摘要

在機器視覺專案中，經常用c#做Winform介面交付給客戶使用，在介面中，可能輸入的圖片比較大，一般的顯示器解析度無法顯示全，然後還需要放大看清楚圖片裡面的文字內容，所以需要用到圖片的拖拽與縮放功能。

首先新建一個窗體，拖一個panel控制元件到窗體中，然後在拖一個pictureobx控制元件到panel中，然後在添加個開啟圖片的按鈕：

全部程式碼：

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;
using System.Reflection;

namespace 影象平移和縮放
{
    public partial class Form1 : Form
    {
        Bitmap myBmp;
        Point mouseDownPoint = new Point(); //記錄拖拽過程滑鼠位置
        bool isMove = false;    //判斷滑鼠在picturebox上移動時，是否處於拖拽過程(滑鼠左鍵是否按下)
 

        int zoomStep = 20;      //縮放步長
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string filename = "";
            OpenFileDialog dlg = new OpenFileDialog();
            dlg.Filter 
 
= "Tiff檔案|*.tif|Bmp檔案|*.bmp|Erdas img檔案|*.img|EVNI檔案|*.hdr|jpeg檔案|*.jpg|raw檔案|*.raw|vrt檔案|*.vrt|所有檔案|*.*";
            dlg.FilterIndex = 8;
            if (dlg.ShowDialog() == DialogResult.OK)
            {
                filename = dlg.FileName;
            }
            if (filename == "")
            {
                return;
            }
            myBmp = new Bitmap(filename);
            if (myBmp == null)
            {
                MessageBox.Show("讀取失敗");
                return;
            }
            textBox1.Text = filename;
            pictureBox1.Image = myBmp;
            pictureBox1.SizeMode = PictureBoxSizeMode.Zoom; //設定picturebox為縮放模式
            pictureBox1.Width = myBmp.Width;
            pictureBox1.Height = myBmp.Height;
        }
        //滑鼠按下功能
        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                mouseDownPoint.X = Cursor.Position.X;
                mouseDownPoint.Y = Cursor.Position.Y;
                isMove = true;
                pictureBox1.Focus();
            }
        }

        //滑鼠鬆開功能
        private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                isMove = false;
            }
        }

        //滑鼠移動功能
        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            pictureBox1.Focus();
            if (isMove)
            {
                int x, y;
                int moveX, moveY;
                moveX = Cursor.Position.X - mouseDownPoint.X;
                moveY = Cursor.Position.Y - mouseDownPoint.Y;
                x = pictureBox1.Location.X + moveX;
                y = pictureBox1.Location.Y + moveY;
                pictureBox1.Location = new Point(x, y);
                mouseDownPoint.X = Cursor.Position.X;
                mouseDownPoint.Y = Cursor.Position.Y;
            }
        }
        //滑鼠滾輪滾動功能
        private void pictureBox1_MouseWheel(object sender, MouseEventArgs e)
        {
            int x = e.Location.X;
            int y = e.Location.Y;
            int ow = pictureBox1.Width;
            int oh = pictureBox1.Height;
            int VX, VY;
            if (e.Delta > 0)
            {
                pictureBox1.Width += zoomStep;
                pictureBox1.Height += zoomStep;

                PropertyInfo pInfo = pictureBox1.GetType().GetProperty("ImageRectangle", BindingFlags.Instance |
                    BindingFlags.NonPublic);
                Rectangle rect = (Rectangle)pInfo.GetValue(pictureBox1, null);

                pictureBox1.Width = rect.Width;
                pictureBox1.Height = rect.Height;
            }
            if (e.Delta < 0)
            {

                if (pictureBox1.Width < myBmp.Width / 10)
                    return;

                pictureBox1.Width -= zoomStep;
                pictureBox1.Height -= zoomStep;
                PropertyInfo pInfo = pictureBox1.GetType().GetProperty("ImageRectangle", BindingFlags.Instance |
                    BindingFlags.NonPublic);
                Rectangle rect = (Rectangle)pInfo.GetValue(pictureBox1, null);
                pictureBox1.Width = rect.Width;
                pictureBox1.Height = rect.Height;
            }

            VX = (int)((double)x * (ow - pictureBox1.Width) / ow);
            VY = (int)((double)y * (oh - pictureBox1.Height) / oh);
            pictureBox1.Location = new Point(pictureBox1.Location.X + VX, pictureBox1.Location.Y + VY);
        }
    }
}

需要注意一點：

類裡面用到了一個pictureBox1_MouseWheel 事件，這個是picturebox控制元件沒有的事件，所以需要手動去新增這個事件，可以直接在form1的Designer.cs中新增：

 this.pictureBox1.MouseWheel += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseWheel); 

實現效果：