How does works QwtScaleDraw::extent()?

why if I call extent() from a QwtScaleDraw object the result is less then if I call from QwtScaleWidget::scaleDraw()?
what do I need to setup in QwtScaleDraw object to make extent() return the sam as QwtScaleWidget::scaleDraw().extent()?

her is the code snippet:

Code:

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// code to test extent() method
 
        QFont f;
 
        QwtScaleDiv *sd = new QwtScaleDiv(-60, 0);
        QList< double > ld;
 
        double q;
        for(q=-60.0; q<=0.0; q+=5.0)
            ld.append(q);
 
        sd->setTicks(QwtScaleDiv::MajorTick, ld);
 
        QwtScaleDraw *sdraw = new QwtScaleDraw;
        sdraw->setScaleDiv(*sd);
        qDebug("extent 1 %f", sdraw->extent(f)); // here is 23.0
 
        QwtScaleWidget *w = new QwtScaleWidget(this);
        w->setScaleDiv(*sd);
 
        qDebug("extent 2 %f", w->scaleDraw()->extent(f)); // here is 31.0

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bets regards
max

Different fonts, different sizes.

Uwe

why do you say "different font"?

I pass the same font to extent() calls: look at lines 16 and 21.
If it uses another font to calculate extent why to pass font as parameter, and how to set the font in QwtScaleDraw?

best regards
max

Quote:

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Originally Posted by mastupristi

I pass the same font to extent() calls: look at lines 16 and 21.

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True, but anyway: Qwt is open source, why not simply checking the code.

Uwe

that's right.

browsing the code I can see that the problem is the orientation, and if I set the right orientation the value are the same:

Code:

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//
        QwtScaleDiv *sd = new QwtScaleDiv(-60, 0);
        QList< double > ld;
 
        double q;
        for(q=-60.0; q<=0.0; q+=5.0)
            ld.append(q);
 
        sd->setTicks(QwtScaleDiv::MajorTick, ld);
 
        QwtScaleWidget *w = new QwtScaleWidget;
        w->setScaleDiv(*sd);
 
        qDebug("orient w %d", w->scaleDraw()->orientation()); // here is Qt::Vertical
        qDebug("extent 2 %f", w->scaleDraw()->extent(w->font())); // is 31.0
 
        QwtScaleDraw *sdraw = new QwtScaleDraw;
        sdraw->setScaleDiv(*sd);
        qDebug("orient sdraw %d", sdraw->orientation()); // here is Qt:Horizontal
        sdraw->setAlignment(QwtScaleDraw::LeftScale); // Change to vertical
 
        qDebug("extent 1 %f", sdraw->extent(w->font())); // here is also 31.0

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best regards
max