qwt_wheel.cpp

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/* -*- 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;
};

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

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

QwtWheel::~QwtWheel()
{
    delete d_data;
}

void QwtWheel::setTracking( bool enable )
{
    d_data->tracking = enable;
}

bool QwtWheel::isTracking() const
{
    return d_data->tracking;
}

void QwtWheel::setUpdateInterval( int interval )
{
    d_data->updateInterval = qMax( interval, 50 );
}

int QwtWheel::updateInterval() const
{
    return d_data->updateInterval;
}

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();
    }
}

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

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

    if ( d_data->mass > 0.0 )
    {
        double ms = d_data->time.restart();

        // the interval when mouse move events are posted are somehow
        // random. To avoid unrealistic speed values we limit ms

        ms = qMax( ms, 5.0 );

        d_data->speed = ( mouseValue - d_data->mouseValue ) / ms;
    }
    
    d_data->mouseValue = mouseValue; 

    double value = boundedValue( mouseValue - d_data->mouseOffset );
    if ( d_data->stepAlignment )
        value = alignedValue( value );
        
    if ( value != d_data->value )
    {
        d_data->value = value;

        update();

        Q_EMIT wheelMoved( d_data->value );

        if ( d_data->tracking )
            Q_EMIT valueChanged( d_data->value );
        else
            d_data->pendingValueChanged = true;
    }
}

void QwtWheel::mouseReleaseEvent( QMouseEvent *event )
{
    Q_UNUSED( event );

    if ( !d_data->isScrolling )
        return;

    d_data->isScrolling = false;

    bool startFlying = false;

    if ( d_data->mass > 0.0 )
    {
        const int ms = d_data->time.elapsed();
        if ( ( qFabs( d_data->speed ) > 0.0 ) && ( ms < 50 ) )
            startFlying = true;
    }

    if ( startFlying )
    {
        d_data->flyingValue = 
            boundedValue( d_data->mouseValue - d_data->mouseOffset );

        d_data->timerId = startTimer( d_data->updateInterval );
    }
    else
    {
        if ( d_data->pendingValueChanged )
            Q_EMIT valueChanged( d_data->value );
    }

    d_data->pendingValueChanged = false;
    d_data->mouseOffset = 0.0;

    Q_EMIT wheelReleased();
}

void QwtWheel::timerEvent( QTimerEvent *event )
{
    if ( event->timerId() != d_data->timerId )
    {
        QWidget::timerEvent( event );
        return;
    }

    d_data->speed *= qExp( -d_data->updateInterval * 0.001 / d_data->mass );

    d_data->flyingValue += d_data->speed * d_data->updateInterval;
    d_data->flyingValue = boundedValue( d_data->flyingValue );

    double value = d_data->flyingValue;
    if ( d_data->stepAlignment )
        value = alignedValue( value );

    if ( qFabs( d_data->speed ) < 0.001 * d_data->singleStep )
    {
        // stop if d_data->speed < one step per second
        stopFlying();
    }

    if ( value != d_data->value )
    {
        d_data->value = value;
        update();

        if ( d_data->tracking || d_data->timerId == 0 )
            Q_EMIT valueChanged( d_data->value );
    }
}


void QwtWheel::wheelEvent( QWheelEvent *event )
{
    if ( !wheelRect().contains( event->pos() ) )
    {
        event->ignore();
        return;
    }

    if ( d_data->isScrolling )
        return;

    stopFlying();

    double increment = 0.0;

    if ( ( event->modifiers() & Qt::ControlModifier) || 
        ( event->modifiers() & Qt::ShiftModifier ) )
    {
        // one page regardless of delta
        increment = d_data->singleStep * d_data->pageStepCount;
        if ( event->delta() < 0 )
            increment = -increment;
    }
    else
    {
        const int numSteps = event->delta() / 120;
        increment = d_data->singleStep * numSteps;
    }

    if ( d_data->orientation == Qt::Vertical && d_data->inverted )
        increment = -increment;

    double value = boundedValue( d_data->value + increment );

    if ( d_data->stepAlignment )
        value = alignedValue( value );

    if ( value != d_data->value )
    {
        d_data->value = value;
        update();

