WinForm实现的图片拖拽与缩放功能示例

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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 图像平移缩放
{
  public partial class Form1 : Form
  {
    Bitmap myBmp;
    Point mouseDownPoint = new Point(); //记录拖拽过程鼠标位置
    bool isMove = false;  //判断鼠标在picturebox上移动时，是否处于拖拽过程(鼠标左键是否按下)
    int zoomStep = 20;   //缩放步长
    public Form1()
    {
      InitializeComponent();
    }
    //图片上传
    private void button1_Click(object sender, EventArgs e)
    {
      string filename = "";
      OpenFileDialog dlg = new OpenFileDialog();
      dlg.Filter = "Tiff文件|*.tif|Bmp文件|*.bmp|Erdas img文件|*.img|EVNI文件|*.hdr|jpeg文件|*.jpg|raw文件|*.raw|vrt文件|*.vrt|所有文件|*.*";
      dlg.FilterIndex = 8;
      if (dlg.ShowDialog() == DialogResult.OK)
      {
        filename = dlg.FileName;
      }
      if (filename == "")
      {
        return;
      }
      myBmp = new Bitmap(filename);
      if (myBmp == null)
      {
        MessageBox.Show("读取失败");
        return;
      }
      textBox1.Text = filename;
      pictureBox1.Image = myBmp;
      pictureBox1.SizeMode = PictureBoxSizeMode.Zoom; //设置picturebox为缩放模式
      pictureBox1.Width = myBmp.Width;
      pictureBox1.Height = myBmp.Height;
    }
    //鼠标按下功能
    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();
      }
    }
    //鼠标松开功能
    private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
    {
      if (e.Button == MouseButtons.Left)
      {
        isMove = false;
      }
    }
    //鼠标移动功能
    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;
      }
    }
    //鼠标滚轮滚动功能
    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);
    }
    private void panel2_MouseDown(object sender, MouseEventArgs e)
    {
      if (e.Button == MouseButtons.Left)
      {
        mouseDownPoint.X = Cursor.Position.X;
        mouseDownPoint.Y = Cursor.Position.Y;
        isMove = true;
      }
    }
    private void panel2_MouseUp(object sender, MouseEventArgs e)
    {
      if (e.Button == MouseButtons.Left)
      {
        isMove = false;
      }
    }
    private void panel2_MouseMove(object sender, MouseEventArgs e)
    {
      panel2.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;
      }
    }
  }
}

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//
// pictureBox1
//
this.pictureBox1.BackColor = System.Drawing.Color.White;
this.pictureBox1.Location = new System.Drawing.Point(20, 20);
this.pictureBox1.Margin = new System.Windows.Forms.Padding(2, 2, 2, 2);
this.pictureBox1.Name = "pictureBox1";
this.pictureBox1.Size = new System.Drawing.Size(67, 34);
this.pictureBox1.TabIndex = 0;
this.pictureBox1.TabStop = false;
this.pictureBox1.MouseDown += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseDown);
this.pictureBox1.MouseMove += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseMove);
this.pictureBox1.MouseUp += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseUp);
this.pictureBox1.MouseWheel += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseWheel);