qwt_plot_scaleitem.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_plot_scaleitem.h"
#include "qwt_plot.h"
#include "qwt_scale_map.h"
#include "qwt_interval.h"
#include <qpalette.h>
#include <qpainter.h>

class QwtPlotScaleItem::PrivateData
{
public:
    PrivateData():
        position( 0.0 ),
        borderDistance( -1 ),
        scaleDivFromAxis( true ),
        scaleDraw( new QwtScaleDraw() )
    {
    }

    ~PrivateData()
    {
        delete scaleDraw;
    }

    QwtInterval scaleInterval( const QRectF &,
        const QwtScaleMap &, const QwtScaleMap & ) const;

    QPalette palette;
    QFont font;
    double position;
    int borderDistance;
    bool scaleDivFromAxis;
    QwtScaleDraw *scaleDraw;
};

QwtInterval QwtPlotScaleItem::PrivateData::scaleInterval( const QRectF &canvasRect,
    const QwtScaleMap &xMap, const QwtScaleMap &yMap ) const
{
    QwtInterval interval;
    if ( scaleDraw->orientation() == Qt::Horizontal )
    {
        interval.setMinValue( xMap.invTransform( canvasRect.left() ) );
        interval.setMaxValue( xMap.invTransform( canvasRect.right() - 1 ) );
    }
    else
    {
        interval.setMinValue( yMap.invTransform( canvasRect.bottom() - 1 ) );
        interval.setMaxValue( yMap.invTransform( canvasRect.top() ) );
    }

    return interval;
}

/*!
   \brief Constructor for scale item at the position pos.

   \param alignment In case of QwtScaleDraw::BottomScale or QwtScaleDraw::TopScale
                    the scale item is corresponding to the xAxis(),
                    otherwise it corresponds to the yAxis().

   \param pos x or y position, depending on the corresponding axis.

   \sa setPosition(), setAlignment()
*/
QwtPlotScaleItem::QwtPlotScaleItem(
        QwtScaleDraw::Alignment alignment, const double pos ):
    QwtPlotItem( QwtText( "Scale" ) )
{
    d_data = new PrivateData;
    d_data->position = pos;
    d_data->scaleDraw->setAlignment( alignment );

    setItemInterest( QwtPlotItem::ScaleInterest, true );
    setZ( 11.0 );
}

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

//! \return QwtPlotItem::Rtti_PlotScale
int QwtPlotScaleItem::rtti() const
{
    return QwtPlotItem::Rtti_PlotScale;
}

/*!
   \brief Assign a scale division

   When assigning a scaleDiv the scale division won't be synchronized
   with the corresponding axis anymore.

   \param scaleDiv Scale division
   \sa scaleDiv(), setScaleDivFromAxis(), isScaleDivFromAxis()
*/
void QwtPlotScaleItem::setScaleDiv( const QwtScaleDiv& scaleDiv )
{
    d_data->scaleDivFromAxis = false;
    d_data->scaleDraw->setScaleDiv( scaleDiv );
}

//! \return Scale division
const QwtScaleDiv& QwtPlotScaleItem::scaleDiv() const
{
    return d_data->scaleDraw->scaleDiv();
}

/*!
   Enable/Disable the synchronization of the scale division with
   the corresponding axis.

   \param on true/false
   \sa isScaleDivFromAxis()
*/
void QwtPlotScaleItem::setScaleDivFromAxis( bool on )
{
    if ( on != d_data->scaleDivFromAxis )
    {
        d_data->scaleDivFromAxis = on;
        if ( on )
        {
            const QwtPlot *plt = plot();
            if ( plt )
            {
                updateScaleDiv( plt->axisScaleDiv( xAxis() ),
                    plt->axisScaleDiv( yAxis() ) );
                itemChanged();
            }
        }
    }
}

/*!
   \return True, if the synchronization of the scale division with
           the corresponding axis is enabled.
   \sa setScaleDiv(), setScaleDivFromAxis()
*/
bool QwtPlotScaleItem::isScaleDivFromAxis() const
{
    return d_data->scaleDivFromAxis;
}

