将画布保存到位图 [英] Save canvas to bitmap

问题描述

我想将画布保存到位图。我在互联网上找到了一些示例，但所有示例仅保存黑色图像（具有画布的大小）。
我该怎么办？

I want to save my canvas to bitmap. I found some examples in internet, but all of those saves only black image (with size of my canvas). What can I do with this?

代码：

    public static void SaveCanvasToFile(Canvas surface, string filename)
    {
        Size size = new Size(surface.Width, surface.Height);

        surface.Measure(size);
        surface.Arrange(new Rect(size));

        // Create a render bitmap and push the surface to it
        RenderTargetBitmap renderBitmap =
          new RenderTargetBitmap(
            (int)size.Width,
            (int)size.Height,
            96d,
            96d,
            PixelFormats.Pbgra32);
        renderBitmap.Render(surface);

        // Create a file stream for saving image
        using (FileStream outStream = new FileStream(filename, FileMode.Create))
        {               
            BmpBitmapEncoder encoder = new BmpBitmapEncoder();
            // push the rendered bitmap to it
            encoder.Frames.Add(BitmapFrame.Create(renderBitmap));
            // save the data to the stream
            encoder.Save(outStream);
        }}

推荐答案

尝试以下答案：

public void ExportToPng(Uri path, Canvas surface)
{
  if (path == null) return;

  // Save current canvas transform
  Transform transform = surface.LayoutTransform;
  // reset current transform (in case it is scaled or rotated)
  surface.LayoutTransform = null;

  // Get the size of canvas
  Size size = new Size(surface.Width, surface.Height);
  // Measure and arrange the surface
  // VERY IMPORTANT
  surface.Measure(size);
  surface.Arrange(new Rect(size));

  // Create a render bitmap and push the surface to it
  RenderTargetBitmap renderBitmap = 
    new RenderTargetBitmap(
      (int)size.Width, 
      (int)size.Height, 
      96d, 
      96d, 
      PixelFormats.Pbgra32);
  renderBitmap.Render(surface);

  // Create a file stream for saving image
  using (FileStream outStream = new FileStream(path.LocalPath, FileMode.Create))
  {
    // Use png encoder for our data
    PngBitmapEncoder encoder = new PngBitmapEncoder();
    // push the rendered bitmap to it
    encoder.Frames.Add(BitmapFrame.Create(renderBitmap));
    // save the data to the stream
    encoder.Save(outStream);
  }

  // Restore previously saved layout
  surface.LayoutTransform = transform;
}

为方便起见，此答案已从[本页]复制到此处。 === LINK死（ http://denisvuyka.wordpress.com/2007/12/03/wpf-diagramming-saving-you-canvas-to-image-xps-document-or-raw-xaml/ ）

This answer was copied here for convenience from [this page.]<====LINK DEAD(http://denisvuyka.wordpress.com/2007/12/03/wpf-diagramming-saving-you-canvas-to-image-xps-document-or-raw-xaml/)

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