        Q_EMIT valueChanged( d_data->value );
        Q_EMIT wheelMoved( d_data->value );
    }
}

void QwtWheel::keyPressEvent( QKeyEvent *event )
{
    if ( d_data->isScrolling )
    {
        // don't interfere mouse scrolling
        return;
    }

    double value = d_data->value;
    double increment = 0.0;

    switch ( event->key() )
    {
        case Qt::Key_Down:
        {
            if ( d_data->orientation == Qt::Vertical && d_data->inverted )
                increment = d_data->singleStep;
            else
                increment = -d_data->singleStep;

            break;
        }
        case Qt::Key_Up:
        {
            if ( d_data->orientation == Qt::Vertical && d_data->inverted )
                increment = -d_data->singleStep;
            else
                increment = d_data->singleStep;

            break;
        }
        case Qt::Key_Left:
        {
            if ( d_data->orientation == Qt::Horizontal )
            {
                if ( d_data->inverted )
                    increment = d_data->singleStep;
                else
                    increment = -d_data->singleStep;
            }
            break;
        }
        case Qt::Key_Right:
        {
            if ( d_data->orientation == Qt::Horizontal )
            {
                if ( d_data->inverted )
                    increment = -d_data->singleStep;
                else
                    increment = d_data->singleStep;
            }
            break;
        }
        case Qt::Key_PageUp:
        {
            increment = d_data->pageStepCount * d_data->singleStep;
            break;
        }
        case Qt::Key_PageDown:
        {
            increment = -d_data->pageStepCount * d_data->singleStep;
            break;
        }
        case Qt::Key_Home:
        {
            value = d_data->minimum;
            break;
        }
        case Qt::Key_End:
        {
            value = d_data->maximum;
            break;
        }
        default:;
        {
            event->ignore();
        }
    }

    if ( event->isAccepted() )
        stopFlying();
    
    if ( increment != 0.0 )
    {
        value = boundedValue( d_data->value + increment );

        if ( d_data->stepAlignment )
            value = alignedValue( value );
    }

    if ( value != d_data->value )
    {
        d_data->value = value;
        update();

        Q_EMIT valueChanged( d_data->value );
        Q_EMIT wheelMoved( d_data->value );
    }
}

void QwtWheel::setTickCount( int count )
{
    count = qBound( 6, count, 50 );

    if ( count != d_data->tickCount )
    {
        d_data->tickCount = qBound( 6, count, 50 );
        update();
    }
}

int QwtWheel::tickCount() const
{
    return d_data->tickCount;
}

void QwtWheel::setWheelBorderWidth( int borderWidth )
{
    const int d = qMin( width(), height() ) / 3;
    borderWidth = qMin( borderWidth, d );
    d_data->wheelBorderWidth = qMax( borderWidth, 1 );
    update();
}

int QwtWheel::wheelBorderWidth() const
{
    return d_data->wheelBorderWidth;
}

void QwtWheel::setBorderWidth( int width )
{
    d_data->borderWidth = qMax( width, 0 );
    update();
}

int QwtWheel::borderWidth() const
{
    return d_data->borderWidth;
}

QRect QwtWheel::wheelRect() const
{
    const int bw = d_data->borderWidth;
    return contentsRect().adjusted( bw, bw, -bw, -bw );
}

void QwtWheel::setTotalAngle( double angle )
{
    if ( angle < 0.0 )
        angle = 0.0;

    d_data->totalAngle = angle;
    update();
}

double QwtWheel::totalAngle() const
{
    return d_data->totalAngle;
}

void QwtWheel::setOrientation( Qt::Orientation orientation )
{
    if ( d_data->orientation == orientation )
        return;

    if ( !testAttribute( Qt::WA_WState_OwnSizePolicy ) )
    {
        QSizePolicy sp = sizePolicy();
        sp.transpose();
        setSizePolicy( sp );

