/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsMathMLChar.h"

#include "gfxContext.h"

#include "gfxTextRun.h"

#include "gfxUtils.h"

#include "mozilla/gfx/2D.h"

#include "mozilla/ComputedStyle.h"

#include "mozilla/MathAlgorithms.h"

#include "mozilla/Unused.h"

#include "nsAutoPtr.h"

#include "nsCOMPtr.h"

#include "nsDeviceContext.h"

#include "nsFontMetrics.h"

#include "nsIFrame.h"

#include "nsLayoutUtils.h"

#include "nsPresContext.h"

#include "nsUnicharUtils.h"

#include "mozilla/Preferences.h"

#include "nsIPersistentProperties2.h"

#include "nsIObserverService.h"

#include "nsIObserver.h"

#include "nsNetUtil.h"

#include "nsContentUtils.h"

#include "mozilla/LookAndFeel.h"

#include "nsCSSRendering.h"

#include "mozilla/Sprintf.h"

#include "nsDisplayList.h"

#include "nsMathMLOperators.h"

#include <algorithm>

#include "gfxMathTable.h"

#include "nsUnicodeScriptCodes.h"

using namespace mozilla;

using namespace mozilla::gfx;

using namespace mozilla::image;

//#define NOISY_SEARCH 1

// BUG 848725 Drawing failure with stretchy horizontal parenthesis when no fonts

// are installed. "kMaxScaleFactor" is required to limit the scale for the

// vertical and horizontal stretchy operators.

static const float kMaxScaleFactor = 20.0;

static const float kLargeOpFactor = float(M_SQRT2);

static const float kIntegralFactor = 2.0;

static void

NormalizeDefaultFont(nsFont& aFont, float aFontSizeInflation)

{

  if (aFont.fontlist.GetDefaultFontType() != eFamily_none) {

    nsTArray<FontFamilyName> names;

    names.AppendElements(aFont.fontlist.GetFontlist()->mNames);

    names.AppendElement(FontFamilyName(aFont.fontlist.GetDefaultFontType()));

    aFont.fontlist.SetFontlist(std::move(names));

    aFont.fontlist.SetDefaultFontType(eFamily_none);

  }

  aFont.size = NSToCoordRound(aFont.size * aFontSizeInflation);

}

// -----------------------------------------------------------------------------

static const nsGlyphCode kNullGlyph = {{{0, 0}}, 0};

// -----------------------------------------------------------------------------

// nsGlyphTable is a class that provides an interface for accessing glyphs

// of stretchy chars. It acts like a table that stores the variants of bigger

// sizes (if any) and the partial glyphs needed to build extensible symbols.

//

// Bigger sizes (if any) of the char can then be retrieved with BigOf(...).

// Partial glyphs can be retrieved with ElementAt(...).

//

// A table consists of "nsGlyphCode"s which are viewed either as Unicode

// points (for nsPropertiesTable) or as direct glyph indices (for

// nsOpenTypeTable)

// -----------------------------------------------------------------------------

class nsGlyphTable {

public:

  virtual ~nsGlyphTable() {}

  virtual const FontFamilyName&

  FontNameFor(const nsGlyphCode& aGlyphCode) const = 0;

  // Getters for the parts

  virtual nsGlyphCode ElementAt(DrawTarget*   aDrawTarget,

                                int32_t       aAppUnitsPerDevPixel,

                                gfxFontGroup* aFontGroup,

                                char16_t      aChar,

                                bool          aVertical,

                                uint32_t      aPosition) = 0;

  virtual nsGlyphCode BigOf(DrawTarget*   aDrawTarget,

                            int32_t       aAppUnitsPerDevPixel,

                            gfxFontGroup* aFontGroup,

                            char16_t      aChar,

                            bool          aVertical,

                            uint32_t      aSize) = 0;

  // True if this table contains parts to render this char

  virtual bool HasPartsOf(DrawTarget*   aDrawTarget,

                          int32_t       aAppUnitsPerDevPixel,

                          gfxFontGroup* aFontGroup,

                          char16_t      aChar,

                          bool          aVertical) = 0;

  virtual already_AddRefed<gfxTextRun>

  MakeTextRun(DrawTarget*        aDrawTarget,

              int32_t            aAppUnitsPerDevPixel,

              gfxFontGroup*      aFontGroup,

              const nsGlyphCode& aGlyph) = 0;

protected:

  nsGlyphTable() : mCharCache(0) {}

  // For speedy re-use, we always cache the last data used in the table.

  // mCharCache is the Unicode point of the last char that was queried in this

  // table.

  char16_t mCharCache;

};

// An instance of nsPropertiesTable is associated with one primary font. Extra

// glyphs can be taken in other additional fonts when stretching certain

// characters.

// These supplementary fonts are referred to as "external" fonts to the table.

// General format of MathFont Property Files from which glyph data are

// retrieved:

// -----------------------------------------------------------------------------

// Each font should have its set of glyph data. For example, the glyph data for

// the "Symbol" font and the "MT Extra" font are in "mathfontSymbol.properties"

// and "mathfontMTExtra.properties", respectively. The mathfont property file

// is a set of all the stretchy MathML characters that can be rendered with that

// font using larger and/or partial glyphs. The entry of each stretchy character

// in the mathfont property file gives, in that order, the 4 partial glyphs:

// Top (or Left), Middle, Bottom (or Right), Glue; and the variants of bigger

// sizes (if any).

// A position that is not relevant to a particular character is indicated there

// with the UNICODE REPLACEMENT CHARACTER 0xFFFD.

// -----------------------------------------------------------------------------

#define NS_TABLE_STATE_ERROR       -1

#define NS_TABLE_STATE_EMPTY        0

#define NS_TABLE_STATE_READY        1

// helper to trim off comments from data in a MathFont Property File

static void

Clean(nsString& aValue)

{

  // chop the trailing # comment portion if any ...

  int32_t comment = aValue.RFindChar('#');

  if (comment > 0) aValue.Truncate(comment);

  aValue.CompressWhitespace();

}

// helper to load a MathFont Property File

static nsresult

LoadProperties(const nsACString& aName,

               nsCOMPtr<nsIPersistentProperties>& aProperties)

{

  nsAutoCString uriStr;

  uriStr.AssignLiteral("resource://gre/res/fonts/mathfont");

  uriStr.Append(aName);

  uriStr.StripWhitespace(); // that may come from aName

  uriStr.AppendLiteral(".properties");

  return NS_LoadPersistentPropertiesFromURISpec(getter_AddRefs(aProperties),

                                                uriStr);

}

class nsPropertiesTable final : public nsGlyphTable {

public:

  explicit nsPropertiesTable(const nsACString& aPrimaryFontName)

    : mState(NS_TABLE_STATE_EMPTY)

  {

    MOZ_COUNT_CTOR(nsPropertiesTable);

    mGlyphCodeFonts.AppendElement(FontFamilyName(aPrimaryFontName,

                                                 eUnquotedName));

  }

  ~nsPropertiesTable()

  {

    MOZ_COUNT_DTOR(nsPropertiesTable);

  }

  const FontFamilyName& PrimaryFontName() const

  {

    return mGlyphCodeFonts[0];

  }

  const FontFamilyName&

  FontNameFor(const nsGlyphCode& aGlyphCode) const override

  {

    NS_ASSERTION(!aGlyphCode.IsGlyphID(),

                 "nsPropertiesTable can only access glyphs by code point");

    return mGlyphCodeFonts[aGlyphCode.font];

  }

  virtual nsGlyphCode ElementAt(DrawTarget*   aDrawTarget,

                                int32_t       aAppUnitsPerDevPixel,

                                gfxFontGroup* aFontGroup,

                                char16_t      aChar,

                                bool          aVertical,

                                uint32_t      aPosition) override;

  virtual nsGlyphCode BigOf(DrawTarget*   aDrawTarget,

                            int32_t       aAppUnitsPerDevPixel,

                            gfxFontGroup* aFontGroup,

                            char16_t      aChar,

                            bool          aVertical,

                            uint32_t      aSize) override

  {

    return ElementAt(aDrawTarget, aAppUnitsPerDevPixel, aFontGroup,

                     aChar, aVertical, 4 + aSize);

  }

  virtual bool HasPartsOf(DrawTarget*   aDrawTarget,

                          int32_t       aAppUnitsPerDevPixel,

                          gfxFontGroup* aFontGroup,

                          char16_t      aChar,

                          bool          aVertical) override

  {

    return (ElementAt(aDrawTarget, aAppUnitsPerDevPixel, aFontGroup,

                      aChar, aVertical, 0).Exists() ||

            ElementAt(aDrawTarget, aAppUnitsPerDevPixel, aFontGroup,

                      aChar, aVertical, 1).Exists() ||

            ElementAt(aDrawTarget, aAppUnitsPerDevPixel, aFontGroup,

                      aChar, aVertical, 2).Exists() ||

            ElementAt(aDrawTarget, aAppUnitsPerDevPixel, aFontGroup,

                      aChar, aVertical, 3).Exists());

  }

  virtual already_AddRefed<gfxTextRun>

  MakeTextRun(DrawTarget*        aDrawTarget,

              int32_t            aAppUnitsPerDevPixel,

              gfxFontGroup*      aFontGroup,

              const nsGlyphCode& aGlyph) override;

private:

  // mGlyphCodeFonts[0] is the primary font associated to this table. The

  // others are possible "external" fonts for glyphs not in the primary font

  // but which are needed to stretch certain characters in the table

  nsTArray<FontFamilyName> mGlyphCodeFonts;

  // Tri-state variable for error/empty/ready

  int32_t mState;

  // The set of glyph data in this table, as provided by the MathFont Property

  // File

  nsCOMPtr<nsIPersistentProperties> mGlyphProperties;

  // mGlyphCache is a buffer containing the glyph data associated with

  // mCharCache.

