QwtPlotMarker not recognized by autoscale

[HappyCoder]

Hello,

i'm using the QwtPlotMarkers to indicate values that underrange a lower limit.
I have enabled autoscale on yLeft. The top part of my picture shows
the plot during measurement and you can see only a part of the arrows going down.

When use the panner to move the content i can see the arrows.

autoscale and QwtPlotMarker.png

Is there a way to change the autoscale function that it recognized my makers?

Hint:
The probem happens only if the curve where i attached the arrows is also
the curve with the lowest measurement points of all attached curves.
If there are lower y values of any curve the yLeft shows the next decade and the arrows are visible.

Stefan

[Uwe]

marker->setItemAttribute( QwtPlotItem::AutoScale, true );

marker->setItemAttribute( QwtPlotItem::AutoScale, true );

To copy to clipboard, switch view to plain text mode 

The default setting for curves is on, for markers it is off.

Uwe

[HappyCoder]

Hello Uwe,

i add that attribute to my item, but it seems not to work in combination with QwtLogScaleEngine

void PlotManager::setSamplesPressure( int curveId, const QPolygonF &points )
{
    d_data->curvesPressure.at( curveId )->setSamples( points );
 
    // underrange
    if( (points.last().y()<d_data->curveMinP.at( curveId )) )
    {
        // an arrow at a specific position
        QwtPlotMarker *mPos = new QwtPlotMarker( QString("%1 underrange").arg( d_data->curvesPressure.at(curveId)->title().text()));
        mPos->setRenderHint( QwtPlotItem::RenderAntialiased, true );
        mPos->setSymbol( new ArrowSymbol( d_data->curveColor.at( curveId ), true ));
        mPos->setValue( QPointF( points.last().x(), points.last().y() ) );
        mPos->setItemAttribute( QwtPlotItem::Legend, d_data->legendUnderrange.at( curveId ) );
        mPos->setItemAttribute( QwtPlotItem::AutoScale, true );
        d_data->legendUnderrange[ curveId ] = false;
        mPos->attach( d_matrix->plotWidgets.at(0) );
        qDebug() << Q_FUNC_INFO << mPos->boundingRect();
        d_data->lockedUnderrange[curveId] = true;
    }
 
    d_matrix->plotWidgets[0]->replot();
}

void PlotManager::setSamplesPressure( int curveId, const QPolygonF &points )
{
    d_data->curvesPressure.at( curveId )->setSamples( points );

    // underrange
    if( (points.last().y()<d_data->curveMinP.at( curveId )) )
    {
        // an arrow at a specific position
        QwtPlotMarker *mPos = new QwtPlotMarker( QString("%1 underrange").arg( d_data->curvesPressure.at(curveId)->title().text()));
        mPos->setRenderHint( QwtPlotItem::RenderAntialiased, true );
        mPos->setSymbol( new ArrowSymbol( d_data->curveColor.at( curveId ), true ));
        mPos->setValue( QPointF( points.last().x(), points.last().y() ) );
        mPos->setItemAttribute( QwtPlotItem::Legend, d_data->legendUnderrange.at( curveId ) );
        mPos->setItemAttribute( QwtPlotItem::AutoScale, true );
        d_data->legendUnderrange[ curveId ] = false;
        mPos->attach( d_matrix->plotWidgets.at(0) );
        qDebug() << Q_FUNC_INFO << mPos->boundingRect();
        d_data->lockedUnderrange[curveId] = true;
    }

    d_matrix->plotWidgets[0]->replot();
}

To copy to clipboard, switch view to plain text mode 

the debug output is

void PlotManager::setSamplesPressure(int, const QPolygonF&) QRectF(71,0.0001 0x0)

void PlotManager::setSamplesPressure(int, const QPolygonF&) QRectF(71,0.0001 0x0)

To copy to clipboard, switch view to plain text mode 

It seems that the boundingRect() is calculated wrong.

Stefan

[Uwe]

In your case the bounding rectangle is a point at 71, 0.0001 - it should be points.last().
Note that the symbol is not part of the bounding rectangle ( plot coordinates ! ).

Uwe

[HappyCoder]

Hello Uwe,

first of all, thank you for your answer on this sunny day in Bavaria :-)
but I don't understand you answer.

The function setSamplesPressure is called every time if a new measurement values was append to the QPolygonF points.
I check if only the last point (the newest) is under a specific value (underrange) and add an arrow to the plot. So i will
get a lot of arrows on plot as you can see in that picture.

I got a lot of Debug outputs...

from

void PlotManager::setSamplesPressure(int, const QPolygonF&) QRectF(60,0.0001 0x0)
void PlotManager::setSamplesPressure(int, const QPolygonF&) QRectF(61,0.0001 0x0)
void PlotManager::setSamplesPressure(int, const QPolygonF&) QRectF(62,0.0001 0x0)
 
....
 
void PlotManager::setSamplesPressure(int, const QPolygonF&) QRectF(120,0.0001 0x0)
void PlotManager::setSamplesPressure(int, const QPolygonF&) QRectF(121,0.0001 0x0)
void PlotManager::setSamplesPressure(int, const QPolygonF&) QRectF(122,0.0001 0x0)

void PlotManager::setSamplesPressure(int, const QPolygonF&) QRectF(60,0.0001 0x0)
void PlotManager::setSamplesPressure(int, const QPolygonF&) QRectF(61,0.0001 0x0)
void PlotManager::setSamplesPressure(int, const QPolygonF&) QRectF(62,0.0001 0x0)

....

void PlotManager::setSamplesPressure(int, const QPolygonF&) QRectF(120,0.0001 0x0)
void PlotManager::setSamplesPressure(int, const QPolygonF&) QRectF(121,0.0001 0x0)
void PlotManager::setSamplesPressure(int, const QPolygonF&) QRectF(122,0.0001 0x0)

To copy to clipboard, switch view to plain text mode 

My guess was that it will be ignored by autoscale, because it is a point and i don't know why?
It seems that settings the QwtPlotItem::AutoScale to true is not all.

From documentation
"The boundingRect() of the item is included in the autoscaling calculation as long as its width or height is >= 0.0."

1) What is the boundingRect() for you? It is a QRectF around the arrow, or not? If i'm right, why is it a point?
2) What shoud be points.last()?

Thx
Stefan

[Uwe]

1) What is the boundingRect() for you? It is a QRectF around the arrow, or not?

It is a rectangle around the marker position ( = a point ) the one you have assigned with QwtPlotMarker::setValue().

2) What shoud be points.last()?

Don't ask me the code snippet is from your application.

Uwe

[HappyCoder]

Maybe i got what you mean. I add a point to the plot at points.last() with a symbol. The point
itself is within the scale but the symbol is not. Due to that

marker->setItemAttribute( QwtPlotItem::AutoScale, true );

marker->setItemAttribute( QwtPlotItem::AutoScale, true );

To copy to clipboard, switch view to plain text mode 

has no effect in my case.