qtextengine.cpp

奇趣公司比较新的qt/emd版本

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#include "qdebug.h"
#include "qtextformat.h"
#include "qtextformat_p.h"
#include "qtextengine_p.h"
#include "qabstracttextdocumentlayout.h"
#include "qtextlayout.h"
#include "qvarlengtharray.h"
#include "qscriptengine_p.h"
#include "qfont.h"
#include "qfont_p.h"
#include "qfontengine_p.h"
#include "qstring.h"
#include <private/qunicodetables_p.h>
#include "qtextdocument_p.h"
#include <qapplication.h>
#include <stdlib.h>


// -----------------------------------------------------------------------------------------------------
//
// The BiDi algorithm
//
// -----------------------------------------------------------------------------------------------------


#define BIDI_DEBUG 0//2
#if (BIDI_DEBUG >= 1)
#include <iostream>
using namespace std;

static const char *directions[] = {
    "DirL", "DirR", "DirEN", "DirES", "DirET", "DirAN", "DirCS", "DirB", "DirS", "DirWS", "DirON",
    "DirLRE", "DirLRO", "DirAL", "DirRLE", "DirRLO", "DirPDF", "DirNSM", "DirBN"
};

#endif

struct QBidiStatus {
    QBidiStatus() {
        eor = QChar::DirON;
        lastStrong = QChar::DirON;
        last = QChar:: DirON;
        dir = QChar::DirON;
    }
    QChar::Direction eor;
    QChar::Direction lastStrong;
    QChar::Direction last;
    QChar::Direction dir;
};

// The Unicode standard says this should be 61, setting it to 29 would save quite some space here.
enum { MaxBidiLevel = 61 };

struct QBidiControl {
    inline QBidiControl(bool rtl)
        : cCtx(0), base(rtl), override(false), level(rtl) {}

    inline void embed(bool rtl, bool o = false) {
        uchar plus2 = 0;
        if((level%2 != 0) == rtl ) {
            level++;
            plus2 = 2;
        }
        level++;
        if (level <= MaxBidiLevel) {
            override = o;
            unsigned char control = (plus2 + (override ? 1 : 0)) << (cCtx % 4)*2;
            unsigned char mask = ~(0x3 << (cCtx % 4)*2);
            ctx[cCtx>>2] &= mask;
            ctx[cCtx>>2] |= control;
            cCtx++;
        }
    }
    inline bool canPop() const { return cCtx != 0; }
    inline void pdf() {
        Q_ASSERT(cCtx);
        (void) --cCtx;
        unsigned char control = (ctx[cCtx>>2] >> ((cCtx % 4)*2)) & 0x3;
        override = control & 0x1;
        level--;
        if (control & 0x2)
            level--;
    }

    inline QChar::Direction basicDirection() const {
        return (base ? QChar::DirR : QChar:: DirL);
    }
    inline uchar baseLevel() const {
        return base;
    }
    inline QChar::Direction direction() const {
        return ((level%2) ? QChar::DirR : QChar:: DirL);
    }

    unsigned char ctx[(MaxBidiLevel+3)/4];
    unsigned char cCtx : 6;
    unsigned char base : 1;
    unsigned char override : 1;
    unsigned char unused : 2;
    unsigned char level : 6;
};

static void qAppendItems(QTextEngine *engine, int &start, int &stop, QBidiControl &control, QChar::Direction dir)
{
    QScriptItemArray &items = engine->layoutData->items;
    const QChar *text = engine->layoutData->string.unicode();

    if (start > stop) {
        // #### the algorithm is currently not really safe against this. Still needs fixing.
//         qWarning("QTextEngine: BiDi internal error in qAppendItems()");
        return;
    }

    int level = control.level;

    if(dir != QChar::DirON && !control.override) {
        // add level of run (cases I1 & I2)
        if(level % 2) {
            if(dir == QChar::DirL || dir == QChar::DirAN || dir == QChar::DirEN)
                level++;
        } else {
            if(dir == QChar::DirR)
                level++;
            else if(dir == QChar::DirAN || dir == QChar::DirEN)
                level += 2;
        }
    }

#if (BIDI_DEBUG >= 1)
    qDebug("new run: dir=%s from %d, to %d level = %d\n", directions[dir], start, stop, level);
#endif
    int script = -1;
    QScriptItem item;
    item.position = start;
    item.analysis.script = script;
    item.analysis.bidiLevel = level;
    item.analysis.override = control.override;
    item.analysis.reserved = 0;

    for (int i = start; i <= stop; i++) {
        unsigned short uc = text[i].unicode();
        int s = QUnicodeTables::script(text[i]);
        if (uc == QChar::ObjectReplacementCharacter || uc == QChar::LineSeparator) {
            item.analysis.bidiLevel = level % 2 ? level-1 : level;
            item.analysis.script = QUnicodeTables::Common;
            item.isObject = true;
            s = -1;
        } else if (uc == 9) {
            item.analysis.script = QUnicodeTables::Common;
            item.isSpace = true;
            item.isTab = true;
            item.analysis.bidiLevel = control.baseLevel();
            s = -1;
        } else if (s != script && (s != QUnicodeTables::Inherited || script == -1)) {
            item.analysis.script = s == QUnicodeTables::Inherited ? QUnicodeTables::Common : s;
            item.analysis.bidiLevel = level;
        } else {
            if (i - start < 32000)
                continue;
            start = i;
        }

        item.position = i;
        items.append(item);
        script = s;
        item.isSpace = item.isTab = item.isObject = false;
    }
    ++stop;
    start = stop;
}

typedef void (* fAppendItems)(QTextEngine *, int &start, int &stop, QBidiControl &control, QChar::Direction dir);
static fAppendItems appendItems = qAppendItems;

