form1.cs

苏金明编写的《用VB.NET和VC#.NET开发交互式CAD系统》一书的源代码

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Drawing.Drawing2D;

namespace 曲线求交
{
	/// <summary>
	/// Form1 的摘要说明。
	/// </summary>
	public class Form1 : System.Windows.Forms.Form
	{
		/// <summary>
		/// 必需的设计器变量。
		/// </summary>
		private System.ComponentModel.Container components = null;

		public Form1()
		{
			//
			// Windows 窗体设计器支持所必需的
			//
			InitializeComponent();

			//
			// TODO: 在 InitializeComponent 调用后添加任何构造函数代码
			//
		}

		/// <summary>
		/// 清理所有正在使用的资源。
		/// </summary>
		protected override void Dispose( bool disposing )
		{
			if( disposing )
			{
				if (components != null) 
				{
					components.Dispose();
				}
			}
			base.Dispose( disposing );
		}

		#region Windows Form Designer generated code
		/// <summary>
		/// 设计器支持所需的方法 - 不要使用代码编辑器修改
		/// 此方法的内容。
		/// </summary>
		private void InitializeComponent()
		{
			this.components = new System.ComponentModel.Container();
			this.Size = new System.Drawing.Size(300,300);
			this.Text = "Form1";
		}
		#endregion

		/// <summary>
		/// 应用程序的主入口点。
		/// </summary>
		[STAThread]
		static void Main() 
		{
			Application.Run(new Form1());
		}

		protected override void OnPaint(PaintEventArgs e)
		{
			Graphics g= e.Graphics;
			//定义转换矩阵
			Matrix mat=new Matrix();
			mat.Translate(0, 0);
			//定义顶点，添加基数样条曲线到路径
			Point point1=new Point(10, 100);
			Point point2=new Point(80, 20);
			Point point3=new Point(150, 300);
			Point point4=new Point(200, 100);
			Point point5=new Point(300, 200);
			Point point6=new Point(500, 150);
			Point[] points= {point1, point2, point3, point4, point5, point6};
			GraphicsPath gp=new GraphicsPath();
			gp.AddCurve(points);
			g.DrawPath(new Pen(Color.Black, 2), gp);
			//展平曲线
			gp.Flatten(mat, 5);
			//获得路径上的关键点
			PointF[] p= gp.PathPoints;
			//给出要与曲线求交的直线段
			CLine line1=new CLine(new PointF(20, 400), new PointF(400, 50));
			line1.Draw(g, Pens.Blue);
			int interNum = -1;
			float[] intersec;
			PointF pos=new PointF(0,0);
			PointF[] interPoints={pos,pos,pos};
			//根据展平以后得到的多条直线段逐个与给定的直线段求交点
			//最终得到的交点即可看作给定直线段与曲线的交点
			Module m=new Module();
			for (int i = 0;i<gp.PointCount - 1;i++)
			{
				CLine line2=new CLine(p[i], p[i + 1]);
				intersec = m.LineLine(line1, line2);
				if (intersec[0] > 0)
				{
					interNum += 1;
					interPoints[interNum] = new PointF(intersec[1], intersec[2]);
				}
			}
			//用红色填充圆表示交点
			for (int i = 0;i<=interNum;i++)
			{
				g.FillEllipse(Brushes.Red, interPoints[i].X - 3, interPoints[i].Y - 3, 6, 6);
			}
		}

	}
}