  // For a property line 'key = value' in the MathFont Property File,

  // mCharCache will retain the 'key' -- which is a Unicode point, while

  // mGlyphCache will retain the 'value', which is a consecutive list of

  // nsGlyphCodes, i.e., the pairs of 'code@font' needed by the char -- in

  // which 'code@0' can be specified

  // without the optional '@0'. However, to ease subsequent processing,

  // mGlyphCache excludes the '@' symbol and explicitly inserts all optional '0'

  // that indicates the primary font identifier. Specifically therefore, the

  // k-th glyph is characterized by :

  // 1) mGlyphCache[3*k],mGlyphCache[3*k+1] : its Unicode point

  // 2) mGlyphCache[3*k+2] : the numeric identifier of the font where it comes

  // from.

  // A font identifier of '0' means the default primary font associated to this

  // table. Other digits map to the "external" fonts that may have been

  // specified in the MathFont Property File.

  nsString  mGlyphCache;

};

/* virtual */

nsGlyphCode

nsPropertiesTable::ElementAt(DrawTarget*   /* aDrawTarget */,

                             int32_t       /* aAppUnitsPerDevPixel */,

                             gfxFontGroup* /* aFontGroup */,

                             char16_t      aChar,

                             bool          /* aVertical */,

                             uint32_t      aPosition)

{

  if (mState == NS_TABLE_STATE_ERROR) return kNullGlyph;

  // Load glyph properties if this is the first time we have been here

  if (mState == NS_TABLE_STATE_EMPTY) {

    nsAutoCString primaryFontName;

    mGlyphCodeFonts[0].AppendToString(primaryFontName);

    nsresult rv = LoadProperties(primaryFontName, mGlyphProperties);

#ifdef DEBUG

    nsAutoCString uriStr;

    uriStr.AssignLiteral("resource://gre/res/fonts/mathfont");

    uriStr.Append(primaryFontName);

    uriStr.StripWhitespace(); // that may come from mGlyphCodeFonts

    uriStr.AppendLiteral(".properties");

    printf("Loading %s ... %s\n",

            uriStr.get(),

            (NS_FAILED(rv)) ? "Failed" : "Done");

#endif

    if (NS_FAILED(rv)) {

      mState = NS_TABLE_STATE_ERROR; // never waste time with this table again

      return kNullGlyph;

    }

    mState = NS_TABLE_STATE_READY;

    // see if there are external fonts needed for certain chars in this table

    nsAutoCString key;

    nsAutoString value;

    for (int32_t i = 1; ; i++) {

      key.AssignLiteral("external.");

      key.AppendInt(i, 10);

      rv = mGlyphProperties->GetStringProperty(key, value);

      if (NS_FAILED(rv)) break;

      Clean(value);

      mGlyphCodeFonts.AppendElement(FontFamilyName(NS_ConvertUTF16toUTF8(value),

                                    eUnquotedName)); // i.e., mGlyphCodeFonts[i] holds this font name

    }

  }

  // Update our cache if it is not associated to this character

  if (mCharCache != aChar) {

    // The key in the property file is interpreted as ASCII and kept

    // as such ...

    char key[10]; SprintfLiteral(key, "\\u%04X", aChar);

    nsAutoString value;

    nsresult rv = mGlyphProperties->GetStringProperty(nsDependentCString(key),

                                                      value);

    if (NS_FAILED(rv)) return kNullGlyph;

    Clean(value);

    // See if this char uses external fonts; e.g., if the 2nd glyph is taken

    // from the external font '1', the property line looks like

    // \uNNNN = \uNNNN\uNNNN@1\uNNNN.

    // This is where mGlyphCache is pre-processed to explicitly store all glyph

    // codes as combined pairs of 'code@font', excluding the '@' separator. This

    // means that mGlyphCache[3*k],mGlyphCache[3*k+1] will later be rendered

    // with mGlyphCodeFonts[mGlyphCache[3*k+2]]

    // Note: font identifier is internally an ASCII digit to avoid the null

    // char issue

    nsAutoString buffer;

    int32_t length = value.Length();

    int32_t i = 0; // index in value

    while (i < length) {

      char16_t code = value[i];

      ++i;

      buffer.Append(code);

      // Read the next word if we have a non-BMP character.

      if (i < length && NS_IS_HIGH_SURROGATE(code)) {

        code = value[i];

        ++i;

      } else {

        code = char16_t('\0');

      }

      buffer.Append(code);

      // See if an external font is needed for the code point.