// creates the next QScript items.
static bool bidiItemize(QTextEngine *engine, bool rightToLeft)
{
#if BIDI_DEBUG >= 2
    cout << "bidiItemize: rightToLeft=" << rightToLeft << endl;
#endif
    QBidiControl control(rightToLeft);

    bool hasBidi = rightToLeft;

    int sor = 0;
    int eor = -1;


    int length = engine->layoutData->string.length();

    if (!length)
        return hasBidi;

    const ushort *unicode = (const ushort *)engine->layoutData->string.unicode();
    int current = 0;

    QChar::Direction dir = rightToLeft ? QChar::DirR : QChar::DirL;
    QBidiStatus status;
    QChar::Direction sdir = QChar::direction(*unicode);
    if (sdir != QChar::DirL && sdir != QChar::DirR && sdir != QChar::DirEN && sdir != QChar::DirAN)
	sdir = QChar::DirON;
    else
        dir = QChar::DirON;
    status.eor = sdir;
    status.lastStrong = rightToLeft ? QChar::DirR : QChar::DirL;
    status.last = status.lastStrong;
    status.dir = sdir;



    while (current <= length) {

        QChar::Direction dirCurrent;
        if (current == (int)length)
            dirCurrent = control.basicDirection();
        else
            dirCurrent = QChar::direction(unicode[current]);

#if (BIDI_DEBUG >= 2)
        cout << "pos=" << current << " dir=" << directions[dir]
             << " current=" << directions[dirCurrent] << " last=" << directions[status.last]
             << " eor=" << eor << "/" << directions[status.eor]
             << " sor=" << sor << " lastStrong="
             << directions[status.lastStrong]
             << " level=" << (int)control.level << " override=" << (bool)control.override << endl;
#endif

        switch(dirCurrent) {

            // embedding and overrides (X1-X9 in the BiDi specs)
        case QChar::DirRLE:
        case QChar::DirRLO:
        case QChar::DirLRE:
        case QChar::DirLRO:
            {
                bool rtl = (dirCurrent == QChar::DirRLE || dirCurrent == QChar::DirRLO);
                hasBidi |= rtl;
                bool override = (dirCurrent == QChar::DirLRO || dirCurrent == QChar::DirRLO);

                uchar level = control.level+1;
                if ((level%2 != 0) == rtl) ++level;
                if(level < MaxBidiLevel) {
                    eor = current-1;
                    appendItems(engine, sor, eor, control, dir);
                    eor = current;
                    control.embed(rtl, override);
                    QChar::Direction edir = (rtl ? QChar::DirR : QChar::DirL);
                    dir = status.eor = edir;
                    status.lastStrong = edir;
                }
                break;
            }
        case QChar::DirPDF:
            {
                if (control.canPop()) {
                    if (dir != control.direction()) {
                        eor = current-1;
                        appendItems(engine, sor, eor, control, dir);
                        dir = control.direction();
                    }
                    eor = current;
                    appendItems(engine, sor, eor, control, dir);
                    control.pdf();
                    dir = QChar::DirON; status.eor = QChar::DirON;
                    status.last = control.direction();
                    if (control.override)
                        dir = control.direction();
                    else
                        dir = QChar::DirON;
                    status.lastStrong = control.direction();
                }
                break;
            }

            // strong types
        case QChar::DirL:
            if(dir == QChar::DirON)
                dir = QChar::DirL;
            switch(status.last)
                {
                case QChar::DirL:
                    eor = current; status.eor = QChar::DirL; break;
                case QChar::DirR:
                case QChar::DirAL:
                case QChar::DirEN:
                case QChar::DirAN:
                    if (eor >= 0) {
                        appendItems(engine, sor, eor, control, dir);
                        dir = eor < length ? QChar::direction(unicode[eor]) : control.basicDirection();
                        status.eor = dir;
                    } else {
                        eor = current; status.eor = dir;
                    }
                    break;
                case QChar::DirES:
                case QChar::DirET:
                case QChar::DirCS:
                case QChar::DirBN:
                case QChar::DirB:
                case QChar::DirS:
                case QChar::DirWS:
                case QChar::DirON:
                    if(dir != QChar::DirL) {
                        //last stuff takes embedding dir
                        if(control.direction() == QChar::DirR) {
                            if(status.eor != QChar::DirR) {
                                // AN or EN
                                appendItems(engine, sor, eor, control, dir);
                                status.eor = QChar::DirON;
                                dir = QChar::DirR;
                            }
                            eor = current - 1;
                            appendItems(engine, sor, eor, control, dir);
                            dir = eor < length ? QChar::direction(unicode[eor]) : control.basicDirection();
                            status.eor = dir;
                        } else {
                            if(status.eor != QChar::DirL) {
                                appendItems(engine, sor, eor, control, dir);
                                status.eor = QChar::DirON;
                                dir = QChar::DirL;
                            } else {
                                eor = current; status.eor = QChar::DirL; break;
                            }
                        }
                    } else {