qopentype.cpp

奇趣公司比较新的qt/emd版本

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#include "qdebug.h"
#include "qopentype_p.h"
#include "qfontengine_ft_p.h"
#if defined(Q_WS_QWS) && !defined(QT_NO_QWS_QPF2)
#include "qfontengine_qpf_p.h"
#endif
#include "qscriptengine_p.h"

#ifndef QT_NO_OPENTYPE
//  --------------------------------------------------------------------------------------------------------------------
// Open type support
//  --------------------------------------------------------------------------------------------------------------------

//#define OT_DEBUG

static inline char *tag_to_string(FT_ULong tag)
{
    static char string[5];
    string[0] = (tag >> 24)&0xff;
    string[1] = (tag >> 16)&0xff;
    string[2] = (tag >> 8)&0xff;
    string[3] = tag&0xff;
    string[4] = 0;
    return string;
}
#ifdef OT_DEBUG
static void dump_string(HB_Buffer buffer)
{
    for (uint i = 0; i < buffer->in_length; ++i) {
        qDebug("    %x: cluster=%d", buffer->in_string[i].gindex, buffer->in_string[i].cluster);
    }
}
#define DEBUG qDebug
#else
#define DEBUG if (1) ; else qDebug
#endif

#define DefaultLangSys 0xffff
#define DefaultScript FT_MAKE_TAG('D', 'F', 'L', 'T')

enum {
    RequiresGsub = 1,
    RequiresGpos = 2
};

struct OTScripts {
    unsigned int tag;
    int flags;
};
static const OTScripts ot_scripts [] = {
    // Common
    { FT_MAKE_TAG('l', 'a', 't', 'n'), 0 },
    // Greek
    { FT_MAKE_TAG('g', 'r', 'e', 'k'), 0 },
    // Cyrillic
    { FT_MAKE_TAG('c', 'y', 'r', 'l'), 0 },
    // Armenian
    { FT_MAKE_TAG('a', 'r', 'm', 'n'), 0 },
    // Hebrew
    { FT_MAKE_TAG('h', 'e', 'b', 'r'), 1 },
    // Arabic
    { FT_MAKE_TAG('a', 'r', 'a', 'b'), 1 },
    // Syriac
    { FT_MAKE_TAG('s', 'y', 'r', 'c'), 1 },
    // Thaana
    { FT_MAKE_TAG('t', 'h', 'a', 'a'), 1 },
    // Devanagari
    { FT_MAKE_TAG('d', 'e', 'v', 'a'), 1 },
    // Bengali
    { FT_MAKE_TAG('b', 'e', 'n', 'g'), 1 },
    // Gurmukhi
    { FT_MAKE_TAG('g', 'u', 'r', 'u'), 1 },
    // Gujarati
    { FT_MAKE_TAG('g', 'u', 'j', 'r'), 1 },
    // Oriya
    { FT_MAKE_TAG('o', 'r', 'y', 'a'), 1 },
    // Tamil
    { FT_MAKE_TAG('t', 'a', 'm', 'l'), 1 },
    // Telugu
    { FT_MAKE_TAG('t', 'e', 'l', 'u'), 1 },
    // Kannada
    { FT_MAKE_TAG('k', 'n', 'd', 'a'), 1 },
    // Malayalam
    { FT_MAKE_TAG('m', 'l', 'y', 'm'), 1 },
    // Sinhala
    { FT_MAKE_TAG('s', 'i', 'n', 'h'), 1 },
    // Thai
    { FT_MAKE_TAG('t', 'h', 'a', 'i'), 1 },
    // Lao
    { FT_MAKE_TAG('l', 'a', 'o', ' '), 1 },
    // Tibetan
    { FT_MAKE_TAG('t', 'i', 'b', 't'), 1 },
    // Myanmar
    { FT_MAKE_TAG('m', 'y', 'm', 'r'), 1 },
    // Georgian
    { FT_MAKE_TAG('g', 'e', 'o', 'r'), 0 },
    // Hangul
    { FT_MAKE_TAG('h', 'a', 'n', 'g'), 1 },
    // Ogham
    { FT_MAKE_TAG('o', 'g', 'a', 'm'), 0 },
    // Runic
    { FT_MAKE_TAG('r', 'u', 'n', 'r'), 0 },
    // Khmer
    { FT_MAKE_TAG('k', 'h', 'm', 'r'), 1 }
};
enum { NumOTScripts = sizeof(ot_scripts)/sizeof(OTScripts) };

