷HollowBrush,//空心刷}//protectedprotected override void OnDrawItem(DrawItemEventArgs e){if (e.Index >= 0)//判断是否需要重绘{int typeId = int.Parse(this.Items[e.Index].ToString());//获取选项idFont font = new Font("宋体", 9);//定义字体Rectangle rect = e.Bounds;//rect.Inflate(-2, -2);//缩放一定大小rect.Inflate(5, -2);//缩放一定大小Pen pen = null;SolidBrush solidBrush = new SolidBrush(Color.Black);float offSet = rect.Height / 2;float x = rect.Width / 10;float y = rect.Top + offSet;//如果设置成e.ItemHeigh*e.Index +offSet,则在选中节点后，由于Item位置固定，因此Item不能显示出来。switch (typeId){case (int)LineType.DoubleHorizontalLine:pen = new Pen(Color.Black, 1);e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(8 * x, y));//绘制水平线e.Graphics.DrawLine(pen, new PointF(x, y + 5), new PointF(8 * x, y + 5));//e.Graphics.DrawLine(pen, new PointF(x, y+2), new PointF(x, y+2));break;case (int)LineType.VerticalLine:pen = new Pen(Color.Black, 1);//绘制垂直线int xNum = 0;for (int i = 0; i < 10; i++){e.Graphics.DrawLine(pen, new PointF(x + xNum, y - 4), new PointF(1 * x + xNum, y + 6));xNum += 7;}break;case (int)LineType.LeftSlash:pen = new Pen(Color.Black, 1);//绘制左斜线int xNumLeftSlash = 0;for (int i = 0; i < 10; i++){e.Graphics.DrawLine(pen, new PointF(x + xNumLeftSlash, y - 4), new PointF(x + 5 + xNumLeftSlash, y + 7));xNumLeftSlash += 7;}break;case (int)LineType.RightSlash:pen = new Pen(Color.Black, 1);//绘制右斜线int xNumRightSlash = 0;for (int i = 0; i < 10; i++){e.Graphics.DrawLine(pen, new PointF(x + xNumRightSlash + 7, y - 4), new PointF(x + xNumRightSlash, y + 7));xNumRightSlash += 7;}break;case (int)LineType.VerticalGridlines:pen = new Pen(Color.Black, 1);//绘制垂直网格线xNum = 0;for (int i = 0; i < 10; i++)//绘制竖线{e.Graphics.DrawLine(pen, new PointF(x + xNum, y - 4), new PointF(1 * x + xNum, y + 6));xNum += 7;}//绘制双横线e.Graphics.DrawLine(pen, new PointF(x - 3, y - 2), new PointF(8 * x, y - 2));e.Graphics.DrawLine(pen, new PointF(x - 3, y + 5), new PointF(8 * x, y + 5));break;case (int)LineType.CrossGridlines:pen = new Pen(Color.Black, 1);//绘制交叉网格线//绘制左斜线xNumLeftSlash = 0;for (int i = 0; i < 10; i++){e.Graphics.DrawLine(pen, new PointF(x + xNumLeftSlash, y - 4), new PointF(x + 10 + xNumLeftSlash, y + 7));xNumLeftSlash += 7;}//绘制右斜线xNumRightSlash = 0;for (int i = 0; i < 10; i++){e.Graphics.DrawLine(pen, new PointF(x + xNumRightSlash + 10, y - 4), new PointF(x + xNumRightSlash, y + 7));xNumRightSlash += 7;}break;case (int)LineType.SolidBrush:pen = new Pen(Color.Black, 10);//绘制实心刷e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(8 * x, y));break;case (int)LineType.HollowBrush:pen = new Pen(Color.Black, 1);//绘制空心刷e.Graphics.DrawLine(pen, new PointF(x, y - 6), new PointF(x, y + 6));//左e.Graphics.DrawLine(pen, new PointF(x, y - 6), new PointF(8 * x, y - 6));//上e.Graphics.DrawLine(pen, new PointF(8 * x, y - 6), new PointF(8 * x, y + 6));//右e.Graphics.DrawLine(pen, new PointF(x, y + 6), new PointF(8 * x, y + 6));//下break;default:pen = new Pen(Color.Black, 1);break;}}}}}
边框线类型列表
using System;using System.Collections.Generic;using ponentModel;using System.Diagnostics;using System.Drawing;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;namespace CustomComponents{/// <summary>/// 线型/// </summary>public partial class LineShapeCbo : ComboBox{public LineShapeCbo(){InitializeComponent();}public LineShapeCbo(IContainer container){container.Add(this);InitializeComponent();InitItems();}private void InitItems(){this.DrawMode = DrawMode.OwnerDrawFixed;//手动绘制所有元素this.DropDownStyle = ComboBoxStyle.DropDownList;//下拉框样式设置为不能编辑this.Items.Clear();//清空原有项 }public enum LineType{SolidLine = 0,//实线LongDisconnection,//长间断线ShortEndLine,//短间端线LongAndShort,//长短相间ShortToLong,//长短短相间EmptyBrushes//空画笔}protected override void OnDrawItem(DrawItemEventArgs e){if (e.Index >= 0)//判断是否需要重绘{int typeId = int.Parse(this.Items[e.Index].ToString());//获取选项idFont font = new Font("宋体", 9);//定义字体Rectangle rect = e.Bounds;//rect.Inflate(-2, -2);//缩放一定大小rect.Inflate(5, -2);//缩放一定大小Pen pen = null;SolidBrush solidBrush = new SolidBrush(Color.Black);float offSet = rect.Height / 2;float x = rect.Width / 10;float y = rect.Top + offSet;//如果设置成e.ItemHeigh*e.Index +offSet,则在选中节点后，由于Item位置固定，因此Item不能显示出来。switch (typeId){case (int)LineType.SolidLine:pen = new Pen(Color.Black, 1);e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(8 * x, y));//绘制实线//e.Graphics.DrawLine(pen, new PointF(x, y+2), new PointF(x, y+2));break;case (int)LineType.LongDisconnection:pen = new Pen(Color.Black, 1);//绘制长间断线int xNum = 0;for (int i = 0; i < 3; i++){e.Graphics.DrawLine(pen, new PointF(x + xNum, y), new PointF(15+x + xNum, y));xNum += 20;}e.Graphics.DrawLine(pen, new PointF(x + xNum, y), new PointF(10 + x + xNum, y));break;case (int)LineType.ShortEndLine:pen = new Pen(Color.Black, 1);//绘制短间端线xNum = 0;for (int i = 0; i < 8; i++){e.Graphics.DrawLine(pen, new PointF(x + xNum, y), new PointF(6 + x + xNum, y));xNum += 9;}break;case (int)LineType.LongAndShort:pen = new Pen(Color.Black, 1);//绘制长短相间e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(x+10, y));e.Graphics.DrawLine(pen, new PointF(x+15, y), new PointF(x+20, y));e.Graphics.DrawLine(pen, new PointF(x+25, y), new PointF(x+35, y));e.Graphics.DrawLine(pen, new PointF(x+40, y), new PointF(x+45, y));e.Graphics.DrawLine(pen, new PointF(x+50, y), new PointF(x+60, y));e.Graphics.DrawLine(pen, new PointF(x+65, y), new PointF(x+70, y));break;case (int)LineType.ShortToLong:pen = new Pen(Color.Black, 1);//绘制长短短相间e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(x + 10, y));e.Graphics.DrawLine(pen, new PointF(x+15, y), new PointF(x + 18, y));e.Graphics.DrawLine(pen, new PointF(x+23, y), new PointF(x + 26, y));e.Graphics.DrawLine(pen, new PointF(x+31, y), new PointF(x + 41, y));e.Graphics.DrawLine(pen, new PointF(x + 46, y), new PointF(x + 49, y));e.Graphics.DrawLine(pen, new PointF(x + 54, y), new PointF(x + 57, y));e.Graphics.DrawLine(pen, new PointF(x + 62, y), new PointF(x + 70, y));break;case (int)LineType.EmptyBrushes:pen = new Pen(Color.Black, 1);//绘制空画笔break;//case (int)LineType.LineWithPoints:default:pen = new Pen(Color.Black, 1);break;}//if (e.Index < 9)//{// e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(8 * x, y));//绘制线// //Rectangle rectColor = new Rectangle(rect.Location, new Size(9 * (int)x, rect.Height));// //e.Graphics.DrawRectangle(Pens.Black, rectColor);//绘制边框//}}}}}
点类型列表
using System;using System.Collections.Generic;using ponentModel;using System.Diagnostics;using System.Drawing;using System.Drawing.Drawing2D;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;namespace CustomComponents{/// <summary>/// 点类型/// </summary>public partial class PointTypeCbo : ComboBox{public PointTypeCbo(){InitializeComponent();}public PointTypeCbo(IContainer container){container.Add(this);InitializeComponent();InitItems();}private void InitItems(){this.DrawMode = DrawMode.OwnerDrawFixed;//手动绘制所有元素this.DropDownStyle = ComboBoxStyle.DropDownList;//下拉框样式设置为不能编辑this.Items.Clear();//清空原有项 }protected override void OnDrawItem(DrawItemEventArgs e){if (e.Index >= 0)//判断是否需要重绘{int typeId = int.Parse(this.Items[e.Index].ToString());//获取选项idFont font = new Font("宋体", 9);//定义字体Rectangle rect = e.Bounds;//rect.Inflate(-2, -2);//缩放一定大小rect.Inflate(5, -2);//缩放一定大小Pen pen = null;SolidBrush solidBrush = new SolidBrush(Color.Black);float offSet = rect.Height / 2;float x = rect.Width / 10;float y = rect.Top + offSet;//如果设置成e.ItemHeigh*e.Index +offSet,则在选中节点后，由于Item位置固定，因此Item不能显示出来。