Zooming two plots simultaneously

[Ban-chan]

I am currently trying to allow two plots (each with the same starting x and y axes and zoom base) to zoom the same amount regardless of which plot is being zoomed in or out.

Currently I have the code below:

zoomerA = new QwtPlotZoomer(plotA->canvas());
zoomerA->setMaxStackDepth(5);
 
zoomerB = new QwtPlotZoomer(plotB->canvas());
zoomerB->setMaxStackDepth(5);
 
connect(zoomerA,SIGNAL(zoomed(const QwtDoubleRect&)),SLOT(updateBZoom()));
connect(zoomerB,SIGNAL(zoomed(const QwtDoubleRect&)),SLOT(updateAZoom()));

zoomerA = new QwtPlotZoomer(plotA->canvas());
zoomerA->setMaxStackDepth(5);
	
zoomerB = new QwtPlotZoomer(plotB->canvas());
zoomerB->setMaxStackDepth(5);

connect(zoomerA,SIGNAL(zoomed(const QwtDoubleRect&)),SLOT(updateBZoom()));
connect(zoomerB,SIGNAL(zoomed(const QwtDoubleRect&)),SLOT(updateAZoom()));

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void graphPage::updateBZoom()
{
	zoomerB->setZoomStack(zoomerA->zoomStack(),zoomerA->zoomRectIndex());
}
 
void graphPage::updateAZoom()
{	zoomerA->setZoomStack(zoomerB->zoomStack(),zoomerB->zoomRectIndex());	
}

void graphPage::updateBZoom()
{
	zoomerB->setZoomStack(zoomerA->zoomStack(),zoomerA->zoomRectIndex());
}

void graphPage::updateAZoom()
{	zoomerA->setZoomStack(zoomerB->zoomStack(),zoomerB->zoomRectIndex());	
}

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With this code it almost works until you get to the last rect in the stack. setZoomStack fails since zoomStack.count() == maxStackDepth() + 1 at this point.

Is this as simple as changing the code in the setZoomStack function from:

if ( d_data->maxStackDepth >= 0 &&
        int(zoomStack.count()) > d_data->maxStackDepth )
    {
        return;
    }

if ( d_data->maxStackDepth >= 0 &&
        int(zoomStack.count()) > d_data->maxStackDepth )
    {
        return;
    }

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to

if ( d_data->maxStackDepth >= 0 &&
        int(zoomStack.count()) > d_data->maxStackDepth + 1 )
    {
        return;
    }

if ( d_data->maxStackDepth >= 0 &&
        int(zoomStack.count()) > d_data->maxStackDepth + 1 )
    {
        return;
    }

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Or am I going about this completely the wrong way?

[Uwe]

See http://qwt.sourceforge.net/class_qwt...7ba91d6de3a882

By setting an upper limit for the zoomstack depth you can try to avoid effects like scales with tick labels that differ below the significance of a double. Then assigning a complete stack with a deeper depth is not allowed.

I guess you misunderstood of the meaning of QwtPlotZoomer::setMaxStackDepth() ?

Uwe

[Ban-chan]

See http://qwt.sourceforge.net/class_qwt...7ba91d6de3a882

By setting an upper limit for the zoomstack depth you can try to avoid effects like scales with tick labels that differ below the significance of a double. Then assigning a complete stack with a deeper depth is not allowed.

I guess you misunderstood of the meaning of QwtPlotZoomer::setMaxStackDepth() ?

Uwe

Ah alrighty. I simply removed the setMaxStackDepth parameters from my zoomers and all is working fine now.