WinForm实现的图片拖拽与缩放功能示例

本文实例讲述了WinForm实现的图片拖拽与缩放功能。分享给大家供大家参考，具体如下：

最近做项目的时候遇到上传施工平面布置图，查看，因为图片比较大，一般的显示器分辨率无法显示全，然后还需要放大看清楚图片里面的文字内容，所以需要用到图片的拖拽与缩放功能。这里整理下具体操作。

首先新建一个窗体，拖一个panel控件到窗体中，然后在拖一个pictureobx控件到panel中，然后在添加个上传图片的按钮：

具体代码：

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;
     }
   }
 }
}

这里需要注意一点，类里面用到了一个 pictureBox1_MouseWheel 时间，这个是picturebox控件没有的时间，所以需要手动去添加这个事件，可以直接在form1的设计类中添加

//
// 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);

这样就能直接运行成功了

希望本文所述对大家C#程序设计有所帮助。