EnumObjectsProc

3.1

int CALLBACK EnumObjectsProc(lpLogObject, lpData)
void FAR* lpLogObject;	/* address of object	*/
LPARAM lpData;	/* address of application-defined data	*/

The EnumObjectsProc function is an application-defined callback function that processes object data from the EnumObjects function.

Parameters

lpLogObject

Points to a LOGPEN or LOGBRUSH structure that contains information about the attributes of the object.

The LOGPEN structure has the following form:

typedef struct tagLOGPEN {  /* lgpn */
    UINT     lopnStyle;
    POINT    lopnWidth;
    COLORREF lopnColor;
} LOGPEN;

The LOGBRUSH structure has the following form:

typedef struct tagLOGBRUSH {    /* lb */
    UINT     lbStyle;
    COLORREF lbColor;
    int      lbHatch;
} LOGBRUSH;

For a full description of these structures, see the Microsoft Windows Programmer's Reference, Volume 3.

lpData

Points to the application-defined data passed by the EnumObjects function.

Return Value

This function must return a nonzero value to continue enumeration; to stop enumeration, it must return zero.

Comments

An application must register this callback function by passing its address to the EnumObjects function. The EnumObjectsProc function is a placeholder for the application-supplied function name. The actual name must be exported by including it in an EXPORTS statement in the application's module-definition (.DEF) file.

Example

The following example retrieves the number of horizontally hatched brushes and fills LOGBRUSH structures with information about each of them:

#define MAXBRUSHES 50

GOBJENUMPROC lpProcCallback;
HGLOBAL hglbl;
LPBYTE lpbCountBrush;

lpProcCallback = (GOBJENUMPROC) MakeProcInstance(
    (FARPROC) Callback, hinst);

hglbl = GlobalAlloc(GMEM_FIXED, sizeof(LOGBRUSH)
    * MAXBRUSHES);
lpbCountBrush = (LPBYTE) GlobalLock(hglbl);
*lpbCountBrush = 0;
EnumObjects(hdc, OBJ_BRUSH, lpProcCallback,
    (LPARAM) lpbCountBrush);

FreeProcInstance((FARPROC) lpProcCallback);

int FAR PASCAL Callback(LPLOGBRUSH lpLogBrush, LPBYTE pbData)
{
    /*
     * The pbData parameter contains the number of horizontally
     * hatched brushes; the lpDest parameter is set to follow the
     * byte reserved for pbData and the LOGBRUSH structures that
     * have been filled with brush information.
     */

    LPLOGBRUSH lpDest =
        (LPLOGBRUSH) (pbData + 1 + (*pbData * sizeof(LOGBRUSH)));

    if (lpLogBrush->lbStyle ==
            BS_HATCHED && /* if horiz hatch */
            lpLogBrush->lbHatch == HS_HORIZONTAL) {
        *lpDest++ = *lpLogBrush; /* fills structure with brush info */
        (*pbData) ++;            /* increments brush count          */
        if (*pbData >= MAXBRUSHES)
            return 0;
    }

    return 1;
}