gecko-dev/gfx/src/nsDeviceContext.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * The contents of this file are subject to the Netscape Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/NPL/
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is Netscape
 * Communications Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation. All
 * Rights Reserved.
 *
 * Contributor(s): 
 * This Original Code has been modified by IBM Corporation. Modifications made by IBM 
 * described herein are Copyright (c) International Business Machines Corporation, 2000.
 * Modifications to Mozilla code or documentation identified per MPL Section 3.3
 *
 * Date             Modified by     Description of modification
 * 04/20/2000       IBM Corp.      OS/2 VisualAge build.
 */

#include "nsDeviceContext.h"
#include "nsFont.h"
#include "nsIView.h"
#include "nsGfxCIID.h"
#include "nsImageNet.h"
#include "nsImageRequest.h"
#include "nsIImageGroup.h"
#include "il_util.h"
#include "nsVoidArray.h"
#include "nsIFontMetrics.h"
#include "nsHashtable.h"
#include "nsILanguageAtomService.h"
#include "nsIServiceManager.h"

// Needed for Localization
#include "nsIServiceManager.h"
#include "nsIIOService.h"
#include "nsIURI.h"
#include "nsIStringBundle.h"
#include "nsITextContent.h"
#include "nsISupportsArray.h"
#include "nsXPIDLString.h"
#include "nsNetCID.h"

static NS_DEFINE_CID(kIOServiceCID,            NS_IOSERVICE_CID);
static NS_DEFINE_CID(kStringBundleServiceCID,  NS_STRINGBUNDLESERVICE_CID);
// done I10N

class nsFontCache
{
public:
  nsFontCache();
  ~nsFontCache();

  nsresult Init(nsIDeviceContext* aContext);
  nsresult GetDeviceContext(nsIDeviceContext *&aContext) const;
  nsresult GetMetricsFor(const nsFont& aFont, nsIAtom* aLangGroup,
                         nsIFontMetrics *&aMetrics);
  nsresult Flush();

protected:
  nsVoidArray       mFontMetrics;
  nsIDeviceContext  *mContext;      //we do not addref this since
                                    //ownership is implied. MMP.
};


NS_IMPL_ISUPPORTS1(DeviceContextImpl, nsIDeviceContext)

DeviceContextImpl :: DeviceContextImpl()
{
  NS_INIT_REFCNT();
  mFontCache = nsnull;
  mDevUnitsToAppUnits = 1.0f;
  mAppUnitsToDevUnits = 1.0f;
  mGammaValue = 1.0f;
  mCPixelScale = 1.0f;
  mGammaTable = new PRUint8[256];
  mZoom = 1.0f;
  mTextZoom = 1.0f;
  mWidget = nsnull;
  mIconImageGroup = nsnull;
  for (PRInt32 i = 0; i < NS_NUMBER_OF_ICONS; i++) {
    mIcons[i] = nsnull;
  }
  mFontAliasTable = nsnull;
  mColorSpace = nsnull;
}

static PRBool PR_CALLBACK DeleteValue(nsHashKey* aKey, void* aValue, void* closure)
{
  delete ((nsString*)aValue);
  return PR_TRUE;
}

DeviceContextImpl :: ~DeviceContextImpl()
{
  if (nsnull != mFontCache)
  {
    delete mFontCache;
    mFontCache = nsnull;
  }

  if (nsnull != mGammaTable)
  {
    delete[] mGammaTable;
    mGammaTable = nsnull;
  }

  for (PRInt32 i = 0; i < NS_NUMBER_OF_ICONS; i++) {
    NS_IF_RELEASE(mIcons[i]);
  }

  /*
   * Destroy the GroupContext after releasing the ImageRequests
   * since IL_DestroyGroupContext(...) will destroy any IL_ImageReq
   * for the context.  These are the same IL_ImgReq being referenced
   * by mIcons[...]
   */
  IL_DestroyGroupContext(mIconImageGroup);

  if (nsnull != mFontAliasTable) {
    mFontAliasTable->Enumerate(DeleteValue);
    delete mFontAliasTable;
  }

  if (nsnull != mColorSpace) {
    IL_ReleaseColorSpace(mColorSpace);
  }
}

NS_IMETHODIMP DeviceContextImpl :: Init(nsNativeWidget aWidget)
{
  mWidget = aWidget;

