Is there examples of using blend2d with native Win32 programs

[xland]

Is there examples of using blend2d with native Win32 programs?
Not Qt

[kobalicek]

There are no official examples for raw Win32. However, the simplest approach would be using Blend2D with DIBSECTION - it would work well and it would be fast.

[xland]

Here are some key codes, maybe helpful to the people who see this post.

HDC hScreen = GetDC(NULL);
BITMAPINFO bmi = {};
bmi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
bmi.bmiHeader.biWidth = w;
bmi.bmiHeader.biHeight = -h; // top-down
bmi.bmiHeader.biPlanes = 1;
bmi.bmiHeader.biBitCount = 32;
bmi.bmiHeader.biCompression = BI_RGB;
//HBITMAP bgHbitmap;
//char* bgPixels;
bgHbitmap = CreateDIBSection(hScreen, &bmi, DIB_RGB_COLORS, reinterpret_cast<void**>(&bgPixels), NULL, NULL);
ReleaseDC(NULL, hScreen);

BLImage img(w, h, BL_FORMAT_PRGB32);
BLContext ctx(img);
BLPath path;
path.moveTo(0, 0);
path.lineTo(w, h);
ctx.setStrokeStyle(BLRgba32(0xFFFFFFFF));
ctx.strokePath(path);
ctx.end();
BLImageData data;
img.getData(&data);
unsigned int dataSize = w * h * 4;
char* tempData = (char*)(data.pixelData);
for (int x = 0; x < dataSize; x += 4)
{
    bgPixels[x + 2] = tempData[x]; //red
    bgPixels[x + 1] = tempData[x+1]; //green
    bgPixels[x] = tempData[x + 2]; //blue
}

case WM_PAINT:
{
    PAINTSTRUCT ps;
    HDC hdc = BeginPaint(hwnd, &ps);
    HDC hdc_bmp = CreateCompatibleDC(hdc);
    DeleteObject(SelectObject(hdc_bmp, mainWin->bgHbitmap));
    BitBlt(hdc, 0, 0, mainWin->w, mainWin->h, hdc_bmp, 0, 0, SRCCOPY);
    DeleteDC(hdc_bmp);
    EndPaint(hwnd, &ps);
    return 0;
}

I will leave this post, maybe there will be a better way in the future

[kobalicek]

I think that you don't have to do any conversion when rendering to a DIBSECTION. Blend2D's XRGB32 and PRGB32 should be compatible. The pointer to pixel data returned by DIBSECTION can be then passed to BLImage::createFromData() - this way you can share the data of DIBSECTION and BLImage and render to it without having to do any copy.

Additionally, for converting pixel data, use BLPixelConverter - it has been optimized and uses SIMD for most common conversions.

[xland]

Thanks.
If I don't do the conversion, it's going to be the wrong color:
BLRgba32(0xFF6622FF) was supposed to be orange, but it ended up being blue.

I think this problem may be caused by the format of Microsoft Bitmap, and has nothing to do with Blend2d.
I am using Direct2D technology to solve this problem(ID2D1Bitmap), and I will post my code here later.
Thanks again for your advice.

[xland]

This is the key code for solution using Direct2D technology.
Better than GDI, but not Window XP/Vista compatible

    unsigned int dataSize = w * h * 4;
    auto bgPixels = new char[dataSize];
    bgImage = new BLImage();  //BLImage* bgImage;
    bgImage->createFromData(w, h, BL_FORMAT_PRGB32, bgPixels, w * 4, [](void* impl, void* externalData, void* userData) {
        delete[] externalData;
    });

    BLContext ctx(*bgImage);
    BLPath path;
    path.moveTo(0, 0);
    path.lineTo(w, h);
    path.moveTo(w, 0);
    path.lineTo(0, h);
    ctx.setStrokeStyle(BLRgba32(0xFF6622FF));
    ctx.setStrokeWidth(12.6);
    ctx.strokePath(path);
    ctx.end();

    case WM_PAINT:
    {
        d2DCreateRes();
        render->BeginDraw();
        render->DrawBitmap(d2DImage, D2D1::RectF(0, 0, w, h));
        auto result = render->EndDraw();
        if (D2DERR_RECREATE_TARGET == result)
        {
            d2DImage->Release();
            render->Release();
            render = nullptr;
        }
        ValidateRect(hwnd, NULL);
        return 0;
    }

// create factory before window created
// D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED, &factory);
//	ID2D1Factory* factory;
//	ID2D1HwndRenderTarget* render;
//	ID2D1Bitmap* d2DImage;
void MainWin::d2DCreateRes()
{
    if (render) return;
    D2D1_SIZE_U size = D2D1::SizeU(w, h);
    factory->CreateHwndRenderTarget(D2D1::RenderTargetProperties(), D2D1::HwndRenderTargetProperties(hwnd, size), &render);
    render->SetTransform(D2D1::Matrix3x2F::Identity());
    D2D1_BITMAP_PROPERTIES bmpPorp;
    bmpPorp.dpiX = 0;
    bmpPorp.dpiY = 0;
    bmpPorp.pixelFormat.format = DXGI_FORMAT_B8G8R8A8_UNORM; 
    bmpPorp.pixelFormat.alphaMode = D2D1_ALPHA_MODE_IGNORE;
    BLImageData imgData;
    bgImage->getData(&imgData);
    render->CreateBitmap(size, imgData.pixelData, imgData.stride, bmpPorp, &d2DImage);
}

[kobalicek]

I would try more formats - there must definitely be a matching one. Blend2D would be BGRA on little endian machines so stored as [B, G, R, A] in memory.

[xland]

I made a mistake, please see my next reply.

[xland]

I think I made a mistake about the GDI solution.
The final key code is like this:

HDC hScreen = GetDC(NULL);
BITMAPINFO info = { sizeof(BITMAPINFOHEADER), w, 0 - h, 1, 32, BI_RGB, dataSize, 0, 0, 0, 0 };    
unsigned int dataSize = w * h * 4;
auto boardPixels = new char[dataSize];
//HBITMAP bgHbitmap;
bgHbitmap = CreateDIBSection(hScreen, &info, DIB_RGB_COLORS, reinterpret_cast<void**>(&boardPixels), NULL, NULL);    
ReleaseDC(NULL, hScreen);

// BLImage* boardImage;
// BLContext* paintCtx;
boardImage = new BLImage();
boardImage->createFromData(w, h, BL_FORMAT_PRGB32, boardPixels, w * 4, [](void* impl, void* externalData, void* userData) {
    delete[] externalData;
    });
paintCtx = new BLContext();

case WM_PAINT:
{
    paintCtx->begin(*boardImage);
    //Here I draw my other two pictures on boardImage
    paintCtx->blitImage(BLRect(0, 0, w, h), *bgImage);
    paintCtx->blitImage(BLRect(0, 0, w, h), *canvasImage);
    paintCtx->end();
    PAINTSTRUCT ps;
    HDC hdc = BeginPaint(hwnd, &ps);
    HDC hdcBmp = CreateCompatibleDC(hdc);
    DeleteObject(SelectObject(hdcBmp, bgHbitmap));
    BitBlt(hdc, 0, 0, w, h, hdcBmp, 0, 0, SRCCOPY);
    DeleteDC(hdcBmp);
    EndPaint(hwnd, &ps);
    ValidateRect(hwnd, NULL);
    return 0;
}

This is my screen drawing program, so far it's just a Demo.
Blend2d is an awesome project!
The library is small and super fast!