Window.create constructor

Window.create({ required String windowCaption, required String className, required Pointer<NativeFunction<WNDPROC>> windowProc, int? hInstance, Rectangle<int>? dimensions, String? iconPath, })

Creates a new Window with the specified parameters.

• windowCaption: The caption/title of the window.
• className: The window class name.
• windowProc: The window procedure callback function.
• hInstance: The instance handle (defaults to GetModuleHandle(nullptr)).
• dimensions: The initial dimensions of the window (optional).
• iconPath: The path to the icon file (.ico) (optional).

Throws an Exception if window creation fails.

Implementation

factory Window.create({
  required String windowCaption,
  required String className,
  required Pointer<NativeFunction<WNDPROC>> windowProc,
  int? hInstance,
  math.Rectangle<int>? dimensions,
  String? iconPath,
}) {
  if (iconPath != null && !iconPath.endsWith('.ico')) {
    throw ArgumentError.value(
      iconPath,
      'iconPath',
      'Must be an icon file (.ico)',
    );
  }

  return using((arena) {
    final classNamePtr = className.toNativeUtf16(allocator: arena);
    final windowCaptionPtr = windowCaption.toNativeUtf16(allocator: arena);
    final iconPathPtr = iconPath?.toNativeUtf16(allocator: arena);
    final wc = arena<WNDCLASS>();
    wc.ref
      ..hbrBackground = GetStockObject(GET_STOCK_OBJECT_FLAGS.WHITE_BRUSH)
      ..hCursor = LoadCursor(NULL, IDC_ARROW)
      ..hInstance = hInstance ?? GetModuleHandle(nullptr)
      ..lpfnWndProc = windowProc
      ..lpszClassName = classNamePtr
      ..style = WNDCLASS_STYLES.CS_HREDRAW | WNDCLASS_STYLES.CS_VREDRAW;
    if (iconPathPtr != null) {
      wc.ref.hIcon = LoadImage(
        NULL,
        iconPathPtr,
        GDI_IMAGE_TYPE.IMAGE_ICON,
        NULL,
        NULL,
        IMAGE_FLAGS.LR_DEFAULTSIZE | IMAGE_FLAGS.LR_LOADFROMFILE,
      );
    }
    RegisterClass(wc);

    final scaleFactor =
        dimensions != null ? scaleFactorForOrigin(dimensions) : 1.0;
    final hwnd = CreateWindowEx(
      0, // Optional window styles.
      classNamePtr, // Window class
      windowCaptionPtr, // Window caption
      WINDOW_STYLE.WS_OVERLAPPEDWINDOW |
          WINDOW_STYLE.WS_VISIBLE, // Window style
      dimensions != null
          ? scale(dimensions.left, scaleFactor)
          : CW_USEDEFAULT,
      dimensions != null ? scale(dimensions.top, scaleFactor) : CW_USEDEFAULT,
      dimensions != null
          ? scale(dimensions.width, scaleFactor)
          : CW_USEDEFAULT,
      dimensions != null
          ? scale(dimensions.height, scaleFactor)
          : CW_USEDEFAULT,
      NULL, // Parent window
      NULL, // Menu
      hInstance ?? GetModuleHandle(nullptr), // Instance handle
      nullptr, // Additional application data
    );
    if (hwnd == FALSE) throw Exception('Unable to create top-level window.');

    return Window(hwnd);
  });
}