stroke.cpp

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.10平台上编译为嵌入式图形界面操作系统。

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**
** This file is part of the Qtopia Environment.
** 
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** under the terms of the GNU General Public License as published by the
** Free Software Foundation; either version 2 of the License, or (at your
** option) any later version.
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** LICENSE.GPL.
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** See the GNU General Public License for more details.
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** the code of this program with Qtopia applications copyrighted, developed
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** in all respects for all of the code used other than the applications
** licensed under the Qtopia Personal Use License Agreement. If you modify
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#include <qfile.h>
#include <qtl.h>
#include <math.h>
#include <limits.h>
#include <qdatastream.h>
#include "stroke.h"

#define QIMPEN_CORRELATION_POINTS   25
//#define DEBUG_QIMPEN

/*!
  \class QIMPenStroke qimpenstroke.h
  \brief The QIMPenStroke class handles a single stroke.

  Can calculate closeness of match to
  another stroke.
*/

bool QIMPenStroke::useVertPos = TRUE;

QIMPenStroke::QIMPenStroke() : cheight(75)
{
}

QIMPenStroke::QIMPenStroke( const QIMPenStroke &st ) : cheight(st.cheight)
{
    startPoint = st.startPoint;
    lastPoint = st.lastPoint;
    links = st.links.copy();
}

QIMPenStroke &QIMPenStroke::operator=( const QIMPenStroke &s )
{
    clear();
    //qDebug( "copy strokes %d", s.links.count() );
    startPoint = s.startPoint;
    lastPoint = s.lastPoint;
    links = s.links.copy();
    cheight = s.cheight;

    return *this;
}

void QIMPenStroke::clear()
{
    startPoint = QPoint(0,0);
    lastPoint = QPoint( 0, 0 );
    links.resize( 0 );
    tsig.resize( 0 );
    dsig.resize( 0 );
    asig.resize( 0 );
}

/*!
  Begin inputting a new stroke at position \a p.
*/
void QIMPenStroke::beginInput( QPoint p )
{
    clear();
    startPoint = p;
    bounding = QRect();
    internalAddPoint( p );
}

/*!
  Add a point \a p to the stroke's shape.
  Returns TRUE if the point was successfully added.
*/
bool QIMPenStroke::addPoint( QPoint p )
{
    if ( links.count() > 500 ) // sanity check (that the user is sane).
        return FALSE;

    int dx = p.x() - lastPoint.x();
    int dy = p.y() - lastPoint.y();
    if ( QABS( dx ) > 1 || QABS( dy ) > 1 ) {
	// The point is not adjacent to the previous point, so we fill
	// in with a straight line.  Some kind of non-linear
	// interpolation might be better.
	int x = lastPoint.x();
	int y = lastPoint.y();
	int ix = 1;
	int iy = 1;
	if ( dx < 0 ) {
	    ix = -1;
	    dx = -dx;
	}
	if ( dy < 0 ) {
	    iy = -1;
	    dy = -dy;
	}
	int d = 0;
	if ( dx < dy ) {
	    d = dx;
	    do {
		y += iy;
		d += dx;
		if ( d > dy ) {
		    x += ix;
		    d -= dy;
		}
		internalAddPoint( QPoint( x, y ) );
	    } while ( y != p.y() );
	} else {
	    d = dy;
	    do {
		x += ix;
		d += dy;
		if ( d > dx ) {
		    y += iy;
		    d -= dx;
		}
		internalAddPoint( QPoint( x, y ) );
	    } while ( x != p.x() );
	}
    } else {
	internalAddPoint( p );
    }

    return TRUE;
}

/*!
  Finish inputting a stroke.
*/
void QIMPenStroke::endInput()
{
    if ( links.count() < 3 ) {
	QIMPenGlyphLink gl;
	links.resize(1);
	gl.dx = 1;
	gl.dy = 0;
	links[0] = gl;
    }

    //qDebug("Points: %d", links.count() );
}

/*!
  Return an indicator of the closeness of this stroke to \a pen.
  Lower value is better.
*/
unsigned int QIMPenStroke::match( QIMPenStroke *pen )
{
    double lratio;

    if ( links.count() > pen->links.count() )
	lratio = (links.count()+2) / (pen->links.count()+2);
    else
	lratio =  (pen->links.count()+2) / (links.count()+2);

    lratio -= 1.0;

    if ( lratio > 2.0 ) {
#ifdef DEBUG_QIMPEN
	qDebug( "stroke length too different" );
#endif
	return 400000;
    }

    createSignatures();
    pen->createSignatures();

    int ch = canvasHeight();
    int pch = pen->canvasHeight();

    int vdiff, evdiff;
    if (!useVertPos) {
	// if they are different, need a differnt way of measureing
	int h = boundingRect().height();
	int ph = pen->boundingRect().height();

	int sh = h * 75 / ch;
	int sph = ph * 75 / pch;

	if (((sh << 1) < sph && sph > 4)
		|| ((sph << 1) < ph && ph > 4)) {
	    return 400000;
	}
	vdiff = 0;
	evdiff = 0;
    } else {
	int sp = startPoint.y();
	int psp = pen->startPoint.y();
	vdiff = QABS(sp - psp);

