making a RubberBand for selecting an area

**Alex22** · 12th July 2016, 20:22

Hi,

I need to select an area with a RubberBand that returns QRectF::top, QRectF::bottom, QRectF::left, QRectF::right. For this I do this:

Qt Code:

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

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

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and by using zoomed (const QRectF &rect) signal, rect can be obtain.

Qt Code:

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connect(zoomer, zoomed (QRectF), this, slot_pos(QRectF));
 
void MyClass::slot_pos(QRectF pos)
{
    qDebug() << pos.top << pos.bottom << pos.left << pos.right;
}

connect(zoomer, zoomed (QRectF), this, slot_pos(QRectF));

void MyClass::slot_pos(QRectF pos)
{
    qDebug() << pos.top << pos.bottom << pos.left << pos.right;
}

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now I have this problem:
Mouse LeftButton causes zooming. I want to to select an area with a RubberBand without zooming by for example LeftButton +ctrl.

**Uwe** · 13th July 2016, 06:37

QwtPlotZoomer - zooming = QwtPlotPicker;

The keys or mouse actions being used for starting,moving and terminating the selection is customizable.

Uwe

**Alex22** · 13th July 2016, 16:01

Thanks Uwe, I used this and nothing happens and no RubberBand has been appeared:

Qt Code:

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QwtPlotPicker* picker= new QwtPlotPicker( canvas );
 
    picker->setRubberBandPen( QColor( Qt::red ) );
    picker->setTrackerPen( QColor( Qt::green ) );
    picker->setMousePattern( QwtEventPattern::MouseSelect2,
        Qt::RightButton, Qt::ControlModifier );

QwtPlotPicker* picker= new QwtPlotPicker( canvas );

    picker->setRubberBandPen( QColor( Qt::red ) );
    picker->setTrackerPen( QColor( Qt::green ) );
    picker->setMousePattern( QwtEventPattern::MouseSelect2,
        Qt::RightButton, Qt::ControlModifier );

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**Uwe** · 13th July 2016, 19:43

This is your initial sequence to get something started:

Qt Code:

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QwtPlotPicker* picker= new QwtPlotPicker( plot->canvas() );
picker->setStateMachine( new QwtPickerDragRectMachine() );
picker->setRubberBand( QwtPlotPicker::RectRubberBand );
picker->setRubberBandPen( QColor( Qt::red ) );
picker->setTrackerPen( QColor( Qt::green ) );
picker->setTrackerMode( QwtPlotPicker::ActiveOnly );
 
connect( picker, SIGNAL( selected( const QRectF &rect ) ), ... );

QwtPlotPicker* picker= new QwtPlotPicker( plot->canvas() );
picker->setStateMachine( new QwtPickerDragRectMachine() );
picker->setRubberBand( QwtPlotPicker::RectRubberBand );
picker->setRubberBandPen( QColor( Qt::red ) );
picker->setTrackerPen( QColor( Qt::green ) );
picker->setTrackerMode( QwtPlotPicker::ActiveOnly );

connect( picker, SIGNAL( selected( const QRectF &rect ) ), ... );

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Choose the type of state machine you like and check its docs, what type of event patterns are used by it. In case of the rectangle machines it is using QwtEventPattern::MouseSelect1 and QwtEventPattern::KeySelect1 - what means changing QwtEventPattern::MouseSelect2 ( like in your code snippet ) will have no effect.

Uwe