本例效果图:
program Project1; uses Windows, Messages; {供 WM_PAINT 消息调用的自定义过程} procedure OnPaint(h: HWND); const str = 'CodeGear Delphi 2007'; var DC: HDC; ps: PAINTSTRUCT; Rect: TRect; begin MessageBeep(0); DC := BeginPaint(h, ps); GetClientRect(h, Rect); DrawText(DC, PChar(str), -1, Rect, DT_SINGLELINE or DT_CENTER or DT_VCENTER); EndPaint(h, ps); end; function WndProc(wnd: HWND; msg: UINT; wParam: Integer; lParam: Integer): Integer; stdcall; begin Result := 0; case msg of WM_PAINT : OnPaint(wnd); {在收到 WM_PAINT 消息时调用自定义的 OnPaint 过程} WM_DESTROY: PostQuitMessage(0); else Result := DefWindowProc(wnd, msg, wParam, lParam); end; end; function RegMyWndClass: Boolean; var cls: TWndClass; begin cls.style := CS_HREDRAW or CS_VREDRAW; cls.lpfnWndProc := @WndProc; cls.cbClsExtra := 0; cls.cbWndExtra := 0; cls.hInstance := HInstance; cls.hIcon := 0; cls.hCursor := LoadCursor(0, IDC_ARROW); cls.hbrBackground := HBRUSH(COLOR_WINDOW + 1); cls.lpszMenuName := nil; cls.lpszClassName := 'MyWnd'; Result := RegisterClass(cls) <> 0; end; {程序入口} const tit = 'New Form'; ws = WS_OVERLAPPEDWINDOW; x = 100; y = 100; w = 300; h = 180; var hWnd: THandle; Msg : TMsg; begin RegMyWndClass; hWnd := CreateWindow('MyWnd', tit, ws, x, y, w, h, 0, 0, HInstance, nil); ShowWindow(hWnd, SW_SHOWNORMAL); UpdateWindow(hWnd); while(GetMessage(Msg, 0, 0, 0)) do begin TranslateMessage(Msg); DispatchMessage(Msg); end; end.