  CommonInit();

  return NS_OK;
}

void DeviceContextImpl :: CommonInit(void)
{
  for (PRInt32 cnt = 0; cnt < 256; cnt++)
    mGammaTable[cnt] = cnt;
}

NS_IMETHODIMP DeviceContextImpl :: GetTwipsToDevUnits(float &aTwipsToDevUnits) const
{
  aTwipsToDevUnits = mTwipsToPixels;
  return NS_OK;
}

NS_IMETHODIMP DeviceContextImpl :: GetDevUnitsToTwips(float &aDevUnitsToTwips) const
{
  aDevUnitsToTwips = mPixelsToTwips;
  return NS_OK;
}

NS_IMETHODIMP DeviceContextImpl :: SetAppUnitsToDevUnits(float aAppUnits)
{
  mAppUnitsToDevUnits = aAppUnits;
  return NS_OK;
}

NS_IMETHODIMP DeviceContextImpl :: SetDevUnitsToAppUnits(float aDevUnits)
{
  mDevUnitsToAppUnits = aDevUnits;
  return NS_OK;
}

NS_IMETHODIMP DeviceContextImpl :: GetAppUnitsToDevUnits(float &aAppUnits) const
{
  aAppUnits = mAppUnitsToDevUnits;
  return NS_OK;
}

NS_IMETHODIMP DeviceContextImpl :: GetDevUnitsToAppUnits(float &aDevUnits) const
{
  aDevUnits = mDevUnitsToAppUnits;
  return NS_OK;
}

NS_IMETHODIMP DeviceContextImpl :: GetCanonicalPixelScale(float &aScale) const
{
  aScale = mCPixelScale;
  return NS_OK;
}

static NS_DEFINE_CID(kRCCID, NS_RENDERING_CONTEXT_CID);

NS_IMETHODIMP DeviceContextImpl :: CreateRenderingContext(nsIView *aView, nsIRenderingContext *&aContext)
{
  nsIRenderingContext *pContext;
  nsIWidget           *win;
  aView->GetWidget(win);
  nsresult             rv;

  aContext = nsnull;
  rv = nsComponentManager::CreateInstance(kRCCID, nsnull, NS_GET_IID(nsIRenderingContext), (void **)&pContext);

  if (NS_OK == rv) {
    rv = InitRenderingContext(pContext, win);
    if (NS_OK != rv) {
      NS_RELEASE(pContext);
    }
  }

  NS_IF_RELEASE(win);
  aContext = pContext;
  return rv;
}

NS_IMETHODIMP DeviceContextImpl :: CreateRenderingContext(nsIWidget *aWidget, nsIRenderingContext *&aContext)
{
  nsIRenderingContext *pContext;
  nsresult             rv;

  aContext = nsnull;
  rv = nsComponentManager::CreateInstance(kRCCID, nsnull, NS_GET_IID(nsIRenderingContext), (void **)&pContext);

  if (NS_OK == rv) {
    rv = InitRenderingContext(pContext, aWidget);
    if (NS_OK != rv) {
      NS_RELEASE(pContext);
    }
  }

  aContext = pContext;
  return rv;
}

NS_IMETHODIMP DeviceContextImpl :: InitRenderingContext(nsIRenderingContext *aContext, nsIWidget *aWin)
{
  return aContext->Init(this, aWin);
}

nsresult DeviceContextImpl::CreateFontCache()
{
  mFontCache = new nsFontCache();
  if (nsnull == mFontCache) {
    return NS_ERROR_OUT_OF_MEMORY;
  }
  mFontCache->Init(this);
  return NS_OK;
}

void
DeviceContextImpl::GetLocaleLangGroup(void)
{
  if (!mLocaleLangGroup) {
    nsCOMPtr<nsILanguageAtomService> langService;
    langService = do_GetService(NS_LANGUAGEATOMSERVICE_CONTRACTID);
    if (langService) {
      langService->GetLocaleLanguageGroup(getter_AddRefs(mLocaleLangGroup));
    }
    if (!mLocaleLangGroup) {
      mLocaleLangGroup = getter_AddRefs(NS_NewAtom("x-western"));
    }
  }
}