        setAttribute( Qt::WA_WState_OwnSizePolicy, false );
    }

    d_data->orientation = orientation;
    update();
}

Qt::Orientation QwtWheel::orientation() const
{
    return d_data->orientation;
}

void QwtWheel::setViewAngle( double angle )
{
    d_data->viewAngle = qBound( 10.0, angle, 175.0 );
    update();
}

double QwtWheel::viewAngle() const
{
    return d_data->viewAngle;
}

double QwtWheel::valueAt( const QPoint &pos ) const
{
    const QRectF rect = wheelRect();

    double w, dx;
    if ( d_data->orientation == Qt::Vertical )
    {
        w = rect.height();
        dx = rect.top() - pos.y();
    }
    else
    {
        w = rect.width();
        dx = pos.x() - rect.left();
    }

    if ( w == 0.0 )
        return 0.0;

    if ( d_data->inverted )
    {
        dx = w - dx;
    }

    // w pixels is an arc of viewAngle degrees,
    // so we convert change in pixels to change in angle
    const double ang = dx * d_data->viewAngle / w;

    // value range maps to totalAngle degrees,
    // so convert the change in angle to a change in value
    const double val = ang * ( maximum() - minimum() ) / d_data->totalAngle;

    return val;
}

void QwtWheel::paintEvent( QPaintEvent *event )
{
    QPainter painter( this );
    painter.setClipRegion( event->region() );

    QStyleOption opt;
    opt.init(this);
    style()->drawPrimitive(QStyle::PE_Widget, &opt, &painter, this);

    qDrawShadePanel( &painter, 
        contentsRect(), palette(), true, d_data->borderWidth );

    drawWheelBackground( &painter, wheelRect() );
    drawTicks( &painter, wheelRect() );

    if ( hasFocus() )
        QwtPainter::drawFocusRect( &painter, this );
}

void QwtWheel::drawWheelBackground( 
    QPainter *painter, const QRectF &rect )
{
    painter->save();

    QPalette pal = palette();

    //  draw shaded background
    QLinearGradient gradient( rect.topLeft(), 
        ( d_data->orientation == Qt::Horizontal ) ? rect.topRight() : rect.bottomLeft() );
    gradient.setColorAt( 0.0, pal.color( QPalette::Button ) );
    gradient.setColorAt( 0.2, pal.color( QPalette::Midlight ) );
    gradient.setColorAt( 0.7, pal.color( QPalette::Mid ) );
    gradient.setColorAt( 1.0, pal.color( QPalette::Dark ) );

    painter->fillRect( rect, gradient );

    // draw internal border

    const QPen lightPen( palette().color( QPalette::Light ), 
        d_data->wheelBorderWidth, Qt::SolidLine, Qt::FlatCap );
    const QPen darkPen( pal.color( QPalette::Dark ), 
        d_data->wheelBorderWidth, Qt::SolidLine, Qt::FlatCap );

    const double bw2 = 0.5 * d_data->wheelBorderWidth;

    if ( d_data->orientation == Qt::Horizontal )
    {
        painter->setPen( lightPen );
        painter->drawLine( QPointF( rect.left(), rect.top() + bw2 ), 
            QPointF( rect.right(), rect.top() + bw2 ) );

        painter->setPen( darkPen );
        painter->drawLine( QPointF( rect.left(), rect.bottom() - bw2 ), 
            QPointF( rect.right(), rect.bottom() - bw2 ) );
    }
    else // Qt::Vertical
    {
        painter->setPen( lightPen );
        painter->drawLine( QPointF( rect.left() + bw2, rect.top() ), 
            QPointF( rect.left() + bw2, rect.bottom() ) );

        painter->setPen( darkPen );
        painter->drawLine( QPointF( rect.right() - bw2, rect.top() ), 
            QPointF( rect.right() - bw2, rect.bottom() ) );
    }

    painter->restore();
}

void QwtWheel::drawTicks( QPainter *painter, const QRectF &rect )
{
    const double range = d_data->maximum - d_data->minimum;

