qwt_knob.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 <qpainter.h>
#include <qpalette.h>
#include <qstyle.h>
#include <qevent.h>
#include "qwt_round_scale_draw.h"
#include "qwt_knob.h"
#include "qwt_math.h"
#include "qwt_painter.h"
#include "qwt_paint_buffer.h"

class QwtKnob::PrivateData
{
public:
    PrivateData()
    {
        angle = 0.0;
        nTurns = 0.0;
        borderWidth = 2;
        borderDist = 4;
        totalAngle = 270.0;
        scaleDist = 4;
        symbol = Line;
        maxScaleTicks = 11;
        knobWidth = 50;
        dotWidth = 8;
    }

    int borderWidth;
    int borderDist;
    int scaleDist;
    int maxScaleTicks;
    int knobWidth;
    int dotWidth;

    Symbol symbol;
    double angle;
    double totalAngle;
    double nTurns;

    QRect knobRect; // bounding rect of the knob without scale
};

QwtKnob::QwtKnob(QWidget* parent): 
    QwtAbstractSlider(Qt::Horizontal, parent)
{
    initKnob();
}

#if QT_VERSION < 0x040000

QwtKnob::QwtKnob(QWidget* parent, const char *name): 
    QwtAbstractSlider(Qt::Horizontal, parent)
{
    setName(name);
    initKnob();
}
#endif

void QwtKnob::initKnob()
{
#if QT_VERSION < 0x040000
    setWFlags(Qt::WNoAutoErase);
#endif

    d_data = new PrivateData;

    setScaleDraw(new QwtRoundScaleDraw());

    setUpdateTime(50);
    setTotalAngle( 270.0 );
    recalcAngle();
    setSizePolicy(QSizePolicy(QSizePolicy::Minimum, QSizePolicy::Minimum));

    setRange(0.0, 10.0, 1.0);
    setValue(0.0);
}

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

void QwtKnob::setSymbol(QwtKnob::Symbol s)
{
    if ( d_data->symbol != s )
    {
        d_data->symbol = s;
        update();
    }
}

QwtKnob::Symbol QwtKnob::symbol() const
{
    return d_data->symbol;
}

void QwtKnob::setTotalAngle (double angle)
{
    if (angle < 10.0)
       d_data->totalAngle = 10.0;
    else
       d_data->totalAngle = angle;

    scaleDraw()->setAngleRange( -0.5 * d_data->totalAngle, 
        0.5 * d_data->totalAngle);
    layoutKnob();
}

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

void QwtKnob::setScaleDraw(QwtRoundScaleDraw *scaleDraw)
{
    setAbstractScaleDraw(scaleDraw);
    setTotalAngle(d_data->totalAngle);
}

const QwtRoundScaleDraw *QwtKnob::scaleDraw() const
{
    return (QwtRoundScaleDraw *)abstractScaleDraw();
}

QwtRoundScaleDraw *QwtKnob::scaleDraw()
{
    return (QwtRoundScaleDraw *)abstractScaleDraw();
}

void QwtKnob::drawKnob(QPainter *painter, const QRect &r)
{
#if QT_VERSION < 0x040000
    const QBrush buttonBrush = colorGroup().brush(QColorGroup::Button);
    const QColor buttonTextColor = colorGroup().buttonText();
    const QColor lightColor = colorGroup().light();
    const QColor darkColor = colorGroup().dark();
#else
    const QBrush buttonBrush = palette().brush(QPalette::Button);
    const QColor buttonTextColor = palette().color(QPalette::ButtonText);
    const QColor lightColor = palette().color(QPalette::Light);
    const QColor darkColor = palette().color(QPalette::Dark);
#endif

    const int bw2 = d_data->borderWidth / 2;

    const int radius = (qwtMin(r.width(), r.height()) - bw2) / 2;

    const QRect aRect( 
        r.center().x() - radius, r.center().y() - radius,
        2 * radius, 2 * radius);

    //
    // draw button face
    //
    painter->setBrush(buttonBrush);
    painter->drawEllipse(aRect);

    //
    // draw button shades
    //
    QPen pn;
    pn.setWidth(d_data->borderWidth);

    pn.setColor(lightColor);
    painter->setPen(pn);
    painter->drawArc(aRect, 45*16, 180*16);

    pn.setColor(darkColor);
    painter->setPen(pn);
    painter->drawArc(aRect, 225*16, 180*16);

    //
    // draw marker
    //
    if ( isValid() )
        drawMarker(painter, d_data->angle, buttonTextColor);
}

void QwtKnob::valueChange()
{
    recalcAngle();
    update();
    QwtAbstractSlider::valueChange();
}

double QwtKnob::getValue(const QPoint &p)
{
    const double dx = double((rect().x() + rect().width() / 2) - p.x() );
    const double dy = double((rect().y() + rect().height() / 2) - p.y() );

    const double arc = atan2(-dx,dy) * 180.0 / M_PI;

    double newValue =  0.5 * (minValue() + maxValue())
       + (arc + d_data->nTurns * 360.0) * (maxValue() - minValue())
      / d_data->totalAngle;

    const double oneTurn = fabs(maxValue() - minValue()) * 360.0 / d_data->totalAngle;
    const double eqValue = value() + mouseOffset();

    if (fabs(newValue - eqValue) > 0.5 * oneTurn)
    {
        if (newValue < eqValue)
           newValue += oneTurn;
        else
           newValue -= oneTurn;
    }

