c# - 在 WPF 中将 Canvas 转换为可写位图的最快方法？

Question

我目前有一个可写的位图图像和一个带有绘图的 Canvas ，我想将图像发送给对等方。为了减少带宽，我想将 Canvas 转换为可写的位图，这样我就可以将两个图像 blit 到一个新的可写位图。问题是我找不到转换 Canvas 的好方法。因此，我想请问是否有直接的方法将 Canvas 转换为可写位图类。

Answer 1

这取自this blog post但它不是写入文件，而是写入 WriteableBitmap。

public WriteableBitmap SaveAsWriteableBitmap(Canvas surface)
{
    if (surface == null) return null;

    // 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.ActualWidth, surface.ActualHeight);
    // 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);


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

    //create and return a new WriteableBitmap using the RenderTargetBitmap
    return new WriteableBitmap(renderBitmap);

}