    if ( range == 0.0 || d_data->totalAngle == 0.0 )
    {
        return;
    }

    const QPen lightPen( palette().color( QPalette::Light ), 
        0, Qt::SolidLine, Qt::FlatCap );
    const QPen darkPen( palette().color( QPalette::Dark ), 
        0, Qt::SolidLine, Qt::FlatCap );

    const double cnvFactor = qAbs( d_data->totalAngle / range );
    const double halfIntv = 0.5 * d_data->viewAngle / cnvFactor;
    const double loValue = value() - halfIntv;
    const double hiValue = value() + halfIntv;
    const double tickWidth = 360.0 / double( d_data->tickCount ) / cnvFactor;
    const double sinArc = qFastSin( d_data->viewAngle * M_PI / 360.0 );

    if ( d_data->orientation == Qt::Horizontal )
    {
        const double radius = rect.width() * 0.5;

        double l1 = rect.top() + d_data->wheelBorderWidth;
        double l2 = rect.bottom() - d_data->wheelBorderWidth - 1;

        // draw one point over the border if border > 1
        if ( d_data->wheelBorderWidth > 1 )
        {
            l1--;
            l2++;
        }

        const double maxpos = rect.right() - 2;
        const double minpos = rect.left() + 2;

        // draw tick marks
        for ( double tickValue = ::ceil( loValue / tickWidth ) * tickWidth;
            tickValue < hiValue; tickValue += tickWidth )
        {
            const double angle = qwtRadians( tickValue - value() );
            const double s = qFastSin( angle * cnvFactor );

            const double off = radius * ( sinArc + s ) / sinArc;

            double tickPos;
            if ( d_data->inverted ) 
                tickPos = rect.left() + off;
            else
                tickPos = rect.right() - off;

            if ( ( tickPos <= maxpos ) && ( tickPos > minpos ) )
            {
                painter->setPen( darkPen );
                painter->drawLine( QPointF( tickPos - 1 , l1 ), 
                    QPointF( tickPos - 1,  l2 ) );
                painter->setPen( lightPen );
                painter->drawLine( QPointF( tickPos, l1 ), 
                    QPointF( tickPos, l2 ) );
            }
        }
    }
    else // Qt::Vertical
    {
        const double radius = rect.height() * 0.5;

        double l1 = rect.left() + d_data->wheelBorderWidth;
        double l2 = rect.right() - d_data->wheelBorderWidth - 1;

        if ( d_data->wheelBorderWidth > 1 )
        {
            l1--;
            l2++;
        }

        const double maxpos = rect.bottom() - 2;
        const double minpos = rect.top() + 2;

        for ( double tickValue = ::ceil( loValue / tickWidth ) * tickWidth;
            tickValue < hiValue; tickValue += tickWidth )
        {
            const double angle = qwtRadians( tickValue - value() );
            const double s = qFastSin( angle * cnvFactor );

            const double off = radius * ( sinArc + s ) / sinArc;

            double tickPos;

            if ( d_data->inverted )
                tickPos = rect.bottom() - off;
            else
                tickPos = rect.top() + off;

            if ( ( tickPos <= maxpos ) && ( tickPos > minpos ) )
            {
                painter->setPen( darkPen );
                painter->drawLine( QPointF( l1, tickPos - 1 ), 
                    QPointF( l2, tickPos - 1 ) );
                painter->setPen( lightPen );
                painter->drawLine( QPointF( l1, tickPos ), 
                    QPointF( l2, tickPos ) );
            }
        }
    }
}

void QwtWheel::setWheelWidth( int width )
{
    d_data->wheelWidth = width;
    update();
}

int QwtWheel::wheelWidth() const
{
    return d_data->wheelWidth;
}

QSize QwtWheel::sizeHint() const
{
    const QSize hint = minimumSizeHint();
    return hint.expandedTo( QApplication::globalStrut() );
}

