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）。

程式参数

程式结果

程式参数

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 ;

}

程式结果

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。