Distrowatch Example - wrong number of ticks

[bisasatan]

Hello everyone,

I am having some trouble customizing the distrowatch example to my needs. The problem occurs, when fewer than 5 bars are added to the plot - for testing I have removed the last 4 entries in the pagehits struct so it looks like that:

pageHits[] =
    {
        { "Arch", 1114, QColor( "DodgerBlue" ) },
        { "Debian", 1373, QColor( "#d70751" ) },
        { "Fedora", 1638, QColor( "SteelBlue" ) },
        { "Mageia", 1395, QColor( "Indigo" ) },
 
    };

pageHits[] =
    {
        { "Arch", 1114, QColor( "DodgerBlue" ) },
        { "Debian", 1373, QColor( "#d70751" ) },
        { "Fedora", 1638, QColor( "SteelBlue" ) },
        { "Mageia", 1395, QColor( "Indigo" ) },

    };

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In that case, the major ticks and labels get messed up and the output is the following:
distro.JPG


I have already tried to come by this by setting a ScaleDiv with the major ticks needed

QList<double> ticks[QwtScaleDiv::NTickTypes] = 
{
    QList<double>(),
    QList<double>(),
    QList<double>()
    << 0
    << 1
    << 2
    << 3
  };
 
QwtScaleDiv scdiv(0,3, ticks);
this->axisScaleDraw(axis1)->setScaleDiv(scdiv);

QList<double> ticks[QwtScaleDiv::NTickTypes] = 
{
    QList<double>(),
    QList<double>(),
    QList<double>()
    << 0
    << 1
    << 2
    << 3
  };

QwtScaleDiv scdiv(0,3, ticks);
this->axisScaleDraw(axis1)->setScaleDiv(scdiv);

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"this" being the plot and "axis1" being the xBottom-axis.
This works at first (qDebug()<<scdiv.ticks(2); gives "(0, 1, 2, 3) "), but after the replot the qDebug gives "(0, 0.5, 1, 1.5, 2, 2.5, 3) "

I have already looked into qwtscaleDiv sources, but was not able to find my mistake - what am I missing?
I am using Qwt 6.1
Thanks in advance

[Uwe]

Instead of:

this->axisScaleDraw(axis1)->setScaleDiv(scdiv);

this->axisScaleDraw(axis1)->setScaleDiv(scdiv);

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do

this->setAxisScaleDiv( axis1, scldiv );

this->setAxisScaleDiv( axis1, scldiv );

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The upper way of assigning the ticks is behind the back of the plot and will have a temporary effect only - until the next call of replot ( or updateAxes() ). The second way is known to the plot and also disables autoscaling.

Uwe