web2c/xetexdir/XeTeXFontInst.cpp

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 Copyright (c) 1994-2008 by SIL International
 Copyright (c) 2009 by Jonathan Kew

 SIL Author(s): Jonathan Kew

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/*
 *   file name:  XeTeXFontInst.cpp
 *
 *   created on: 2005-10-22
 *   created by: Jonathan Kew
 *
 *     originally based on PortableFontInstance.cpp from ICU
 */

#include <w2c/config.h>

#include "XeTeXFontInst.h"
#include "XeTeXLayoutInterface.h"
#include "XeTeX_ext.h"

#include <string.h>
#include FT_GLYPH_H
#include FT_ADVANCES_H

FT_Library gFreeTypeLibrary = 0;

static hb_font_funcs_t* hbFontFuncs = NULL;

XeTeXFontInst::XeTeXFontInst(const char* pathname, int index, float pointSize, int &status)
    : m_pointSize(pointSize)
    , m_unitsPerEM(0)
    , m_ascent(0)
    , m_descent(0)
    , m_capHeight(0)
    , m_xHeight(0)
    , m_italicAngle(0)
    , m_vertical(false)
    , m_filename(NULL)
    , m_index(0)
    , m_ftFace(0)
    , m_hbFont(NULL)
    , m_math(NULL)
{
    if (pathname != NULL)
        initialize(pathname, index, status);
}

XeTeXFontInst::~XeTeXFontInst()
{
    if (m_ftFace != 0) {
        FT_Done_Face(m_ftFace);
        m_ftFace = 0;
    }
    hb_font_destroy(m_hbFont);
    delete[] m_filename;
    free((void*) m_math);
}

/* HarfBuzz font functions */

static hb_bool_t
_get_glyph(hb_font_t*, void *font_data, hb_codepoint_t ch, hb_codepoint_t vs, hb_codepoint_t *gid, void*)
{
    FT_Face face = (FT_Face) font_data;
    *gid = 0;

    if (vs)
        *gid = FT_Face_GetCharVariantIndex (face, ch, vs);

    if (*gid == 0)
        *gid = FT_Get_Char_Index (face, ch);

    return *gid != 0;
}

static FT_Fixed
_get_glyph_advance(FT_Face face, FT_UInt gid, bool vertical)
{
    FT_Error error;
    FT_Fixed advance;
    int flags = FT_LOAD_NO_SCALE;

    if (vertical)
        flags |= FT_LOAD_VERTICAL_LAYOUT;

    error = FT_Get_Advance(face, gid, flags, &advance);
    if (error)
        advance = 0;
    else
        advance = advance;

    /* FreeType's vertical metrics grows downward */
    if (vertical)
        advance = -advance;

    return advance;
}

static hb_position_t
_get_glyph_h_advance(hb_font_t*, void *font_data, hb_codepoint_t gid, void*)
{
    return _get_glyph_advance((FT_Face) font_data, gid, false);
}

static hb_position_t
_get_glyph_v_advance(hb_font_t*, void *font_data, hb_codepoint_t gid, void*)
{
    return _get_glyph_advance((FT_Face) font_data, gid, true);
}

static hb_bool_t
_get_glyph_h_origin(hb_font_t*, void *font_data, hb_codepoint_t gid, hb_position_t *x, hb_position_t *y, void*)
{
    // horizontal origin is (0, 0)
    return true;
}

static hb_bool_t
_get_glyph_v_origin(hb_font_t*, void *font_data, hb_codepoint_t gid, hb_position_t *x, hb_position_t *y, void*)
{
    // vertical origin is (0, 0) for now
    return true;

    // TODO
    // Keep the code below for reference, for now we want to keep vertical
    // origin at (0, 0) for compatibility with pre-0.9999.
    // Reconsider this (e.g. using BASE table) when we get around overhauling
    // the text directionality model and implementing real vertical typesetting.