switch (typeId){case 0:pen = new Pen(Color.Red, 1);//设置边框//SolidBrush sb0 = new SolidBrush(Color.Black);//设置填充颜色//绘制//e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(8 * x, y));//Graphics g = CreateGraphics();//Brush myBrush = new SolidBrush(Color.Green);//string str = "just for fun";//Font myFont = new Font("宋体", 9, FontStyle.Bold);//e.Graphics.DrawString(str, myFont, myBrush, 60, 20);//e.Graphics.FillEllipse(sb0, 10 ,10 , 10, 10);e.Graphics.DrawEllipse(pen, 9, 5, 10, 10);break;case 1:pen = new Pen(Color.Red, 1);//绘制正方形e.Graphics.DrawLine(pen, new PointF(x, y - 5), new PointF(x, y + 5));//左e.Graphics.DrawLine(pen, new PointF(x, y - 5), new PointF(x + 10, y - 5));//上e.Graphics.DrawLine(pen, new PointF(x + 10, y - 5), new PointF(x + 10, y + 5));//右e.Graphics.DrawLine(pen, new PointF(x, y + 5), new PointF(x + 10, y + 5));//下//Rectangle rectColor = new Rectangle(rect.Location, new Size(10, 10));//e.Graphics.DrawRectangle(Pens.Black, rectColor);//绘制边框break;case 2:pen = new Pen(Color.Red, 1);//绘制十字形e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(x + 10, y));//横e.Graphics.DrawLine(pen, new PointF(x + 5, y - 5), new PointF(x + 5, y + 5));//竖break;case 3:pen = new Pen(Color.Red, 1);//绘制三角形e.Graphics.DrawLine(pen, new PointF(x, y + 5), new PointF(x + 5, y - 5));//左e.Graphics.DrawLine(pen, new PointF(x + 5, y - 5), new PointF(x + 10, y + 5));//右e.Graphics.DrawLine(pen, new PointF(x, y + 5), new PointF(x + 10, y + 5));//下break;case 4:pen = new Pen(Color.Red, 1);//绘制右（三角）红旗e.Graphics.DrawLine(pen, new PointF(x + 5, y + 5), new PointF(x + 5, y - 5));//竖杆e.Graphics.DrawLine(pen, new PointF(x + 5, y - 5), new PointF(x + 10, y));//红旗右边e.Graphics.DrawLine(pen, new PointF(x + 5, y), new PointF(x + 10, y));//红旗下边break;case 5:pen = new Pen(Color.Red, 1);//绘制左（三角）红旗 e.Graphics.DrawLine(pen, new PointF(x + 5, y + 5), new PointF(x + 5, y - 5));//竖杆e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(x + 5, y - 5));//红旗左边e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(x + 5, y));//红旗下边break;case 6:pen = new Pen(Color.Red, 1);//绘制右方旗e.Graphics.DrawLine(pen, new PointF(x + 5, y + 5), new PointF(x + 5, y - 5));//竖杆e.Graphics.DrawLine(pen, new PointF(x + 5, y - 5), new PointF(x + 10, y - 5));//右上边e.Graphics.DrawLine(pen, new PointF(x + 10, y - 5), new PointF(x + 10, y));//右右边e.Graphics.DrawLine(pen, new PointF(x + 5, y), new PointF(x + 10, y));//右下边break;case 7:pen = new Pen(Color.Red, 1);//绘制大圆包小圆//e.Graphics.DrawEllipse(pen, 20, 115, 10, 10);//空心大圆//e.Graphics.DrawEllipse(pen, 13, 118, 4, 4);//空心小圆 e.Graphics.DrawEllipse(pen, x, y - 5, 10, 10);//空心大圆e.Graphics.DrawEllipse(pen, x + 3, y - 5 + 3, 4, 4);//空心小圆//Rectangle rectColor = new Rectangle(rect.Location, new Size(9 * (int)x, rect.Height));//e.Graphics.DrawRectangle(Pens.Black, rectColor);//绘制边框break;case 8:pen = new Pen(Color.Red, 1);//绘制大圆加十字e.Graphics.DrawEllipse(pen, x, y - 5, 10, 10);//空心大圆//绘制十字形e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(x + 10, y));//横e.Graphics.DrawLine(pen, new PointF(x + 5, y - 5), new PointF(x + 5, y + 5));//竖break;case 9:pen = new Pen(Color.Red, 1);//绘制实心圆SolidBrush sb9 = new