实现图片盖章功能，在图片上点击，增加“图章”小图片，可以拖拽“图章”到任意位置，也可以点击图章右下角园框，令图片跟着鼠标旋转和放缩。

操作方法：1.点击增加“图章”2.选中移动图标3.点中右下角放缩旋转图章。

效果图：

实现代码如下：

1. 窗口Xaml代码
复制代码 代码如下:<Window x:Class="Lenovo.YogaPaster.ImageEditWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="ImageEditWindow" Height="300" Width="300">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="20*"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Canvas x:Name="canvas"
Background="Yellow" />
<Button Content="保存成图片" Click="Button_Click_1" Grid.Row="1" HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Grid>
</Window>
2. 窗口后台代码：
复制代码 代码如下:using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;
using Lenovo.YP.Utils;
using Microsoft.Win32;
using Point = System.Windows.Point;

namespace Lenovo.YogaPaster
{
/// <summary>
/// ImageEditWindow.xaml 的交互逻辑
/// </summary>
public partial class ImageEditWindow : Window
{
public ImageEditWindow()
{
InitializeComponent();
this.Loaded += (sender, e) =>
{
canvas.MouseLeftButtonDown += canvas_MouseLeftButtonDown;
};
}
private void canvas_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
PhotoEditHelper.CommomMaxZIndex++;
var image = new MoveImage { ContainerCanvas = canvas };
Point point = e.GetPosition(canvas);
image.CreateImage(point);
}
/// <summary>
/// 保存方法
/// </summary>
public void SavePicture()
{
//TODO: openFile对话框
SaveFileDialog saveFileDialog = new SaveFileDialog();
saveFileDialog.FileName = "图片"; // Default file name
saveFileDialog.DefaultExt = ".bmp"; // Default file extension
saveFileDialog.Filter = "图片文件 (.bmp)|*.bmp"; // Filter files by extension

// Show save file dialog box
Nullable<bool> result = saveFileDialog.ShowDialog();

// Process save file dialog box results
if (result == true)
{
// Save document
string filename = saveFileDialog.FileName;
if (File.Exists(filename))
{
File.Delete(filename);
}
BitmapSource bitmapSource = PictureMergeHelper.CreateNotRanderElementScreenshot(canvas, 1800, 1080);
BitmapEncoder bitmapEncoder = new BmpBitmapEncoder();
bitmapEncoder.Frames.Add(BitmapFrame.Create(bitmapSource));
FileStream fileStream = new FileStream(filename, FileMode.Create);
bitmapEncoder.Save(fileStream);
fileStream.Dispose();
}
}

private void Button_Click_1(object sender, RoutedEventArgs e)
{
SavePicture();
}
}
}

3. MoveImage 类文件如下：
复制代码 代码如下:using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;

namespace Lenovo.YP.Utils
{
/// <summary>
/// 添加一个image控件，并实现拖动效果
/// </summary>
public class MoveImage
{
#region 字段
private int m_ZIndex;
/// <summary>
/// 当前图章的位置
/// </summary>
///
/// <summary>
/// 旋转图标的起始位置
/// </summary>
private Point m_ImageRoundStartOffset;
/// <summary>
/// 旋转图标的当前位置
/// </summary>
private Point m_ImageRoundOffset;
/// <summary>
/// 标识图章是否被拖拽
/// </summary>
private bool m_IsDragging;
/// <summary>
/// 标识旋转图标是否被是否被拖拽
/// </summary>
private bool m_IsimageRoundDragging;
/// <summary>
/// 图章的父容器
/// </summary>
public Canvas ContainerCanvas { get; set; }
/// <summary>
/// 图章图片
/// </summary>
private Image m_FlogImage;
/// <summary>
/// 旋转按钮图片
/// </summary>
private Image m_RotateImage;
/// <summary>
/// 图章和旋转图片的容器
/// </summary>
private Grid m_MoveImageGrid;
/// <summary>
/// 选转
/// </summary>
private RotateTransform m_ImageRotate;
/// <summary>
/// 缩放
/// </summary>
private ScaleTransform m_ImageScale;
/// <summary>
/// 上次位置
/// </summary>
private Point m_OldPos;
#endregion

