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gapezoomableslider.h

//Code in this file was primarily written by Randal Leistikow randal@ccrma.stanford.edu

#ifndef _GAPE_ZOOMABLE_SLIDER_H
#define _GAPE_ZOOMABLE_SLIDER_H

#include <qslider.h>
#include <qevent.h>

// names of keys are in Qt's qnamespace.h
#define ZOOMABLESLIDER_DEFAULT_KEY             Qt::Key_Shift
#define ZOOMABLESLIDER_DEFAULT_ZOOM_PERCENT    5.0
#define ZOOMABLESLIDER_DEFAULT_ARROW_PERCENT   0.05

class GapeZoomableSlider : public QSlider
{
  Q_OBJECT

  // private data
  int    d_minValue, d_maxValue, d_key;
  double d_minMaxScalar, d_arrowScalar;


 public:
  GapeZoomableSlider ( int minValue, int maxValue,
          int pageStep, int value,
          Orientation orientation,
          QWidget * parent,
          const char * name=0,
          int zoomKey = ZOOMABLESLIDER_DEFAULT_KEY,
          double zoomPercent  = ZOOMABLESLIDER_DEFAULT_ZOOM_PERCENT,
          double arrowPercent = ZOOMABLESLIDER_DEFAULT_ARROW_PERCENT )
   : QSlider( minValue, maxValue, pageStep, value, orientation, parent, name ),
     d_minValue( minValue ),
     d_maxValue( maxValue ),
     d_key( zoomKey ),
     d_minMaxScalar( zoomPercent / 100.0 ),
     d_arrowScalar( arrowPercent / 100.0 )

   {
      setFocusPolicy( QWidget::StrongFocus );
   }


  ~GapeZoomableSlider() {}


  void keyPressEvent( QKeyEvent *e )
  {
    // for zoom
    if( e->key() == d_key )  zoomIn();

    // for arrow keys
    if( (e->key() == Qt::Key_Down || e->key() == Qt::Key_Right) &&
    value() < d_maxValue )  arrowIncrease();

    if( (e->key() == Qt::Key_Up || e->key() == Qt::Key_Left) &&
    value() > d_minValue )  arrowDecrease();

  }


  void keyReleaseEvent( QKeyEvent *e )
  {
    if(e->key() == d_key)  zoomOut();
  }


  void focusOutEvent( QFocusEvent *e )
  {
      zoomOut();
  }


  private:
    void zoomIn()
    {
    int minMaxOffset = (int)( value() * d_minMaxScalar );
    int possibleMax = value() + minMaxOffset;
    int possibleMin = value() - minMaxOffset;

    setMaxValue( (possibleMax > d_maxValue) ? d_maxValue : possibleMax );
    setMinValue( (possibleMin < d_minValue) ? d_minValue : possibleMin );
    }

    void zoomOut()
    {
    setMaxValue( d_maxValue );
    setMinValue( d_minValue );
    }


    void arrowIncrease()
    {
      int possibleNewValue = value() + (int)(value() * d_arrowScalar);
      setValue( (possibleNewValue >= d_maxValue) ?
        d_maxValue : possibleNewValue );
      emit sliderMoved( value() );
    }

    void arrowDecrease()
    {
      int possibleNewValue = value() - (int)(value() * d_arrowScalar);
      setValue( (possibleNewValue <= d_minValue) ?
        d_minValue : possibleNewValue );
      emit sliderMoved( value() );
    }


};


#endif

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