程式5-1所示的DEVCAPS1程式显示了以一个视讯显示器的装置内容为参数时，可以从 GetDeviceCaps函式中获得的部分资讯（该程式的另一个扩充版本DEVCAPS2将在第十三章给出，用於取得印表机资讯）。
程式5-1 DEVCAPS1
DEVCAPS1.C
/*------------------------------------------------------------------------
DEVCAPS1.C -- Device Capabilities Display Program No. 1
(c) Charles Petzold, 1998
----------------------------------------------------------------------*/
#include <windows.h>
#define NUMLINES ((int) (sizeof devcaps / sizeof devcaps [0]))
struct
{
int iIndex ;
TCHAR * szLabel ;
TCHAR * szDesc ;
}
devcaps [] =
{
HORZSIZE, TEXT ("HORZSIZE"),TEXT ("Width in millimeters:"),
VERTSIZE, TEXT ("VERTSIZE"),TEXT ("Height in millimeters:"),
HORZRES, TEXT ("HORZRES"), TEXT ("Width in pixels:"),
VERTRES, TEXT ("VERTRES"), TEXT ("Height in raster lines:"),
BITSPIXEL, TEXT ("BITSPIXEL"),TEXT ("Color bits per pixel:"),
PLANES, TEXT ("PLANES"), TEXT ("Number of color planes:"),
NUMBRUSHES, TEXT ("NUMBRUSHES"), TEXT ("Number of device brushes:"),
NUMPENS, TEXT ("NUMPENS"), TEXT ("Number of device pens:"),
NUMMARKERS, TEXT ("NUMMARKERS"), TEXT ("Number of device markers:"),
NUMFONTS, TEXT ("NUMFONTS"), TEXT ("Number of device fonts:"),
NUMCOLORS, TEXT ("NUMCOLORS"), TEXT ("Number of device colors:"),
PDEVICESIZE, TEXT ("PDEVICESIZE"), TEXT ("Size of device structure:"),
ASPECTX, TEXT ("ASPECTX"), TEXT ("Relative width of pixel:"),
ASPECTY, TEXT ("ASPECTY"), TEXT ("Relative height of pixel:"),
ASPECTXY, TEXT ("ASPECTXY"), TEXT ("Relative diagonal of pixel:"),
LOGPIXELSX, TEXT ("LOGPIXELSX"), TEXT ("Horizontal dots per inch:"),
LOGPIXELSY, TEXT ("LOGPIXELSY"), TEXT ("Vertical dots per inch:"),
SIZEPALETTE, TEXT ("SIZEPALETTE"), TEXT ("Number of palette entries:"),
NUMRESERVED, TEXT ("NUMRESERVED"), TEXT ("Reserved palette entries:"),
COLORRES, TEXT ("COLORRES"), TEXT ("Actual color resolution:")
} ;
LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT ("DevCaps1") ;
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 ("Device Capabilities"),
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 ;
TCHAR szBuffer[10] ;
HDC hdc ;
int i ;
PAINTSTRUCT ps ;
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,
devcaps.szLabel,
lstrlen (devcaps.szLabel)) ;
TextOut ( hdc, 14 * cxCaps, cyChar * i,
devcaps.szDesc,
lstrlen (devcaps.szDesc)) ;
SetTextAlign (hdc, TA_RIGHT | TA_TOP) ;
TextOut (hdc, 14*cxCaps+35*cxChar, cyChar*i, szBuffer,
wsprintf (szBuffer, TEXT ("%5d"),
GetDeviceCaps (hdc, devcaps.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) ;
}
可以看到，这个程式非常类似第四章的SYSMETS1。为了保持程式码的短小，我没有使用卷动列，因为我知道资讯可以在一个画面上显示出来。