      // Limit of 9 external fonts

      char16_t font = 0;

      if (i+1 < length && value[i] == char16_t('@') &&

          value[i+1] >= char16_t('0') && value[i+1] <= char16_t('9')) {

        ++i;

        font = value[i] - '0';

        ++i;

        if (font >= mGlyphCodeFonts.Length()) {

          NS_ERROR("Nonexistent font referenced in glyph table");

          return kNullGlyph;

        }

        // The char cannot be handled if this font is not installed

        if (!mGlyphCodeFonts[font].mName) {

          return kNullGlyph;

        }

      }

      buffer.Append(font);

    }

    // update our cache with the new settings

    mGlyphCache.Assign(buffer);

    mCharCache = aChar;

  }

  // 3* is to account for the code@font pairs

  uint32_t index = 3*aPosition;

  if (index+2 >= mGlyphCache.Length()) return kNullGlyph;

  nsGlyphCode ch;

  ch.code[0] = mGlyphCache.CharAt(index);

  ch.code[1] = mGlyphCache.CharAt(index + 1);

  ch.font = mGlyphCache.CharAt(index + 2);

  return ch.code[0] == char16_t(0xFFFD) ? kNullGlyph : ch;

}

/* virtual */

already_AddRefed<gfxTextRun>

nsPropertiesTable::MakeTextRun(DrawTarget*        aDrawTarget,

                               int32_t            aAppUnitsPerDevPixel,

                               gfxFontGroup*      aFontGroup,

                               const nsGlyphCode& aGlyph)

{

  NS_ASSERTION(!aGlyph.IsGlyphID(),

               "nsPropertiesTable can only access glyphs by code point");

  return aFontGroup->

    MakeTextRun(aGlyph.code, aGlyph.Length(), aDrawTarget, aAppUnitsPerDevPixel,

                gfx::ShapedTextFlags(), nsTextFrameUtils::Flags(), nullptr);

}

// An instance of nsOpenTypeTable is associated with one gfxFontEntry that

// corresponds to an Open Type font with a MATH table. All the glyphs come from

// the same font and the calls to access size variants and parts are directly

// forwarded to the gfx code.

class nsOpenTypeTable final : public nsGlyphTable {

public:

  ~nsOpenTypeTable()

  {

    MOZ_COUNT_DTOR(nsOpenTypeTable);

  }

  virtual nsGlyphCode ElementAt(DrawTarget*   aDrawTarget,

                                int32_t       aAppUnitsPerDevPixel,

                                gfxFontGroup* aFontGroup,

                                char16_t      aChar,

                                bool          aVertical,

                                uint32_t      aPosition) override;

  virtual nsGlyphCode BigOf(DrawTarget*   aDrawTarget,

                            int32_t       aAppUnitsPerDevPixel,

                            gfxFontGroup* aFontGroup,

                            char16_t      aChar,

                            bool          aVertical,

                            uint32_t      aSize) override;

  virtual bool HasPartsOf(DrawTarget*   aDrawTarget,

                          int32_t       aAppUnitsPerDevPixel,

                          gfxFontGroup* aFontGroup,

                          char16_t      aChar,

                          bool          aVertical) override;

  const FontFamilyName&

  FontNameFor(const nsGlyphCode& aGlyphCode) const override {

    NS_ASSERTION(aGlyphCode.IsGlyphID(),

                 "nsOpenTypeTable can only access glyphs by id");

    return mFontFamilyName;

  }

  virtual already_AddRefed<gfxTextRun>

  MakeTextRun(DrawTarget*        aDrawTarget,

              int32_t            aAppUnitsPerDevPixel,

              gfxFontGroup*      aFontGroup,

              const nsGlyphCode& aGlyph) override;

  // This returns a new OpenTypeTable instance to give access to OpenType MATH

  // table or nullptr if the font does not have such table. Ownership is passed

  // to the caller.

  static nsOpenTypeTable* Create(gfxFont* aFont)

  {

    if (!aFont->TryGetMathTable()) {

      return nullptr;

    }

    return new nsOpenTypeTable(aFont);

  }

private:

  RefPtr<gfxFont> mFont;

  FontFamilyName mFontFamilyName;

  uint32_t mGlyphID;

  explicit nsOpenTypeTable(gfxFont* aFont)

