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.Runtime.InteropServices;

namespace 橡皮线
{
	/// <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()
		{
			// 
			// Form1
			// 
			this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
			this.ClientSize = new System.Drawing.Size(320, 286);
			this.Name = "Form1";
			this.Text = "Form1";

		}
		#endregion

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

		[DllImport("gdi32.dll")] 
		private static extern bool SetROP2(IntPtr hdc,int nDrawMode);

		[DllImport("gdi32.dll")] 
		private static extern bool  Rectangle 
			(IntPtr hdc, int X1, int Y1,int X2, int Y2);

		private int m_StartX, m_StartY;
		private int m_EndX, m_EndY;
		private int m_Step = 0;

		protected override void OnMouseDown(MouseEventArgs e )
		{
			Graphics g =this.CreateGraphics();
			IntPtr hdc= g.GetHdc();
			m_Step += 1;
			SetROP2(hdc, 10);
			if (m_Step == 1)
			{
				m_StartX = e.X;
				m_StartY = e.Y;
				m_EndX = e.X;
				m_EndY = e.Y;
			}
			else if (m_Step == 2)
			{
				Rectangle(hdc, m_StartX, m_StartY, m_EndX, m_EndY);
				Rectangle(hdc, m_StartX, m_StartY, e.X, e.Y);
				m_Step = 0;
			}
			g.ReleaseHdc(hdc);
		}

		protected override void OnMouseMove(MouseEventArgs e)
		{
			Graphics g =this.CreateGraphics();
			int prex, prey;
			if (m_Step == 1)
			{
				IntPtr hdc= g.GetHdc();
				prex = m_EndX;
				prey = m_EndY;
				SetROP2(hdc, 10);
				Rectangle(hdc, m_StartX, m_StartY, prex, prey);
				Rectangle(hdc, m_StartX, m_StartY, e.X, e.Y);
				m_EndX = e.X;
				m_EndY = e.Y;
				g.ReleaseHdc(hdc);
			}
		}

		protected override void OnPaint(PaintEventArgs e)
		{
			Graphics g= e.Graphics;
			g.FillRectangle(Brushes.White, this.ClientRectangle);
		}
	}
}