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WPF把Canvas保存为图片，文本文件，xps文件

由于wpf的UI使用xaml来表达的，所以我们们可利用这个优点，把WPF中的xaml元素另存为各样的文件，在很多时候我们都不须要这样的操作。把xaml保存为图片、字符串、XPS等等。这里我写了一些方法，以供大家参考.。

注意：以下保存操作前，一定要确保参数中的canvas有高和宽。

1.把canvas保存为文本文件

using System.IO;
public void Export(Uri path, Canvas surface)
{
      if (path == null) return;
      if (surface == null) return;
      string xaml = XamlWriter.Save(surface);
      File.WriteAllText(path.LocalPath, xaml);

2.把canvas保存为xps文件,xps命名空间在ReachFramework.dll中

using System.IO.Packaging;
  using System.Windows.Xps;
  using System.Windows.Xps.Packaging;
  using System.IO;
  public void Export(Uri path, Canvas surface)
  {
      if (path == null) return;
    
      Transform transform = surface.LayoutTransform;
      surface.LayoutTransform = null;
    
      Size size = new Size(surface.Width, surface.Height);
      surface.Measure(size);
     surface.Arrange(new Rect(size));
   
     Package package = Package.Open(path.LocalPath, FileMode.Create);
     XpsDocument doc = new XpsDocument(package);
     XpsDocumentWriter writer = XpsDocument.CreateXpsDocumentWriter(doc);
     writer.Write(surface);
     doc.Close();
     package.Close();
     surface.LayoutTransform = transform;
 }

3.把canvas保存为图片

public void ExportToPng(Uri path, Canvas surface)
   {
       if (path == null) return;
     
       Transform transform = surface.LayoutTransform;
       surface.LayoutTransform = null;
     
       Size size = new Size(surface.Width, surface.Height);
       surface.Measure(size);
       surface.Arrange(new Rect(size));
    
       RenderTargetBitmap renderBitmap =
       new RenderTargetBitmap(
       (int)size.Width,
       (int)size.Height,
       96d,
       96d,
       PixelFormats.Pbgra32);
       renderBitmap.Render(surface);
   
       using (FileStream outStream = new FileStream(path.LocalPath, FileMode.Create))
       {
           PngBitmapEncoder encoder = new PngBitmapEncoder();
           encoder.Frames.Add(BitmapFrame.Create(renderBitmap));
           encoder.Save(outStream);
       }
           surface.LayoutTransform = transform;
   }