// Copyright (c) 2007-2009 Nokia Corporation and/or its subsidiary(-ies).

// All rights reserved.

// This component and the accompanying materials are made available

// under the terms of "Eclipse Public License v1.0"

// which accompanies this distribution, and is available

// at the URL "http://www.eclipse.org/legal/epl-v10.html".

//

// Initial Contributors:

// Nokia Corporation - initial contribution.

//

// Contributors:

//

// Description:

// FONT related functions and the font cache

// 

//

#include "wsfont.h"

CWsFontCache * CWsFontCache::iSelf = NULL;

TDblQue<CWsFbsFont> * CWsFontCache::iList = NULL;

CWsFontCache::CWsFontCache()

	{

	}

CWsFontCache::~CWsFontCache()

	{

	}

void CWsFontCache::CreateInstanceL()

	{

	// The list MUST exist before creation of the cache since the cache

	// contains an array of fonts. When the array is created the fonts add themselves

	// to the list.

	// The list is ordered from newest to oldest font used.

	iList = new (ELeave) TDblQue<CWsFbsFont>(_FOFF(CWsFbsFont,iLink));

	CleanupStack::PushL(iList);

	iSelf = new (ELeave) CWsFontCache;

	CleanupStack::Pop(iList);

	}

void CWsFontCache::DestroyInstance()

	{

	// The cache has to be destroyed first since the fonts are

	// destroyed when the cache's array if destroyed. The fonts 

	// remove themselves from the list

	delete iSelf;

	iSelf = NULL;

	delete iList;

	iList = NULL;

	}

void CWsFontCache::ReleaseFont(CWsFbsFont *&aFont)

	{

	if (aFont)

		{

		WS_ASSERT_DEBUG(aFont->iCount>0, EWsPanicFontCacheCount);

		// decrease usage count

		aFont->iCount--;

		// when the font reaches zero then the font entry can be reused later

		aFont = NULL;

		}

	}

TBool CWsFontCache::UseFont(CWsFbsFont *&aFont, TInt aHandle)

	{

	ReleaseFont(aFont);

	CWsFbsFont *font = NULL;

	// The list is ordered from newest to oldest font used.

	TDblQueIter<CWsFbsFont> iter(*iList);

	// Search for the font from newest to oldest font

	while ((font = iter++) != NULL)

		{

		// if the font handle already exists use existing font

		if (font->Handle() == aHandle)

			{

			break;

			}

		}

	// Font not found in cache so find an unused entry

	if (!font)

		{

		// Starting search from oldest to newest font unsed

		iter.SetToLast();

		while((font = iter--) != NULL)

			{

			// if you find an unused font then use that font entry

			if (font->iCount == 0)

				{

				break;

				}

			}

		// if an unused font is not found then all fonts are being used and 

		// the font can not be created

		if (!font)

			{

			return(ETrue);	// No room in cache

			}

		// release and reuse the font entry to create a new font

		font->Reset();

		if (font->Duplicate(aHandle) != KErrNone)

			{

			return(EFalse);	// Bad handle, (indicated by aFont=NULL)

			}

		}

	// put font at the font of the list as the font is the newest font

	font->iLink.Deque();

	iList->AddFirst(*font);

	// increase usage count

	font->iCount++;

	aFont = font;

	return(EFalse);

	}

TDblQue<CWsFbsFont>& CWsFontCache::List()

	{

	return *Instance()->iList;

	}

CWsFbsFont::CWsFbsFont()

	{

	// add itself to the font cache

	CWsFontCache::List().AddLast(*this);

	}

CWsFbsFont::~CWsFbsFont()

	{

	// remove itself from the font cache

	iLink.Deque();

	WS_ASSERT_DEBUG(iCount==0, EWsPanicFontCacheCount);

	}