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：
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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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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
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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);
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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。