NS_IMETHODIMP DeviceContextImpl::GetMetricsFor(const nsFont& aFont,
  nsIAtom* aLangGroup, nsIFontMetrics*& aMetrics)
{
  if (nsnull == mFontCache) {
    nsresult  rv = CreateFontCache();
    if (NS_FAILED(rv)) {
      aMetrics = nsnull;
      return rv;
    }
    // XXX temporary fix for performance problem -- erik
    GetLocaleLangGroup();
  }

  // XXX figure out why aLangGroup is NULL sometimes
  if (!aLangGroup) {
    aLangGroup = mLocaleLangGroup;
  }

  return mFontCache->GetMetricsFor(aFont, aLangGroup, aMetrics);
}

NS_IMETHODIMP DeviceContextImpl::GetMetricsFor(const nsFont& aFont, nsIFontMetrics*& aMetrics)
{
  if (nsnull == mFontCache) {
    nsresult  rv = CreateFontCache();
    if (NS_FAILED(rv)) {
      aMetrics = nsnull;
      return rv;
    }
    // XXX temporary fix for performance problem -- erik
    GetLocaleLangGroup();
  }
  return mFontCache->GetMetricsFor(aFont, mLocaleLangGroup, aMetrics);
}

NS_IMETHODIMP DeviceContextImpl :: SetZoom(float aZoom)
{
  if (mZoom != aZoom) {
    mZoom = aZoom;
    if (mFontCache) {
      mFontCache->Flush();
    }
  }
  return NS_OK;
}

NS_IMETHODIMP DeviceContextImpl :: GetZoom(float &aZoom) const
{
  aZoom = mZoom;
  return NS_OK;
}

NS_IMETHODIMP DeviceContextImpl :: SetTextZoom(float aTextZoom)
{
  if (mTextZoom != aTextZoom) {
    mTextZoom = aTextZoom;
    if (mFontCache) {
      mFontCache->Flush();
    }
  }
  return NS_OK;
}

NS_IMETHODIMP DeviceContextImpl :: GetTextZoom(float &aTextZoom) const
{
  aTextZoom = mTextZoom;
  return NS_OK;
}

NS_IMETHODIMP DeviceContextImpl :: GetGamma(float &aGamma)
{
  aGamma = mGammaValue;
  return NS_OK;
}

NS_IMETHODIMP DeviceContextImpl :: SetGamma(float aGamma)
{
  if (aGamma != mGammaValue)
  {
    //we don't need to-recorrect existing images for this case
    //so pass in 1.0 for the current gamma regardless of what it
    //really happens to be. existing images will get a one time
    //re-correction when they're rendered the next time. MMP

    SetGammaTable(mGammaTable, 1.0f, aGamma);

    mGammaValue = aGamma;
  }
  return NS_OK;
}

NS_IMETHODIMP DeviceContextImpl :: GetGammaTable(PRUint8 *&aGammaTable)
{
  //XXX we really need to ref count this somehow. MMP
  aGammaTable = mGammaTable;
  return NS_OK;
}

void DeviceContextImpl :: SetGammaTable(PRUint8 * aTable, float aCurrentGamma, float aNewGamma)
{
  double fgval = (1.0f / aCurrentGamma) * (1.0f / aNewGamma);

  for (PRInt32 cnt = 0; cnt < 256; cnt++)
    aTable[cnt] = (PRUint8)(pow((double)cnt * (1. / 256.), fgval) * 255.99999999);
}

NS_IMETHODIMP DeviceContextImpl::GetDepth(PRUint32& aDepth)
{
  aDepth = 24;
  return NS_OK;
}

nsresult DeviceContextImpl::CreateIconILGroupContext()
{
  ilIImageRenderer* renderer;
  nsresult          result;
   
