getWindowIcon

getWindowIcon.dart

  static Uint8List getWindowIcon(hWnd, {background = 0xffffff, hover = false}) {
    var icon = SendMessage(hWnd, WM_GETICON, 2, 0); // ICON_SMALL2 - User Made Apps
    if (icon == 0) icon = GetClassLongPtr(hWnd, -14); // GCLP_HICON - Microsoft Win Apps
    //final xIcon = icon;

    final piconinfo = calloc<ICONINFO>();

    GetIconInfo(icon, piconinfo);
    final hICON = calloc<BITMAP>();
    GetObject(piconinfo.ref.hbmColor, sizeOf<BITMAP>(), hICON);

    final int hScreen = GetDC(hWnd);
    final int hDC = CreateCompatibleDC(hScreen);
    final int hBitmap = CreateCompatibleBitmap(hScreen, GetSystemMetrics(SM_CXICON), GetSystemMetrics(SM_CYICON));
    SelectObject(hDC, hBitmap);
    final clientRect = calloc<RECT>()
      ..ref.left = 0
      ..ref.right = GetSystemMetrics(SM_CXICON)
      ..ref.bottom = GetSystemMetrics(SM_CYICON)
      ..ref.top = 0;
    FillRect(hDC, clientRect, CreateSolidBrush(background));
    DrawIconEx(hDC, 0, 0, icon, GetSystemMetrics(SM_CXICON), GetSystemMetrics(SM_CYICON), NULL, NULL, 3);

    final bmpScreen = calloc<BITMAP>();
    GetObject(hBitmap, sizeOf<BITMAP>(), bmpScreen);
    final bitmapFileHeader = calloc<BITMAPFILEHEADER>();
    final bitmapInfoHeader = calloc<BITMAPINFOHEADER>()
      ..ref.biSize = sizeOf<BITMAPINFOHEADER>()
      ..ref.biWidth = bmpScreen.ref.bmWidth
      ..ref.biHeight = bmpScreen.ref.bmHeight
      ..ref.biPlanes = 1
      ..ref.biBitCount = 32
      ..ref.biCompression = BI_RGB;

    final dwBmpSize = ((bmpScreen.ref.bmWidth * bitmapInfoHeader.ref.biBitCount + 31) / 32 * 4 * bmpScreen.ref.bmHeight).toInt();

    final lpBitmap = calloc<Uint8>(dwBmpSize);
    GetDIBits(hDC, hBitmap, 0, bmpScreen.ref.bmHeight, lpBitmap, bitmapInfoHeader.cast(), DIB_RGB_COLORS);

    final dwSizeOfDIB = dwBmpSize + sizeOf<BITMAPFILEHEADER>() + sizeOf<BITMAPINFOHEADER>();
    bitmapFileHeader.ref.bfOffBits = sizeOf<BITMAPFILEHEADER>() + sizeOf<BITMAPINFOHEADER>();

    bitmapFileHeader.ref.bfSize = dwSizeOfDIB;
    bitmapFileHeader.ref.bfType = 0x4D42; // BM

    var b = BytesBuilder();
    b.add(Pointer<Uint8>.fromAddress(bitmapFileHeader.address).asTypedList(sizeOf<BITMAPFILEHEADER>()));
    b.add(Pointer<Uint8>.fromAddress(bitmapInfoHeader.address).asTypedList(sizeOf<BITMAPINFOHEADER>()));
    b.add(lpBitmap.asTypedList(dwBmpSize));
    DeleteDC(hDC);
    DeleteObject(hBitmap);
    ReleaseDC(NULL, hScreen);
    free(bmpScreen);
    free(bitmapFileHeader);
    free(bitmapInfoHeader);
    free(lpBitmap);
    free(piconinfo);
    free(hICON);
    free(clientRect);
    return b.takeBytes();
  }