C#用鼠标绘图笔记（一）

       这是本人第一次在blog上发一个小代码,水平有限,慢慢努力
       这是用C#编写的关于用鼠标绘图代码,代码及讲解如下

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

namespace Test
...{
    public class Form3 : System.Windows.Forms.Form
    ...{
        private System.ComponentModel.Container components = null;
        private System.Windows.Forms.PictureBox pictureBox1;
        private System.Drawing.Point startPoint;
        private System.Drawing.Bitmap bitmap;
        private bool CanMove=false;

        public Form3()
        ...{
            InitializeComponent();

                //创建缓冲
            this.SetStyle(ControlStyles.UserPaint, true);
            this.SetStyle(ControlStyles.AllPaintingInWmPaint, true);    
            this.SetStyle(ControlStyles.DoubleBuffer, true);
            bitmap = new Bitmap(this.pictureBox1.Width,this.pictureBox1.Height);
            this.pictureBox1.Image=bitmap;
        }
        protected override void Dispose( bool disposing )
        ...{
            if( disposing )
            ...{
                if(components != null)
                ...{
                    components.Dispose();
                }
            }
            base.Dispose( disposing );
        }

        Windows 窗体设计器生成的代码#region Windows 窗体设计器生成的代码
        private void InitializeComponent()
        ...{
            this.pictureBox1 = new System.Windows.Forms.PictureBox();
            this.SuspendLayout();
            // 
            // pictureBox1
            // 
            this.pictureBox1.BackColor = System.Drawing.SystemColors.ActiveCaptionText;
            this.pictureBox1.Dock = System.Windows.Forms.DockStyle.Fill;
            this.pictureBox1.Location = new System.Drawing.Point(0, 0);
            this.pictureBox1.Name = "pictureBox1";
            this.pictureBox1.Size = new System.Drawing.Size(520, 437);
            this.pictureBox1.TabIndex = 0;
            this.pictureBox1.TabStop = false;
            this.pictureBox1.MouseUp += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseUp);
            this.pictureBox1.MouseMove += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseMove);
            this.pictureBox1.MouseDown += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseDown);
            // 
            // Form3
            // 
            this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
            this.ClientSize = new System.Drawing.Size(520, 437);
            this.Controls.Add(this.pictureBox1);
            this.Name = "Form3";
            this.Text = "Form3";
            this.ResumeLayout(false);

        }
        #endregion

        private void pictureBox1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
        ...{
            this.CanMove=true;
            this.startPoint=new Point(e.X,e.Y);
        }

        private void pictureBox1_MouseMove(object sender, System.Windows.Forms.MouseEventArgs e)
        ...{
            if(this.CanMove==true)
            ...{
                this.pictureBox1.Image=(Bitmap)this.bitmap.Clone();
                using(Graphics graphics = Graphics.FromImage(this.pictureBox1.Image))
                      ...{
                    graphics.Clear(Color.Transparent);//清除
                    graphics.DrawLine(new Pen(Color.Red,1),this.startPoint,new Point(e.X,e.Y));//重绘
                    graphics.DrawImage(this.bitmap,this.pictureBox1.Location.X,this.pictureBox1.Location.Y,this.pictureBox1.Width,this.pictureBox1.Height);
                }
            }        
        }

        private void pictureBox1_MouseUp(object sender, System.Windows.Forms.MouseEventArgs e)
        ...{
            this.pictureBox1.Image = this.bitmap;
            using(Graphics graphics = Graphics.FromImage(this.pictureBox1.Image))
                  ...{
                graphics.DrawLine(new Pen(Color.Red,1),this.startPoint,new Point(e.X,e.Y));
            }
            this.CanMove=false;
        }
    }
}

参考:
http://www.codeproject.com/dotnet/rubberbandline.asp