public MoveImage()
{ }
/// <summary>
/// 创建一个图标
/// </summary>
/// <param name="position">图标的位置</param>
public void CreateImage(Point position)
{
#region 设置布局
m_FlogImage = new Image
{
//Width = 100,
//Height = 100,
Source = new BitmapImage(new Uri("/Images/shuzi.jpg", UriKind.RelativeOrAbsolute))
};
m_RotateImage = new Image
{
Width = 20,
Height = 20,
Source = new BitmapImage(new Uri("/Images/round.jpg", UriKind.RelativeOrAbsolute))
};
m_RotateImage.HorizontalAlignment = HorizontalAlignment.Right;
m_RotateImage.VerticalAlignment = VerticalAlignment.Bottom;
m_RotateImage.Visibility = Visibility.Hidden;
m_MoveImageGrid = new Grid();
m_MoveImageGrid.Width = 110;
m_MoveImageGrid.Height = 110;
m_MoveImageGrid.Children.Add(m_FlogImage);
m_MoveImageGrid.Children.Add(m_RotateImage);
m_MoveImageGrid.MouseEnter += RootGridMouseEnter;
m_MoveImageGrid.MouseLeave += RootGridMouseLeave;
m_RotateImage.MouseLeftButtonDown += imageRound_MouseLeftButtonDown;
m_RotateImage.MouseMove += imageRound_MouseMove;
m_RotateImage.MouseLeftButtonUp += imageRound_MouseLeftButtonUp;
// Image in den Vordergrund bringen
Canvas.SetZIndex(m_MoveImageGrid, m_ZIndex++);
#endregion
// Event Handler für das Image installieren
m_MoveImageGrid.MouseLeftButtonDown += RootGridMouseLeftButtonDown;
m_MoveImageGrid.MouseLeftButtonUp += RootGridMouseLeftButtonUp;
m_MoveImageGrid.MouseMove += RootGridMouseMove;
// Image leicht transparent machen
m_MoveImageGrid.Opacity = 0.8;
m_ImageRotate = new RotateTransform(0, 0, 0);
m_ImageScale = new ScaleTransform();
//m_ImageScale.ScaleX = 1;
//m_ImageScale.ScaleY = 1;
TransformGroup transformGroup = new TransformGroup();
transformGroup.Children.Add(m_ImageRotate);
transformGroup.Children.Add(m_ImageScale);
m_MoveImageGrid.RenderTransform = transformGroup;
//m_ImageScale111 = new ScaleTransform();
//m_ImageScale111.ScaleX = 0.5;
//m_ImageScale111.ScaleY = 0.5;
//imageRound.RenderTransform = m_ImageScale111;
m_MoveImageGrid.RenderTransformOrigin = new Point(0.5, 0.5);
// Image positionieren
var pos = position;
Canvas.SetLeft(m_MoveImageGrid, pos.X - (m_MoveImageGrid.Width / 2));
Canvas.SetTop(m_MoveImageGrid, pos.Y - (m_MoveImageGrid.Height / 2));
// Image zum Canvas hinzufügen
ContainerCanvas.Children.Add(m_MoveImageGrid);
}

/// <summary>
/// 控制旋转图标隐藏
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void RootGridMouseLeave(object sender, MouseEventArgs e)
{
m_RotateImage.Visibility = Visibility.Hidden;
}

/// <summary>
/// 控制选择图标显示
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void RootGridMouseEnter(object sender, MouseEventArgs e)
{
m_RotateImage.Visibility = Visibility.Visible;
}

#region 控制盖章的移动
private void RootGridMouseMove(object sender, MouseEventArgs e)
{
if (m_IsDragging)
{
var pos = e.GetPosition(ContainerCanvas);
Canvas.SetLeft(m_MoveImageGrid, Canvas.GetLeft(m_MoveImageGrid) + pos.X - m_OldPos.X);
Canvas.SetTop(m_MoveImageGrid, Canvas.GetTop(m_MoveImageGrid) + pos.Y - m_OldPos.Y);
m_OldPos = pos;
}
}

private void RootGridMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
var grid = sender as Grid;