  // Create an image renderer
  result = NS_NewImageRenderer(&renderer);
  if (NS_FAILED(result)) {
    return result;
  }

  // Create an image group context. The image renderer code expects the
  // display_context to be a pointer to a device context
  mIconImageGroup = IL_NewGroupContext((void*)this, renderer);
  if (nsnull == mIconImageGroup) {
    NS_RELEASE(renderer);
    return NS_ERROR_OUT_OF_MEMORY;
  }

  // Initialize the image group context.
  IL_ColorSpace* colorSpace;
  result = GetILColorSpace(colorSpace);
  if (NS_FAILED(result)) {
    NS_RELEASE(renderer);
    IL_DestroyGroupContext(mIconImageGroup);
    return result;
  }

  // Icon loading is synchronous, so don't waste time with progressive display
  IL_DisplayData displayData;
  displayData.dither_mode = IL_Auto;
  displayData.color_space = colorSpace;
  displayData.progressive_display = PR_FALSE;
  IL_SetDisplayMode(mIconImageGroup, IL_COLOR_SPACE | IL_DITHER_MODE, &displayData);
  IL_ReleaseColorSpace(colorSpace);

  return NS_OK;
}

NS_IMETHODIMP DeviceContextImpl::LoadIconImage(PRInt32 aId, nsIImage*& aImage)
{
  nsresult  result;

  // Initialize out parameter
  aImage = nsnull;

  // Make sure the icon number is valid
  if ((aId < 0) || (aId >= NS_NUMBER_OF_ICONS)) {
    return NS_ERROR_ILLEGAL_VALUE;
  }

  // See if the icon is already loaded
  if (nsnull != mIcons[aId]) {
    aImage = mIcons[aId]->GetImage();
    return NS_OK;
  }

  // Make sure we have an image group context
  if (nsnull == mIconImageGroup) {
    result = CreateIconILGroupContext();
    if (NS_FAILED(result)) {
      return result;
    }
  }

  // Build the URL string
  char  url[128];
  sprintf(url, "resource:/res/gfx/icon_%d.gif", aId);

  // Use a sync net context
  nsCOMPtr<ilINetContext> netContext;
  result = NS_NewImageNetContextSync(getter_AddRefs(netContext));
  if (NS_FAILED(result)) {
    return result;
  }

  // Create an image request object which will do the actual load
  ImageRequestImpl* imageReq = new ImageRequestImpl();
  if (nsnull == imageReq) {
    result = NS_ERROR_OUT_OF_MEMORY;

  } else {
    // addref so it has nonzero refcount
    NS_ADDREF(imageReq);
    
    // Load the image
    result = imageReq->Init(mIconImageGroup, url, nsnull, nsnull, 0, 0,
                            nsImageLoadFlags_kHighPriority, netContext);
    aImage = imageReq->GetImage();
    if(!aImage) {
      // XXX This happens more often than just when out of memory.
      NS_RELEASE(imageReq);
      return NS_ERROR_OUT_OF_MEMORY; //ptn some error msg
    }

    // Keep the image request object around and avoid reloading the image
    mIcons[aId] = imageReq; // owns reference from addref above
  }
  
  return result;
}

struct FontEnumData {
  FontEnumData(nsIDeviceContext* aDC, nsString& aFaceName)
    : mDC(aDC), mFaceName(aFaceName)
  {}
  nsIDeviceContext* mDC;
  nsString&         mFaceName;
};

static PRBool FontEnumCallback(const nsString& aFamily, PRBool aGeneric, void *aData)
{
  FontEnumData* data = (FontEnumData*)aData;
  // XXX for now, all generic fonts are presumed to exist
  //     we may want to actually check if there's an installed conversion
  if (aGeneric) {
    data->mFaceName = aFamily;
    return PR_FALSE; // found one, stop.
  }
  else {
    nsAutoString  local;
    PRBool        aliased;
    data->mDC->GetLocalFontName(aFamily, local, aliased);
    if (aliased || (NS_OK == data->mDC->CheckFontExistence(local))) {
      data->mFaceName = local;
      return PR_FALSE; // found one, stop.
    }
  }
  return PR_TRUE; // didn't exist, continue looking
}

