qwt_wheel.cpp

/* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
 * Qwt Widget Library
 * Copyright (C) 1997   Josef Wilgen
 * Copyright (C) 2002   Uwe Rathmann
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the Qwt License, Version 1.0
 *****************************************************************************/

#include "qwt_wheel.h"
#include "qwt_math.h"
#include "qwt_painter.h"
#include <qevent.h>
#include <qdrawutil.h>
#include <qpainter.h>
#include <qstyle.h>
#include <qstyleoption.h>
#include <qapplication.h>
#include <qdatetime.h>

#if QT_VERSION < 0x040601
#define qFabs(x) ::fabs(x)
#define qFastSin(x) ::sin(x)
#define qExp(x) ::exp(x)
#endif

class QwtWheel::PrivateData
{
public:
    PrivateData():
        orientation( Qt::Horizontal ),
        viewAngle( 175.0 ),
        totalAngle( 360.0 ),
        tickCount( 10 ),
        wheelBorderWidth( 2 ),
        borderWidth( 2 ),
        wheelWidth( 20 ),
        isScrolling( false ),
        mouseOffset( 0.0 ),
        tracking( true ),
        pendingValueChanged( false ),
        updateInterval( 50 ),
        mass( 0.0 ),
        timerId( 0 ),
        speed( 0.0 ),
        mouseValue( 0.0 ),
        flyingValue( 0.0 ),
        minimum( 0.0 ),
        maximum( 100.0 ),
        singleStep( 1.0 ),
        pageStepCount( 1 ),
        stepAlignment( true ),
        value( 0.0 ),
        inverted( false ),
        wrapping( false )
    {
    };

    Qt::Orientation orientation;
    double viewAngle;
    double totalAngle;
    int tickCount;
    int wheelBorderWidth;
    int borderWidth;
    int wheelWidth;

    bool isScrolling;
    double mouseOffset;

    bool tracking;
    bool pendingValueChanged; // when not tracking

    int updateInterval;
    double mass;

    // for the flying wheel effect
    int timerId;
    QTime time;
    double speed;
    double mouseValue;
    double flyingValue;

    double minimum;
    double maximum;

    double singleStep;
    int pageStepCount;
    bool stepAlignment;

    double value;

    bool inverted;
    bool wrapping;
};

//! Constructor
QwtWheel::QwtWheel( QWidget *parent ):
    QWidget( parent )
{
    d_data = new PrivateData;

    setFocusPolicy( Qt::StrongFocus );
    setSizePolicy( QSizePolicy::Preferred, QSizePolicy::Fixed );
    setAttribute( Qt::WA_WState_OwnSizePolicy, false );
}

//! Destructor
QwtWheel::~QwtWheel()
{
    delete d_data;
}

/*!
  \brief En/Disable tracking

  If tracking is enabled (the default), the wheel emits the valueChanged() 
  signal while the wheel is moving. If tracking is disabled, the wheel 
  emits the valueChanged() signal only when the wheel movement is terminated.

  The wheelMoved() signal is emitted regardless id tracking is enabled or not.

  \param enable On/Off
  \sa isTracking()
 */
void QwtWheel::setTracking( bool enable )
{
    d_data->tracking = enable;
}

/*!
  \return True, when tracking is enabled
  \sa setTracking(), valueChanged(), wheelMoved()
*/
bool QwtWheel::isTracking() const
{
    return d_data->tracking;
}

/*!
  \brief Specify the update interval when the wheel is flying

  Default and minimum value is 50 ms.

  \param interval Interval in milliseconds
  \sa updateInterval(), setMass(), setTracking()
*/
void QwtWheel::setUpdateInterval( int interval )
{
    d_data->updateInterval = qMax( interval, 50 );
}

/*!
  \return Update interval when the wheel is flying
  \sa setUpdateInterval(), mass(), isTracking()
 */
int QwtWheel::updateInterval() const
{
    return d_data->updateInterval;
}

/*!
   \brief Mouse press event handler

   Start movement of the wheel. 

   \param event Mouse event
*/
void QwtWheel::mousePressEvent( QMouseEvent *event )
{
    stopFlying();

    d_data->isScrolling = wheelRect().contains( event->pos() );

    if ( d_data->isScrolling )
    {
        d_data->time.start();
        d_data->speed = 0.0;
        d_data->mouseValue = valueAt( event->pos() );
        d_data->mouseOffset = d_data->mouseValue - d_data->value;
        d_data->pendingValueChanged = false;

        Q_EMIT wheelPressed();
    }
}

/*!
   \brief Mouse Move Event handler

   Turn the wheel according to the mouse position

   \param event Mouse event
*/
void QwtWheel::mouseMoveEvent( QMouseEvent *event )
{
    if ( !d_data->isScrolling )
        return;

    double mouseValue = valueAt( event->pos() );

    if ( d_data->mass > 0.0 )