SystemMetrics
头文件：
#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：
#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。
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；
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" ;
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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。