	// Insanely offset?
	if ( vdiff > 18 ) {
	    return 400000;
	}

	vdiff -= 4;
	if ( vdiff < 0 )
	    vdiff = 0;

	// Ending point offset
	int lp = lastPoint.y();
	int plp = pen->lastPoint.y();
	evdiff = QABS(lp - plp);
	// Insanely offset?
	if ( evdiff > 20 ) {
	    return 400000;
	}

	evdiff -= 5;
	if ( evdiff < 0 )
	    evdiff = 0;
    }

    // do a correlation with the three available signatures.
    int err1 = INT_MAX;
    int err2 = INT_MAX;
    int err3 = INT_MAX;

    err1 = tsig.calcError(pen->tsig);
    if ( err1 > tsig.maxError() ) {  // no need for more matching
#ifdef DEBUG_QIMPEN
	qDebug( "tsig too great: %d", err1 );
#endif
        return 400000;
    }

    // maybe a sliding window is worthwhile for these too.
    err2 = dsig.calcError( pen->dsig );
    if ( err2 > dsig.maxError() ) {
#ifdef DEBUG_QIMPEN
	qDebug( "dsig too great: %d", err2 );
#endif
	return 400000;
    }

    err3 = asig.calcError( pen->asig );
    if ( err3 > asig.maxError() ) {
#ifdef DEBUG_QIMPEN
	qDebug( "asig too great: %d", err3 );
#endif
	return 400000;
    }

    // Some magic numbers here - the addition reduces the weighting of
    // the error and compensates for the different error scales.  I
    // consider the tangent signature to be the best indicator, so it
    // has the most weight.  This ain't rocket science.
    // Basically, these numbers are the tuning factors.
    unsigned int err = ( err1 + tsig.weight() )
	    * ( err2 + dsig.weight() )
	    * ( err3 + asig.weight() )
	    + vdiff * 1000 + evdiff * 500
	    + (unsigned int)(lratio * 5000.0);

#ifdef DEBUG_QIMPEN
    qDebug( "err %d   ( %d, %d, %d, %d)", err, err1, err2, err3, vdiff);
#endif

    return err;
}

/*!
  Return the bounding rect of this stroke.
*/
QRect QIMPenStroke::boundingRect() const
{
    if ( !bounding.isValid() ) {
	int x = startPoint.x();
	int y = startPoint.y();
	bounding = QRect( x, y, 1, 1 );

	for ( int i = 0; i < (int)links.count(); i++ ) {
	    x += links[i].dx;
	    y += links[i].dy;
	    if ( x < bounding.left() )
		bounding.setLeft( x );
	    if ( x > bounding.right() )
		bounding.setRight( x );
	    if ( y < bounding.top() )
		bounding.setTop( y );
	    if ( y > bounding.bottom() )
		bounding.setBottom( y );
	}
    }

    return bounding;
}


/*!
  Creates signatures used in matching if not already created.
*/
void QIMPenStroke::createSignatures()
{
    if ( tsig.isEmpty() )
	tsig.setStroke(*this);
    if ( asig.isEmpty() )
	asig.setStroke(*this);
    if ( dsig.isEmpty() )
	dsig.setStroke(*this);
}

/*!
  Add another point \a p to the stroke's shape.
*/
void QIMPenStroke::internalAddPoint( QPoint p )
{
    if ( p == lastPoint )
        return;

    if ( !lastPoint.isNull() ) {
        QIMPenGlyphLink gl;
        gl.dx = p.x() - lastPoint.x();
        gl.dy = p.y() - lastPoint.y();

	/*ALARM BELLS*/
        links.resize( links.size() + 1 );   //### resize by 1 is bad
        links[(int)links.size() - 1] = gl;
    }

    lastPoint = p;
    bounding = QRect();
}

/*!
  Calculate the center of gravity of the stroke.
*/
QPoint QIMPenStroke::center() const
{
    QPoint pt( 0, 0 );
    int ax = 0;
    int ay = 0;

    for ( int i = 0; i < (int)links.count(); i++ ) {
        pt.rx() += links[i].dx;
        pt.ry() += links[i].dy;
        ax += pt.x();
        ay += pt.y();
    }

    ax /= (int)links.count();
    ay /= (int)links.count();

    return QPoint( ax, ay );
}
/*!
  Write the character's data to the stream.
*/
QDataStream &operator<< (QDataStream &s, const QIMPenStroke &ws)
{
    s << ws.startPoint;
    s << ws.links.count();
    for ( int i = 0; i < (int)ws.links.count(); i++ ) {
        s << (Q_INT8)ws.links[i].dx;
        s << (Q_INT8)ws.links[i].dy;
    }

    return s;
}

/*!
  Read the character's data from the stream.
*/
QDataStream &operator>> (QDataStream &s, QIMPenStroke &ws)
{
    Q_INT8 i8;
    s >> ws.startPoint;
    ws.lastPoint = ws.startPoint;
    unsigned size;
    s >> size;
    ws.links.resize( size );
    for ( int i = 0; i < (int)size; i++ ) {
        s >> i8;
	ws.links[i].dx = i8;
        s >> i8;
	ws.links[i].dy = i8;
	ws.lastPoint += QPoint( ws.links[i].dx, ws.links[i].dy );
    }

    return s;
}