SystemMetrics

头文件：

/*-----------------------------------------------    sysmets.H -- System metrics display structure   -----------------------------------------------*/  #define NUMLINES ((int) (sizeof sysmetrics / sizeof sysmetrics [0]))  struct {       int     iIndex ;      TCHAR * szLabel ;      TCHAR * szDesc ; } sysmetrics [] = {      SM_CXSCREEN,             TEXT ("SM_CXSCREEN"),                                             TEXT ("Screen width in pixels"),      SM_CYSCREEN,             TEXT ("SM_CYSCREEN"),                                             TEXT ("Screen height in pixels"),      SM_CXVSCROLL,            TEXT ("SM_CXVSCROLL"),                                            TEXT ("Vertical scroll width"),      SM_CYHSCROLL,            TEXT ("SM_CYHSCROLL"),                                            TEXT ("Horizontal scroll height"),      SM_CYCAPTION,            TEXT ("SM_CYCAPTION"),                                            TEXT ("Caption bar height"),      SM_CXBORDER,             TEXT ("SM_CXBORDER"),                                             TEXT ("Window border width"),      SM_CYBORDER,             TEXT ("SM_CYBORDER"),                                             TEXT ("Window border height"),      SM_CXFIXEDFRAME,         TEXT ("SM_CXFIXEDFRAME"),                                         TEXT ("Dialog window frame width"),      SM_CYFIXEDFRAME,         TEXT ("SM_CYFIXEDFRAME"),                                         TEXT ("Dialog window frame height"),      SM_CYVTHUMB,             TEXT ("SM_CYVTHUMB"),                                             TEXT ("Vertical scroll thumb height"),      SM_CXHTHUMB,             TEXT ("SM_CXHTHUMB"),                                             TEXT ("Horizontal scroll thumb width"),      SM_CXICON,               TEXT ("SM_CXICON"),                                               TEXT ("Icon width"),      SM_CYICON,               TEXT ("SM_CYICON"),                                               TEXT ("Icon height"),      SM_CXCURSOR,             TEXT ("SM_CXCURSOR"),                                             TEXT ("Cursor width"),      SM_CYCURSOR,             TEXT ("SM_CYCURSOR"),                                             TEXT ("Cursor height"),      SM_CYMENU,               TEXT ("SM_CYMENU"),                                               TEXT ("Menu bar height"),      SM_CXFULLSCREEN,         TEXT ("SM_CXFULLSCREEN"),                                         TEXT ("Full screen client area width"),      SM_CYFULLSCREEN,         TEXT ("SM_CYFULLSCREEN"),                                         TEXT ("Full screen client area height"),      SM_CYKANJIWINDOW,        TEXT ("SM_CYKANJIWINDOW"),                                        TEXT ("Kanji window height"),      SM_MOUSEPRESENT,         TEXT ("SM_MOUSEPRESENT"),                                         TEXT ("Mouse present flag"),      SM_CYVSCROLL,            TEXT ("SM_CYVSCROLL"),                                            TEXT ("Vertical scroll arrow height"),      SM_CXHSCROLL,            TEXT ("SM_CXHSCROLL"),                                            TEXT ("Horizontal scroll arrow width"),      SM_DEBUG,                TEXT ("SM_DEBUG"),                                                TEXT ("Debug version flag"),      SM_SWAPBUTTON,           TEXT ("SM_SWAPBUTTON"),                                           TEXT ("Mouse buttons swapped flag"),      SM_CXMIN,                TEXT ("SM_CXMIN"),                                                TEXT ("Minimum window width"),      SM_CYMIN,                TEXT ("SM_CYMIN"),                                                TEXT ("Minimum window height"),      SM_CXSIZE,               TEXT ("SM_CXSIZE"),                                               TEXT ("Min/Max/Close button width"),      SM_CYSIZE,               TEXT ("SM_CYSIZE"),                                               TEXT ("Min/Max/Close button height"),      SM_CXSIZEFRAME,          TEXT ("SM_CXSIZEFRAME"),                                          TEXT ("Window sizing frame width"),      SM_CYSIZEFRAME,          TEXT ("SM_CYSIZEFRAME"),                                          TEXT ("Window sizing frame height"),      SM_CXMINTRACK,           TEXT ("SM_CXMINTRACK"),                                           TEXT ("Minimum window tracking width"),      SM_CYMINTRACK,           TEXT ("SM_CYMINTRACK"),                                           TEXT ("Minimum window tracking height"),      SM_CXDOUBLECLK,          TEXT ("SM_CXDOUBLECLK"),                                          TEXT ("Double click x tolerance"),      SM_CYDOUBLECLK,          TEXT ("SM_CYDOUBLECLK"),                                          TEXT ("Double click y tolerance"),      SM_CXICONSPACING,        TEXT ("SM_CXICONSPACING"),                                        TEXT ("Horizontal icon spacing"),      SM_CYICONSPACING,        TEXT ("SM_CYICONSPACING"),                                        TEXT ("Vertical icon spacing"),      SM_MENUDROPALIGNMENT,    