NS_IMETHODIMP DeviceContextImpl::FirstExistingFont(const nsFont& aFont, nsString& aFaceName)
{
  FontEnumData  data(this, aFaceName);
  if (aFont.EnumerateFamilies(FontEnumCallback, &data)) {
    return NS_ERROR_FAILURE;  // ran out
  }
  return NS_OK;
}

class FontAliasKey: public nsHashKey 
{
public:
  FontAliasKey(const nsString& aString)
  {mString.Assign(aString);}

  virtual PRUint32 HashCode(void) const;
  virtual PRBool Equals(const nsHashKey *aKey) const;
  virtual nsHashKey *Clone(void) const;

  nsAutoString  mString;
};

PRUint32 FontAliasKey::HashCode(void) const
{
  PRUint32 hash = 0;
  const PRUnichar* string = mString.GetUnicode();
  PRUnichar ch;
  while ((ch = *string++) != 0) {
    // FYI: hash = hash*37 + ch
    ch = nsCRT::ToUpper(ch);
    hash = ((hash << 5) + (hash << 2) + hash) + ch;
  }
  return hash;
}

PRBool FontAliasKey::Equals(const nsHashKey *aKey) const
{
  return mString.EqualsIgnoreCase(((FontAliasKey*)aKey)->mString);
}

nsHashKey* FontAliasKey::Clone(void) const
{
  return new FontAliasKey(mString);
}
nsresult DeviceContextImpl::CreateFontAliasTable()
{
  nsresult result = NS_OK;

  if (nsnull == mFontAliasTable) {
    mFontAliasTable = new nsHashtable();
    if (nsnull != mFontAliasTable) {

      nsAutoString  times;              times.AssignWithConversion("Times");
      nsAutoString  timesNewRoman;      timesNewRoman.AssignWithConversion("Times New Roman");
      nsAutoString  timesRoman;         timesRoman.AssignWithConversion("Times Roman");
      nsAutoString  arial;              arial.AssignWithConversion("Arial");
      nsAutoString  helvetica;          helvetica.AssignWithConversion("Helvetica");
      nsAutoString  courier;            courier.AssignWithConversion("Courier");
      nsAutoString  courierNew;         courierNew.AssignWithConversion("Courier New");
      nsAutoString  nullStr;

      AliasFont(times, timesNewRoman, timesRoman, PR_FALSE);
      AliasFont(timesRoman, timesNewRoman, times, PR_FALSE);
      AliasFont(timesNewRoman, timesRoman, times, PR_FALSE);
      AliasFont(arial, helvetica, nullStr, PR_FALSE);
      AliasFont(helvetica, arial, nullStr, PR_FALSE);
      AliasFont(courier, courierNew, nullStr, PR_TRUE);
      AliasFont(courierNew, courier, nullStr, PR_FALSE);
    }
    else {
      result = NS_ERROR_OUT_OF_MEMORY;
    }
  }
  return result;
}

nsresult DeviceContextImpl::AliasFont(const nsString& aFont, 
                                      const nsString& aAlias, const nsString& aAltAlias,
                                      PRBool aForceAlias)
{
  nsresult result = NS_OK;

  if (nsnull != mFontAliasTable) {
    if (aForceAlias || (NS_OK != CheckFontExistence(aFont))) {
      if (NS_OK == CheckFontExistence(aAlias)) {
        nsString* entry = aAlias.ToNewString();
        if (nsnull != entry) {
          FontAliasKey key(aFont);
          mFontAliasTable->Put(&key, entry);
        }
        else {
          result = NS_ERROR_OUT_OF_MEMORY;
        }
      }
      else if ((0 < aAltAlias.Length()) && (NS_OK == CheckFontExistence(aAltAlias))) {
        nsString* entry = aAltAlias.ToNewString();
        if (nsnull != entry) {
          FontAliasKey key(aFont);
          mFontAliasTable->Put(&key, entry);
        }
        else {
          result = NS_ERROR_OUT_OF_MEMORY;
        }
      }
    }
  }
  else {
    result = NS_ERROR_FAILURE;
  }
  return result;
}