    : mFont(aFont)

    , mFontFamilyName(aFont->GetFontEntry()->FamilyName(), eUnquotedName)

    , mGlyphID(0)

  {

    MOZ_COUNT_CTOR(nsOpenTypeTable);

  }

  void UpdateCache(DrawTarget*   aDrawTarget,

                   int32_t       aAppUnitsPerDevPixel,

                   gfxFontGroup* aFontGroup,

                   char16_t      aChar);

};

void

nsOpenTypeTable::UpdateCache(DrawTarget*   aDrawTarget,

                             int32_t       aAppUnitsPerDevPixel,

                             gfxFontGroup* aFontGroup,

                             char16_t      aChar)

{

  if (mCharCache != aChar) {

    RefPtr<gfxTextRun> textRun = aFontGroup->

      MakeTextRun(&aChar, 1, aDrawTarget, aAppUnitsPerDevPixel,

                  gfx::ShapedTextFlags(), nsTextFrameUtils::Flags(),

                  nullptr);

    const gfxTextRun::CompressedGlyph& data = textRun->GetCharacterGlyphs()[0];

    if (data.IsSimpleGlyph()) {

      mGlyphID = data.GetSimpleGlyph();

    } else if (data.GetGlyphCount() == 1) {

      mGlyphID = textRun->GetDetailedGlyphs(0)->mGlyphID;

    } else {

      mGlyphID = 0;

    }

    mCharCache = aChar;

  }

}

/* virtual */

nsGlyphCode

nsOpenTypeTable::ElementAt(DrawTarget*   aDrawTarget,

                           int32_t       aAppUnitsPerDevPixel,

                           gfxFontGroup* aFontGroup,

                           char16_t      aChar,

                           bool          aVertical,

                           uint32_t      aPosition)

{

  UpdateCache(aDrawTarget, aAppUnitsPerDevPixel, aFontGroup, aChar);

  uint32_t parts[4];

  if (!mFont->MathTable()->VariantsParts(mGlyphID, aVertical, parts)) {

    return kNullGlyph;

  }

  uint32_t glyphID = parts[aPosition];

  if (!glyphID) {

    return kNullGlyph;

  }

  nsGlyphCode glyph;

  glyph.glyphID = glyphID;

  glyph.font = -1;

  return glyph;

}

/* virtual */

nsGlyphCode

nsOpenTypeTable::BigOf(DrawTarget*   aDrawTarget,

                       int32_t       aAppUnitsPerDevPixel,

                       gfxFontGroup* aFontGroup,

                       char16_t      aChar,

                       bool          aVertical,

                       uint32_t      aSize)

{

  UpdateCache(aDrawTarget, aAppUnitsPerDevPixel, aFontGroup, aChar);

  uint32_t glyphID =

    mFont->MathTable()->VariantsSize(mGlyphID, aVertical, aSize);

  if (!glyphID) {

    return kNullGlyph;

  }

  nsGlyphCode glyph;

  glyph.glyphID = glyphID;

  glyph.font = -1;

  return glyph;

}

/* virtual */

bool

nsOpenTypeTable::HasPartsOf(DrawTarget*   aDrawTarget,

                            int32_t       aAppUnitsPerDevPixel,

                            gfxFontGroup* aFontGroup,

                            char16_t      aChar,

                            bool          aVertical)

{

  UpdateCache(aDrawTarget, aAppUnitsPerDevPixel, aFontGroup, aChar);

  uint32_t parts[4];

  if (!mFont->MathTable()->VariantsParts(mGlyphID, aVertical, parts)) {

    return false;

  }

  return parts[0] || parts[1] || parts[2] || parts[3];

}

/* virtual */

already_AddRefed<gfxTextRun>

nsOpenTypeTable::MakeTextRun(DrawTarget*        aDrawTarget,

                             int32_t            aAppUnitsPerDevPixel,

                             gfxFontGroup*      aFontGroup,

                             const nsGlyphCode& aGlyph)

{

  NS_ASSERTION(aGlyph.IsGlyphID(),

               "nsOpenTypeTable can only access glyphs by id");

  gfxTextRunFactory::Parameters params = {

    aDrawTarget, nullptr, nullptr, nullptr, 0, aAppUnitsPerDevPixel

  };

  RefPtr<gfxTextRun> textRun =

    gfxTextRun::Create(&params, 1, aFontGroup,

                       gfx::ShapedTextFlags(), nsTextFrameUtils::Flags());

  textRun->AddGlyphRun(aFontGroup->GetFirstValidFont(),

                       gfxTextRange::MatchType::kFontGroup, 0,

                       false, gfx::ShapedTextFlags::TEXT_ORIENT_HORIZONTAL);

