本例效果图:
![](https://www.cnblogs.com/images/cnblogs_com/del/129733/o_84191.gif)
![](https://www.cnblogs.com/images/cnblogs_com/del/129733/o_84191.gif)
program Project1; uses Windows, Messages; {供 WM_SIZE 消息调用的自定义过程} procedure OnSize(h: HWND); var Rect: TRect; pt: TPoint; buf: array[0..255] of Char; begin GetWindowRect(h, Rect); {获取窗口矩形} pt.X := Rect.Right - Rect.Left; {提取宽度} pt.Y := Rect.Bottom - Rect.Top; {提取高度} wvsprintf(buf, '宽度:%d, 高度:%d', @pt); {格式化到缓冲区} SetWindowText(h, buf); {显示在标题} end; function WndProc(wnd: HWND; msg: UINT; wParam: Integer; lParam: Integer): Integer; stdcall; begin Result := 0; case msg of WM_SIZE : OnSize(wnd); {改变窗口大小的消息} 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.