Windows2000/private/shell/ext/settings/folder.cpp

// This module was originally designed to provide category and topic extensibility
// through the registry and COM objects.  You could add new categories by adding
// the CLSID of a COM object to the registry.  The standard 3 categories were
// in fact implemented as the "standard" extension.
// This code would enumerate these CLSIDs
// and instantiate the corresponding settings folder extension objects which
// in turn enumerate the topics that they provide.  This extensibility
// was found to be unnecessary so I removed the registry-reading code
// to reduce code size.  However, I left much of the
// characteristics untouched in case the need for this flexibility returns
// at some future date.  BrianAu - 1/13/97

#include "precomp.hxx"
#pragma hdrstop

#include "folder.h"
#include "stdext.h"


SettingsFolder::SettingsFolder(
    VOID
    ) : m_iCurrentTopic(0)
{
    DebugMsg(DM_CONSTRUCT, TEXT("SettingsFolder::SettingsFolder, 0x%08X"), this);
}


SettingsFolder::~SettingsFolder(
    VOID
    )
{
    PSETTINGS_FOLDER_TOPIC pITopic = NULL;


    // Release the topic objects.

    while(m_lstTopics.Remove((LPVOID *)&pITopic, 0))
    {
        Assert(NULL != pITopic);
        pITopic->Release();
        pITopic = NULL;
    }
}



// For each extension specified in the registry,
// load the categories and topics supplied by the extension.

HRESULT
SettingsFolder::LoadTopics(
    VOID
    ) throw(OutOfMemory)
{
    HRESULT hResult = NO_ERROR;

    PointerList Extensions;
    PSETTINGS_FOLDER_EXT pExt = NULL;

    try
    {
        hResult = LoadExtensions(Extensions);
        if (SUCCEEDED(hResult))
        {
            UINT cExtensions = Extensions.Count();
            while(Extensions.Remove((LPVOID *)&pExt, 0))
            {
                Assert(NULL != pExt);
                hResult = LoadExtensionTopics(pExt);   // Can throw OutOfMemory.
                pExt->Release();                       // Release extension from list.
            }
        }
        if (E_OUTOFMEMORY == hResult)
        {

            // The callers of this are set up to expect an
            // OutOfMemory exception when we're out of memory.
            //
            throw OutOfMemory();
        }

    }
    catch(...)
    {
        //
        // Clean up after exception.
        //
        while(Extensions.Remove((LPVOID *)&pExt, 0))
        {
            Assert(NULL != pExt);
            pExt->Release();
        }
        throw;
    }

    return hResult;
}



HRESULT
SettingsFolder::LoadExtensions(
    PointerList& list
    ) throw(OutOfMemory)
{
    PSETTINGS_FOLDER_EXT pExt = NULL;;

    try
    {
        pExt = new SettingsFolderExt();
        pExt->AddRef();

        //
        // Transfer ref count of 1 to list.
        //
        list.Append((LPVOID)pExt);  // Add extension to our list.
                                     // Can throw OutOfMemory.
    }
    catch(...)
    {
        if (NULL != pExt)
            pExt->Release();
        throw;
    }
    return NO_ERROR;
}




// Load all individual topics supplied by the extension.

HRESULT
SettingsFolder::LoadExtensionTopics(
    PSETTINGS_FOLDER_EXT pExt
    ) throw(OutOfMemory)
{
    Assert(NULL != pExt);

    PENUM_SETTINGS_TOPICS pEnum = NULL;

    HRESULT hResult = NO_ERROR;
    hResult = pExt->EnumTopics(&pEnum);
    if (SUCCEEDED(hResult))
    {
        PSETTINGS_FOLDER_TOPIC pITopic = NULL;
        try
        {
            while(SUCCEEDED(hResult) && S_OK == pEnum->Next(1, &pITopic, NULL))
            {
                //
                // Transfer ref count of 1 to topic descriptor.
                //
                hResult = AddTopic(pITopic);
                pITopic = NULL;
            }
            pEnum->Release();
        }
        catch(...)
        {
            if (NULL != pITopic)
                pITopic->Release();
            pEnum->Release();
            throw;
        }
    }
    return hResult;
}




// Assumes caller has AddRef'd pITopic.

HRESULT
SettingsFolder::AddTopic(
    PSETTINGS_FOLDER_TOPIC pITopic
    ) throw(OutOfMemory)
{
    Assert(NULL != pITopic);

    m_lstTopics.Append((LPVOID)pITopic);
    return NO_ERROR;
}


PSETTINGS_FOLDER_TOPIC
SettingsFolder::GetTopic(
    INT iTopic
    )
{
    HRESULT hResult = NO_ERROR;
    PSETTINGS_FOLDER_TOPIC pITopic = NULL;

    if (m_lstTopics.Retrieve((LPVOID *)&pITopic, iTopic))
    {
        //
        // AddRef interface pointer before returning copy.
        //
        Assert(NULL != pITopic);
        pITopic->AddRef();
    }

    return pITopic;
}


BOOL
SettingsFolder::SetCurrentTopicIndex(
    INT iTopic
    )
{
    if (iTopic < (INT)m_lstTopics.Count())
    {
        m_iCurrentTopic = iTopic;
        return TRUE;
    }
    return FALSE;
}