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（代码不多，就只放代码了）

一、WPF中图片局部放大

1.xaml中代码：

<Window x:Class="WpfZoom.MainWindow"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"Title="WPF局部放大效果" Height="370" Width="700" WindowStartupLocation="CenterScreen"><Canvas x:Name="RootCanvas"><!--左侧小图--><Canvas x:Name="SmallBox" MouseMove="MoveRect_MouseMove" MouseEnter="SmallBox_MouseEnter" MouseLeave="SmallBox_MouseLeave" Width="320" Height="180" Canvas.Left="20" Canvas.Top="20"><Canvas.Background><ImageBrush ImageSource="Images/mm.jpg" Stretch="Fill" TileMode="None" /></Canvas.Background><!--半透明矩形框--><Rectangle x:Name="MoveRect" Fill="White" Opacity="0.3" Stroke="Blue" Width="50" Height="50" Canvas.Top="78" Canvas.Left="202"/></Canvas><!--右侧大图--><Canvas x:Name="BigBox" Width="300" Height="300" Canvas.Left="360" Canvas.Top="20" Visibility="Collapsed"><!--右侧原图片 注意尺寸--><Image x:Name="bigImg" Width="1920" Height="1080" Canvas.Left="0" Canvas.Top="-780" Source="Images/mm.jpg" /><Canvas.Clip><RectangleGeometry Rect="0,0,300,300" /></Canvas.Clip></Canvas></Canvas>
</Window>

2.xaml.cs中代码：

private void MoveRect_MouseMove(object sender, MouseEventArgs e){FrameworkElement element = sender as FrameworkElement;//计算鼠标在X轴的移动距离double deltaV = e.GetPosition(MoveRect).Y - MoveRect.Height / 2;//计算鼠标在Y轴的移动距离double deltaH = e.GetPosition(MoveRect).X - MoveRect.Width / 2; ;//得到图片Top新位置double newTop = deltaV + (double)MoveRect.GetValue(Canvas.TopProperty);//得到图片Left新位置double newLeft = deltaH + (double)MoveRect.GetValue(Canvas.LeftProperty);//边界的判断if (newLeft <= 0){newLeft = 0;}//左侧图片框宽度 - 半透明矩形框宽度if (newLeft >= (this.SmallBox.Width - this.MoveRect.Width)){newLeft = this.SmallBox.Width - this.MoveRect.Width;}if (newTop <= 0){newTop = 0;}//左侧图片框高度度 - 半透明矩形框高度度if (newTop >= this.SmallBox.Height - this.MoveRect.Height){newTop = this.SmallBox.Height - this.MoveRect.Height;}MoveRect.SetValue(Canvas.TopProperty, newTop);MoveRect.SetValue(Canvas.LeftProperty, newLeft);#region//获取右侧大图框与透明矩形框的尺寸比率double n = this.BigBox.Width / this.MoveRect.Width;//获取半透明矩形框在左侧小图中的位置double left = (double)this.MoveRect.GetValue(Canvas.LeftProperty);double top = (double)this.MoveRect.GetValue(Canvas.TopProperty);//计算和设置原图在右侧大图框中的Canvas.Left 和 Canvas.TopbigImg.SetValue(Canvas.LeftProperty, -left * n);bigImg.SetValue(Canvas.TopProperty, -top * n);#endregion}private void SmallBox_MouseEnter(object sender, MouseEventArgs e){BigBox.Visibility = Visibility.Visible;}private void SmallBox_MouseLeave(object sender, MouseEventArgs e){BigBox.Visibility = Visibility.Hidden;}