TEXT ("SM_MENUDROPALIGNMENT"),                                    TEXT ("Left or right menu drop"),      SM_PENWINDOWS,           TEXT ("SM_PENWINDOWS"),                                           TEXT ("Pen extensions installed"),      SM_DBCSENABLED,          TEXT ("SM_DBCSENABLED"),                                          TEXT ("Double-Byte Char Set enabled"),      SM_CMOUSEBUTTONS,        TEXT ("SM_CMOUSEBUTTONS"),                                        TEXT ("Number of mouse buttons"),      SM_SECURE,               TEXT ("SM_SECURE"),                                               TEXT ("Security present flag"),      SM_CXEDGE,               TEXT ("SM_CXEDGE"),                                               TEXT ("3-D border width"),      SM_CYEDGE,               TEXT ("SM_CYEDGE"),                                               TEXT ("3-D border height"),      SM_CXMINSPACING,         TEXT ("SM_CXMINSPACING"),                                         TEXT ("Minimized window spacing width"),      SM_CYMINSPACING,         TEXT ("SM_CYMINSPACING"),                                         TEXT ("Minimized window spacing height"),      SM_CXSMICON,             TEXT ("SM_CXSMICON"),                                             TEXT ("Small icon width"),      SM_CYSMICON,             TEXT ("SM_CYSMICON"),                                             TEXT ("Small icon height"),      SM_CYSMCAPTION,          TEXT ("SM_CYSMCAPTION"),                                          TEXT ("Small caption height"),      SM_CXSMSIZE,             TEXT ("SM_CXSMSIZE"),                                             TEXT ("Small caption button width"),      SM_CYSMSIZE,             TEXT ("SM_CYSMSIZE"),                                             TEXT ("Small caption button height"),      SM_CXMENUSIZE,           TEXT ("SM_CXMENUSIZE"),                                           TEXT ("Menu bar button width"),      SM_CYMENUSIZE,           TEXT ("SM_CYMENUSIZE"),                                           TEXT ("Menu bar button height"),      SM_ARRANGE,              TEXT ("SM_ARRANGE"),                                              TEXT ("How minimized windows arranged"),      SM_CXMINIMIZED,          TEXT ("SM_CXMINIMIZED"),                                          TEXT ("Minimized window width"),      SM_CYMINIMIZED,          TEXT ("SM_CYMINIMIZED"),                                          TEXT ("Minimized window height"),      SM_CXMAXTRACK,           TEXT ("SM_CXMAXTRACK"),                                           TEXT ("Maximum draggable width"),      SM_CYMAXTRACK,           TEXT ("SM_CYMAXTRACK"),                                           TEXT ("Maximum draggable height"),      SM_CXMAXIMIZED,          TEXT ("SM_CXMAXIMIZED"),                                          TEXT ("Width of maximized window"),      SM_CYMAXIMIZED,          TEXT ("SM_CYMAXIMIZED"),                                          TEXT ("Height of maximized window"),      SM_NETWORK,              TEXT ("SM_NETWORK"),                                              TEXT ("Network present flag"),      SM_CLEANBOOT,            TEXT ("SM_CLEANBOOT"),                                            TEXT ("How system was booted"),      SM_CXDRAG,               TEXT ("SM_CXDRAG"),                                               TEXT ("Avoid drag x tolerance"),      SM_CYDRAG,               TEXT ("SM_CYDRAG"),                                               TEXT ("Avoid drag y tolerance"),      SM_SHOWSOUNDS,           TEXT ("SM_SHOWSOUNDS"),                                           TEXT ("Present sounds visually"),      SM_CXMENUCHECK,          TEXT ("SM_CXMENUCHECK"),                                          TEXT ("Menu check-mark width"),      SM_CYMENUCHECK,          TEXT ("SM_CYMENUCHECK"),                                          TEXT ("Menu check-mark height"),      SM_SLOWMACHINE,          TEXT ("SM_SLOWMACHINE"),                                          TEXT ("Slow processor flag"),      SM_MIDEASTENABLED,       TEXT ("SM_MIDEASTENABLED"),                                       TEXT ("Hebrew and Arabic enabled flag"),      SM_MOUSEWHEELPRESENT,    TEXT ("SM_MOUSEWHEELPRESENT"),                                    TEXT ("Mouse wheel present flag"),      SM_XVIRTUALSCREEN,       TEXT ("SM_XVIRTUALSCREEN"),                                       TEXT ("Virtual screen x origin"),      SM_YVIRTUALSCREEN,       TEXT ("SM_YVIRTUALSCREEN"),                                       TEXT ("Virtual screen y origin"),      SM_CXVIRTUALSCREEN,      TEXT ("SM_CXVIRTUALSCREEN"),                                      TEXT ("Virtual screen width"),      SM_CYVIRTUALSCREEN,      TEXT ("SM_CYVIRTUALSCREEN"),                                      TEXT ("Virtual screen height"),      SM_CMONITORS,            TEXT ("SM_CMONITORS"),                                            TEXT ("Number of monitors"),      SM_SAMEDISPLAYFORMAT,    TEXT ("SM_SAMEDISPLAYFORMAT"),                                    TEXT ("Same color format flag") } ;

