Windows的小历史：第一篇如何写作Windows程序的介绍文章出现在《Microsoft Systems Journal》1986年12月号上。在那篇文章中，范例程序叫做WSZ（「what size：什么尺寸」），它以图素、英寸和毫米为单位显示了显示区域的大小。那个程序的更简易版本是WHATSIZE，如程序5-6所示。程序显示了以五种度量映像方式显示的窗口显示区域的大小。
程序5-6 WHATSIZE WHATSIZE.C /*------------------------------------------------------------ WHATSIZE.C -- What Size is the Window (c) Charles Petzold, 1998 ----------------------------------------------------------*/ #include <windows.h> LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ; int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) { static TCHAR szAppName[] = TEXT ("WhatSize") ; HWND hwnd ; MSG msg ; WNDCLASS wndclass ; wndclass.style = CS_HREDRAW | CS_VREDRAW; wndclass.lpfnWndProc= WndProc ; wndclass.cbClsExtra = 0 ; wndclass.cbWndExtra = 0 ; wndclass.hInstance = hInstance ; wndclass.hIcon= LoadIcon (NULL, IDI_APPLICATION) ; wndclass.hCursor= LoadCursor (NULL, IDC_ARROW) ; wndclass.hbrBackground= (HBRUSH) GetStockObject (WHITE_BRUSH) ; wndclass.lpszMenuName = NULL ; wndclass.lpszClassName= szAppName ; if (!RegisterClass (&wndclass)) { MessageBox (NULL, TEXT ("This program requires Windows NT!"), szAppName, MB_ICONERROR) ; return 0 ; } hwnd = CreateWindow (szAppName, TEXT ("What Size is the Window "), WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL, NULL, hInstance, NULL) ; ShowWindow (hwnd, iCmdShow) ; UpdateWindow (hwnd) ; while (GetMessage (&msg, NULL, 0, 0)) { TranslateMessage (&msg) ; DispatchMessage (&msg) ; } return msg.wParam ; } void Show (HWND hwnd, HDC hdc, int xText, int yText, int iMapMode, TCHAR * szMapMode) { TCHAR szBuffer [60] ; RECT rect ; SaveDC (hdc) ; SetMapMode (hdc, iMapMode) ; GetClientRect (hwnd, &rect) ; DPtoLP (hdc, (PPOINT) &rect, 2) ; RestoreDC (hdc, -1) ; TextOut ( hdc, xText, yText, szBuffer, wsprintf (szBuffer, TEXT ("%-20s %7d %7d %7d %7d"), szMapMode, rect.left, rect.right, rect.top, rect.bottom)) ; } LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) { static TCHAR szHeading [] = TEXT ("Mapping Mode Left Right Top Bottom") ; static TCHAR szUndLine [] = TEXT ("------------ ---- ----- --- ------") ; static int cxChar, cyChar ; HDC hdc ; PAINTSTRUCT ps ; TEXTMETRIC tm ; switch (message) { case WM_CREATE: hdc = GetDC (hwnd) ; SelectObject (hdc, GetStockObject (SYSTEM_FIXED_FONT)) ; GetTextMetrics (hdc, &tm) ; cxChar = tm.tmAveCharWidth ; cyChar = tm.tmHeight + tm.tmExternalLeading ; ReleaseDC (hwnd, hdc) ; return 0 ; case WM_PAINT: hdc = BeginPaint (hwnd, &ps) ; SelectObject (hdc, GetStockObject (SYSTEM_FIXED_FONT)) ; SetMapMode (hdc, MM_ANISOTROPIC) ; SetWindowExtEx (hdc, 1, 1, NULL) ; SetViewportExtEx (hdc, cxChar, cyChar, NULL) ; TextOut (hdc, 1, 1, szHeading, lstrlen (szHeading)) ; TextOut (hdc, 1, 2, szUndLine, lstrlen (szUndLine)) ; Show (hwnd, hdc, 1, 3, MM_TEXT, TEXT ("TEXT (pixels)")) ; Show (hwnd, hdc, 1, 4, MM_LOMETRIC, TEXT ("LOMETRIC (.1 mm)")) ; Show (hwnd, hdc, 1, 5, MM_HIMETRIC, TEXT ("HIMETRIC (.01 mm)")) ; Show (hwnd, hdc, 1, 6, MM_LOENGLISH, TEXT ("LOENGLISH (.01 in)")) ; Show (hwnd, hdc, 1, 7, MM_HIENGLISH,TEXT ("HIENGLISH (.001 in)")) ; Show (hwnd, hdc, 1, 8, MM_TWIPS, EXT ("TWIPS (1/1440 in)")) ; EndPaint (hwnd, &ps) ; return 0 ; case WM_DESTROY: PostQuitMessage (0) ; return 0 ; } return DefWindowProc (hwnd, message, wParam, lParam) ; }