static HRESULT Direct3D9TakeScreenshots(uint adapter, int count)
{
    using (var d3d = new ComObject<IDirect3D9>(Functions.Direct3DCreate9(Constants.D3D_SDK_VERSION)))
    {
        var mode = new _D3DDISPLAYMODE();
        d3d.Object.GetAdapterDisplayMode(adapter, ref mode).ThrowOnError();

        var parameters = new _D3DPRESENT_PARAMETERS_();
        parameters.Windowed = true;
        parameters.BackBufferCount = 1;
        parameters.BackBufferHeight = mode.Height;
        parameters.BackBufferWidth = mode.Width;
        parameters.SwapEffect = _D3DSWAPEFFECT.D3DSWAPEFFECT_DISCARD;

        d3d.Object.CreateDevice(adapter, _D3DDEVTYPE.D3DDEVTYPE_HAL, IntPtr.Zero, Constants.D3DCREATE_SOFTWARE_VERTEXPROCESSING, ref parameters, out var dev).ThrowOnError();
        using (var device = new ComObject<IDirect3DDevice9>(dev))
        {
            dev.CreateOffscreenPlainSurface(mode.Width, mode.Height, _D3DFORMAT.D3DFMT_A8R8G8B8, _D3DPOOL.D3DPOOL_SYSTEMMEM, out var surf, IntPtr.Zero).ThrowOnError();
            using (var surface = new ComObject<IDirect3DSurface9>(surf))
            {
                var rc = new _D3DLOCKED_RECT();
                var rect = new tagRECT();
                surf.LockRect(ref rc, ref rect, 0).ThrowOnError();
                var pitch = rc.Pitch;
                surf.UnlockRect();

                var shots = new byte[count][];
                for (var i = 0; i < count; i++)
                {
                    shots[i] = new byte[pitch * mode.Height];
                }

                var sw = new Stopwatch();
                sw.Start();
                for (var i = 0; i < count; i++)
                {
                    dev.GetFrontBufferData(0, surf).ThrowOnError();
                    surf.LockRect(ref rc, ref rect, 0).ThrowOnError();
                    Marshal.Copy(rc.pBits, shots[i], 0, shots[i].Length);
                    surf.UnlockRect().ThrowOnError();
                }
                Console.WriteLine("Elapsed: " + sw.Elapsed);

                for (var i = 0; i < count; i++)
                {
                    SavePixelsToFile32bppPBGRA(mode.Width, mode.Height, (uint)pitch, shots[i], "cap" + i + ".png", WICConstants.GUID_ContainerFormatPng).ThrowOnError();
                }
            }
        }
    }
    return 0;
}

static HRESULT SavePixelsToFile32bppPBGRA(uint width, uint height, uint stride, byte[] pixels, string filePath, Guid format)
{
    if (filePath == null)
        throw new ArgumentNullException(nameof(filePath));

    using (var fac = new ComObject<IWICImagingFactory>((IWICImagingFactory)new WicImagingFactory()))
    {
        fac.Object.CreateStream(out var stream).ThrowOnError();
        using (new ComObject<IWICStream>(stream))
        {
            const int GENERIC_WRITE = 0x40000000;
            stream.InitializeFromFilename(filePath, GENERIC_WRITE).ThrowOnError();
            fac.Object.CreateEncoder(format, IntPtr.Zero, out var encoder).ThrowOnError();
            using (new ComObject<IWICBitmapEncoder>(encoder))
            {
                encoder.Initialize(stream, WICBitmapEncoderCacheOption.WICBitmapEncoderNoCache).ThrowOnError();
                encoder.CreateNewFrame(out var frame, out var bag).ThrowOnError();
                using (new ComObject<IWICBitmapFrameEncode>(frame))
                {
                    frame.Initialize(null).ThrowOnError();
                    frame.SetSize(width, height).ThrowOnError();
                    frame.SetPixelFormat(ref format).ThrowOnError();
                    frame.WritePixels(height, stride, (int)(stride * height), pixels).ThrowOnError();
                    frame.Commit().ThrowOnError();
                    encoder.Commit().ThrowOnError();
                }
            }
        }
    }
    return 0;
}