WindowsXP-SP1/shell/shell32/psxa.c

//
// PropSheetExtArray implementation, use for control panel applets to extend their pages
//
// Manipulates a group of property sheet extension objects (see PSXA.H)
//
#include "shellprv.h"
#pragma  hdrstop

// header for an array of IShellPropSheetExt interface pointers

typedef struct
{
    UINT count, alloc;
    IShellPropSheetExt *interfaces[ 0 ];
} PSXA;


// used to forward LPFNADDPROPSHEETPAGE calls with added error checking

typedef struct
{
    LPFNADDPROPSHEETPAGE pfn;
    LPARAM lparam;
    UINT count;
    BOOL allowmulti;
    BOOL alreadycalled;
} _PSXACALLINFO;


// forwards an LPFNADDPROPSHEETPAGE call with added error checking

BOOL CALLBACK _PsxaCallOwner(HPROPSHEETPAGE hpage, LPARAM lparam)
{
    _PSXACALLINFO *callinfo = (_PSXACALLINFO *)lparam;
    if (callinfo)
    {
        if (!callinfo->allowmulti && callinfo->alreadycalled)
            return FALSE;

        if (callinfo->pfn(hpage, callinfo->lparam))
        {
            callinfo->alreadycalled = TRUE;
            callinfo->count++;
            return TRUE;
        }
    }
    return FALSE;
}

// creates an instance of the property sheet extension referred to by szCLSID
// initializes it via the IShellExtInit (if IShellExtInit is supported)

BOOL InitPropSheetExt(IShellPropSheetExt **ppspx, LPCTSTR pszCLSID, HKEY hKey, IDataObject *pDataObj)
{
    if (SUCCEEDED(SHExtCoCreateInstance(pszCLSID, NULL, NULL, &IID_IShellPropSheetExt, ppspx)))
    {
        IShellExtInit *psxi;

        if (SUCCEEDED((*ppspx)->lpVtbl->QueryInterface(*ppspx, &IID_IShellExtInit, &psxi)))
        {
            if (FAILED(psxi->lpVtbl->Initialize(psxi, NULL, pDataObj, hKey)))
            {
                (*ppspx)->lpVtbl->Release(*ppspx);
                *ppspx = NULL;
            }

            psxi->lpVtbl->Release(psxi);
        }
    }

    return BOOLFROMPTR(*ppspx);
}


// uses hKey and pszSubKey to find property sheet handlers in the registry
// loads up to max_iface IShellPropSheetExt interfaces (so I'm lazy...)
// returns a handle (pointer) to a newly allocated PSXA

HPSXA SHCreatePropSheetExtArrayEx(HKEY hKey, LPCTSTR pszLocation, UINT max_iface, IDataObject *pDataObj)
{
    BOOL success = FALSE;

    PSXA *psxa = LocalAlloc(LPTR, sizeof(*psxa) + sizeof(IShellPropSheetExt *) * max_iface);
    if (psxa)
    {
        IShellPropSheetExt **spsx = psxa->interfaces;
        HKEY hkLocation;
        UINT i;

        psxa->count = 0;
        psxa->alloc = max_iface;

        for (i = 0; i < psxa->alloc; i++, spsx++)
            *spsx = NULL;

        if (RegOpenKey(hKey, pszLocation, &hkLocation) == ERROR_SUCCESS)
        {
            HKEY hkHandlers;

            if (RegOpenKey(hkLocation, STRREG_SHEX_PROPSHEET, &hkHandlers) == ERROR_SUCCESS)
            {
                TCHAR szChild[ 64 ]; // yes, this is totally arbitrary...

                // fill until there's no room or no more subkeys to get
                for (i = 0;
                    (psxa->count < psxa->alloc) &&
                    (RegEnumKey(hkHandlers, (int)i, szChild,
                    ARRAYSIZE(szChild)) == ERROR_SUCCESS);
                    i++)
                {
                    TCHAR szCLSID[ MAX_PATH ];
                    LONG len_szCLSID = ARRAYSIZE(szCLSID);

                    if (SHRegQueryValue(hkHandlers, szChild, szCLSID,
                        &len_szCLSID) == ERROR_SUCCESS)
                    {
                        if (InitPropSheetExt(&psxa->interfaces[ psxa->count ],
                            szCLSID, hKey, pDataObj))
                        {
                            psxa->count++;
                        }
                    }
                }

                RegCloseKey(hkHandlers);
                success = TRUE;
            }

            RegCloseKey(hkLocation);
        }
    }

    if (!success && psxa)
    {
        SHDestroyPropSheetExtArray((HPSXA)psxa);
        psxa = NULL;
    }

    return (HPSXA)psxa;
}

HPSXA SHCreatePropSheetExtArray(HKEY hKey, LPCTSTR pszLocation, UINT max_iface)
{
    return SHCreatePropSheetExtArrayEx(hKey, pszLocation, max_iface, NULL);
}

// releases interfaces in a PSXA and frees the memory it occupies

void SHDestroyPropSheetExtArray(HPSXA hpsxa)
{
    PSXA *psxa = (PSXA *)hpsxa;
    IShellPropSheetExt **spsx = psxa->interfaces;
    UINT i;

    // release the interfaces
    for (i = 0; i < psxa->count; i++, spsx++)
        (*spsx)->lpVtbl->Release(*spsx);

    LocalFree(psxa);
}


// asks each interface in a PSXA to add pages for a proprty sheet
// returns the number of pages actually added

UINT SHAddFromPropSheetExtArray(HPSXA hpsxa, LPFNADDPROPSHEETPAGE lpfnAddPage, LPARAM lParam)
{
    PSXA *psxa = (PSXA *)hpsxa;
    IShellPropSheetExt **spsx = psxa->interfaces;
    _PSXACALLINFO callinfo = { lpfnAddPage, lParam, 0, TRUE, FALSE };
    UINT i;

    for (i = 0; i < psxa->count; i++, spsx++)
        (*spsx)->lpVtbl->AddPages(*spsx, _PsxaCallOwner, (LPARAM)&callinfo);

    return callinfo.count;
}


// asks each interface in a PSXA to replace a page in a prop sheet
// each interface is only allowed to add up to one replacement
// returns the total number of replacements added

UINT SHReplaceFromPropSheetExtArray(HPSXA hpsxa, UINT uPageID,
                                    LPFNADDPROPSHEETPAGE lpfnReplaceWith, LPARAM lParam)
{
    PSXA *psxa = (PSXA *)hpsxa;
    IShellPropSheetExt **spsx = psxa->interfaces;
    _PSXACALLINFO callinfo = { lpfnReplaceWith, lParam, 0, FALSE, FALSE };
    UINT i;

    for (i = 0; i < psxa->count; i++, spsx++)
    {
        // reset the call flag so that each provider gets a chance
        callinfo.alreadycalled = FALSE;

        if ((*spsx)->lpVtbl->ReplacePage)
            (*spsx)->lpVtbl->ReplacePage(*spsx, uPageID, _PsxaCallOwner, (LPARAM)&callinfo);
    }

    return callinfo.count;
}