NS_IMETHODIMP DeviceContextImpl::GetLocalFontName(const nsString& aFaceName, nsString& aLocalName,
                                                  PRBool& aAliased)
{
  nsresult result = NS_OK;

  if (nsnull == mFontAliasTable) {
    result = CreateFontAliasTable();
  }

  if (nsnull != mFontAliasTable) {
    FontAliasKey key(aFaceName);
    const nsString* alias = (const nsString*)mFontAliasTable->Get(&key);
    if (nsnull != alias) {
      aLocalName = *alias;
      aAliased = PR_TRUE;
    }
    else {
      aLocalName = aFaceName;
      aAliased = PR_FALSE;
    }
  }
  return result;
}

NS_IMETHODIMP DeviceContextImpl :: FlushFontCache(void)
{
  if (nsnull != mFontCache)
    mFontCache->Flush();

  return NS_OK;
}

NS_IMETHODIMP DeviceContextImpl::GetILColorSpace(IL_ColorSpace*& aColorSpace)
{
  if (nsnull == mColorSpace) {
    IL_RGBBits colorRGBBits;
  
    // Default is to create a 24-bit color space
    colorRGBBits.red_shift = 16;  
    colorRGBBits.red_bits = 8;
    colorRGBBits.green_shift = 8;
    colorRGBBits.green_bits = 8; 
    colorRGBBits.blue_shift = 0; 
    colorRGBBits.blue_bits = 8;  
  
    mColorSpace = IL_CreateTrueColorSpace(&colorRGBBits, 24);
    if (nsnull == mColorSpace) {
      aColorSpace = nsnull;
      return NS_ERROR_OUT_OF_MEMORY;
    }
  }

  NS_POSTCONDITION(nsnull != mColorSpace, "null color space");
  aColorSpace = mColorSpace;
  IL_AddRefToColorSpace(aColorSpace);
  return NS_OK;
}

NS_IMETHODIMP DeviceContextImpl::GetPaletteInfo(nsPaletteInfo& aPaletteInfo)
{
  aPaletteInfo.isPaletteDevice = PR_FALSE;
  aPaletteInfo.sizePalette = 0;
  aPaletteInfo.numReserved = 0;
  aPaletteInfo.palette = nsnull;
  return NS_OK;
}

//----------------------------------------------------------------------------------
// Return localized bundle for resource strings
nsresult
DeviceContextImpl::GetLocalizedBundle(const char * aPropFileName, nsIStringBundle** aStrBundle)
{
  NS_ENSURE_ARG_POINTER(aPropFileName);
  NS_ENSURE_ARG_POINTER(aStrBundle);

  nsresult rv;
  nsCOMPtr<nsIStringBundle> bundle;
  
  // Create a URL for the string resource file
  // Create a bundle for the localization
  NS_WITH_SERVICE(nsIIOService, pNetService, kIOServiceCID, &rv);
  if (NS_SUCCEEDED(rv) && pNetService) {
    nsCOMPtr<nsIURI> uri;
    rv = pNetService->NewURI(aPropFileName, nsnull, getter_AddRefs(uri));
    if (NS_SUCCEEDED(rv) && uri) {

      // Create bundle
      NS_WITH_SERVICE(nsIStringBundleService, stringService, kStringBundleServiceCID, &rv);
      if (NS_SUCCEEDED(rv) && stringService) {
        nsXPIDLCString spec;
        rv = uri->GetSpec(getter_Copies(spec));
        if (NS_SUCCEEDED(rv) && spec) {
          rv = stringService->CreateBundle(spec, aStrBundle);
        }
      }
    }
  }
  return rv;
}

