将RenderTargetBitmap转换为BitmapImage

Question

如何在Windows8.1的RenderTargetBitmap XAML中将BitmapImage转换成C#？

我试过了

// rendered is the RenderTargetBitmap 
BitmapImage img = new BitmapImage();
InMemoryRandomAccessStream randomAccessStream = new InMemoryRandomAccessStream();
await randomAccessStream.WriteAsync(await rendered.GetPixelsAsync());
randomAccessStream.Seek(0); 
await img.SetSourceAsync(randomAccessStream);

但它总是给我们带来错误

img.SetSourceAsync(randomAccessStream);

在WPF中有很多种方法，但是在WinRT中？我怎么能这么做？

非常感谢!

Answer 1

这就是使用Sharing render to bitmap image in windows phone 8.1的那个

结果发现我不能直接用

stream.WriteAsync(byteArray.AsBuffer());

你必须使用位图编码器，最后的工作代码：

InMemoryRandomAccessStream stream = new InMemoryRandomAccessStream();
        var buffer = await rendered.GetPixelsAsync();
      //  await stream.ReadAsync(buffer, (uint)buffer.Length, InputStreamOptions.None);
        BitmapImage img = new BitmapImage();
        var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId, stream);
        encoder.SetPixelData(
            BitmapPixelFormat.Bgra8,
            BitmapAlphaMode.Straight,
            (uint)rendered.PixelWidth,
            (uint)rendered.PixelHeight,
            DisplayInformation.GetForCurrentView().LogicalDpi,
            DisplayInformation.GetForCurrentView().LogicalDpi,
            buffer.ToArray());
        await encoder.FlushAsync();
        await img.SetSourceAsync(stream);
        preview.Source = img;

Answer 2

你试过这个吗？

  var bitmap = new  RenderTargetBitmap();

  await bitmap.RenderAsync(elementToRender);

  image.Source = bitmap;

参考资料：http://social.technet.microsoft.com/wiki/contents/articles/20648.using-the-rendertargetbitmap-in-windows-store-apps-with-xaml-and-c.aspx

更新:

另一个参..。可能会有帮助：

• Sharing render to bitmap image in windows phone 8.1
• https://code.msdn.microsoft.com/windowsapps/File-access-sample-d723e597。

更新2 :

试试这个：

private async Task<BitmapImage> ByteArrayToBitmapImage(byte[] byteArray)
    {
        var bitmapImage = new BitmapImage();

        var stream = new InMemoryRandomAccessStream();
        await stream.WriteAsync(byteArray.AsBuffer());
        stream.Seek(0);

        bitmapImage.SetSource(stream);
        return bitmapImage;
    }

参考文献：C# Windows 8 Store (Metro, WinRT) Byte array to BitmapImage