1 files changed, 240 insertions, 0 deletions
diff --git a/gfx/thebes/gfxHarfBuzzShaper.h b/gfx/thebes/gfxHarfBuzzShaper.h
new file mode 100644
index 0000000000..4e4e899660
--- /dev/null
+++ b/gfx/thebes/gfxHarfBuzzShaper.h
@@ -0,0 +1,240 @@
+/* -*- 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_HARFBUZZSHAPER_H
+#define GFX_HARFBUZZSHAPER_H
+
+#include "gfxFont.h"
+
+#include "harfbuzz/hb.h"
+#include "nsUnicodeProperties.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/MruCache.h"
+#include "mozilla/Mutex.h"
+
+class gfxHarfBuzzShaper : public gfxFontShaper {
+ public:
+  explicit gfxHarfBuzzShaper(gfxFont* aFont);
+  virtual ~gfxHarfBuzzShaper();
+
+  /*
+   * For HarfBuzz font callback functions, font_data is a ptr to a
+   * FontCallbackData struct
+   */
+  struct FontCallbackData {
+    gfxHarfBuzzShaper* mShaper;
+  };
+
+  // Initializes the shaper and returns whether this was successful.
+  bool Initialize();
+
+  // Returns whether the shaper has been successfully initialized.
+  bool IsInitialized() const { return mHBFont != nullptr; }
+
+  bool ShapeText(DrawTarget* aDrawTarget, const char16_t* aText,
+                 uint32_t aOffset, uint32_t aLength, Script aScript,
+                 nsAtom* aLanguage, bool aVertical, RoundingFlags aRounding,
+                 gfxShapedText* aShapedText) override;
+
+  // get a given font table in harfbuzz blob form
+  hb_blob_t* GetFontTable(hb_tag_t aTag) const;
+
+  // map unicode character to glyph ID
+  hb_codepoint_t GetNominalGlyph(hb_codepoint_t unicode) const;
+  unsigned int GetNominalGlyphs(unsigned int count,
+                                const hb_codepoint_t* first_unicode,
+                                unsigned int unicode_stride,
+                                hb_codepoint_t* first_glyph,
+                                unsigned int glyph_stride);
+  hb_codepoint_t GetVariationGlyph(hb_codepoint_t unicode,
+                                   hb_codepoint_t variation_selector) const;
+
+  // get harfbuzz glyph advance, in font design units
+  hb_position_t GetGlyphHAdvance(hb_codepoint_t glyph) const;
+  void GetGlyphHAdvances(unsigned int count, const hb_codepoint_t* first_glyph,
+                         unsigned int glyph_stride,
+                         hb_position_t* first_advance,
+                         unsigned int advance_stride) const;
+
+  // Get vertical glyph advance, or -1 if not available; caller should check
+  // for a negative result and provide a fallback or fail, as appropriate.
+  hb_position_t GetGlyphVAdvance(hb_codepoint_t glyph);
+
+  void GetGlyphVOrigin(hb_codepoint_t aGlyph, hb_position_t* aX,
+                       hb_position_t* aY) const;
+
+  hb_position_t GetHKerning(uint16_t aFirstGlyph, uint16_t aSecondGlyph) const;
+
+  hb_bool_t GetGlyphExtents(hb_codepoint_t aGlyph,
+                            hb_glyph_extents_t* aExtents) const;
+
+  bool UseVerticalPresentationForms() const {
+    return mUseVerticalPresentationForms;
+  }
+
+  static hb_script_t GetHBScriptUsedForShaping(Script aScript) {
+    // Decide what harfbuzz script code will be used for shaping
+    hb_script_t hbScript;
+    if (aScript <= Script::INHERITED) {
+      // For unresolved "common" or "inherited" runs,
+      // default to Latin for now.
+      hbScript = HB_SCRIPT_LATIN;
+    } else {
+      hbScript = hb_script_t(mozilla::unicode::GetScriptTagForCode(aScript));
+    }
+    return hbScript;
+  }
+
+  static hb_codepoint_t GetVerticalPresentationForm(hb_codepoint_t aUnicode);
+
+  // Create an hb_font corresponding to the given gfxFont instance, with size
+  // and variations set appropriately. If aFontFuncs and aCallbackData are
+  // provided, they may be used as harfbuzz font callbacks for advances, glyph
+  // bounds, etc; if not, the built-in hb_ot font functions will be used.
+  static hb_font_t* CreateHBFont(gfxFont* aFont,
+                                 hb_font_funcs_t* aFontFuncs = nullptr,
+                                 FontCallbackData* aCallbackData = nullptr);
+
+  hb_font_t* GetHBFont() const { return mHBFont; }
+  hb_face_t* GetHBFace() const { return hb_font_get_face(mHBFont); }
+
+ protected:
+  // This is called with the cache locked, but if mUseFontGetGlyph is true, it
+  // may unlock it temporarily. So in this case, it may invalidate an earlier
+  // cache entry reference.