//--------------------------------------------------------
// Return localized string 
nsresult
DeviceContextImpl::GetLocalizedString(nsIStringBundle* aStrBundle, const char* aKey, nsString& oVal)
{
  NS_ENSURE_ARG_POINTER(aStrBundle);
  NS_ENSURE_ARG_POINTER(aKey);

  // Determine default label from string bundle
  nsXPIDLString valUni;
  nsAutoString key; 
  key.AssignWithConversion(aKey);
  nsresult rv = aStrBundle->GetStringFromName(key.GetUnicode(), getter_Copies(valUni));
  if (NS_SUCCEEDED(rv) && valUni) {
    oVal.Assign(valUni);
  } else {
    oVal.Truncate();
  }
  return rv;
}


/////////////////////////////////////////////////////////////

MOZ_DECL_CTOR_COUNTER(nsFontCache)

nsFontCache :: nsFontCache()
{
  MOZ_COUNT_CTOR(nsFontCache);
  mContext = nsnull;
}

nsFontCache :: ~nsFontCache()
{
  MOZ_COUNT_DTOR(nsFontCache);
  Flush();
}

nsresult nsFontCache :: Init(nsIDeviceContext* aContext)
{
  NS_PRECONDITION(nsnull != aContext, "null ptr");
  // Note: we don't hold a reference to the device context, because it
  // holds a reference to us and we don't want circular references
  mContext = aContext;
  return NS_OK;
}

nsresult nsFontCache :: GetDeviceContext(nsIDeviceContext *&aContext) const
{
  NS_IF_ADDREF(mContext);
  aContext = mContext;
  return NS_OK;
}

nsresult nsFontCache :: GetMetricsFor(const nsFont& aFont, nsIAtom* aLangGroup,
  nsIFontMetrics *&aMetrics)
{
  // First check our cache
  PRInt32 n = mFontMetrics.Count();

  for (PRInt32 cnt = 0; cnt < n; cnt++)
  {
    nsIFontMetrics* metrics = NS_STATIC_CAST(nsIFontMetrics*, mFontMetrics[cnt]);

    const nsFont* font;
    metrics->GetFont(font);
    if (aFont.Equals(*font)) {
      nsCOMPtr<nsIAtom> langGroup;
      metrics->GetLangGroup(getter_AddRefs(langGroup));
      if (aLangGroup == langGroup.get()) {
        if (cnt != 0) {
          // promote it to the front of the cache
          for (PRInt32 i = cnt; i > 0; --i)
            mFontMetrics.ReplaceElementAt(mFontMetrics[i - 1], i);

          mFontMetrics.ReplaceElementAt(metrics, 0);
        }
        NS_ADDREF(aMetrics = metrics);
        return NS_OK;
      }
    }
  }

  // It's not in the cache. Get font metrics and then cache them.

  static NS_DEFINE_CID(kFontMetricsCID, NS_FONT_METRICS_CID);

  nsIFontMetrics* fm;
  nsresult        rv = nsComponentManager::CreateInstance(kFontMetricsCID, nsnull,
                                                    NS_GET_IID(nsIFontMetrics), (void **)&fm);
  if (NS_OK != rv) {
    aMetrics = nsnull;
    return rv;
  }

  rv = fm->Init(aFont, aLangGroup, mContext);

  if (NS_OK != rv) {
    aMetrics = nsnull;
    return rv;
  }

  mFontMetrics.AppendElement(fm);

  NS_ADDREF(fm);
  aMetrics = fm;
  return NS_OK;
}

nsresult nsFontCache :: Flush()
{
  PRInt32 i, n = mFontMetrics.Count();

  for (i = 0; i < n; i++)
  {
    nsIFontMetrics* fm = (nsIFontMetrics*) mFontMetrics.ElementAt(i);
    fm->Destroy();
    NS_RELEASE(fm);
  }

  mFontMetrics.Clear();

  return NS_OK;
}

#if defined(XP_PC) && !defined(XP_OS2)
// XXX I had to add this because I changed the link order on Windows
void notCalled()
{
  nsCID cid;
  (void)NSGetFactory(nsnull, cid, nsnull, nsnull, nsnull);
}
#endif