QSize QwtWheel::minimumSizeHint() const
{
    QSize sz( 3 * d_data->wheelWidth + 2 * d_data->borderWidth,
        d_data->wheelWidth + 2 * d_data->borderWidth );
    if ( d_data->orientation != Qt::Horizontal )
        sz.transpose();

    return sz;
}

void QwtWheel::setSingleStep( double stepSize )
{
    d_data->singleStep = qMax( stepSize, 0.0 );
}

double QwtWheel::singleStep() const
{
    return d_data->singleStep;
}

void QwtWheel::setStepAlignment( bool on )
{
    if ( on != d_data->stepAlignment )
    {
        d_data->stepAlignment = on;
    }
}

bool QwtWheel::stepAlignment() const
{
    return d_data->stepAlignment;
}

void QwtWheel::setPageStepCount( int count )
{
    d_data->pageStepCount = qMax( 0, count );
}

int QwtWheel::pageStepCount() const
{
    return d_data->pageStepCount;
}

void QwtWheel::setRange( double min, double max )
{
    max = qMax( min, max );

    if ( d_data->minimum == min && d_data->maximum == max )
        return;

    d_data->minimum = min;
    d_data->maximum = max;

    if ( d_data->value < min || d_data->value > max )
    {
        d_data->value = qBound( min, d_data->value, max );

        update();
        Q_EMIT valueChanged( d_data->value );
    }
}
void QwtWheel::setMinimum( double value )
{
    setRange( value, maximum() );
}

double QwtWheel::minimum() const
{
    return d_data->minimum;
}

void QwtWheel::setMaximum( double value )
{
    setRange( minimum(), value );
}

double QwtWheel::maximum() const
{
    return d_data->maximum;
}

void QwtWheel::setValue( double value )
{
    stopFlying();
    d_data->isScrolling = false;

    value = qBound( d_data->minimum, value, d_data->maximum );

    if ( d_data->value != value )
    {
        d_data->value = value;

        update();
        Q_EMIT valueChanged( d_data->value );
    }
}

double QwtWheel::value() const
{
    return d_data->value;
}

void QwtWheel::setInverted( bool on )
{
    if ( d_data->inverted != on )
    {
        d_data->inverted = on;
        update();
    }
}

bool QwtWheel::isInverted() const
{
    return d_data->inverted;
}

void QwtWheel::setWrapping( bool on )
{
    d_data->wrapping = on;
}

bool QwtWheel::wrapping() const
{
    return d_data->wrapping;
}

void QwtWheel::setMass( double mass )
{
    if ( mass < 0.001 )
    {
        d_data->mass = 0.0;
    }
    else
    {
        d_data->mass = qMin( 100.0, mass );
    }

    if ( d_data->mass <= 0.0 )
        stopFlying();
}

double QwtWheel::mass() const
{
    return d_data->mass;
}

void QwtWheel::stopFlying()
{
    if ( d_data->timerId != 0 )
    {
        killTimer( d_data->timerId );
        d_data->timerId = 0;
        d_data->speed = 0.0;
    }
}

double QwtWheel::boundedValue( double value ) const
{
    const double range = d_data->maximum - d_data->minimum;
    
    if ( d_data->wrapping && range >= 0.0 )
    {
        if ( value < d_data->minimum )
        {
            value += ::ceil( ( d_data->minimum - value ) / range ) * range;
        }       
        else if ( value > d_data->maximum )
        {
            value -= ::ceil( ( value - d_data->maximum ) / range ) * range;
        }
    }
    else
    {
        value = qBound( d_data->minimum, value, d_data->maximum );
    }

    return value;
}

double QwtWheel::alignedValue( double value ) const
{
    const double stepSize = d_data->singleStep;

    if ( stepSize > 0.0 )
    {
        value = d_data->minimum +
            qRound( ( value - d_data->minimum ) / stepSize ) * stepSize;

        if ( stepSize > 1e-12 )
        {
            if ( qFuzzyCompare( value + 1.0, 1.0 ) )
            {
                // correct rounding error if value = 0
                value = 0.0;
            }
            else if ( qFuzzyCompare( value, d_data->maximum ) )
            {
                // correct rounding error at the border
                value = d_data->maximum;
            }
        }
    }       

    return value;
}