SolidBrush(Color.Green);//设置填充颜色e.Graphics.DrawEllipse(pen, x, y - 5, 10, 10);//实心圆边框e.Graphics.FillEllipse(sb9, x, y - 5, 10, 10);//实心圆填充break;case 10:pen = new Pen(Color.Red, 1);//绘制实心正方形//绘制正方形e.Graphics.DrawRectangle(pen, x, y - 5, 10, 10);SolidBrush sb10 = new SolidBrush(Color.Green);//设置填充颜色e.Graphics.FillRectangle(sb10, x, y - 5, 10, 10);break;case 11:pen = new Pen(Color.Red, 1);//绘制PointF p1 = new PointF(x + 5, y - 5);PointF p2 = new PointF(x, y + 5);PointF p3 = new PointF(x + 10, y + 5);PointF[] points = new PointF[3];Brush myBrush = new SolidBrush(Color.Green);points[0] = p1;points[1] = p2;points[2] = p3;e.Graphics.FillPolygon(myBrush, points, FillMode.Alternate);e.Graphics.DrawPolygon(pen, points);break;//case (int)LineType.LineWithPoints:default:pen = new Pen(Color.Black, 1);break;}if (e.Index < 12){//e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(8 * x, y));//绘制线//设置后面的字符串Rectangle Rect = new Rectangle(rect.Location, new Size(5 * (int)x, rect.Height));//文本内容显示区域Rectangle textRect =new Rectangle(Rect.Right + 2, Rect.Y, e.Bounds.Width - Rect.Width, e.Bounds.Height - 2);//文本格式垂直居中StringFormat strFormat = new StringFormat();strFormat.LineAlignment = StringAlignment.Center;e.Graphics.DrawString((e.Index + 1).ToString(), new Font("微软雅黑", 12), Brushes.Black, textRect, strFormat);}}}}}
带图片的列表
using System;using System.Collections.Generic;using ponentModel;using System.Diagnostics;using System.Drawing;using System.Drawing.Drawing2D;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;namespace ShowState{/// <summary>/// 下拉框 下拉列表 图片显示/// </summary>public partial class ComboBoxImg : ComboBox{public ComboBoxImg(){InitializeComponent();DrawMode = DrawMode.OwnerDrawFixed;DropDownStyle = ComboBoxStyle.DropDownList;ItemHeight = 50;Width = 40;}public ComboBoxImg(IContainer container){container.Add(this);InitializeComponent();DrawMode = DrawMode.OwnerDrawFixed;DropDownStyle = ComboBoxStyle.DropDownList;ItemHeight = 200;Width = 40;}protected override void OnDrawItem(DrawItemEventArgs e){if (Items.Count == 0 || e.Index == -1)return;if ((e.State & DrawItemState.Selected) != 0){//渐变画刷LinearGradientBrush brush = new LinearGradientBrush(e.Bounds, Color.FromArgb(255, 251, 237),Color.FromArgb(255, 236, 181), LinearGradientMode.Vertical);//填充区域Rectangle borderRect = new Rectangle(3, e.Bounds.Y, e.Bounds.Width - 5, e.Bounds.Height - 2);e.Graphics.FillRectangle(brush, borderRect);//画边框Pen pen = new Pen(Color.FromArgb(229, 195, 101));e.Graphics.DrawRectangle(pen, borderRect);}else{SolidBrush brush = new SolidBrush(Color.FromArgb(255, 255, 255));e.Graphics.FillRectangle(brush, e.Bounds);}//获得项图片,绘制图片ItemEx item = (ItemEx)Items[e.Index];Image img = item.Image;//图片绘制的区域Rectangle imgRect = new Rectangle(6, e.Bounds.Y + 3, 45, 45);e.Graphics.DrawImage(img, imgRect);//文本内容显示区域Rectangle textRect =new Rectangle(imgRect.Right + 2, imgRect.Y, e.Bounds.Width - imgRect.Width, e.Bounds.Height - 2);//获得项文本内容,绘制文本String itemText = Items[e.Index].ToString();//文本格式垂直居中StringFormat strFormat = new StringFormat();strFormat.LineAlignment = StringAlignment.Center;e.Graphics.DrawString(itemText, new Font("微软雅黑", 12), Brushes.Black, textRect, strFormat);base.OnDrawItem(e);}}/// <summary>/// 下拉框 下拉列表 图片显示/// </summary>public class ItemEx{/// <summary>/// 图片显示/// </summary>/// <param name="text">文本</param>/// <param name="img">图片（图片路径）</param>public ItemEx(string text, Image img){Text = text;Image = img;}public string Text { get; set; }public Image Image { get; set; }public override string ToString(){return Text;}}}