    FT_Face face = (FT_Face) font_data;
    FT_Error error;

    error = FT_Load_Glyph (face, gid, FT_LOAD_NO_SCALE);
    if (!error) {
        *x = face->glyph->metrics.horiBearingX -   face->glyph->metrics.vertBearingX;
        *y = face->glyph->metrics.horiBearingY - (-face->glyph->metrics.vertBearingY);
    }

    return !error;
}

static hb_position_t
_get_glyph_h_kerning(hb_font_t*, void *font_data, hb_codepoint_t gid1, hb_codepoint_t gid2, void*)
{
    FT_Face face = (FT_Face) font_data;
    FT_Error error;
    FT_Vector kerning;
    hb_position_t ret;

    error = FT_Get_Kerning (face, gid1, gid2, FT_KERNING_UNFITTED, &kerning);
    if (error)
        ret = 0;
    else
        ret = kerning.x;
    return ret;
}

static hb_position_t
_get_glyph_v_kerning(hb_font_t*, void *font_data, hb_codepoint_t gid1, hb_codepoint_t gid2, void*)
{
    /* FreeType does not support vertical kerning */
    return 0;
}

static hb_bool_t
_get_glyph_extents(hb_font_t*, void *font_data, hb_codepoint_t gid, hb_glyph_extents_t *extents, void*)
{
    FT_Face face = (FT_Face) font_data;
    FT_Error error;

    error = FT_Load_Glyph (face, gid, FT_LOAD_NO_SCALE);
    if (!error) {
        extents->x_bearing = face->glyph->metrics.horiBearingX;
        extents->y_bearing = face->glyph->metrics.horiBearingY;
        extents->width  =  face->glyph->metrics.width;
        extents->height = -face->glyph->metrics.height;
    }

    return !error;
}

static hb_bool_t
_get_glyph_contour_point(hb_font_t*, void *font_data, hb_codepoint_t gid, unsigned int point_index, hb_position_t *x, hb_position_t *y, void*)
{
    FT_Face face = (FT_Face) font_data;
    FT_Error error;
    bool ret = false;

    error = FT_Load_Glyph (face, gid, FT_LOAD_NO_SCALE);
    if (!error) {
        if (face->glyph->format == FT_GLYPH_FORMAT_OUTLINE) {
            if (point_index < (unsigned int) face->glyph->outline.n_points) {
                *x = face->glyph->outline.points[point_index].x;
                *y = face->glyph->outline.points[point_index].y;
                ret = true;
            }
        }
    }

    return ret;
}

static hb_bool_t
_get_glyph_name(hb_font_t *, void *font_data, hb_codepoint_t gid, char *name, unsigned int size, void *)
{
    FT_Face face = (FT_Face) font_data;
    bool ret = false;

    ret = !FT_Get_Glyph_Name (face, gid, name, size);
    if (ret && (size && !*name))
        ret = false;

    return ret;
}

static hb_font_funcs_t *
_get_font_funcs(void)
{
    static hb_font_funcs_t* funcs = hb_font_funcs_create();

    hb_font_funcs_set_glyph_func                (funcs, _get_glyph, NULL, NULL);
    hb_font_funcs_set_glyph_h_advance_func      (funcs, _get_glyph_h_advance, NULL, NULL);
    hb_font_funcs_set_glyph_v_advance_func      (funcs, _get_glyph_v_advance, NULL, NULL);
    hb_font_funcs_set_glyph_h_origin_func       (funcs, _get_glyph_h_origin, NULL, NULL);
    hb_font_funcs_set_glyph_v_origin_func       (funcs, _get_glyph_v_origin, NULL, NULL);
    hb_font_funcs_set_glyph_h_kerning_func      (funcs, _get_glyph_h_kerning, NULL, NULL);
    hb_font_funcs_set_glyph_v_kerning_func      (funcs, _get_glyph_v_kerning, NULL, NULL);
    hb_font_funcs_set_glyph_extents_func        (funcs, _get_glyph_extents, NULL, NULL);
    hb_font_funcs_set_glyph_contour_point_func  (funcs, _get_glyph_contour_point, NULL, NULL);
    hb_font_funcs_set_glyph_name_func           (funcs, _get_glyph_name, NULL, NULL);

    return funcs;
}

static hb_blob_t *
_get_table(hb_face_t *, hb_tag_t tag, void *user_data)
{
    FT_Face face = (FT_Face) user_data;
    FT_ULong length = 0;
    FT_Byte *table;
    FT_Error error;
    hb_blob_t* blob = NULL;