源代码：

/*----------------------------------------------------    sysmets1.C -- System Metrics Display Program No. 1                  (c) Charles Petzold, 1998   ----------------------------------------------------*/  #define WINVER 0x0500 #include <windows.h> #include "sysmets.h"  LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;  int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,                     PSTR szCmdLine, int iCmdShow) {      static TCHAR szAppName[] = TEXT ("SysMets1") ;      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 ("Get System Metrics No. 1"),                           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 ; }  LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) {      static int  cxChar, cxCaps, cyChar ;      HDC         hdc ;      int         i ;      PAINTSTRUCT ps ;      TCHAR       szBuffer [10] ;      TEXTMETRIC  tm ;       switch (message)      {      case WM_CREATE:           hdc = GetDC (hwnd) ;            GetTextMetrics (hdc, &tm) ;           cxChar = tm.tmAveCharWidth ;           cxCaps = (tm.tmPitchAndFamily & 1 ? 3 : 2) * cxChar / 2 ;           cyChar = tm.tmHeight + tm.tmExternalLeading ;            ReleaseDC (hwnd, hdc) ;           return 0 ;       case WM_PAINT :           hdc = BeginPaint (hwnd, &ps) ;            for (i = 0 ; i < NUMLINES ; i++)           {                TextOut (hdc, 0, cyChar * i,                                               sysmetrics[i].szLabel,                         lstrlen (sysmetrics[i].szLabel)) ;                 TextOut (hdc, 22 * cxCaps, cyChar * i,                               sysmetrics[i].szDesc,                         lstrlen (sysmetrics[i].szDesc)) ;                 SetTextAlign (hdc, TA_RIGHT | TA_TOP) ;                 TextOut (hdc, 22 * cxCaps + 40 * cxChar, cyChar * i, szBuffer,                         wsprintf (szBuffer, TEXT ("%5d"),                              GetSystemMetrics (sysmetrics[i].iIndex))) ;                 SetTextAlign (hdc, TA_LEFT | TA_TOP) ;           }           EndPaint (hwnd, &ps) ;           return 0 ;       case WM_DESTROY :           PostQuitMessage (0) ;           return 0 ;      }      return DefWindowProc (hwnd, message, wParam, lParam) ; }

关于#define WINVER 0x0500 这句话必须放在程序最开始.