    return newValue;    
}

void QwtKnob::getScrollMode(const QPoint &p, int &scrollMode, int &direction)
{
    const int r = d_data->knobRect.width() / 2;

    const int dx = d_data->knobRect.x() + r - p.x();
    const int dy = d_data->knobRect.y() + r - p.y();

    if ( (dx * dx) + (dy * dy) <= (r * r)) // point is inside the knob
    {
        scrollMode = ScrMouse;
        direction = 0;
    }
    else                                // point lies outside
    {
        scrollMode = ScrTimer;
        double arc = atan2(double(-dx),double(dy)) * 180.0 / M_PI;
        if ( arc < d_data->angle)
           direction = -1;
        else if (arc > d_data->angle)
           direction = 1;
        else
           direction = 0;
    }
}


void QwtKnob::rangeChange()
{
    if (autoScale())
        rescale(minValue(), maxValue());

    layoutKnob();
    recalcAngle();
}

void QwtKnob::resizeEvent(QResizeEvent *)
{
    layoutKnob( false );
}

//  the current rect and fonts.
//  \param update_geometry  notify the layout system and call update
//         to redraw the scale
void QwtKnob::layoutKnob( bool update_geometry )
{
    const QRect r = rect();
    const int radius = d_data->knobWidth / 2;

    d_data->knobRect.setWidth(2 * radius);
    d_data->knobRect.setHeight(2 * radius);
    d_data->knobRect.moveCenter(r.center());

    scaleDraw()->setRadius(radius + d_data->scaleDist);
    scaleDraw()->moveCenter(r.center());

    if ( update_geometry )
    {
        updateGeometry();
        update();
    }
}

void QwtKnob::paintEvent(QPaintEvent *e)
{
    const QRect &ur = e->rect();
    if ( ur.isValid() ) 
    {
#if QT_VERSION < 0x040000
        QwtPaintBuffer paintBuffer(this, ur);
        draw(paintBuffer.painter(), ur);
#else
        QPainter painter(this);
        painter.setRenderHint(QPainter::Antialiasing);
        draw(&painter, ur);
#endif
    }
}

void QwtKnob::draw(QPainter *painter, const QRect& ur)
{
    if ( !d_data->knobRect.contains( ur ) ) // event from valueChange()
    {
#if QT_VERSION < 0x040000
        scaleDraw()->draw( painter, colorGroup() );
#else
        scaleDraw()->draw( painter, palette() );
#endif
    }

    drawKnob( painter, d_data->knobRect );

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

void QwtKnob::drawMarker(QPainter *p, double arc, const QColor &c)
{
    const double rarc = arc * M_PI / 180.0;
    const double ca = cos(rarc);
    const double sa = - sin(rarc);

    int radius = d_data->knobRect.width() / 2 - d_data->borderWidth;
    if (radius < 3) 
        radius = 3; 

    const int ym = d_data->knobRect.y() + radius + d_data->borderWidth;
    const int xm = d_data->knobRect.x() + radius + d_data->borderWidth;

    switch (d_data->symbol)
    {
        case Dot:
        {
            p->setBrush(c);
            p->setPen(Qt::NoPen);

            const double rb = double(qwtMax(radius - 4 - d_data->dotWidth / 2, 0));
            p->drawEllipse(xm - qRound(sa * rb) - d_data->dotWidth / 2,
                   ym - qRound(ca * rb) - d_data->dotWidth / 2,
                   d_data->dotWidth, d_data->dotWidth);
            break;
        }
        case Line:
        {
            p->setPen(QPen(c, 2));

            const double rb = qwtMax(double((radius - 4) / 3.0), 0.0);
            const double re = qwtMax(double(radius - 4), 0.0);
            
            p->drawLine ( xm - qRound(sa * rb), ym - qRound(ca * rb),
                xm - qRound(sa * re), ym - qRound(ca * re));
            
            break;
        }
    }
}

void QwtKnob::setKnobWidth(int w)
{
    d_data->knobWidth = qwtMax(w,5);
    layoutKnob();
}

int QwtKnob::knobWidth() const 
{
    return d_data->knobWidth;
}

void QwtKnob::setBorderWidth(int bw)
{
    d_data->borderWidth = qwtMax(bw, 0);
    layoutKnob();
}

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

void QwtKnob::recalcAngle()
{
    //
    // calculate the angle corresponding to the value
    //
    if (maxValue() == minValue())
    {
        d_data->angle = 0;
        d_data->nTurns = 0;
    }
    else
    {
        d_data->angle = (value() - 0.5 * (minValue() + maxValue()))
            / (maxValue() - minValue()) * d_data->totalAngle;
        d_data->nTurns = floor((d_data->angle + 180.0) / 360.0);
        d_data->angle = d_data->angle - d_data->nTurns * 360.0;
    }
}


void QwtKnob::scaleChange()
{
    layoutKnob();
}

void QwtKnob::fontChange(const QFont &f)
{
    QwtAbstractSlider::fontChange( f );
    layoutKnob();
}

QSize QwtKnob::sizeHint() const
{
    return minimumSizeHint();
}

QSize QwtKnob::minimumSizeHint() const
{
    // Add the scale radial thickness to the knobWidth
    const int sh = scaleDraw()->extent( QPen(), font() );
    const int d = 2 * sh + 2 * d_data->scaleDist + d_data->knobWidth;

    return QSize( d, d );
}

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