利用C#的視窗程式開發一個簡易畫板

父窗體

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Sketchpad
{
    public partial class Form1
 
 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            儲存SToolStripMenuItem.Enabled = false;
            this.timer1.Interval = 1000;
            this.timer1.Enabled = true;
            IsMdiContainer =
 
 true;
            垂直平鋪ToolStripMenuItem.Enabled = false;
            水平平鋪ToolStripMenuItem.Enabled = false;
            疊加ToolStripMenuItem.Enabled = false;
            重排ToolStripMenuItem.Enabled = false;
        }

        private void 開啟OToolStripMenuItem_Click(object sender, EventArgs e)
        {
 

            OpenFileDialog ofd = new OpenFileDialog();
            ofd.Title = "開啟檔案";
            ofd.Filter = "圖片檔案(*.jpg;*.png)|*.jpg;*.png|所有檔案(*.*)|*.*";
            if(ofd.ShowDialog()==DialogResult.OK)
            {
                Form2 form = new Form2();
                form.MdiParent = this;
                form.Show();
                form.Text = ofd.FileName;
                string imgPath = ofd.FileName;
                form.pictureBox1.Load(imgPath);
                if (ofd.FileName != "")
                {
                    儲存SToolStripMenuItem.Enabled = true;
                    垂直平鋪ToolStripMenuItem.Enabled = true;
                    水平平鋪ToolStripMenuItem.Enabled = true;
                    疊加ToolStripMenuItem.Enabled = true;
                    重排ToolStripMenuItem.Enabled = true;
                }
            }   
        }

        private void 儲存SToolStripMenuItem_Click(object sender, EventArgs e)
        {
            SaveFileDialog sfd = new SaveFileDialog();
            sfd.Title = "儲存檔案";
            sfd.Filter = "圖片檔案(*.jpg)|*.jpg|所有檔案(*.*)|*.*";
            sfd.ShowDialog();
        }

        private void 新建NToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Form2 form = new Form2();
            form.MdiParent = this;
            form.Show();
            儲存SToolStripMenuItem.Enabled = true;
            垂直平鋪ToolStripMenuItem.Enabled = true;
            水平平鋪ToolStripMenuItem.Enabled = true;
            疊加ToolStripMenuItem.Enabled = true;
            重排ToolStripMenuItem.Enabled = true;
        }

        private void 垂直平鋪ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.LayoutMdi(MdiLayout.TileVertical);
        }

        private void 水平平鋪ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.LayoutMdi(MdiLayout.TileHorizontal);
        }

        private void 疊加ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.LayoutMdi(MdiLayout.Cascade);
        }

        private void 重排ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.LayoutMdi(MdiLayout.ArrangeIcons);
        }

        private void 關於AToolStripMenuItem_Click(object sender, EventArgs e)
        {
            MessageBox.Show("製作者：");
        }

        private void 顏色CToolStripMenuItem_Click(object sender, EventArgs e)
        {
            ColorDialog color = new ColorDialog();
            color.ShowDialog();
        }

        private void toolStripButton1_Click(object sender, EventArgs e)
        {
            開啟OToolStripMenuItem_Click(sender, e);
        }

        private void toolStripButton2_Click(object sender, EventArgs e)
        {
            儲存SToolStripMenuItem_Click(sender, e);
        }

        private void toolStripButton3_Click(object sender, EventArgs e)
        {
            新建NToolStripMenuItem_Click(sender, e);
        }

        private void 工具欄TToolStripMenuItem_Click(object sender, EventArgs e)
        {
            工具欄TToolStripMenuItem.Checked = !工具欄TToolStripMenuItem.Checked;
            toolStrip1.Visible = !toolStrip1.Visible;
        }

        private void 狀態條SToolStripMenuItem_Click(object sender, EventArgs e)
        {
            狀態條SToolStripMenuItem.Checked = !狀態條SToolStripMenuItem.Checked;
            statusStrip1.Visible = !statusStrip1.Visible;
        }

        private void timer1_Tick_1(object sender, EventArgs e)
        {
            toolStripStatusLabel1.Text = "時間：" + DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");
            this.statusStrip1.Refresh();
        }

        private void 退出XToolStripMenuItem_Click(object sender, EventArgs e)
        {

            if (this.ActiveMdiChild == null)
            {
                Application.Exit();
            }
            else
            {
                this.ActiveMdiChild.Close();
                Application.Exit();
            }
        }
    }
}

子窗體

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Sketchpad
{
    public partial class Form2 : Form
    {
        private int pictype = 0;
        private Point orgP, endP, mP;
        public Pen myPen = new Pen(Color.Black, 3);
        Graphics g;
        public Form2()
        {
            InitializeComponent();
        }

        private void Form2_Load(object sender, EventArgs e)
        {
        }

        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            if(e.Button==MouseButtons.Left)
            {
                orgP.X = e.X;
                orgP.Y = e.Y;
            }
        }

        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                g = this.pictureBox1.CreateGraphics();
                endP.X = e.X;
                endP.Y = e.Y;
                if (pictype == 4)
                {
                    g.DrawLine(myPen, mP, endP);
                    mP = endP;
                }
                if (pictype != 4)
                {
                    pictureBox1.Refresh();
                }
            }
        }

        private void pictureBox1_Paint(object sender, PaintEventArgs e)
        {
            switch (pictype)
            {
                case 1:
                    e.Graphics.DrawLine(myPen, orgP, endP);//直線
                    break;
                case 2:
                    Rectangle rectangle = new Rectangle(orgP.X, orgP.Y, System.Math.Abs(endP.X), System.Math.Abs(endP.Y));//矩形
                    e.Graphics.DrawRectangle(myPen, rectangle);
                    break;
                case 3:
                    Rectangle Rec = new Rectangle(orgP.X, orgP.Y, System.Math.Abs(endP.X), System.Math.Abs(endP.Y));//橢圓
                    e.Graphics.DrawEllipse(myPen, Rec);
                    break;
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            pictype = 1;
            pictureBox1.Cursor = Cursors.Cross;
        }

        private void button2_Click(object sender, EventArgs e)
        {
            pictype = 2;
            pictureBox1.Cursor = Cursors.Cross;
        }

        private void button3_Click(object sender, EventArgs e)
        {
            pictype = 3;
            pictureBox1.Cursor = Cursors.Cross;
        }

        private void button4_Click(object sender, EventArgs e)
        {
            pictype = 4;
            pictureBox1.Cursor = Cursors.Cross;
        }

        private void button5_Click(object sender, EventArgs e)
        {
            pictype = 5;
            pictureBox1.Cursor = Cursors.Cross;
        }
    }
}