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201 lines
7.6 KiB
C++
201 lines
7.6 KiB
C++
/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef GFX_HARFBUZZSHAPER_H
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#define GFX_HARFBUZZSHAPER_H
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#include "gfxFont.h"
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#include "harfbuzz/hb.h"
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#include "nsUnicodeProperties.h"
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#include "mozilla/gfx/2D.h"
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class gfxHarfBuzzShaper : public gfxFontShaper {
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public:
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explicit gfxHarfBuzzShaper(gfxFont* aFont);
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virtual ~gfxHarfBuzzShaper();
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/*
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* For HarfBuzz font callback functions, font_data is a ptr to a
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* FontCallbackData struct
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*/
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struct FontCallbackData {
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gfxHarfBuzzShaper* mShaper;
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};
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// Initializes the shaper and returns whether this was successful.
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bool Initialize();
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// Returns whether the shaper has been successfully initialized.
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bool IsInitialized() const { return mHBFont != nullptr; }
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bool ShapeText(DrawTarget* aDrawTarget, const char16_t* aText,
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uint32_t aOffset, uint32_t aLength, Script aScript,
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nsAtom* aLanguage, bool aVertical, RoundingFlags aRounding,
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gfxShapedText* aShapedText) override;
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// get a given font table in harfbuzz blob form
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hb_blob_t* GetFontTable(hb_tag_t aTag) const;
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// map unicode character to glyph ID
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hb_codepoint_t GetNominalGlyph(hb_codepoint_t unicode) const;
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hb_codepoint_t GetVariationGlyph(hb_codepoint_t unicode,
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hb_codepoint_t variation_selector) const;
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// get harfbuzz glyph advance, in font design units
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hb_position_t GetGlyphHAdvance(hb_codepoint_t glyph) const;
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// Get vertical glyph advance, or -1 if not available; caller should check
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// for a negative result and provide a fallback or fail, as appropriate.
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hb_position_t GetGlyphVAdvance(hb_codepoint_t glyph);
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void GetGlyphVOrigin(hb_codepoint_t aGlyph, hb_position_t* aX,
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hb_position_t* aY) const;
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// get harfbuzz horizontal advance in 16.16 fixed point format.
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static hb_position_t HBGetGlyphHAdvance(hb_font_t* font, void* font_data,
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hb_codepoint_t glyph,
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void* user_data);
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// get harfbuzz vertical advance in 16.16 fixed point format.
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static hb_position_t HBGetGlyphVAdvance(hb_font_t* font, void* font_data,
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hb_codepoint_t glyph,
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void* user_data);
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static hb_bool_t HBGetGlyphVOrigin(hb_font_t* font, void* font_data,
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hb_codepoint_t glyph, hb_position_t* x,
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hb_position_t* y, void* user_data);
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hb_position_t GetHKerning(uint16_t aFirstGlyph, uint16_t aSecondGlyph) const;
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hb_bool_t GetGlyphExtents(hb_codepoint_t aGlyph,
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hb_glyph_extents_t* aExtents) const;
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bool UseVerticalPresentationForms() const {
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return mUseVerticalPresentationForms;
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}
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static hb_script_t GetHBScriptUsedForShaping(Script aScript) {
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// Decide what harfbuzz script code will be used for shaping
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hb_script_t hbScript;
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if (aScript <= Script::INHERITED) {
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// For unresolved "common" or "inherited" runs,
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// default to Latin for now.
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hbScript = HB_SCRIPT_LATIN;
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} else {
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hbScript = hb_script_t(mozilla::unicode::GetScriptTagForCode(aScript));
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}
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return hbScript;
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}
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static hb_codepoint_t GetVerticalPresentationForm(hb_codepoint_t aUnicode);
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// Create an hb_font corresponding to the given gfxFont instance, with size
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// and variations set appropriately. If aFontFuncs and aCallbackData are
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// provided, they may be used as harfbuzz font callbacks for advances, glyph
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// bounds, etc; if not, the built-in hb_ot font functions will be used.
