/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-

 * 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"

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;

        // initialized to a DrawTarget owned by our caller on every call to

        // ShapeText

        mozilla::gfx::DrawTarget* MOZ_NON_OWNING_REF mDrawTarget;

    };

    bool Initialize();

    bool ShapeText(DrawTarget      *aDrawTarget,

                   const char16_t *aText,

                   uint32_t         aOffset,

                   uint32_t         aLength,

                   Script           aScript,

                   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;

    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;

    hb_position_t GetGlyphVAdvance(hb_codepoint_t glyph) const;

    void GetGlyphVOrigin(mozilla::gfx::DrawTarget& aDT,

                         hb_codepoint_t aGlyph,

                         hb_position_t *aX, hb_position_t *aY) const;

    // get harfbuzz horizontal advance in 16.16 fixed point format.

    static hb_position_t

    HBGetGlyphHAdvance(hb_font_t *font, void *font_data,

                       hb_codepoint_t glyph, void *user_data);

    // get harfbuzz vertical advance in 16.16 fixed point format.

    static hb_position_t

    HBGetGlyphVAdvance(hb_font_t *font, void *font_data,

                       hb_codepoint_t glyph, void *user_data);

    static hb_bool_t

    HBGetGlyphVOrigin(hb_font_t *font, void *font_data,

                      hb_codepoint_t glyph,

                      hb_position_t *x, hb_position_t *y,

                      void *user_data);

    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);

protected:

    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;

    // harfbuzz face object: we acquire a reference from the font entry

    // on shaper creation, and release it in our destructor

    hb_face_t         *mHBFace;

    // size-specific font object, owned by the gfxHarfBuzzShaper

    hb_font_t         *mHBFont;

    // harfbuzz buffer for the shaping process

    hb_buffer_t       *mBuffer;

    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 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 */