    error = FT_Load_Sfnt_Table(face, tag, 0, NULL, &length);
    if (!error) {
        table = (FT_Byte *) xmalloc(length * sizeof(char));
        if (table != NULL) {
            error = FT_Load_Sfnt_Table(face, tag, 0, (FT_Byte*)table, &length);
            if (!error) {
                blob = hb_blob_create((const char*) table, length, HB_MEMORY_MODE_WRITABLE, table, free);
            } else {
                free(table);
            }
        }
    }

    return blob;
}

void
XeTeXFontInst::initialize(const char* pathname, int index, int &status)
{
    TT_Postscript *postTable;
    TT_OS2* os2Table;
    FT_Error error;
    hb_face_t *hbFace;

    if (!gFreeTypeLibrary) {
        error = FT_Init_FreeType(&gFreeTypeLibrary);
        if (error) {
            fprintf(stderr, "FreeType initialization failed! (%d)\n", error);
            exit(1);
        }
    }

    error = FT_New_Face(gFreeTypeLibrary, (char*)pathname, index, &m_ftFace);
    if (error) {
        status = 1;
        return;
    }

    if (!FT_IS_SCALABLE(m_ftFace)) {
        status = 1;
        return;
    }

    /* for non-sfnt-packaged fonts (presumably Type 1), see if there is an AFM file we can attach */
    if (index == 0 && !FT_IS_SFNT(m_ftFace)) {
        char* afm = new char[strlen((const char*)pathname) + 5]; // room to append ".afm"
        strcpy(afm, (const char*)pathname);
        char* p = strrchr(afm, '.');
        if (p == NULL || strlen(p) != 4 || tolower(*(p+1)) != 'p' || tolower(*(p+2)) != 'f')
            strcat(afm, ".afm");   // append .afm if the extension didn't seem to be .pf[ab]
        else
            strcpy(p, ".afm");     // else replace extension with .afm
        FT_Attach_File(m_ftFace, afm); // ignore error code; AFM might not exist
        delete[] afm;
    }

    m_filename = xstrdup(pathname);
    m_index = index;
    m_unitsPerEM = m_ftFace->units_per_EM;
    m_ascent = unitsToPoints(m_ftFace->ascender);
    m_descent = unitsToPoints(m_ftFace->descender);

    postTable = (TT_Postscript *) getFontTable(ft_sfnt_post);
    if (postTable != NULL) {
        m_italicAngle = Fix2D(postTable->italicAngle);
    }

    os2Table = (TT_OS2*) getFontTable(ft_sfnt_os2);
    if (os2Table) {
        m_capHeight = unitsToPoints(os2Table->sCapHeight);
        m_xHeight = unitsToPoints(os2Table->sxHeight);
    }

    // Set up HarfBuzz font
    hbFace = hb_face_create_for_tables(_get_table, m_ftFace, NULL);
    hb_face_set_index(hbFace, index);
    hb_face_set_upem(hbFace, m_unitsPerEM);
    m_hbFont = hb_font_create(hbFace);
    hb_face_destroy(hbFace);

    if (hbFontFuncs == NULL)
        hbFontFuncs = _get_font_funcs();

    hb_font_set_funcs(m_hbFont, hbFontFuncs, m_ftFace, NULL);
    hb_font_set_scale(m_hbFont, m_unitsPerEM, m_unitsPerEM);
    // We don’t want device tables adjustments
    hb_font_set_ppem(m_hbFont, 0, 0);

    return;
}

void
XeTeXFontInst::setLayoutDirVertical(bool vertical)
{
    m_vertical = vertical;
}

const void *
XeTeXFontInst::getFontTable(OTTag tag) const
{
    FT_ULong tmpLength = 0;
    FT_Error error = FT_Load_Sfnt_Table(m_ftFace, tag, 0, NULL, &tmpLength);
    if (error)
        return NULL;