因为VC6.0 的默认编译环境为WINVER=0x0400,也就是在Windows95，或WindowsNT4.0以及以上运行的 。

WINVER>=0X0500 指Win2000以上。有些API 或常数只有在Win2000以上才支持。

WINVER 定义了决定构建应用程序所需的最低平台SDK,而这又将在编译时确定哪些例程是由头文件找到的。

这个程序和 HELLOWIN 唯一不同的就是窗口过程函数了。

cxChar变量表示平均字符宽度，字符的总高度(包括外部间距)保存在 cyChar变量中，将大写字符的平均宽度保存在cxCaps中。

前缀c代表"count"，也就是"个数"。在这里代表像素数。它们被定义为静态变量，是因为它们必须在Windows处理其他消息时还有效。

变量 i 表示字符行数。

TEXTMETRIC 结构体用来保存字符尺寸的值。程序通过调用 GetSystemMetrics() 函数来获取用户界面尺寸，同样的，通过

调用GetTextMetrics() 函数，程序可以获取字体尺寸。GetTextMetrics() 函数需要一个设备环境句柄，因为它会返回

该设备环境中当前选定的字体的信息，并将这些值复制到类型为 TEXTMETRIC的结构体中，该结构体有20个字段，但我们

现在仅关心其中前7个

typedef struct tagTEXTMETRIC {  LONG tmHeight; //字符高度 LONG tmAscent; //字符上部高度(基线以上) LONG tmDescent; //字符下部高度(基线以下) LONG tmInternalLeading, //由tmHeight定义的字符高度的顶部空间数目 LONG tmExternalLeading, //夹在两行之间的空间数目 LONG tmAveCharWidth, //平均字符宽度 LONG tmMaxCharWidth, //最宽字符的宽度 LONG tmWeight; //字体的粗细轻重程度 LONG tmOverhang, //加入某些拼接字体上的附加高度 LONG tmDigitizedAspectX, //字体设计所针对的设备水平方向 LONG tmDigitizedAspectY, //字体设计所针对的设备垂直方向 BCHAR tmFirstChar; //为字体定义的第一个字符 BCHAR tmLastChar; //为字体定义的最后一个字符 BCHAR tmDefaultChar; //字体中所没有字符的替代字符 BCHAR tmBreakChar; //用于拆字的字符 BYTE tmItalic, //字体为斜体时非零 BYTE tmUnderlined, //字体为下划线时非零 BYTE tmStruckOut, //字体被删去时非零 BYTE tmPitchAndFamily, //字体间距(低4位)和族(高4位) BYTE tmCharSet; //字体的字符集 } TEXTMETRIC;

这些字段的值的单位取决于设备环境中当前选定的映射模式。默认的映射模式是MM_TEXT,所以它们的值是以像素为单位的。

在调用GetTextMetrics() 函数前，首先要定义一个结构变量，通常命名为 tm；

需要获取字号时，首先获取设备环境句柄，然后调用GetTextMetrics；

cxCaps = (tm.tmPitchAndFamily & 1 ? 3 : 2) * cxChar / 2 ;

在等宽字体中，cxCaps设为cxChar的1.5倍。在TEXTMETRIC结构中，tmPitchAndFamily字段的低位决定字体是否为等宽

字体：1 代表变量字体，0 代表等宽字体。

在早期的Windows中，系统字体是一种等宽字体：所有字符的宽度是一样的。但从 Windows 3.0开始，系统字体变成了

变宽字体：每一个字符的宽度是不一样的，例如字符"w"就比字符"i"要宽。很明显变宽字体比等宽字体可读性强。

系统字体是一种“点阵字体”：每个字符由像素点构成。在某种程度上，系统字体中字符的大小取决于显示器的大小：

系统字体的设计要求能够在显示器上起码显示25行80列字符。

值得重视的是，系统字体的尺寸取决于Windows运行时的显示分辨率，有时还取决于用户选定的系统字号。

注意了：头文件的结构体的大括号后面没有分号，所以头文件的意思就是：

sysmetrics[0].iIndex 也就是 SM_CXSCREEN ;

sysmetrics[0].szlabel 也就是 "SM_CXSCREEN" ;

sysmetrics[0].szDesc 也就是 "screen width in pixels" ;

......

......

......

至于第二个TextOut 里的 22*cxCaps 意思是在第一栏的字符最长的有20个字符，多出来的2个是为了留出两栏间的空隙。

使用 SetTextAlign() 函数的目的仅是为了让右边对齐。

好了，程序意思就是这样。

程序运行效果如图：

可以看到程序下面无法显示，并且也没有滚动条来拖动。

接下来我们将对程序进行完善。

文章来源: SystemMetrics