gfxFT2FontBase.h - mozsearch

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/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-

 * 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/. */

#ifndef GFX_FT2FONTBASE_H

#define GFX_FT2FONTBASE_H

#include "gfxContext.h"

#include "gfxFont.h"

#include "gfxFontEntry.h"

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

#include "mozilla/gfx/UnscaledFontFreeType.h"

#include "nsTHashMap.h"

#include "nsHashKeys.h"

class gfxFT2FontBase;

class gfxFT2FontEntryBase : public gfxFontEntry {

 public:

  explicit gfxFT2FontEntryBase(const nsACString& aName) : gfxFontEntry(aName) {}

  uint32_t GetGlyph(uint32_t aCharCode, gfxFT2FontBase* aFont);

  static bool FaceHasTable(mozilla::gfx::SharedFTFace*, uint32_t aTableTag);

  static nsresult CopyFaceTable(mozilla::gfx::SharedFTFace*, uint32_t aTableTag,

                                nsTArray<uint8_t>&);

 private:

  enum { kNumCmapCacheSlots = 256 };

  struct CmapCacheSlot {

    CmapCacheSlot() : mCharCode(0), mGlyphIndex(0) {}

    uint32_t mCharCode;

    uint32_t mGlyphIndex;

};

  mozilla::UniquePtr<CmapCacheSlot[]> mCmapCache MOZ_GUARDED_BY(mLock);

};

class gfxFT2FontBase : public gfxFont {

 public:

  gfxFT2FontBase(

      const RefPtr<mozilla::gfx::UnscaledFontFreeType>& aUnscaledFont,

      RefPtr<mozilla::gfx::SharedFTFace>&& aFTFace, gfxFontEntry* aFontEntry,

      const gfxFontStyle* aFontStyle, int aLoadFlags, bool aEmbolden);

  uint32_t GetGlyph(uint32_t aCharCode) {

    auto* entry = static_cast<gfxFT2FontEntryBase*>(mFontEntry.get());

    return entry->GetGlyph(aCharCode, this);

  bool ProvidesGetGlyph() const override { return true; }

  virtual uint32_t GetGlyph(uint32_t unicode,

                            uint32_t variation_selector) override;

  bool ProvidesGlyphWidths() const override { return true; }

  int32_t GetGlyphWidth(uint16_t aGID) override {

    return GetCachedGlyphMetrics(aGID).mAdvance;

  bool GetGlyphBounds(uint16_t aGID, gfxRect* aBounds, bool aTight) override;

  FontType GetType() const override { return FONT_TYPE_FT2; }

  bool ShouldRoundXOffset(cairo_t* aCairo) const override;

  static void SetupVarCoords(FT_MM_Var* aMMVar,

                             const nsTArray<gfxFontVariation>& aVariations,

                             FT_Face aFTFace);

  FT_Face LockFTFace() const;

  void UnlockFTFace() const;

 private:

  uint32_t GetCharExtents(uint32_t aChar, gfxFloat* aWidth,

                          gfxRect* aBounds = nullptr);

  // Get advance (and optionally bounds) of a single glyph from FreeType,

  // and return true, or return false if we failed.

  bool GetFTGlyphExtents(uint16_t aGID, int32_t* aWidth,

                         mozilla::gfx::IntRect* aBounds = nullptr);

 protected:

  ~gfxFT2FontBase() override;

  void InitMetrics();

  const Metrics& GetHorizontalMetrics() const override { return mMetrics; }

  FT_Vector GetEmboldenStrength(FT_Face aFace) const;

  RefPtr<mozilla::gfx::SharedFTFace> mFTFace;

  Metrics mMetrics;

  int mFTLoadFlags;

  bool mEmbolden;

  gfxFloat mFTSize;

  // For variation/multiple-master fonts, this will be an array of the values

  // for each axis, as specified by mStyle.variationSettings (or the font's

  // default for axes not present in variationSettings). Values here are in

  // freetype's 16.16 fixed-point format, and clamped to the valid min/max

  // range reported by the face.

  nsTArray<FT_Fixed> mCoords;

  // Store cached glyph metrics for reasonably small glyph sizes. The bounds

  // are stored unscaled to losslessly compress 26.6 fixed point to an int16_t.

  // Larger glyphs are handled directly via GetFTGlyphExtents.

  struct GlyphMetrics {

    // Set the X coord to INT16_MIN to signal the bounds are invalid, or

    // INT16_MAX to signal that the bounds would overflow an int16_t.

    enum { INVALID = INT16_MIN, LARGE = INT16_MAX };

    GlyphMetrics() : mAdvance(0), mX(INVALID), mY(0), mWidth(0), mHeight(0) {}

    bool HasValidBounds() const { return mX != INVALID; }

    bool HasCachedBounds() const { return mX != LARGE; }

    // If the bounds can fit in an int16_t, set them. Otherwise, leave the

    // bounds invalid to signal that GetFTGlyphExtents should be queried

    // directly.

    void SetBounds(const mozilla::gfx::IntRect& aBounds) {

      if (aBounds.x > INT16_MIN && aBounds.x < INT16_MAX &&

          aBounds.y > INT16_MIN && aBounds.y < INT16_MAX &&

          aBounds.width <= UINT16_MAX && aBounds.height <= UINT16_MAX) {

        mX = aBounds.x;

        mY = aBounds.y;

        mWidth = aBounds.width;

        mHeight = aBounds.height;

      } else {

        mX = LARGE;

    mozilla::gfx::IntRect GetBounds() const {

      return mozilla::gfx::IntRect(mX, mY, mWidth, mHeight);

    int32_t mAdvance;

    int16_t mX;

    int16_t mY;

    uint16_t mWidth;

    uint16_t mHeight;

};

  const GlyphMetrics& GetCachedGlyphMetrics(

      uint16_t aGID, mozilla::gfx::IntRect* aBounds = nullptr);

  mozilla::UniquePtr<nsTHashMap<nsUint32HashKey, GlyphMetrics>> mGlyphMetrics

      MOZ_GUARDED_BY(mLock);

};

#endif /* GFX_FT2FONTBASE_H */