Hi,
The following is my test codes.

Qt Code: 
  1. char label[MAX_LABEL_LENGTH];
  2.     QList<double> lMajorTicks, lMinorTicks;
  3.     _pEngine -> buildTicks( _oAttribute._fStart, _oAttribute._fEnd, _nMaxMajorTickNumber, lMajorTicks, lMinorTicks );
  4.  
  5.     int nCount = lMajorTicks.count();
  6.     for( int i = 0; i < nCount; i ++ )
  7.     {
  8.         int nPos = (lMajorTicks[i]-_oAttribute._fStart)*_fScale;
  9.         painter -> drawLine( nPos, _oAttribute._nMargin, nPos, _oAttribute._nMargin+_oAttribute._nMajorTickLen );
  10.  
  11.         memset( label, '\0', MAX_LABEL_LENGTH );
  12.         sprintf( label, _oAttribute._sMajorLabelFormat, lMajorTicks[i] );
  13.         QString text = QString::fromStdString( label );
  14.         QRect rc = painter -> boundingRect( QRect(0,0,0,0), Qt::AlignCenter, text );
  15.         QRect qrc = QRect( nPos, _oAttribute._nMargin+_oAttribute._nMajorTickLen+15, rc.width()+10, rc.height()+10 );
  16.         if( i > 0 && i < nCount-1);
  17.             painter -> drawText( qrc, Qt::AlignCenter, text );    
  18.  
  19.     }
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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