3.效果：

二、Winform中图片局部放大

1.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;namespace 图片局部放大
{public partial class Form1 : Form{public static int i = 0;private Point m_ptStart = new Point(0, 0);private Point m_ptEnd = new Point(0, 0);private bool m_bMouseDown = false;private float xRate, yRate, realX1, realY1, realX2, realY2;int pLeft = 0;int pTop = 0;public Form1(){InitializeComponent();}private void Form1_Load(object sender, EventArgs e){xRate = (float)pictureBox1.Image.Width / pictureBox1.Width;yRate = (float)pictureBox1.Image.Height / pictureBox1.Height;SetStyle(ControlStyles.UserPaint, true);SetStyle(ControlStyles.AllPaintingInWmPaint, true); // 禁止擦除背景.SetStyle(ControlStyles.DoubleBuffer, true); //双缓冲}private void pictureBox1_MouseDown(object sender, MouseEventArgs e){if (pictureBox1.HasChildren){for (int i = 0; i < pictureBox1.Controls.Count; i++){pictureBox1.Controls.RemoveAt(0);}}if (e.Button != MouseButtons.Left){return;}m_ptEnd = new Point(e.X, e.Y);this.pictureBox1.Refresh();realX1 = e.X * xRate;realY1 = e.Y * yRate;if (!m_bMouseDown){m_ptStart = new Point(e.X, e.Y);m_ptEnd = new Point(e.X, e.Y);}m_bMouseDown = !m_bMouseDown;}private void pictureBox1_Paint(object sender, PaintEventArgs e){if (m_ptEnd.X - m_ptStart.X < 0 || m_ptEnd.Y - m_ptStart.Y < 0){return;}if (m_ptEnd.X - m_ptStart.X >= 100){m_ptEnd.X = m_ptStart.X + 100;}if (m_ptEnd.Y - m_ptStart.Y >= 100){m_ptEnd.Y = m_ptStart.Y + 100;}e.Graphics.DrawRectangle(System.Drawing.Pens.Blue, m_ptStart.X, m_ptStart.Y, m_ptEnd.X - m_ptStart.X, m_ptEnd.Y - m_ptStart.Y);}private void pictureBox1_MouseUp(object sender, MouseEventArgs e){int eX = 0, eY = 0;if (e.Button != MouseButtons.Left){return;}if (e.X - m_ptStart.X >= 100){if (e.X >= pictureBox1.Width - 1){if (pictureBox1.Width - m_ptStart.X - 1 > 100){eX = m_ptStart.X + 100;}else{eX = pictureBox1.Width - 1;}}else{eX = m_ptStart.X + 100;}}else{if (e.X >= pictureBox1.Width - 1){eX = pictureBox1.Width - 1;}else{eX = e.X;}}if (e.Y - m_ptStart.Y >= 100){if (e.Y >= pictureBox1.Height - 1){if (pictureBox1.Height - m_ptStart.Y - 1 > 100){eX = m_ptStart.Y + 100;}else{eY = pictureBox1.Height - 1;}}else{eY = m_ptStart.Y + 100;}}else{if (e.Y >= pictureBox1.Height - 1){eY = pictureBox1.Height - 1;}else{eY = e.Y;}}if (m_ptStart.X >= 0 && m_ptEnd.X >= 0&& m_ptStart.Y >= 0 && m_ptEnd.Y >= 0&& m_ptStart.X <= 254 && m_ptEnd.X <= 254&& m_ptStart.Y <= 163 && m_ptEnd.Y <= 163){m_ptEnd = new Point(eX, eY);m_bMouseDown = !m_bMouseDown;this.pictureBox1.Refresh();}else{m_ptEnd = new Point(eX, eY);m_ptEnd = m_ptStart;m_bMouseDown = !m_bMouseDown;this.pictureBox1.Refresh();}realX2 = eX * xRate;realY2 = eY * yRate;Crop((Bitmap)pictureBox1.Image);Panel p = new Panel();p.Name = "panel1";p.Location = new Point((int)(realX1 / xRate), (int)(realY1 / yRate));p.Size = new Size((int)(realX2 / xRate - realX1 / xRate), (int)(realY2 / yRate - realY1 / yRate));//p.BackColor = Color.Transparent;p.BackColor = Color.FromArgb(100, 135, 206, 250);//Azure 240 255 255p.BorderStyle = BorderStyle.FixedSingle;p.MouseDown += (s1, e1) =>{pLeft = e1.X;pTop = e1.Y;};p.MouseMove += (s2, e2) =>{GC.Collect();if (e2.Button.ToString().Equals("Left")){if (p.Location.X + e2.X - pLeft <= 1){p.Left = 1;}else if (p.Location.X + e2.X - pLeft >= pictureBox1.Width - p.Width){p.Left = pictureBox1.Width - p.Width - 1;}else{p.Left = p.Location.X + e2.X - pLeft;}if (p.Location.Y + e2.Y - pTop <= 1){p.Top = 1;}else if (p.Location.Y + e2.Y - pTop >= pictureBox1.Height - p.Height){p.Top = pictureBox1.Height - p.Height - 1;}else{p.Top = p.Location.Y + e2.Y - pTop;}}Crop((Bitmap)pictureBox1.Image, Convert.ToInt32(p.Location.X * xRate), Convert.ToInt32(p.Location.Y * yRate), Convert.ToInt32(p.Width), Convert.ToInt32(p.Height));};pictureBox1.Controls.Add(p);}private void pictureBox1_MouseMove(object sender, MouseEventArgs e){if (e.Button != MouseButtons.Left){return;}m_ptEnd = new Point(e.X, e.Y);this.pictureBox1.Refresh();}private void Crop(Bitmap bitmap){if ((int)(realX2 - realX1) > 0 && (int)(realY2 - realY1) > 0){GC.Collect();//GC.WaitForPendingFinalizers();Rectangle rec = new Rectangle((int)realX1, (int)realY1, (int)(realX2 - realX1), (int)(realY2 - realY1));pictureBox2.Image = bitmap.Clone(rec, System.Drawing.Imaging.PixelFormat.Format32bppArgb);}}private void Crop(Bitmap bitmap, int X, int Y, int width, int height){if (width > 0 && height > 0){Rectangle rec = new Rectangle(X, Y, width, height);try{GC.Collect();//GC.WaitForPendingFinalizers();pictureBox2.Image = bitmap.Clone(rec, System.Drawing.Imaging.PixelFormat.Format32bppArgb);//bitmap.Dispose();}catch (Exception ex){i++;}finally{}}}}
}

2.效果：