form1.cs

JAVA实例,画图功能强大,

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

namespace DrawLine
{
    public partial class Form1 : Form
    {
        Image BG_Img;
        Point OldPos = new Point(-1, -1);
        Point CurPos = new Point(0, 0);

        public Form1()
        {
            InitializeComponent();
            BG_Img = new Bitmap(ClientRectangle.Width, ClientRectangle.Height);
        }

        private void Form1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Right)
            {
                // 放弃最后一次未确认的线条
                Graphics g = this.CreateGraphics();
                SolidBrush brush = new SolidBrush(this.BackColor);
                g.FillRectangle(brush, ClientRectangle);
                g.DrawImage(BG_Img, new Point(0, 0));

                OldPos.X = -1;
                g.Dispose();
                return;
            }

            if (OldPos.X == -1)
            {
                OldPos = CurPos;
                return;
            }
            // 绘制确认的线条到BG_Img上
            Graphics g1 = Graphics.FromImage(BG_Img);
            g1.DrawLine(new Pen(Color.Red, 1), OldPos, CurPos);
            
            OldPos = CurPos;
            g1.Dispose();
       }

        private void Form1_MouseMove(object sender, MouseEventArgs e)
        {
            CurPos = new Point(e.X, e.Y);

            if (OldPos.X == -1)
                return;

            // 创建临时绘图板
            Image tempImg = new Bitmap(ClientRectangle.Width, ClientRectangle.Height);
            Graphics g1 = Graphics.FromImage(tempImg);
            SolidBrush brush = new SolidBrush(this.BackColor);
            g1.FillRectangle(brush, ClientRectangle);
            // 加载已绘图形
            g1.DrawImage(BG_Img, new Point(0, 0));
            // 绘制临时线
            g1.DrawLine(new Pen(Color.Red, 1), OldPos, CurPos);
                   
            // 显示到窗口上
            Graphics g = this.CreateGraphics();
            g.DrawImage(tempImg, new Point(0, 0));

            g.Dispose();
            g1.Dispose();
            tempImg.Dispose();
        }
    }
}