// Canvas.SetZIndex(image, m_ZIndex++);
// Bild wieder leicht transparent machen
grid.Opacity = 0.8;
grid.ReleaseMouseCapture();
m_IsDragging = false;
}

private void RootGridMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{

var grid = sender as Grid;

// auf "nicht"-transparent setzen
grid.Opacity = 1;

// Position des Pointers relativ zum Bild speichern
m_OldPos = e.GetPosition(ContainerCanvas);

// isDragging auf true setzen für MouseMove
m_IsDragging = true;
// Image in den Vordergrund bringen
Canvas.SetZIndex(grid, PhotoEditHelper.CommomMaxZIndex++);
// Den Pointer einfangen. Bei schnellen Bewegungen kann der
// Pointer aus dem Image bewegt werden. Damit die Pointer-
// Events weiterhin stattfinden, wird der Pointer eingefangen.
grid.CaptureMouse();
// als behandelt markieren, damit nicht noch der
// PointerPressed-Event Handler des Canvas aufgerufen wird.
e.Handled = true;
}
#endregion

#region 控制图章的旋转
private void imageRound_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
var image = sender as Image;

m_MoveImageGrid.Opacity = 1;
image.ReleaseMouseCapture();
m_IsimageRoundDragging = false;
}

private void imageRound_MouseMove(object sender, MouseEventArgs e)
{
if (m_IsimageRoundDragging)
{
//鼠标当前点的坐标
m_ImageRoundOffset = e.GetPosition(ContainerCanvas);
m_ImageScale.ScaleX =
m_ImageScale.ScaleY = GetLength(currCenter, m_ImageRoundStartOffset, m_ImageRoundOffset);
m_ImageRotate.Angle = GetAngle(currCenter, m_ImageRoundStartOffset, m_ImageRoundOffset) - 45;
}
}

private Point currCenter;
private void imageRound_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
var image = sender as Image;
m_MoveImageGrid.Opacity = 1;

//中心点坐标
currCenter = new Point(Canvas.GetLeft(m_MoveImageGrid) + m_MoveImageGrid.Width / 2, Canvas.GetTop(m_MoveImageGrid) + m_MoveImageGrid.Height / 2);
m_ImageRoundStartOffset = new Point(currCenter.X + m_MoveImageGrid.Width / 2, currCenter.Y);
m_IsimageRoundDragging = true;
Canvas.SetZIndex(m_MoveImageGrid, PhotoEditHelper.CommomMaxZIndex++);
image.CaptureMouse();
e.Handled = true;
}

/// 根据余弦定理求两个线段夹角
/// </summary>
/// <param name="origin">原点</param>
/// <param name="start">start点</param>
/// <param name="end">end点</param>
/// <returns></returns>
private double GetAngle(Point origin, Point start, Point end)
{
double cosfi = 0, fi = 0, norm = 0;
double dsx = start.X - origin.X;
double dsy = start.Y - origin.Y;
double dex = end.X - origin.X;
double dey = end.Y - origin.Y;

cosfi = dsx * dex + dsy * dey;
norm = (dsx * dsx + dsy * dsy) * (dex * dex + dey * dey);
if (norm == 0) return 0; // origin和end坐标一样
cosfi /= Math.Sqrt(norm);

if (cosfi >= 1.0) return 0;
if (cosfi <= -1.0) return 180;
fi = Math.Acos(cosfi);

double angle = 180 * fi / Math.PI;

if (dey > 0)
{
return angle;
}
return -angle;
}

private double GetLength(Point origin, Point start, Point end)
{
double dex = end.X - origin.X;
double dey = end.Y - origin.Y;
double dsx = start.X - origin.X;
double dsy = start.Y - origin.Y;
double startLength = Math.Sqrt(Math.Pow(dsx, 2) + Math.Pow(dsy, 2));
double endLength = Math.Sqrt(Math.Pow(dex, 2) + Math.Pow(dey, 2));
return endLength / startLength;
}

#endregion
}