winfrom-画图学习

川长思鸟来 2022-07-12 02:12 172阅读 0赞

![SouthEast][]

namespace Painter
    {
        partial class FormPainter
        {        
            private System.ComponentModel.IContainer components = null;
    
            protected override void Dispose(bool disposing)
            {
                if (disposing && (components != null))
                {
                    components.Dispose();
                }
                base.Dispose(disposing);
            }
          
            private void InitializeComponent()
            {
                this.toolStrip1 = new System.Windows.Forms.ToolStrip();
                this.toolStripComboBoxMode = new System.Windows.Forms.ToolStripComboBox();
                this.pictureBox1 = new System.Windows.Forms.PictureBox();
                this.toolStrip1.SuspendLayout();
                ((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).BeginInit();
                this.SuspendLayout();
                // 
                // toolStrip1
                // 
                this.toolStrip1.Items.AddRange(new System.Windows.Forms.ToolStripItem[] {
                this.toolStripComboBoxMode});
                this.toolStrip1.Location = new System.Drawing.Point(0, 0);
                this.toolStrip1.Name = "toolStrip1";
                this.toolStrip1.Size = new System.Drawing.Size(468, 25);
                this.toolStrip1.TabIndex = 0;
                this.toolStrip1.Text = "toolStrip1";
                // 
                // toolStripComboBoxMode
                // 
                this.toolStripComboBoxMode.Items.AddRange(new object[] {
                "画笔",
                "直线",
                "矩形",
                "圆形"});
                this.toolStripComboBoxMode.Name = "toolStripComboBoxMode";
                this.toolStripComboBoxMode.Size = new System.Drawing.Size(75, 25);
                this.toolStripComboBoxMode.Text = "画笔";
                // 
                // pictureBox1
                // 
                this.pictureBox1.Location = new System.Drawing.Point(0, 28);
                this.pictureBox1.Name = "pictureBox1";
                this.pictureBox1.Size = new System.Drawing.Size(456, 381);
                this.pictureBox1.TabIndex = 1;
                this.pictureBox1.TabStop = false;
                this.pictureBox1.MouseDown += new System.Windows.Forms.MouseEventHandler(this.FormPainter_MouseDown);
                this.pictureBox1.MouseMove += new System.Windows.Forms.MouseEventHandler(this.FormPainter_MouseMove);
                this.pictureBox1.MouseUp += new System.Windows.Forms.MouseEventHandler(this.FormPainter_MouseUp);
                // 
                // FormPainter
                // 
                this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
                this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
                this.ClientSize = new System.Drawing.Size(468, 421);
                this.Controls.Add(this.pictureBox1);
                this.Controls.Add(this.toolStrip1);
                this.Name = "FormPainter";
                this.Text = "Form1";
                this.toolStrip1.ResumeLayout(false);
                this.toolStrip1.PerformLayout();
                ((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).EndInit();
                this.ResumeLayout(false);
                this.PerformLayout();
    
            }
    
            private System.Windows.Forms.ToolStrip toolStrip1;
            private System.Windows.Forms.ToolStripComboBox toolStripComboBoxMode;
            private System.Windows.Forms.PictureBox pictureBox1;
        }
    }

using System;
    using System.Collections.Generic;
    using System.Drawing;
    using System.Windows.Forms;
    
    namespace Painter
    {
        public partial class FormPainter : Form
        {
            Graphics g;
            Bitmap img;
            Bitmap buf;
            Pen pen = new Pen(Color.Black, 3);
    
            public FormPainter()
            {
                InitializeComponent();
    
                img = new Bitmap(pictureBox1.Width, pictureBox1.Height);
                g = Graphics.FromImage(img);
            }
    
            bool isMouseDown = false;
            List<Point> points = new List<Point>();
    
            private void FormPainter_MouseDown(object sender, MouseEventArgs e)
            {
                Point p = new Point(e.X, e.Y);
                isMouseDown = true;
                points.Clear();
                points.Add(p);
                pictureBox1.Image = img;
            }
    
            private void FormPainter_MouseUp(object sender, MouseEventArgs e)
            {
                isMouseDown = false;
                img = buf; // 将上次 MouseMove 画的暂存结果取回
                pictureBox1.Image = img; // 然后显示出來
            }
    
            private void FormPainter_MouseMove(object sender, MouseEventArgs e)
            {
                Point p = new Point(e.X, e.Y);
    
                buf = new Bitmap(img); // 建立一个新的 buf 缓存区，画的时候
                Graphics g = Graphics.FromImage(buf);
    
                if (points.Count > 0 && isMouseDown)
                {
                    Point pStart = points[0];
                    Point pLast = points[points.Count - 1];
                    if (toolStripComboBoxMode.Text.Equals("画笔"))
                    {
                        Point p0 = pStart;
                        foreach (Point p1 in points)
                        {
                            g.DrawLine(pen, p0, p1);
                            p0 = p1;
                        }
                    }
                    else if (toolStripComboBoxMode.Text.Equals("直线"))
                    {
                        g.DrawLine(pen, pStart, p);
                    }
                    else if (toolStripComboBoxMode.Text.Equals("矩形"))
                    {
                        g.DrawRectangle(pen, pStart.X, pStart.Y, p.X - pStart.X, p.Y - pStart.Y);
                    }
                    else if (toolStripComboBoxMode.Text.Equals("圆形"))
                    {
                        g.DrawEllipse(pen, pStart.X, pStart.Y, p.X - pStart.X, p.Y - pStart.Y);
                    }
                }
    
                points.Add(p);
                pictureBox1.Image = buf;
            }
    
            //...
    
        }
    }

![SouthEast 1][]

[SouthEast]: /images/20220711/ae1bb10ab7d54df6a8d79e11402478af.png
[SouthEast 1]: /images/20220711/bb0222c068584106b15a833e578a2b46.png