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static hb_font_t* CreateHBFont(gfxFont* aFont,
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hb_font_funcs_t* aFontFuncs = nullptr,
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FontCallbackData* aCallbackData = nullptr);
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protected:
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nsresult SetGlyphsFromRun(gfxShapedText* aShapedText, uint32_t aOffset,
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uint32_t aLength, const char16_t* aText,
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bool aVertical, RoundingFlags aRounding);
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// retrieve glyph positions, applying advance adjustments and attachments
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// returns results in appUnits
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nscoord GetGlyphPositions(gfxContext* aContext, nsTArray<nsPoint>& aPositions,
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uint32_t aAppUnitsPerDevUnit);
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void InitializeVertical();
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bool LoadHmtxTable();
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struct Glyf { // we only need the bounding-box at the beginning
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// of the glyph record, not the actual outline data
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mozilla::AutoSwap_PRInt16 numberOfContours;
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mozilla::AutoSwap_PRInt16 xMin;
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mozilla::AutoSwap_PRInt16 yMin;
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mozilla::AutoSwap_PRInt16 xMax;
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mozilla::AutoSwap_PRInt16 yMax;
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};
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const Glyf* FindGlyf(hb_codepoint_t aGlyph, bool* aEmptyGlyf) const;
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// size-specific font object, owned by the gfxHarfBuzzShaper
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hb_font_t* mHBFont;
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// harfbuzz buffer for the shaping process
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hb_buffer_t* mBuffer;
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FontCallbackData mCallbackData;
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// Following table references etc are declared "mutable" because the
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// harfbuzz callback functions take a const ptr to the shaper, but
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// wish to cache tables here to avoid repeatedly looking them up
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// in the font.
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// Old-style TrueType kern table, if we're not doing GPOS kerning
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mutable hb_blob_t* mKernTable;
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// Cached copy of the hmtx table.
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mutable hb_blob_t* mHmtxTable;
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// For vertical fonts, cached vmtx and VORG table, if present.
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mutable hb_blob_t* mVmtxTable;
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mutable hb_blob_t* mVORGTable;
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// And for vertical TrueType (not CFF) fonts that have vmtx,
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// we also use loca and glyf to get glyph bounding boxes.
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mutable hb_blob_t* mLocaTable;
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mutable hb_blob_t* mGlyfTable;
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// Cached pointer to cmap subtable to be used for char-to-glyph mapping.
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// This comes from GetFontTablePtr; if it is non-null, our destructor
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// must call ReleaseFontTablePtr to avoid permanently caching the table.
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mutable hb_blob_t* mCmapTable;
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mutable int32_t mCmapFormat;
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mutable uint32_t mSubtableOffset;
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mutable uint32_t mUVSTableOffset;
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// Cached copy of numLongMetrics field from the hhea table,
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// for use when looking up glyph metrics; initialized to 0 by the
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// constructor so we can tell it hasn't been set yet.
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// This is a signed value so that we can use -1 to indicate
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// an error (if the hhea table was not available).
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mutable int32_t mNumLongHMetrics;
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// Similarly for vhea if it's a vertical font.
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mutable int32_t mNumLongVMetrics;
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// Default y-coordinate for glyph vertical origin, used if the font
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// does not actually have vertical-layout metrics.
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mutable gfxFloat mDefaultVOrg;
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// Whether the font implements GetGlyph, or we should read tables
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// directly
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bool mUseFontGetGlyph;
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// Whether the font is an MS Symbol-encoded font, in which case we will
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// try remapping U+0020..00FF to U+F020..F0FF for characters in the U+00xx
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// range that are otherwise unsupported.
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bool mIsSymbolFont;
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// Whether the font implements GetGlyphWidth, or we should read tables
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// directly to get ideal widths
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bool mUseFontGlyphWidths;
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bool mInitialized;
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bool mVerticalInitialized;
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// Whether to use vertical presentation forms for CJK characters
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// when available (only set if the 'vert' feature is not available).
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bool mUseVerticalPresentationForms;
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// these are set from the FindGlyf callback on first use of the glyf data
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mutable bool mLoadedLocaGlyf;
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mutable bool mLocaLongOffsets;
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};
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#endif /* GFX_HARFBUZZSHAPER_H */
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