about QPainter::drawText()

[Nicho]

Hi,
The following is my test codes.

char label[MAX_LABEL_LENGTH];
    QList<double> lMajorTicks, lMinorTicks;
    _pEngine -> buildTicks( _oAttribute._fStart, _oAttribute._fEnd, _nMaxMajorTickNumber, lMajorTicks, lMinorTicks );
 
    int nCount = lMajorTicks.count();
    for( int i = 0; i < nCount; i ++ )
    {
        int nPos = (lMajorTicks[i]-_oAttribute._fStart)*_fScale;
        painter -> drawLine( nPos, _oAttribute._nMargin, nPos, _oAttribute._nMargin+_oAttribute._nMajorTickLen );
 
        memset( label, '\0', MAX_LABEL_LENGTH );
        sprintf( label, _oAttribute._sMajorLabelFormat, lMajorTicks[i] );
        QString text = QString::fromStdString( label );
        QRect rc = painter -> boundingRect( QRect(0,0,0,0), Qt::AlignCenter, text );
        QRect qrc = QRect( nPos, _oAttribute._nMargin+_oAttribute._nMajorTickLen+15, rc.width()+10, rc.height()+10 );
        if( i > 0 && i < nCount-1);
            painter -> drawText( qrc, Qt::AlignCenter, text );    
 
    }

char label[MAX_LABEL_LENGTH];
    QList<double> lMajorTicks, lMinorTicks;
    _pEngine -> buildTicks( _oAttribute._fStart, _oAttribute._fEnd, _nMaxMajorTickNumber, lMajorTicks, lMinorTicks );

    int nCount = lMajorTicks.count();
    for( int i = 0; i < nCount; i ++ )
    {
        int nPos = (lMajorTicks[i]-_oAttribute._fStart)*_fScale;
        painter -> drawLine( nPos, _oAttribute._nMargin, nPos, _oAttribute._nMargin+_oAttribute._nMajorTickLen );

        memset( label, '\0', MAX_LABEL_LENGTH );
        sprintf( label, _oAttribute._sMajorLabelFormat, lMajorTicks[i] );
        QString text = QString::fromStdString( label );
        QRect rc = painter -> boundingRect( QRect(0,0,0,0), Qt::AlignCenter, text );
        QRect qrc = QRect( nPos, _oAttribute._nMargin+_oAttribute._nMajorTickLen+15, rc.width()+10, rc.height()+10 );
        if( i > 0 && i < nCount-1);
            painter -> drawText( qrc, Qt::AlignCenter, text );    
        
    }

To copy to clipboard, switch view to plain text mode 

If the drawText() is commented off, the program is ok, or it crashes.
I tried many many times but I failed.
I don't know why and how to solve it.
Maybe my way to use QPainter is not right?


Thanks

Nicho

[Nicho]

Sorry, it's my fault.
The drawLine() before goes out of the range of the device.

Nicho

[anda_skoa]

Btw, QString::sprintf()

Cheers,
_