src/core/SkAdvancedTypefaceMetrics.h

/*
 * Copyright 2011 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */


#ifndef SkAdvancedTypefaceMetrics_DEFINED
#define SkAdvancedTypefaceMetrics_DEFINED

#include "SkRect.h"
#include "SkRefCnt.h"
#include "SkString.h"
#include "SkTDArray.h"
#include "SkTemplates.h"
#include "SkSinglyLinkedList.h"

/** \class SkAdvancedTypefaceMetrics

    The SkAdvancedTypefaceMetrics class is used by the PDF backend to correctly
    embed typefaces. This class is created and filled in with information by
    SkTypeface::getAdvancedTypefaceMetrics.
*/

class SkAdvancedTypefaceMetrics : public SkRefCnt {
public:

    SkAdvancedTypefaceMetrics()
        : fType(SkAdvancedTypefaceMetrics::kOther_Font)
        , fFlags(SkAdvancedTypefaceMetrics::kEmpty_FontFlag)
        , fLastGlyphID(0)
        , fEmSize(0)
        , fStyle(0)
        , fItalicAngle(0)
        , fAscent(0)
        , fDescent(0)
        , fStemV(0)
        , fCapHeight(0)
        , fBBox(SkIRect::MakeEmpty()) {}

    ~SkAdvancedTypefaceMetrics();

    /** Retrieve advance data for glyphs. Used by the PDF backend. It
        calls underlying platform dependent API getAdvance to acquire
        the data.
        @param num_glyphs    Total number of glyphs in the given font.
        @param glyphIDs      For per-glyph info, specify subset of the
                             font by giving glyph ids.  Each integer
                             represents a glyph id.  Passing nullptr
                             means all glyphs in the font.
        @param glyphIDsCount Number of elements in subsetGlyphIds.
                             Ignored if glyphIDs is nullptr.
        @param  getAdvance   A function that takes a glyph id and
                             passes back advance data from the
                             typeface.  Returns false on failure.
    */
    typedef std::function<bool(int glyphId, int16_t* advanceData)> GetAdvance;
    void setGlyphWidths(int num_glyphs,
                        const uint32_t* subsetGlyphIDs,
                        uint32_t subsetGlyphIDsLength,
                        GetAdvance getAdvance);

    SkString fFontName;

    enum FontType {
        kType1_Font,
        kType1CID_Font,
        kCFF_Font,
        kTrueType_Font,
        kOther_Font,
    };
    // The type of the underlying font program.  This field determines which
    // of the following fields are valid.  If it is kOther_Font the per glyph
    // information will never be populated.
    FontType fType;

    enum FontFlags {
        kEmpty_FontFlag          = 0x0,  //!<No flags set
        kMultiMaster_FontFlag    = 0x1,  //!<May be true for Type1, CFF, or TrueType fonts.
        kNotEmbeddable_FontFlag  = 0x2,  //!<May not be embedded.
        kNotSubsettable_FontFlag = 0x4,  //!<May not be subset.
    };
    // Global font flags.
    FontFlags fFlags;

    uint16_t fLastGlyphID; // The last valid glyph ID in the font.
    uint16_t fEmSize;  // The size of the em box (defines font units).

    // These enum values match the values used in the PDF file format.
    enum StyleFlags {
        kFixedPitch_Style  = 0x00001,
        kSerif_Style       = 0x00002,
        kScript_Style      = 0x00008,
        kItalic_Style      = 0x00040,
        kAllCaps_Style     = 0x10000,
        kSmallCaps_Style   = 0x20000,
        kForceBold_Style   = 0x40000
    };
    uint16_t fStyle;        // Font style characteristics.
    int16_t fItalicAngle;   // Counterclockwise degrees from vertical of the
                            // dominant vertical stroke for an Italic face.
    // The following fields are all in font units.
    int16_t fAscent;       // Max height above baseline, not including accents.
    int16_t fDescent;      // Max depth below baseline (negative).
    int16_t fStemV;        // Thickness of dominant vertical stem.
    int16_t fCapHeight;    // Height (from baseline) of top of flat capitals.

    SkIRect fBBox;  // The bounding box of all glyphs (in font units).

    template <typename Data>
    struct AdvanceMetric {
        enum MetricType {
            kDefault,  // Default advance: fAdvance.count = 1
            kRange,    // Advances for a range: fAdvance.count = fEndID-fStartID
            kRun       // fStartID-fEndID have same advance: fAdvance.count = 1
        };
        MetricType fType;
        uint16_t fStartId;
        uint16_t fEndId;
        SkTDArray<Data> fAdvance;
        AdvanceMetric(uint16_t startId) : fStartId(startId) {}
        AdvanceMetric(AdvanceMetric&& other)
            : fType(other.fType)
            , fStartId(other.fStartId)
            , fEndId(other.fEndId) {
            fAdvance.swap(other.fAdvance);
        }
        AdvanceMetric& operator=(AdvanceMetric&& other) {
            fType = other.fType;
            fStartId = other.fStartId;
            fEndId = other.fEndId;
            fAdvance.swap(other.fAdvance);
            return *this;
        }
        AdvanceMetric(const AdvanceMetric&) = delete;
        AdvanceMetric& operator=(const AdvanceMetric&) = delete;
    };

    struct VerticalMetric {
        int16_t fVerticalAdvance;
        int16_t fOriginXDisp;  // Horiz. displacement of the secondary origin.
        int16_t fOriginYDisp;  // Vert. displacement of the secondary origin.
    };
    typedef AdvanceMetric<int16_t> WidthRange;
    typedef AdvanceMetric<VerticalMetric> VerticalAdvanceRange;

    // This is indexed by glyph id.
    SkSinglyLinkedList<WidthRange> fGlyphWidths;
    // Only used for Vertical CID fonts.
    SkSinglyLinkedList<VerticalAdvanceRange> fVerticalMetrics;

    // The names of each glyph, only populated for postscript fonts.
    SkAutoTDelete<SkAutoTArray<SkString> > fGlyphNames;

    // The mapping from glyph to Unicode, only populated if
    // kToUnicode_PerGlyphInfo is passed to GetAdvancedTypefaceMetrics.
    SkTDArray<SkUnichar> fGlyphToUnicode;

    static void FinishRange(WidthRange* range,
                            int endId,
                            WidthRange::MetricType type);

private:
    typedef SkRefCnt INHERITED;
};


#endif