C# 我的小画板

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
//**********************金燕电子****************************************
namespace huaban
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            toolStrip1.Enabled = false;
            foreColor = Color.Black ;
            backColor = Color.White ; 
        }
        Color backColor = new Color();
        private void 新建ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Graphics g = this.CreateGraphics();
            g.Clear(backColor);
            toolStrip1.Enabled = true;
            //创建一个Bitmap 
            theImage = new Bitmap(this.ClientRectangle.Width, this.ClientRectangle.Height);
            editFileName = "新建文件";
            //修改窗口标题 
            this.Text = "MyDraw\t" + editFileName;
            ig = Graphics.FromImage(theImage);
            ig.Clear(backColor);
        }
        string editFileName = "";
        private Image theImage;
        public Graphics ig { get; private set; }

        private void 打开ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            openFileDialog1.Multiselect = false;
            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                //修改窗口标题 
                this.Text = "MyDraw\t" + openFileDialog1.FileName;
                editFileName = openFileDialog1.FileName;
                theImage = Image.FromFile(openFileDialog1.FileName);
                Graphics g = this.CreateGraphics();
                g.DrawImage(theImage, this.ClientRectangle);
                ig = Graphics.FromImage(theImage);
                ig.DrawImage(theImage, this.ClientRectangle);
                //ToolBar可以使用了 
                toolStrip1.Enabled = true;
            }
        }

        private void 保存ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            saveFileDialog1.Filter = "图像(*.bmp)|*.bmp";
            saveFileDialog1.FileName = editFileName;
            if (saveFileDialog1.ShowDialog() == DialogResult.OK)
            {
                theImage.Save(saveFileDialog1.FileName, ImageFormat.Bmp);
                this.Text = "MyDraw\t" + saveFileDialog1.FileName;
                editFileName = saveFileDialog1.FileName;
            }
        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            //将Image中保存的图像，绘制出来 
            Graphics g = this.CreateGraphics();
            if (theImage != null)
            {
                g.Clear(Color.White);
                g.DrawImage(theImage, this.ClientRectangle);
            }
        }
        Color foreColor = new Color();
        private void Form1_MouseDown(object sender, MouseEventArgs e)
        {

            if (e.Button == MouseButtons.Left)        
            {
                //如果选择文字输入，则打开strInput窗体 
                if (drawTool == (int)drawTools.String)
                {
                    Frm_Text inputBox = new Frm_Text();
                    inputBox.StartPosition = FormStartPosition.CenterParent;
                    if (inputBox.ShowDialog() == DialogResult.OK)
                    {
                        Graphics g = this.CreateGraphics();
                        Font theFont = this.Font;
                        g.DrawString(inputBox.textBox1.Text, theFont, new SolidBrush(foreColor), e.X, e.Y);
                        ig.DrawString(inputBox.textBox1.Text, theFont, new SolidBrush(foreColor), e.X, e.Y);
                    }
                }
                //如果开始绘制，则开始记录鼠标位置 
                else if ((isDrawing = !isDrawing) == true)
                {
                    startPoint = new Point(e.X, e.Y);
                    oldPoint = new Point(e.X, e.Y);
                }
            }
        }
        int  drawTool = 0;
        enum drawTools
        {
             None = 0,
             Pen = 1,
             Line = 2,
             Ellipse = 3,
             Rectangle = 4,
             String = 5,
             Rubber =6
        }
        Point oldPoint = new Point();
        Point startPoint = new Point();
        private void Form1_MouseMove(object sender, MouseEventArgs e)
        {
            Graphics g;
            g = this.CreateGraphics();

            if (isDrawing)
            {
                switch (drawTool)
                {
                    case (int)drawTools.None:
                        break;
                    case (int)drawTools.Pen:
                        //从上一个点到当前点绘制线段 
                        g.DrawLine(new Pen(foreColor, 1), oldPoint, new Point(e.X, e.Y));
                        ig.DrawLine(new Pen(foreColor, 1), oldPoint, new Point(e.X, e.Y));
                        oldPoint.X = e.X;
                        oldPoint.Y = e.Y;
                        break;
                    case (int)drawTools.Line:
                        //首先恢复此次操作之前的图像，然后再添加Line 
                        this.Frm_Main_Paint(this, new PaintEventArgs(this.CreateGraphics(), this.ClientRectangle));
                        g.DrawLine(new Pen(foreColor, 1), startPoint, new Point(e.X, e.Y));
                        break;
                    case (int)drawTools.Ellipse:
                        //首先恢复此次操作之前的图像，然后再添加Ellipse 
                        this.Frm_Main_Paint(this, new PaintEventArgs(this.CreateGraphics(), this.ClientRectangle));
                        g.DrawEllipse(new Pen(foreColor, 1), startPoint.X, startPoint.Y, e.X - startPoint.X, e.Y - startPoint.Y);
                        break;
                    case (int)drawTools.Rectangle:
                        //首先恢复此次操作之前的图像，然后再添加Rectangle 
                        this.Frm_Main_Paint(this, new PaintEventArgs(this.CreateGraphics(), this.ClientRectangle));
                        g.DrawRectangle(new Pen(foreColor, 1), startPoint.X, startPoint.Y, e.X - startPoint.X, e.Y - startPoint.Y);
                        break;
                    case (int)drawTools.String:
                        break;
                    case (int)drawTools.Rubber:
                        //用背景色绘制宽线段 
                        g.DrawLine(new Pen(backColor, 20), oldPoint, new Point(e.X, e.Y));
                        ig.DrawLine(new Pen(backColor, 20), oldPoint, new Point(e.X, e.Y));
                        oldPoint.X = e.X;
                        oldPoint.Y = e.Y;
                        break;
                }
            }
        }
        bool isDrawing = false;
        private void Form1_MouseUp(object sender, MouseEventArgs e)
        {
            isDrawing = false;
            switch (drawTool)
            {
                case (int)drawTools.Line:
                    ig.DrawLine(new Pen(foreColor, 1), startPoint, new Point(e.X, e.Y));
                    break;
                case (int)drawTools.Ellipse:
                    ig.DrawEllipse(new Pen(foreColor, 1), startPoint.X, startPoint.Y, e.X - startPoint.X, e.Y - startPoint.Y);
                    break;
                case (int)drawTools.Rectangle:
                    ig.DrawRectangle(new Pen(foreColor, 1), startPoint.X, startPoint.Y, e.X - startPoint.X, e.Y - startPoint.Y);
                    break;
            }
        }