+  hb_codepoint_t GetGlyphUncached(hb_codepoint_t unicode) const
+      MOZ_REQUIRES(mCacheLock);
+
+  hb_position_t GetGlyphHAdvanceUncached(hb_codepoint_t gid) const;
+
+  nsresult SetGlyphsFromRun(gfxShapedText* aShapedText, uint32_t aOffset,
+                            uint32_t aLength, const char16_t* aText,
+                            bool aVertical, RoundingFlags aRounding);
+
+  // retrieve glyph positions, applying advance adjustments and attachments
+  // returns results in appUnits
+  nscoord GetGlyphPositions(gfxContext* aContext, nsTArray<nsPoint>& aPositions,
+                            uint32_t aAppUnitsPerDevUnit);
+
+  void InitializeVertical();
+  bool LoadHmtxTable();
+
+  struct Glyf {  // we only need the bounding-box at the beginning
+                 // of the glyph record, not the actual outline data
+    mozilla::AutoSwap_PRInt16 numberOfContours;
+    mozilla::AutoSwap_PRInt16 xMin;
+    mozilla::AutoSwap_PRInt16 yMin;
+    mozilla::AutoSwap_PRInt16 xMax;
+    mozilla::AutoSwap_PRInt16 yMax;
+  };
+
+  const Glyf* FindGlyf(hb_codepoint_t aGlyph, bool* aEmptyGlyf) const;
+
+  // size-specific font object, owned by the gfxHarfBuzzShaper
+  hb_font_t* mHBFont;
+
+  // harfbuzz buffer for the shaping process
+  hb_buffer_t* mBuffer;
+
+  mutable mozilla::Mutex mCacheLock = mozilla::Mutex("shaperCacheMutex");
+
+  struct CmapCacheData {
+    uint32_t mCodepoint;
+    uint32_t mGlyphId;
+  };
+
+  struct CmapCache
+      : public mozilla::MruCache<uint32_t, CmapCacheData, CmapCache, 251> {
+    static mozilla::HashNumber Hash(const uint32_t& aKey) { return aKey; }
+    static bool Match(const uint32_t& aKey, const CmapCacheData& aData) {
+      return aKey == aData.mCodepoint;
+    }
+  };
+
+  mutable mozilla::UniquePtr<CmapCache> mCmapCache MOZ_GUARDED_BY(mCacheLock);
+
+  struct WidthCacheData {
+    hb_codepoint_t mGlyphId;
+    hb_position_t mAdvance;
+  };
+
+  struct WidthCache
+      : public mozilla::MruCache<uint32_t, WidthCacheData, WidthCache, 251> {
+    static mozilla::HashNumber Hash(const hb_codepoint_t& aKey) { return aKey; }
+    static bool Match(const uint32_t& aKey, const WidthCacheData& aData) {
+      return aKey == aData.mGlyphId;
+    }
+  };
+
+  mutable mozilla::UniquePtr<WidthCache> mWidthCache MOZ_GUARDED_BY(mCacheLock);
+
+  FontCallbackData mCallbackData;
+
+  // Following table references etc are declared "mutable" because the
+  // harfbuzz callback functions take a const ptr to the shaper, but
+  // wish to cache tables here to avoid repeatedly looking them up
+  // in the font.
+
+  // Old-style TrueType kern table, if we're not doing GPOS kerning
+  mutable hb_blob_t* mKernTable;
+
+  // Cached copy of the hmtx table.
+  mutable hb_blob_t* mHmtxTable;
+
+  // For vertical fonts, cached vmtx and VORG table, if present.
+  mutable hb_blob_t* mVmtxTable;
+  mutable hb_blob_t* mVORGTable;
+  // And for vertical TrueType (not CFF) fonts that have vmtx,
+  // we also use loca and glyf to get glyph bounding boxes.
+  mutable hb_blob_t* mLocaTable;
+  mutable hb_blob_t* mGlyfTable;
+
+  // Cached pointer to cmap subtable to be used for char-to-glyph mapping.
+  // This comes from GetFontTablePtr; if it is non-null, our destructor
+  // must call ReleaseFontTablePtr to avoid permanently caching the table.
+  mutable hb_blob_t* mCmapTable;
+  mutable int32_t mCmapFormat;
+  mutable uint32_t mSubtableOffset;
+  mutable uint32_t mUVSTableOffset;
+
+  // Cached copy of numLongMetrics field from the hhea table,
+  // for use when looking up glyph metrics; initialized to 0 by the
+  // constructor so we can tell it hasn't been set yet.
+  // This is a signed value so that we can use -1 to indicate
+  // an error (if the hhea table was not available).
+  mutable int32_t mNumLongHMetrics;
+  // Similarly for vhea if it's a vertical font.
+  mutable int32_t mNumLongVMetrics;
+
+  // Default y-coordinate for glyph vertical origin, used if the font
+  // does not actually have vertical-layout metrics.
+  mutable gfxFloat mDefaultVOrg;
+
+  // Whether the font implements GetGlyph, or we should read tables
+  // directly
+  bool mUseFontGetGlyph;
+
+  // Whether the font is an MS Symbol-encoded font, in which case we will
+  // try remapping U+0020..00FF to U+F020..F0FF for characters in the U+00xx
+  // range that are otherwise unsupported.
+  bool mIsSymbolFont;
+
+  // Whether the font implements GetGlyphWidth, or we should read tables
+  // directly to get ideal widths
+  bool mUseFontGlyphWidths;
+
+  bool mInitialized;
+  bool mVerticalInitialized;
+
+  // Whether to use vertical presentation forms for CJK characters
+  // when available (only set if the 'vert' feature is not available).
+  bool mUseVerticalPresentationForms;
+
+  // these are set from the FindGlyf callback on first use of the glyf data
+  mutable bool mLoadedLocaGlyf;
+  mutable bool mLocaLongOffsets;
+};
+
+#endif /* GFX_HARFBUZZSHAPER_H */