                              // We don't care about CSS writing mode here;

                              // math runs are assumed to be horizontal.

  gfxTextRun::DetailedGlyph detailedGlyph;

  detailedGlyph.mGlyphID = aGlyph.glyphID;

  detailedGlyph.mAdvance =

    NSToCoordRound(aAppUnitsPerDevPixel *

                   aFontGroup->GetFirstValidFont()->

                   GetGlyphHAdvance(aDrawTarget, aGlyph.glyphID));

  textRun->SetGlyphs(0,

                     gfxShapedText::CompressedGlyph::MakeComplex(true, true, 1),

                     &detailedGlyph);

  return textRun.forget();

}

// -----------------------------------------------------------------------------

// This is the list of all the applicable glyph tables.

// We will maintain a single global instance that will only reveal those

// glyph tables that are associated to fonts currently installed on the

// user' system. The class is an XPCOM shutdown observer to allow us to

// free its allocated data at shutdown

class nsGlyphTableList final : public nsIObserver

{

public:

  NS_DECL_ISUPPORTS

  NS_DECL_NSIOBSERVER

  nsPropertiesTable mUnicodeTable;

  nsGlyphTableList()

    : mUnicodeTable(NS_LITERAL_CSTRING("Unicode"))

  {

  }

  nsresult Initialize();

  nsresult Finalize();

  // Add a glyph table in the list, return the new table that was added

  nsGlyphTable*

  AddGlyphTable(const nsACString& aPrimaryFontName);

  // Find the glyph table in the list corresponding to the given font family.

  nsGlyphTable*

  GetGlyphTableFor(const nsACString& aFamily);

private:

  ~nsGlyphTableList()

  {

  }

  nsPropertiesTable* PropertiesTableAt(int32_t aIndex) {

    return &mPropertiesTableList.ElementAt(aIndex);

  }

  int32_t PropertiesTableCount() {

    return mPropertiesTableList.Length();

  }

  // List of glyph tables;

  nsTArray<nsPropertiesTable> mPropertiesTableList;

};

NS_IMPL_ISUPPORTS(nsGlyphTableList, nsIObserver)

// -----------------------------------------------------------------------------

// Here is the global list of applicable glyph tables that we will be using

static nsGlyphTableList* gGlyphTableList = nullptr;

static bool gGlyphTableInitialized = false;

// XPCOM shutdown observer

NS_IMETHODIMP

nsGlyphTableList::Observe(nsISupports*     aSubject,

                          const char* aTopic,

                          const char16_t* someData)

{

  Finalize();

  return NS_OK;

}

// Add an observer to XPCOM shutdown so that we can free our data at shutdown

nsresult

nsGlyphTableList::Initialize()

{

  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();

  if (!obs)

    return NS_ERROR_FAILURE;

  nsresult rv = obs->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false);

  NS_ENSURE_SUCCESS(rv, rv);

  return NS_OK;

}

// Remove our observer and free the memory that were allocated for us

nsresult

nsGlyphTableList::Finalize()

{

  // Remove our observer from the observer service

  nsresult rv = NS_OK;

  nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();

  if (obs)

    rv = obs->RemoveObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID);

  else

    rv = NS_ERROR_FAILURE;

  gGlyphTableInitialized = false;

  // our oneself will be destroyed when our |Release| is called by the observer

  NS_IF_RELEASE(gGlyphTableList);

  return rv;

}

nsGlyphTable*

nsGlyphTableList::AddGlyphTable(const nsACString& aPrimaryFontName)

{

  // See if there is already a special table for this family.

  nsGlyphTable* glyphTable = GetGlyphTableFor(aPrimaryFontName);

  if (glyphTable != &mUnicodeTable)

    return glyphTable;

  // allocate a table

  glyphTable = mPropertiesTableList.AppendElement(aPrimaryFontName);

  return glyphTable;

}

nsGlyphTable*

nsGlyphTableList::GetGlyphTableFor(const nsACString& aFamily)

{

  for (int32_t i = 0; i < PropertiesTableCount(); i++) {

    nsPropertiesTable* glyphTable = PropertiesTableAt(i);

    const FontFamilyName& primaryFontName = glyphTable->PrimaryFontName();

    nsAutoCString primaryFontNameStr;

    primaryFontName.AppendToString(primaryFontNameStr);

    // TODO: would be nice to consider StripWhitespace and other aliasing

    if (primaryFontNameStr.Equals(aFamily, nsCaseInsensitiveCStringComparator())) {

      return glyphTable;

    }

  }

  // Fall back to default Unicode table

  return &mUnicodeTable;

}

// -----------------------------------------------------------------------------

static nsresult

InitCharGlobals()

{

  NS_ASSERTION(!gGlyphTableInitialized, "Error -- already initialized");

  gGlyphTableInitialized = true;

  // Allocate the placeholders for the preferred parts and variants

  nsresult rv = NS_ERROR_OUT_OF_MEMORY;

  RefPtr<nsGlyphTableList> glyphTableList = new nsGlyphTableList();

  if (glyphTableList) {

    rv = glyphTableList->Initialize();

  }

  if (NS_FAILED(rv)) {

    return rv;

  }

  // The gGlyphTableList has been successfully registered as a shutdown

  // observer and will be deleted at shutdown. We now add some private

  // per font-family tables for stretchy operators, in order of preference.