    void* table = xmalloc(tmpLength * sizeof(char));
    if (table != NULL) {
        error = FT_Load_Sfnt_Table(m_ftFace, tag, 0, (FT_Byte*)table, &tmpLength);
        if (error) {
            free((void *) table);
            return NULL;
        }
    }

    return table;
}

const char *
XeTeXFontInst::getMathTable()
{
    if (m_math == NULL)
        m_math = (const char*) getFontTable(MATH_TAG);
    return m_math;
}

const void *
XeTeXFontInst::getFontTable(FT_Sfnt_Tag tag) const
{
    return FT_Get_Sfnt_Table(m_ftFace, tag);
}

void
XeTeXFontInst::getGlyphBounds(GlyphID gid, GlyphBBox* bbox)
{
    bbox->xMin = bbox->yMin = bbox->xMax = bbox->yMax = 0.0;

    FT_Error error = FT_Load_Glyph(m_ftFace, gid, FT_LOAD_NO_SCALE);
    if (error)
        return;

    FT_Glyph glyph;
    error = FT_Get_Glyph(m_ftFace->glyph, &glyph);
    if (error == 0) {
        FT_BBox ft_bbox;
        FT_Glyph_Get_CBox(glyph, FT_GLYPH_BBOX_UNSCALED, &ft_bbox);
        bbox->xMin = unitsToPoints(ft_bbox.xMin);
        bbox->yMin = unitsToPoints(ft_bbox.yMin);
        bbox->xMax = unitsToPoints(ft_bbox.xMax);
        bbox->yMax = unitsToPoints(ft_bbox.yMax);
        FT_Done_Glyph(glyph);
    }
}

GlyphID
XeTeXFontInst::mapCharToGlyph(UChar32 ch) const
{
    return FT_Get_Char_Index(m_ftFace, ch);
}

uint16_t
XeTeXFontInst::getNumGlyphs() const
{
    return m_ftFace->num_glyphs;
}

float
XeTeXFontInst::getGlyphWidth(GlyphID gid)
{
    return unitsToPoints(_get_glyph_advance(m_ftFace, gid, false));
}

void
XeTeXFontInst::getGlyphHeightDepth(GlyphID gid, float* ht, float* dp)
{
    GlyphBBox bbox;
    getGlyphBounds(gid, &bbox);

    if (ht)
        *ht = bbox.yMax;
    if (dp)
        *dp = -bbox.yMin;
}

void
XeTeXFontInst::getGlyphSidebearings(GlyphID gid, float* lsb, float* rsb)
{
    float width = getGlyphWidth(gid);

    GlyphBBox bbox;
    getGlyphBounds(gid, &bbox);

    if (lsb)
        *lsb = bbox.xMin;
    if (rsb)
        *rsb = width - bbox.xMax;
}

float
XeTeXFontInst::getGlyphItalCorr(GlyphID gid)
{
    float rval = 0.0;

    float width = getGlyphWidth(gid);

    GlyphBBox bbox;
    getGlyphBounds(gid, &bbox);

    if (bbox.xMax > width)
        rval = bbox.xMax - width;

    return rval;
}

GlyphID
XeTeXFontInst::mapGlyphToIndex(const char* glyphName) const
{
    return FT_Get_Name_Index(m_ftFace, const_cast<char*>(glyphName));
}

const char*
XeTeXFontInst::getGlyphName(GlyphID gid, int& nameLen)
{
    if (FT_HAS_GLYPH_NAMES(m_ftFace)) {
        static char buffer[256];
        FT_Get_Glyph_Name(m_ftFace, gid, buffer, 256);
        nameLen = strlen(buffer);
        return &buffer[0];
    }
    else {
        nameLen = 0;
        return NULL;
    }
}

UChar32
XeTeXFontInst::getFirstCharCode()
{
    FT_UInt gindex;
    return FT_Get_First_Char(m_ftFace, &gindex);
}

UChar32
XeTeXFontInst::getLastCharCode()
{
    FT_UInt gindex;
    UChar32 ch = FT_Get_First_Char(m_ftFace, &gindex);
    UChar32 prev = ch;
    while (gindex != 0) {
        prev = ch;
        ch = FT_Get_Next_Char(m_ftFace, ch, &gindex);
    }
    return prev;
}