        private void Frm_Main_Paint(object sender, PaintEventArgs e)
        {
            //将Image中保存的图像，绘制出来 
            Graphics g = this.CreateGraphics();
            if (theImage != null)
            {
                g.Clear(Color.White);
                g.DrawImage(theImage, this.ClientRectangle);
            }
        }

        private void toolStripButton1_Click(object sender, EventArgs e)
        {
            toolStripButton6.Checked = false;
            toolStripButton2.Checked = false;
            toolStripButton3.Checked = false;
            toolStripButton4.Checked = false;
            toolStripButton5.Checked = false;
            if (drawTool == (int)drawTools.Pen)
            {
                drawTool = (int)drawTools.None ;
                toolStripButton1.Checked = false ;
            }
            else
            {
                drawTool = (int)drawTools.Pen;
                toolStripButton1.Checked = true;
            }   
        }

        private void toolStripButton2_Click(object sender, EventArgs e)
        {
            toolStripButton1.Checked = false;
            toolStripButton6.Checked = false;
            toolStripButton3.Checked = false;
            toolStripButton4.Checked = false;
            toolStripButton5.Checked = false;
            if (drawTool == (int)drawTools.Line)
            {
                drawTool = (int)drawTools.None;
                toolStripButton2.Checked = false;
            }
            else
            {
                drawTool = (int)drawTools.Line;
                toolStripButton2.Checked = true;
            }
        }

        private void toolStripButton3_Click(object sender, EventArgs e)
        {

            toolStripButton1.Checked = false;
            toolStripButton2.Checked = false;
            toolStripButton6.Checked = false;
            toolStripButton4.Checked = false;
            toolStripButton5.Checked = false;
            if (drawTool == (int)drawTools.Rectangle)
            {
                drawTool = (int)drawTools.None;
                toolStripButton3.Checked = false;
            }
            else
            {
                drawTool = (int)drawTools.Rectangle;
                toolStripButton3.Checked = true;
            }           
        }

        private void toolStripButton4_Click(object sender, EventArgs e)
        {
            toolStripButton1.Checked = false;
            toolStripButton2.Checked = false;
            toolStripButton3.Checked = false;
            toolStripButton6.Checked = false;
            toolStripButton5.Checked = false;
            if (drawTool == (int)drawTools.Ellipse)
            {
                drawTool = (int)drawTools.None;
                toolStripButton4.Checked = false;
            }
            else
            {
                drawTool = (int)drawTools.Ellipse;
                toolStripButton4.Checked = true;
            }  
        }

        private void toolStripButton5_Click(object sender, EventArgs e)
        {

            toolStripButton1.Checked = false;
            toolStripButton2.Checked = false;
            toolStripButton3.Checked = false;
            toolStripButton4.Checked = false;
            toolStripButton6.Checked = false;
            if (drawTool == (int)drawTools.String)
            {
                drawTool = (int)drawTools.None;
                toolStripButton5.Checked = false;
            }
            else
            {
                drawTool = (int)drawTools.String;
                toolStripButton5.Checked = true;
            }  
        }

        private void toolStripButton6_Click(object sender, EventArgs e)
        {
            toolStripButton1.Checked = false;
            toolStripButton2.Checked = false;
            toolStripButton3.Checked = false;
            toolStripButton4.Checked = false;
            toolStripButton5.Checked = false;
            if (drawTool == (int)drawTools.Rubber )
            {
                drawTool = (int)drawTools.None;
                toolStripButton6.Checked = false;
            }
            else
            {
                drawTool = (int)drawTools.Rubber;
                toolStripButton6.Checked = true;
            }  
        }

        private void 颜色ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (colorDialog1.ShowDialog() == DialogResult.OK)
            {
                foreColor = colorDialog1.Color  ;
            }
            
        }
    }
}