C# 拓展ComboBox设置线条属性
目前由于项目需要,要实现线条属性设置的功能,就如Visio中点击线端时,可以弹出一个窗口设置线条的各种属性。
其中线条属性选择时,是在ComboBox控件中,显示各种箭头或者颜色等,此时就需要拓展ComboBox组件了。
开始做这个程序时,我没有思路,在csdn上参考一位伙伴的程序,他主要是实现了颜色的设置。
废话不多说了,上图看看:
步骤一:新建Winform工程
先添加用户组件继承自ComboBox。
系统自动生成的代码:
1 public partial class MyColorComboBox : ComboBox
2 {
3 public MyColorComboBox()
4 {
5 InitializeComponent();
6 InitItems();
7 }
8
9 public MyColorComboBox(IContainer container)
10 {
11 container.Add(this);
12 InitializeComponent();
13 InitItems();
14 }
15 }
因为我们要显示箭头或者颜色,都是需要自己绘制图形的。
步骤二:设置自定义组件的一些属性
1 private void InitItems()
2 {
3 this.DrawMode = DrawMode.OwnerDrawFixed;//手动绘制所有元素
4 this.DropDownStyle = ComboBoxStyle.DropDownList;//下拉框样式设置为不能编辑
5 this.Items.Clear();//清空原有项
6 }
1 public enum LineType
2 {
3 TheStartOfLineWithArrow=0,//起始点有箭头
4 TheEndOfLineWithArrow,//终止点有箭头
5 LineWithArrows,//线的两端带箭头
6 TheStartOfBoldLineWithArrow,//粗线起始点带箭头
7 TheEndOfBoldLineWithArrow,//粗线终止点带箭头
8 BoldLineWithArrows,//粗线两端带箭头
9 TheStartOfLineWithPoint,//起始点带圆点
10 TheEndOfLineWithPoint,//终止点带圆点
11 LineWithPoints,//线两端带圆点
12 MoreLineType//更多线型选项
13 }
步骤三:重写OnDrawItem方法
然后在OnDrawItem中写绘制线条的方法
这里主要是使用e.Graphics绘制图形了。
1 protected override void OnDrawItem(DrawItemEventArgs e)
2 {
3 if (e.Index >= 0)//判断是否需要重绘
4 {
5 int typeId = int.Parse(this.Items[e.Index].ToString());//获取选项id
6
7 Font font = new Font("宋体", 9);//定义字体
8 Rectangle rect = e.Bounds;
9 rect.Inflate(-2, -2);//缩放一定大小
10 Pen pen = null;
11 SolidBrush solidBrush = new SolidBrush(Color.Black);
12
13 float offSet = rect.Height / 2;
14 float x = rect.Width / 10;
15 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。
16
17 switch (typeId)
18 {
19 case (int)LineType.TheStartOfLineWithArrow:
20 pen = new Pen(Color.Black, 1);
21 e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(x + offSet, y - offSet));//绘制起始点带箭头的线
22 e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(x + offSet, y + offSet));
23 break;
24 case (int)LineType.TheEndOfLineWithArrow:
25 pen = new Pen(Color.Black, 1);
26 e.Graphics.DrawLine(pen, new PointF(8 * x, y), new PointF(8 * x - offSet, y - offSet));//绘制终端带箭头的线
27 e.Graphics.DrawLine(pen, new PointF(8 * x, y), new PointF(8 * x - offSet, y + offSet));
28 break;
29 case (int)LineType.LineWithArrows:
30 pen = new Pen(Color.Black, 1);
31 e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(x + offSet, y - offSet));//绘制两端带箭头的线
32 e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(x + offSet, y + offSet));
33 e.Graphics.DrawLine(pen, new PointF(8 * x, y), new PointF(8 * x - offSet, y - offSet));
34 e.Graphics.DrawLine(pen, new PointF(8 * x, y), new PointF(8 * x - offSet, y + offSet));
35 break;
36 case (int)LineType.TheStartOfBoldLineWithArrow:
37 pen = new Pen(Color.Black, 2);
38 e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(x + offSet, y - offSet));//绘制起始端带箭头的粗线
39 e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(x + offSet, y + offSet));
40 break;
41 case (int)LineType.TheEndOfBoldLineWithArrow:
42 pen = new Pen(Color.Black, 2);
43 e.Graphics.DrawLine(pen, new PointF(8 * x, y), new PointF(8 * x - offSet, y - offSet));//绘制终端带箭头的粗线
44 e.Graphics.DrawLine(pen, new PointF(8 * x, y), new PointF(8 * x - offSet, y + offSet));
45 break;
46 case (int)LineType.BoldLineWithArrows:
47 pen = new Pen(Color.Black, 2);
48 e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(x + offSet, y - offSet));
49 e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(x + offSet, y + offSet));
50 e.Graphics.DrawLine(pen, new PointF(8 * x, y), new PointF(8 * x - offSet, y - offSet));
51 e.Graphics.DrawLine(pen, new PointF(8 * x, y), new PointF(8 * x - offSet, y + offSet));
52 break;
53 case (int)LineType.TheStartOfLineWithPoint:
54 pen = new Pen(Color.Black, 1);
55 e.Graphics.FillEllipse(solidBrush, new Rectangle(new Point((int)x - 3, (int)y - 3), new Size(8, 8)));//绘制起始端带圆的线
56 break;
57 case (int)LineType.TheEndOfLineWithPoint:
58 pen = new Pen(Color.Black, 1);
59 e.Graphics.FillEllipse(solidBrush, new Rectangle(new Point((int)(8 * x) - 3, (int)y - 3), new Size(8, 8)));//绘制终端带圆的线
60 break;
61 case (int)LineType.LineWithPoints:
62 pen = new Pen(Color.Black, 1);
63 e.Graphics.FillEllipse(solidBrush, new Rectangle(new Point((int)x - 3, (int)y - 3), new Size(8, 8)));//绘制两端都带圆的线
64 e.Graphics.FillEllipse(solidBrush, new Rectangle(new Point((int)(8 * x) - 3, (int)y - 3), new Size(8, 8)));
65 break;
66 case (int)LineType.MoreLineType:
67 e.Graphics.DrawString("更多线型选项...", font, solidBrush, new PointF(x - 3, y - offSet));
68 break;
69 default:
70 pen = new Pen(Color.Black, 1);
71 break;
72 }
73 if (e.Index < 9)
74 {
75 e.Graphics.DrawLine(pen, new PointF(x, y), new PointF(8 * x, y));//绘制线
76 Rectangle rectColor = new Rectangle(rect.Location, new Size(9 * (int)x, rect.Height));
77 e.Graphics.DrawRectangle(Pens.Black, rectColor);//绘制边框
78
79 }
80 }
81 }
这个坐标的设置可能麻烦了些,不过具体实现就是这样了。
步骤四:保存程序后,编译程序,可以在工具箱--指针栏看到MyLineComboBox这个自定义组件了。
然后在Form中添加它,再添加MyLineComboBox的Items(0,1,2,3,4,5,6,7,8,9)。
运行程序,可以效果了,当然这里还需要自己再拓展。