Double-Click Zoom out feature

[novackb]

I'm attempting to implement a double-click zoom out feature to mimic Matlab behavior. I've successfully implemented a custom QwtPickerClickPointMachine which catches the double-click of mouse button 1 and I can perform the necessary actions.

My problem is I still need the zoom capability provided in the QwtPlotZoomer class which I think uses the QwtPickerDragRectMachine as the QwtPickerMachine. When I use the setStateMachine() method on the zoomer instance it replaces the current QwtPickerMachine with my custom PickerMachine, which is exactly as I would expect based on documentation. So I gain my double-click functionality but lose the zoom functionality.

So my question is how do I use the functionality provided in my custom Picker Machine and the QwtPickerDragRectMachine at the same time within my QwtPlotZoomer? Or is there a much easier approach that I'm just overlooking.

Any advice is appreciated.
Thanks!

FYI: working with qwt6.0.0_rc5

[FelixB]

why don't you use a QwtPlotZoomer and call "zoom(0)" when you want to zoom out? your approach sounds a bit complicated to me...

[novackb]

I agree it seems complicated, but customer has requested the double-click zoom out capability because their users are so familiar with current Matlab plot functionality.

I am already using a zoomer that I pulled and modified slightly from one of the examples:

//   LeftButton for the zooming
//   MidButton for the panning
//   RightButton: zoom out by 1
//   Ctrl+RightButton: zoom out to full size
 
  QwtPlotZoomer* zoomer = new QwtPlotZoomer(canvas());
  zoomer->setRubberBandPen(QColor(Qt::red));
  zoomer->setTrackerPen(QColor(Qt::red));
  zoomer->setMousePattern(QwtEventPattern::MouseSelect2,
                          Qt::RightButton, Qt::ControlModifier);
  zoomer->setMousePattern(QwtEventPattern::MouseSelect3,
                          Qt::RightButton);

//   LeftButton for the zooming
//   MidButton for the panning
//   RightButton: zoom out by 1
//   Ctrl+RightButton: zoom out to full size

  QwtPlotZoomer* zoomer = new QwtPlotZoomer(canvas());
  zoomer->setRubberBandPen(QColor(Qt::red));
  zoomer->setTrackerPen(QColor(Qt::red));
  zoomer->setMousePattern(QwtEventPattern::MouseSelect2,
                          Qt::RightButton, Qt::ControlModifier);
  zoomer->setMousePattern(QwtEventPattern::MouseSelect3,
                          Qt::RightButton);

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Now I'm trying to somehow 'capture' a Qt::LeftButton double-click which will then use zoom(0) as you mention.

[FelixB]

zooming out via double click is nothing complicated just your ideas with statemachines etc...

install an event filter on your canvas and react on the doubleclick event. that's the way I do it...

[Uwe]

Now I'm trying to somehow 'capture' a Qt::LeftButton double-click which will then use zoom(0) as you mention.

class YourZoomer: public QwtPlotZoomer
{
    YourZoomer( ... )
    {
        // disable MouseSelect2 ( default for zooming out )
        setMousePattern(QwtEventPattern::MouseSelect2, Qt::NoButton );
    }
 ...
    virtual void widgetMouseDoubleClickEvent( QMouseEvent *me )
    {
        if ( me->button() == ... )
          zoom( 0 );
    }
};

class YourZoomer: public QwtPlotZoomer
{
    YourZoomer( ... )
    {
        // disable MouseSelect2 ( default for zooming out )
        setMousePattern(QwtEventPattern::MouseSelect2, Qt::NoButton );
    }
 ...
    virtual void widgetMouseDoubleClickEvent( QMouseEvent *me )
    {
        if ( me->button() == ... )
          zoom( 0 );
    }
};

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Untested,
Uwe