/*!
   Set the palette
   \sa QwtAbstractScaleDraw::draw(), palette()
*/
void QwtPlotScaleItem::setPalette( const QPalette &palette )
{
    if ( palette != d_data->palette )
    {
        d_data->palette = palette;

        legendChanged();
        itemChanged();
    }
}

/*!
   \return palette
   \sa setPalette()
*/
QPalette QwtPlotScaleItem::palette() const
{
    return d_data->palette;
}

/*!
   Change the tick label font
   \sa font()
*/
void QwtPlotScaleItem::setFont( const QFont &font )
{
    if ( font != d_data->font )
    {
        d_data->font = font;
        itemChanged();
    }
}

/*!
   \return tick label font
   \sa setFont()
*/
QFont QwtPlotScaleItem::font() const
{
    return d_data->font;
}

/*!
  \brief Set a scale draw

  \param scaleDraw object responsible for drawing scales.

  The main use case for replacing the default QwtScaleDraw is
  to overload QwtAbstractScaleDraw::label, to replace or swallow
  tick labels.

  \sa scaleDraw()
*/
void QwtPlotScaleItem::setScaleDraw( QwtScaleDraw *scaleDraw )
{
    if ( scaleDraw == NULL )
        return;

    if ( scaleDraw != d_data->scaleDraw )
        delete d_data->scaleDraw;

    d_data->scaleDraw = scaleDraw;

    const QwtPlot *plt = plot();
    if ( plt )
    {
        updateScaleDiv( plt->axisScaleDiv( xAxis() ),
            plt->axisScaleDiv( yAxis() ) );
    }

    itemChanged();
}

/*!
   \return Scale draw
   \sa setScaleDraw()
*/
const QwtScaleDraw *QwtPlotScaleItem::scaleDraw() const
{
    return d_data->scaleDraw;
}

/*!
   \return Scale draw
   \sa setScaleDraw()
*/
QwtScaleDraw *QwtPlotScaleItem::scaleDraw()
{
    return d_data->scaleDraw;
}

/*!
   Change the position of the scale

   The position is interpreted as y value for horizontal axes
   and as x value for vertical axes.

   The border distance is set to -1.

   \param pos New position
   \sa position(), setAlignment()
*/
void QwtPlotScaleItem::setPosition( double pos )
{
    if ( d_data->position != pos )
    {
        d_data->position = pos;
        d_data->borderDistance = -1;
        itemChanged();
    }
}

/*!
   \return Position of the scale
   \sa setPosition(), setAlignment()
*/
double QwtPlotScaleItem::position() const
{
    return d_data->position;
}

/*!
   \brief Align the scale to the canvas

   If distance is >= 0 the scale will be aligned to a
   border of the contents rectangle of the canvas. If
   alignment() is QwtScaleDraw::LeftScale, the scale will
   be aligned to the right border, if it is QwtScaleDraw::TopScale
   it will be aligned to the bottom (and vice versa),

   If distance is < 0 the scale will be at the position().

   \param distance Number of pixels between the canvas border and the
                   backbone of the scale.

   \sa setPosition(), borderDistance()
*/
void QwtPlotScaleItem::setBorderDistance( int distance )
{
    if ( distance < 0 )
        distance = -1;

    if ( distance != d_data->borderDistance )
    {
        d_data->borderDistance = distance;
        itemChanged();
    }
}

/*!
   \return Distance from a canvas border
   \sa setBorderDistance(), setPosition()
*/
int QwtPlotScaleItem::borderDistance() const
{
    return d_data->borderDistance;
}

/*!
   Change the alignment of the scale

   The alignment sets the orientation of the scale and the position of
   the ticks:

   - QwtScaleDraw::BottomScale: horizontal, ticks below
   - QwtScaleDraw::TopScale: horizontal, ticks above
   - QwtScaleDraw::LeftScale: vertical, ticks left
   - QwtScaleDraw::RightScale: vertical, ticks right

   For horizontal scales the position corresponds to QwtPlotItem::yAxis(),
   otherwise to QwtPlotItem::xAxis().