  // Do not include the Unicode table in this list.

  if (!glyphTableList->AddGlyphTable(NS_LITERAL_CSTRING("STIXGeneral"))) {

    rv = NS_ERROR_OUT_OF_MEMORY;

  }

  glyphTableList.forget(&gGlyphTableList);

  return rv;

}

// -----------------------------------------------------------------------------

// And now the implementation of nsMathMLChar

nsMathMLChar::~nsMathMLChar()

{

  MOZ_COUNT_DTOR(nsMathMLChar);

}

ComputedStyle*

nsMathMLChar::GetComputedStyle() const

{

  NS_ASSERTION(mComputedStyle, "chars should always have a ComputedStyle");

  return mComputedStyle;

}

void

nsMathMLChar::SetComputedStyle(ComputedStyle* aComputedStyle)

{

  MOZ_ASSERT(aComputedStyle);

  mComputedStyle = aComputedStyle;

}

void

nsMathMLChar::SetData(nsString& aData)

{

  if (!gGlyphTableInitialized) {

    InitCharGlobals();

  }

  mData = aData;

  // some assumptions until proven otherwise

  // note that mGlyph is not initialized

  mDirection = NS_STRETCH_DIRECTION_UNSUPPORTED;

  mBoundingMetrics = nsBoundingMetrics();

  // check if stretching is applicable ...

  if (gGlyphTableList && (1 == mData.Length())) {

    mDirection = nsMathMLOperators::GetStretchyDirection(mData);

    // default tentative table (not the one that is necessarily going

    // to be used)

  }

}

// -----------------------------------------------------------------------------

/*

 The Stretch:

 @param aContainerSize - suggested size for the stretched char

 @param aDesiredStretchSize - OUT parameter. The desired size

 after stretching. If no stretching is done, the output will

 simply give the base size.

 How it works?

 Summary:-

 The Stretch() method first looks for a glyph of appropriate

 size; If a glyph is found, it is cached by this object and

 its size is returned in aDesiredStretchSize. The cached

 glyph will then be used at the painting stage.

 If no glyph of appropriate size is found, a search is made

 to see if the char can be built by parts.

 Details:-

 A character gets stretched through the following pipeline :

 1) If the base size of the char is sufficient to cover the

    container' size, we use that. If not, it will still be

    used as a fallback if the other stages in the pipeline fail.

    Issues :

    a) The base size, the parts and the variants of a char can

       be in different fonts. For eg., the base size for '(' should

       come from a normal ascii font if CMEX10 is used, since CMEX10

       only contains the stretched versions. Hence, there are two

       ComputedStyles in use throughout the process. The leaf style

       context of the char holds fonts with which to try to stretch

       the char. The parent ComputedStyle of the char contains fonts

       for normal rendering. So the parent context is the one used

       to get the initial base size at the start of the pipeline.

    b) For operators that can be largeop's in display mode,

       we will skip the base size even if it fits, so that

       the next stage in the pipeline is given a chance to find

       a largeop variant. If the next stage fails, we fallback

       to the base size.

 2) We search for the first larger variant of the char that fits the

    container' size.  We first search for larger variants using the glyph

    table corresponding to the first existing font specified in the list of

    stretchy fonts held by the leaf ComputedStyle (from -moz-math-stretchy in

    mathml.css).  Generic fonts are resolved by the preference

    "font.mathfont-family".

    Issues :

    a) the largeop and display settings determine the starting

       size when we do the above search, regardless of whether

       smaller variants already fit the container' size.

    b) if it is a largeopOnly request (i.e., a displaystyle operator

       with largeop=true and stretchy=false), we break after finding

       the first starting variant, regardless of whether that

       variant fits the container's size.

 3) If a variant of appropriate size wasn't found, we see if the char

    can be built by parts using the same glyph table.

    Issue:

       There are chars that have no middle and glue glyphs. For

       such chars, the parts need to be joined using the rule.

       By convention (TeXbook p.225), the descent of the parts is

       zero while their ascent gives the thickness of the rule that

       should be used to join them.

