Source code
Revision control
Copy as Markdown
Other Tools
/* -*- 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
#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 */