How can I save image captured from DirectX context without using FileSavePicker?

Question

Hi, everyone, 

I am trying to save the image captured from DirectX context as png or jpeg, and I don't want to use FileSavePicker because the file name will be the combination of date and time. Do I need to use some stream techniques ? Please advise me, thanks. 

Answer 1

Here is a file sample with the filepicker, I will let you convert it to not using the filepicker. Note you will need to include shcore.lib or you will get an error.

void SimpleTextRenderer::blockprintclick2()
{

    
    // Prepare a file picker for customers to input image file name.
    Pickers::FileSavePicker^ savePicker = ref new Pickers::FileSavePicker();
    auto bmpExtensions = ref new Platform::Collections::Vector<Platform::String^>();
    bmpExtensions->Append(".bmp");
    savePicker->FileTypeChoices->Insert("BMP file", bmpExtensions);
    savePicker->DefaultFileExtension = ".bmp";
    savePicker->SuggestedFileName = "SaveScreen";
    savePicker->SuggestedStartLocation = Pickers::PickerLocationId::PicturesLibrary;

    std::shared_ptr<GUID> wicFormat = std::make_shared<GUID>(GUID_ContainerFormatPng);

    create_task(savePicker->PickSaveFileAsync()).then([=](StorageFile^ file)
    {
        if (file == nullptr)
        {
            // If user clicks "Cancel", reset the saving state, then cancel the current task.
            
            cancel_current_task();
        }

       String^  m_imageFileName = file->Name;
        if (file->FileType == ".bmp")
        {
            *wicFormat = GUID_ContainerFormatBmp;
        }
        
        return file->OpenAsync(FileAccessMode::ReadWrite);

    }).then([=](Streams::IRandomAccessStream^ randomAccessStream)
    {
        // Convert the RandomAccessStream to an IStream.
        ComPtr<IStream> stream;

	        DX::ThrowIfFailed(
			CreateStreamOverRandomAccessStream(randomAccessStream, IID_PPV_ARGS(&stream))
            );
	



        // Render the screen contents to an off-screen bitmap and then save that bitmap to a file.
        ComPtr<ID2D1Bitmap1> targetBitmap;
        D2D1_SIZE_U pixelSize = m_d2dContext->GetPixelSize();

        DX::ThrowIfFailed(
            m_d2dContext->CreateBitmap(
                pixelSize,
                nullptr,
                pixelSize.width * 4,    // pitch = width * size of pixel (4 bytes for B8G8R8A8)
                D2D1::BitmapProperties1(
                    D2D1_BITMAP_OPTIONS_TARGET,
                    D2D1::PixelFormat(DXGI_FORMAT_B8G8R8A8_UNORM, D2D1_ALPHA_MODE_PREMULTIPLIED)
                    ),
                &targetBitmap
                )
            );

        m_d2dContext->SetTarget(targetBitmap.Get());
        PrintRender();
        m_d2dContext->SetTarget(m_d2dTargetBitmap.Get());

        SaveBitmapToStream(targetBitmap, m_wicFactory, m_d2dContext, *wicFormat, stream.Get());




		

    });
}

// Save render target bitmap to a stream using WIC.
void SaveBitmapToStream(
    _In_ ComPtr<ID2D1Bitmap1> d2dBitmap,
    _In_ ComPtr<IWICImagingFactory2> wicFactory2,
    _In_ ComPtr<ID2D1DeviceContext> d2dContext,
    _In_ REFGUID wicFormat,
    _In_ IStream* stream
    )
{
    // Create and initialize WIC Bitmap Encoder.
    ComPtr<IWICBitmapEncoder> wicBitmapEncoder;
    DX::ThrowIfFailed(
        wicFactory2->CreateEncoder(
            wicFormat,
            nullptr,    // No preferred codec vendor.
            &wicBitmapEncoder
            )
        );

    DX::ThrowIfFailed(
        wicBitmapEncoder->Initialize(
            stream,
            WICBitmapEncoderNoCache
            )
        );

    // Create and initialize WIC Frame Encoder.
    ComPtr<IWICBitmapFrameEncode> wicFrameEncode;
    DX::ThrowIfFailed(
        wicBitmapEncoder->CreateNewFrame(
            &wicFrameEncode,
            nullptr     // No encoder options.
            )
        );

    DX::ThrowIfFailed(
        wicFrameEncode->Initialize(nullptr)
        );

    // Retrieve D2D Device.
    ComPtr<ID2D1Device> d2dDevice;
    d2dContext->GetDevice(&d2dDevice);

    // Create IWICImageEncoder.
    ComPtr<IWICImageEncoder> imageEncoder;
    DX::ThrowIfFailed(
        wicFactory2->CreateImageEncoder(
            d2dDevice.Get(),
            &imageEncoder
            )
        );

    DX::ThrowIfFailed(
        imageEncoder->WriteFrame(
            d2dBitmap.Get(),
            wicFrameEncode.Get(),
            nullptr     // Use default WICImageParameter options.
            )
        );

    DX::ThrowIfFailed(
        wicFrameEncode->Commit()
        );

    DX::ThrowIfFailed(
        wicBitmapEncoder->Commit()
        );

    // Flush all memory buffers to the next-level storage object.
    DX::ThrowIfFailed(
        stream->Commit(STGC_DEFAULT)
        );
}

---

n.Wright

Answer 2

Thank, Wright, 

My code is pretty much like this, I am trying to save the image with the raw stream.

Answer 3

You might want to check out the ScreenGrab module in the DirectXTex package.