QOpenType::QOpenType(QFontEngine *fe, FT_Face _face)
    : fontEngine(fe), face(_face), gdef(0), gsub(0), gpos(0), current_script(0xffffffff)
    , allocated(0)
{
    Q_ASSERT(NumOTScripts == (int)QUnicodeTables::ScriptCount);

    hb_buffer_new(face->memory, &hb_buffer);
    tmpAttributes = 0;
    tmpLogClusters = 0;

    kerning_feature_selected = false;
    glyphs_substituted = false;

    FT_Error error;
    if ((error = HB_Load_GDEF_Table(face, &gdef))) {
        DEBUG("error loading gdef table: %d", error);
        gdef = 0;
    }

    DEBUG() << "trying to load gsub table";
    if ((error = HB_Load_GSUB_Table(face, &gsub, gdef))) {
        gsub = 0;
        if (error != FT_Err_Table_Missing) {
            DEBUG("error loading gsub table: %d", error);
        } else {
            DEBUG("face doesn't have a gsub table");
        }
    }

    if ((error = HB_Load_GPOS_Table(face, &gpos, gdef))) {
        gpos = 0;
        DEBUG("error loading gpos table: %d", error);
    }

    for (uint i = 0; i < QUnicodeTables::ScriptCount; ++i)
        supported_scripts[i] = checkScript(i);
}

QOpenType::~QOpenType()
{
    if (gpos)
        HB_Done_GPOS_Table(gpos);
    if (gsub)
        HB_Done_GSUB_Table(gsub);
    if (gdef)
        HB_Done_GDEF_Table(gdef);
    if (hb_buffer)
        hb_buffer_free(hb_buffer);
    if (tmpAttributes)
        free(tmpAttributes);
    if (tmpLogClusters)
        free(tmpLogClusters);
}

bool QOpenType::checkScript(unsigned int script)
{
    Q_ASSERT(script < QUnicodeTables::ScriptCount);

    uint tag = ot_scripts[script].tag;
    int requirements = ot_scripts[script].flags;

    if (requirements & RequiresGsub) {
        if (!gsub)
            return false;

        FT_UShort script_index;
        FT_Error error = HB_GSUB_Select_Script(gsub, tag, &script_index);
        if (error) {
            DEBUG("could not select script %d in GSub table: %d", (int)script, error);
            error = HB_GSUB_Select_Script(gsub, FT_MAKE_TAG('D', 'F', 'L', 'T'), &script_index);
            if (error)
                return false;
        }
    }

    if (requirements & RequiresGpos) {
        if (!gpos)
            return false;

        FT_UShort script_index;
        FT_Error error = HB_GPOS_Select_Script(gpos, script, &script_index);
        if (error) {
            DEBUG("could not select script in gpos table: %d", error);
            error = HB_GPOS_Select_Script(gpos, FT_MAKE_TAG('D', 'F', 'L', 'T'), &script_index);
            if (error)
                return false;
        }

    }
    return true;
}


void QOpenType::selectScript(QShaperItem *item, unsigned int script, const Features *features)
{
    if (current_script == script && kerning_feature_selected == item->kerning_enabled)
        return;

    has_features = false;
    Q_ASSERT(script < QUnicodeTables::ScriptCount);
    // find script in our list of supported scripts.
    uint tag = ot_scripts[script].tag;

    if (gsub && features) {
#ifdef OT_DEBUG
        {
            HB_FeatureList featurelist = gsub->FeatureList;
            int numfeatures = featurelist.FeatureCount;
            DEBUG("gsub table has %d features", numfeatures);
            for (int i = 0; i < numfeatures; i++) {
                HB_FeatureRecord *r = featurelist.FeatureRecord + i;
                DEBUG("   feature '%s'", tag_to_string(r->FeatureTag));
            }
        }
#endif
        HB_GSUB_Clear_Features(gsub);
        FT_UShort script_index;
        FT_Error error = HB_GSUB_Select_Script(gsub, tag, &script_index);
        if (!error) {
            DEBUG("script %s has script index %d", tag_to_string(script), script_index);
            while (features->tag) {
                FT_UShort feature_index;
                error = HB_GSUB_Select_Feature(gsub, features->tag, script_index, 0xffff, &feature_index);
                if (!error) {
                    DEBUG("  adding feature %s", tag_to_string(features->tag));
                    HB_GSUB_Add_Feature(gsub, feature_index, features->property);
                    has_features = true;
                }
                ++features;
            }
        }
    }