   \sa scaleDraw(), QwtScaleDraw::alignment(), setPosition()
*/
void QwtPlotScaleItem::setAlignment( QwtScaleDraw::Alignment alignment )
{
    QwtScaleDraw *sd = d_data->scaleDraw;
    if ( sd->alignment() != alignment )
    {
        sd->setAlignment( alignment );
        itemChanged();
    }
}

/*!
  \brief Draw the scale
*/
void QwtPlotScaleItem::draw( QPainter *painter,
    const QwtScaleMap &xMap, const QwtScaleMap &yMap,
    const QRectF &canvasRect ) const
{
    QwtScaleDraw *sd = d_data->scaleDraw;

    if ( d_data->scaleDivFromAxis )
    {
        const QwtInterval interval =
            d_data->scaleInterval( canvasRect, xMap, yMap );

        if ( interval != sd->scaleDiv().interval() )
        {
            QwtScaleDiv scaleDiv = sd->scaleDiv();
            scaleDiv.setInterval( interval );
            sd->setScaleDiv( scaleDiv );
        }
    }

    QPen pen = painter->pen();
    pen.setStyle( Qt::SolidLine );
    painter->setPen( pen );

    if ( sd->orientation() == Qt::Horizontal )
    {
        double y;
        if ( d_data->borderDistance >= 0 )
        {
            if ( sd->alignment() == QwtScaleDraw::BottomScale )
                y = canvasRect.top() + d_data->borderDistance;
            else
            {
                y = canvasRect.bottom() - d_data->borderDistance;
            }

        }
        else
        {
            y = yMap.transform( d_data->position );
        }

        if ( y < canvasRect.top() || y > canvasRect.bottom() )
            return;

        sd->move( canvasRect.left(), y );
        sd->setLength( canvasRect.width() - 1 );

        QwtTransform *transform = NULL;
        if ( xMap.transformation() )
            transform = xMap.transformation()->copy();

        sd->setTransformation( transform );
    }
    else // == Qt::Vertical
    {
        double x;
        if ( d_data->borderDistance >= 0 )
        {
            if ( sd->alignment() == QwtScaleDraw::RightScale )
                x = canvasRect.left() + d_data->borderDistance;
            else
            {
                x = canvasRect.right() - d_data->borderDistance;
            }
        }
        else
        {
            x = xMap.transform( d_data->position );
        }
        if ( x < canvasRect.left() || x > canvasRect.right() )
            return;

        sd->move( x, canvasRect.top() );
        sd->setLength( canvasRect.height() - 1 );

        QwtTransform *transform = NULL;
        if ( yMap.transformation() )
            transform = yMap.transformation()->copy();

        sd->setTransformation( transform );
    }

    painter->setFont( d_data->font );

    sd->draw( painter, d_data->palette );
}

/*!
   \brief Update the item to changes of the axes scale division

   In case of isScaleDivFromAxis(), the scale draw is synchronized
   to the correspond axis.

   \param xScaleDiv Scale division of the x-axis
   \param yScaleDiv Scale division of the y-axis

   \sa QwtPlot::updateAxes()
*/

void QwtPlotScaleItem::updateScaleDiv( const QwtScaleDiv& xScaleDiv,
    const QwtScaleDiv& yScaleDiv )
{
    QwtScaleDraw *scaleDraw = d_data->scaleDraw;

    if ( d_data->scaleDivFromAxis && scaleDraw )
    {
        const QwtScaleDiv &scaleDiv =
            scaleDraw->orientation() == Qt::Horizontal ? xScaleDiv : yScaleDiv;

        const QwtPlot *plt = plot();
        if ( plt != NULL )
        {
            const QRectF canvasRect = plt->canvas()->contentsRect();

            const QwtInterval interval = d_data->scaleInterval(
                canvasRect, plt->canvasMap( xAxis() ), plt->canvasMap( yAxis() ) );

            QwtScaleDiv sd = scaleDiv;
            sd.setInterval( interval );

            if ( sd != scaleDraw->scaleDiv() )
            {
                // the internal label cache of QwtScaleDraw
                // is cleared here, so better avoid pointless
                // assignments.

                scaleDraw->setScaleDiv( sd );
            }
        }
        else
        {
            scaleDraw->setScaleDiv( scaleDiv );
        }
    }
}