How do I create a SoftwaraBitmap from pixel data using C++/WinRT?

Question

Hi.

I'm developing an application using C++/WinRT and want to display a SoftwareBitmap created from a vector with RGB information on the screen. I've searched the official documentation, but the provided samples are in C# and not C++/WinRT. I need help implementing this in C++/WinRT.

Similar C# sample. > Create or edit a SoftwareBitmap programmatically

Can you guide me on how to create a SoftwareBitmap from pixel data using C++/WinRT? For your reference, I've attached a code snippet (which throws an exception and stops) that I attempted.

winrt::Windows::Foundation::IAsyncAction MainPage::Async_DrawBitmap(int width, int height )
{
    auto lifetime = get_strong();

    SoftwareBitmap softwareBitmap(BitmapPixelFormat::Bgra8, width, height, BitmapAlphaMode::Premultiplied);
    BitmapBuffer buffer = softwareBitmap.LockBuffer(BitmapBufferAccessMode::Write);

    auto reference = buffer.CreateReference();
    BitmapPlaneDescription bufferLayout = buffer.GetPlaneDescription(0);

    for (int i = 0; i < bufferLayout.Height; i++) {
        for (int j = 0; j < bufferLayout.Width; j++) {
        byte value = (byte)(float)j / bufferLayout.Width * 255;
        reference.data()[bufferLayout.StartIndex + bufferLayout.Stride * i + 4 * j + 0] = value; // Blue
        reference.data()[bufferLayout.StartIndex + bufferLayout.Stride * i + 4 * j + 1] = value; // Green
        reference.data()[bufferLayout.StartIndex + bufferLayout.Stride * i + 4 * j + 2] = value; // Red
        reference.data()[bufferLayout.StartIndex + bufferLayout.Stride * i + 4 * j + 3] = 255; // Alpha
        }
    }

    buffer.Close();

    Media::Imaging::SoftwareBitmapSource source;
    co_await source.SetBitmapAsync(softwareBitmap);
    imageControl().Source(source);
}

Answer 1

Can you guide me on how to create a SoftwareBitmap from pixel data using C++/WinRT?

For example, this test creates a SoftwareBitmap with a blue rectangle and sets it to an Image control (Img1) :

  SoftwareBitmap softwareBitmap = GetSoftwareBitmap(400, 400);
  SetImageSourceFromSoftwareBitmap(softwareBitmap, Img1());

    SoftwareBitmap GetSoftwareBitmap(int nWidth, int nHeight)
    {
        SoftwareBitmap softwareBitmap(BitmapPixelFormat::Bgra8, nWidth, nHeight, BitmapAlphaMode::Premultiplied);
        BitmapBuffer buffer = softwareBitmap.LockBuffer(BitmapBufferAccessMode::Write);
        uint8_t* pixels = buffer.CreateReference().data();
        int nPixelsSize = nWidth * nHeight * 4;
        for (int i = 0; i < nPixelsSize; i += 4)
        {
            pixels[i] = 255;
            pixels[i + 1] = 0;
            pixels[i + 2] = 0;
        }
        return softwareBitmap;
    }

    IAsyncAction SetImageSourceFromSoftwareBitmap(SoftwareBitmap softwareBitmap, winrt::Windows::UI::Xaml::Controls::Image image)
    {
        SoftwareBitmapSource bitmapSource;
        co_await bitmapSource.SetBitmapAsync(softwareBitmap);
        image.Source(bitmapSource);
    }