WPF图像裁剪控件

 在项目中经常会遇到上传图像，并且在上传图片之前可以对图像进行修改，比如下面这个 采用vue做的后台管理系统，有这样的功能。

具体见下图：

  

 Wpf客户端也有这样需求，于是用Wpf模拟下。直接上效果。

总结一下当时遇到的主要几个问题。

1、裁剪区域透明 可以调整大小和移动，调整后也需要保持透明。

2、背景图像移动、缩放需要与预览同步

3、最底层的那个图像需要保持不失帧 

解决方法

问题1，布局采用左右上下，中间变化的时候 改变其他大小， 其他四个区域用一层半透明遮挡。

问题2，记录放大缩小倍数 和移动位置，好在原始图片上进行裁剪

问题3  图片容易失帧，就采取绘制，背景样式如下:

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<DrawingBrush x:Key="background"                       TileMode="Tile"                       Viewport="0,0,20,20"                       ViewportUnits="Absolute">             <DrawingBrush.Drawing>                 <DrawingGroup>                     <DrawingGroup.Children>                         <GeometryDrawing>                             <GeometryDrawing.Geometry>                                 <RectangleGeometry Rect="0,0,0.5,0.5" />                             </GeometryDrawing.Geometry>                             <GeometryDrawing.Brush>                                 <SolidColorBrush Color="#7f7f7f" />                             </GeometryDrawing.Brush>                         </GeometryDrawing>                           <GeometryDrawing>                             <GeometryDrawing.Geometry>                                 <RectangleGeometry Rect="0.5,0,0.5,0.5" />                             </GeometryDrawing.Geometry>                             <GeometryDrawing.Brush>                                 <SolidColorBrush Color="#666666" />                             </GeometryDrawing.Brush>                         </GeometryDrawing>                         <GeometryDrawing>                             <GeometryDrawing.Geometry>                                 <RectangleGeometry Rect="0,0.5,0.5,0.5" />                             </GeometryDrawing.Geometry>                             <GeometryDrawing.Brush>                                 <SolidColorBrush Color="#666666" />                             </GeometryDrawing.Brush>                         </GeometryDrawing>                         <GeometryDrawing>                             <GeometryDrawing.Geometry>                                 <RectangleGeometry Rect="0.5,0.5,0.5,0.5" />                             </GeometryDrawing.Geometry>                             <GeometryDrawing.Brush>                                 <SolidColorBrush Color="#7f7f7f" />                             </GeometryDrawing.Brush>                         </GeometryDrawing>                     </DrawingGroup.Children>                 </DrawingGroup>             </DrawingBrush.Drawing>         </DrawingBrush>

　　录制效果有些卡顿，实际操作还算流畅， 完整源码。