Convert vector <unsigned char> to HBITMAP in C++

Question

I have used the code here to load a PNG image into a BMP raw vector std::vector <unsigned char>. Now, I need to apply this image as background to a WinAPI window and I don't know how could I convert it to HBITMAP. Maybe somebody did it before or maybe I could use another format or variable type

Answer 1

You can use Gdiplus from the start, to open png file and get HBITMAP handle

//initialize Gdiplus:
Gdiplus::GdiplusStartupInput gdiplusStartupInput;
ULONG_PTR gdiplusToken;
Gdiplus::GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);

HBITMAP hbitmap;
HBRUSH hbrush;

Gdiplus::Bitmap *bmp = Gdiplus::Bitmap::FromFile(L"filename.png");
bmp->GetHBITMAP(0, &hbitmap);
hbrush = CreatePatternBrush(hbitmap);

//register classname and assign background brush
WNDCLASSEX wcex;
...
wcex.hbrBackground = hbrush;

CreateWindow...

Cleanup:

DeleteObject(hbrush);
DeleteObject(hbitmap);

delete bmp;

Gdiplus::GdiplusShutdown(gdiplusToken);

You need to include "gdiplus.h" and link to "gdiplus.lib" library. The header files should be available by default.

In Visual Studio you can link to Gdiplus as follows:

#pragma comment( lib, "Gdiplus.lib")

---

Edit

or use Gdiplus::Image in WM_PAINT

Gdiplus::Image *image = Gdiplus::Image::FromFile(L"filename.png");

WM_PAINT in Window procedure:

case WM_PAINT:
{
    PAINTSTRUCT ps;
    HDC hdc = BeginPaint(hwnd, &ps);

    if (image)
    {
        RECT rc;
        GetClientRect(hwnd, &rc);
        Gdiplus::Graphics g(hdc);
        g.DrawImage(image, Gdiplus::Rect(0, 0, rc.right, rc.bottom));
    }

    EndPaint(hwnd, &ps);
    return 0;
}