Saving a Texture2D using SharpDX when targeting Win8.1 + Metro?

Question

I'm trying to save a user-generated Texture2D to disk, but it looks like the standard ways of accomplishing this aren't available when targeting DirectX11.1 / Win8.1 / Metro. ToStream/FromStream are absent, and the DX11 methods for writing a texture to disk are absent as well.

Any ideas or suggestions?

Answer 1

Here's the general solution I ended up with. Getting a DataStream through mapping a texture resource is what got me on the right track.

General flow is create a texture with CpuAccessFlags.Read, then CopyResource from the source texture to the new texture, then read data from the new texture into a WIC Bitmap.

public static class Texture2DExtensions
{
    public static void Save(this Texture2D texture, IRandomAccessStream stream, DeviceManager deviceManager)
    {
        var textureCopy = new Texture2D(deviceManager.DeviceDirect3D, new Texture2DDescription
        {
            Width = (int)texture.Description.Width,
            Height = (int)texture.Description.Height,
            MipLevels = 1,
            ArraySize = 1,
            Format = texture.Description.Format,
            Usage = ResourceUsage.Staging,
            SampleDescription = new SampleDescription(1, 0),
            BindFlags = BindFlags.None,
            CpuAccessFlags = CpuAccessFlags.Read,
            OptionFlags = ResourceOptionFlags.None
        });
        deviceManager.ContextDirect3D.CopyResource(texture, textureCopy);

        DataStream dataStream;
        var dataBox = deviceManager.ContextDirect3D.MapSubresource(
            textureCopy,
            0,
            0,
            MapMode.Read,
            SharpDX.Direct3D11.MapFlags.None,
            out dataStream);

        var dataRectangle = new DataRectangle
        {
            DataPointer = dataStream.DataPointer,
            Pitch = dataBox.RowPitch
        };

        var bitmap = new Bitmap(
            deviceManager.WICFactory,
            textureCopy.Description.Width,
            textureCopy.Description.Height,
            PixelFormat.Format32bppBGRA,
            dataRectangle);

        using (var s = stream.AsStream())
        {
            s.Position = 0;
            using (var bitmapEncoder = new PngBitmapEncoder(deviceManager.WICFactory, s))
            {
                using (var bitmapFrameEncode = new BitmapFrameEncode(bitmapEncoder))
                {
                    bitmapFrameEncode.Initialize();
                    bitmapFrameEncode.SetSize(bitmap.Size.Width, bitmap.Size.Height);
                    var pixelFormat = PixelFormat.FormatDontCare;
                    bitmapFrameEncode.SetPixelFormat(ref pixelFormat);
                    bitmapFrameEncode.WriteSource(bitmap);
                    bitmapFrameEncode.Commit();
                    bitmapEncoder.Commit();
                }
            }
        }

        deviceManager.ContextDirect3D.UnmapSubresource(textureCopy, 0);
        textureCopy.Dispose();
        bitmap.Dispose();
    }
}