 4) If a match was not found in that glyph table, repeat from 2 to search the

    ordered list of stretchy fonts for the first font with a glyph table that

    provides a fit to the container size.  If no fit is found, the closest fit

    is used.

 Of note:

 When the pipeline completes successfully, the desired size of the

 stretched char can actually be slightly larger or smaller than

 aContainerSize. But it is the responsibility of the caller to

 account for the spacing when setting aContainerSize, and to leave

 any extra margin when placing the stretched char.

*/

// -----------------------------------------------------------------------------

// plain TeX settings (TeXbook p.152)

#define NS_MATHML_DELIMITER_FACTOR             0.901f

#define NS_MATHML_DELIMITER_SHORTFALL_POINTS   5.0f

static bool

IsSizeOK(nscoord a, nscoord b, uint32_t aHint)

{

  // Normal: True if 'a' is around +/-10% of the target 'b' (10% is

  // 1-DelimiterFactor). This often gives a chance to the base size to

  // win, especially in the context of <mfenced> without tall elements

  // or in sloppy markups without protective <mrow></mrow>

  bool isNormal =

    (aHint & NS_STRETCH_NORMAL) &&

    Abs<float>(a - b) < (1.0f - NS_MATHML_DELIMITER_FACTOR) * float(b);

  // Nearer: True if 'a' is around max{ +/-10% of 'b' , 'b' - 5pt },

  // as documented in The TeXbook, Ch.17, p.152.

  // i.e. within 10% and within 5pt

  bool isNearer = false;

  if (aHint & (NS_STRETCH_NEARER | NS_STRETCH_LARGEOP)) {

    float c = std::max(float(b) * NS_MATHML_DELIMITER_FACTOR,

                     float(b) - nsPresContext::

                     CSSPointsToAppUnits(NS_MATHML_DELIMITER_SHORTFALL_POINTS));

    isNearer = Abs<float>(b - a) <= float(b) - c;

  }

  // Smaller: Mainly for transitory use, to compare two candidate

  // choices

  bool isSmaller =

    (aHint & NS_STRETCH_SMALLER) &&

    float(a) >= NS_MATHML_DELIMITER_FACTOR * float(b) &&

    a <= b;

  // Larger: Critical to the sqrt code to ensure that the radical

  // size is tall enough

  bool isLarger =

    (aHint & (NS_STRETCH_LARGER | NS_STRETCH_LARGEOP)) &&

    a >= b;

  return (isNormal || isSmaller || isNearer || isLarger);

}

static bool

IsSizeBetter(nscoord a, nscoord olda, nscoord b, uint32_t aHint)

{

  if (0 == olda)

    return true;

  if (aHint & (NS_STRETCH_LARGER | NS_STRETCH_LARGEOP))

    return (a >= olda) ? (olda < b) : (a >= b);

  if (aHint & NS_STRETCH_SMALLER)

    return (a <= olda) ? (olda > b) : (a <= b);

  // XXXkt prob want log scale here i.e. 1.5 is closer to 1 than 0.5

  return Abs(a - b) < Abs(olda - b);

}

// We want to place the glyphs even when they don't fit at their

// full extent, i.e., we may clip to tolerate a small amount of

// overlap between the parts. This is important to cater for fonts

// with long glues.

static nscoord

ComputeSizeFromParts(nsPresContext* aPresContext,

                     nsGlyphCode* aGlyphs,

                     nscoord*     aSizes,

                     nscoord      aTargetSize)

{

  enum {first, middle, last, glue};

  // Add the parts that cannot be left out.

  nscoord sum = 0;

  for (int32_t i = first; i <= last; i++) {

    sum += aSizes[i];

  }

  // Determine how much is used in joins

  nscoord oneDevPixel = aPresContext->AppUnitsPerDevPixel();

  int32_t joins = aGlyphs[middle] == aGlyphs[glue] ? 1 : 2;

  // Pick a maximum size using a maximum number of glue glyphs that we are

  // prepared to draw for one character.

  const int32_t maxGlyphs = 1000;

  // This also takes into account the fact that, if the glue has no size,

  // then the character can't be lengthened.

  nscoord maxSize = sum - 2 * joins * oneDevPixel + maxGlyphs * aSizes[glue];

  if (maxSize < aTargetSize)

    return maxSize; // settle with the maximum size

  // Get the minimum allowable size using some flex.

  nscoord minSize = NSToCoordRound(NS_MATHML_DELIMITER_FACTOR * sum);

  if (minSize > aTargetSize)

    return minSize; // settle with the minimum size

  // Fill-up the target area

  return aTargetSize;

}

// Update the font if there is a family change and returns the font group.