qwt_plot_layout.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_plot_layout.h"
#include "qwt_text.h"
#include "qwt_text_label.h"
#include "qwt_scale_widget.h"
#include "qwt_abstract_legend.h"
#include <qscrollbar.h>
#include <qmath.h>

class QwtPlotLayout::LayoutData
{
public:
    void init( const QwtPlot *, const QRectF &rect );

    struct t_legendData
    {
        int frameWidth;
        int hScrollExtent;
        int vScrollExtent;
        QSize hint;
    } legend;

    struct t_titleData
    {
        QwtText text;
        int frameWidth;
    } title;

    struct t_footerData
    {
        QwtText text;
        int frameWidth;
    } footer;

    struct t_scaleData
    {
        bool isEnabled;
        const QwtScaleWidget *scaleWidget;
        QFont scaleFont;
        int start;
        int end;
        int baseLineOffset;
        double tickOffset;
        int dimWithoutTitle;
    } scale[QwtPlot::axisCnt];

    struct t_canvasData
    {
        int contentsMargins[ QwtPlot::axisCnt ];

    } canvas;
};

/*
  Extract all layout relevant data from the plot components
*/
void QwtPlotLayout::LayoutData::init( const QwtPlot *plot, const QRectF &rect )
{
    // legend

    if ( plot->legend() )
    {
        legend.frameWidth = plot->legend()->frameWidth();
        legend.hScrollExtent =
            plot->legend()->scrollExtent( Qt::Horizontal );
        legend.vScrollExtent =
            plot->legend()->scrollExtent( Qt::Vertical );

        const QSize hint = plot->legend()->sizeHint();

        const int w = qMin( hint.width(), qFloor( rect.width() ) );

        int h = plot->legend()->heightForWidth( w );
        if ( h <= 0 )
            h = hint.height();

        legend.hint = QSize( w, h );
    }

    // title

    title.frameWidth = 0;
    title.text = QwtText();

    if ( plot->titleLabel() )
    {
        const QwtTextLabel *label = plot->titleLabel();
        title.text = label->text();
        if ( !( title.text.testPaintAttribute( QwtText::PaintUsingTextFont ) ) )
            title.text.setFont( label->font() );

        title.frameWidth = plot->titleLabel()->frameWidth();
    }

    // footer

    footer.frameWidth = 0;
    footer.text = QwtText();

    if ( plot->footerLabel() )
    {
        const QwtTextLabel *label = plot->footerLabel();
        footer.text = label->text();
        if ( !( footer.text.testPaintAttribute( QwtText::PaintUsingTextFont ) ) )
            footer.text.setFont( label->font() );

        footer.frameWidth = plot->footerLabel()->frameWidth();
    }

    // scales

    for ( int axis = 0; axis < QwtPlot::axisCnt; axis++ )
    {
        if ( plot->axisEnabled( axis ) )
        {
            const QwtScaleWidget *scaleWidget = plot->axisWidget( axis );

            scale[axis].isEnabled = true;

            scale[axis].scaleWidget = scaleWidget;

            scale[axis].scaleFont = scaleWidget->font();

            scale[axis].start = scaleWidget->startBorderDist();
            scale[axis].end = scaleWidget->endBorderDist();

            scale[axis].baseLineOffset = scaleWidget->margin();
            scale[axis].tickOffset = scaleWidget->margin();
            if ( scaleWidget->scaleDraw()->hasComponent(
                QwtAbstractScaleDraw::Ticks ) )
            {
                scale[axis].tickOffset +=
                    scaleWidget->scaleDraw()->maxTickLength();
            }

            scale[axis].dimWithoutTitle = scaleWidget->dimForLength(
                QWIDGETSIZE_MAX, scale[axis].scaleFont );

            if ( !scaleWidget->title().isEmpty() )
            {
                scale[axis].dimWithoutTitle -=
                    scaleWidget->titleHeightForWidth( QWIDGETSIZE_MAX );
            }
        }
        else
        {
            scale[axis].isEnabled = false;
            scale[axis].start = 0;
            scale[axis].end = 0;
            scale[axis].baseLineOffset = 0;
            scale[axis].tickOffset = 0.0;
            scale[axis].dimWithoutTitle = 0;
        }
    }

    // canvas

    plot->canvas()->getContentsMargins( 
        &canvas.contentsMargins[ QwtPlot::yLeft ], 
        &canvas.contentsMargins[ QwtPlot::xTop ],
        &canvas.contentsMargins[ QwtPlot::yRight ],
        &canvas.contentsMargins[ QwtPlot::xBottom ] );
}

class QwtPlotLayout::PrivateData
{
public:
    PrivateData():
        spacing( 5 )
    {
    }

    QRectF titleRect;
    QRectF footerRect;
    QRectF legendRect;
    QRectF scaleRect[QwtPlot::axisCnt];
    QRectF canvasRect;

    QwtPlotLayout::LayoutData layoutData;

    QwtPlot::LegendPosition legendPos;
    double legendRatio;
    unsigned int spacing;
    unsigned int canvasMargin[QwtPlot::axisCnt];
    bool alignCanvasToScales[QwtPlot::axisCnt];
};

QwtPlotLayout::QwtPlotLayout()
{
    d_data = new PrivateData;

    setLegendPosition( QwtPlot::BottomLegend );
    setCanvasMargin( 4 );
    setAlignCanvasToScales( false );

    invalidate();
}

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

void QwtPlotLayout::setCanvasMargin( int margin, int axis )
{
    if ( margin < -1 )
        margin = -1;

    if ( axis == -1 )
    {
        for ( axis = 0; axis < QwtPlot::axisCnt; axis++ )
            d_data->canvasMargin[axis] = margin;
    }
    else if ( axis >= 0 && axis < QwtPlot::axisCnt )
        d_data->canvasMargin[axis] = margin;
}

int QwtPlotLayout::canvasMargin( int axisId ) const
{
    if ( axisId < 0 || axisId >= QwtPlot::axisCnt )
        return 0;

    return d_data->canvasMargin[axisId];
}

void QwtPlotLayout::setAlignCanvasToScales( bool on )
{
    for ( int axis = 0; axis < QwtPlot::axisCnt; axis++ )
        d_data->alignCanvasToScales[axis] = on;
}

void QwtPlotLayout::setAlignCanvasToScale( int axisId, bool on )
{
    if ( axisId >= 0 && axisId < QwtPlot::axisCnt )
        d_data->alignCanvasToScales[axisId] = on;
}

bool QwtPlotLayout::alignCanvasToScale( int axisId ) const
{
    if ( axisId < 0 || axisId >= QwtPlot::axisCnt )
        return false;

    return d_data->alignCanvasToScales[ axisId ];
}

void QwtPlotLayout::setSpacing( int spacing )
{
    d_data->spacing = qMax( 0, spacing );
}

int QwtPlotLayout::spacing() const
{
    return d_data->spacing;
}

void QwtPlotLayout::setLegendPosition( QwtPlot::LegendPosition pos, double ratio )
{
    if ( ratio > 1.0 )
        ratio = 1.0;

    switch ( pos )
    {
        case QwtPlot::TopLegend:
        case QwtPlot::BottomLegend:
            if ( ratio <= 0.0 )
                ratio = 0.33;
            d_data->legendRatio = ratio;
            d_data->legendPos = pos;
            break;
        case QwtPlot::LeftLegend:
        case QwtPlot::RightLegend:
            if ( ratio <= 0.0 )
                ratio = 0.5;
            d_data->legendRatio = ratio;
            d_data->legendPos = pos;
            break;
        default:
            break;
    }
}

void QwtPlotLayout::setLegendPosition( QwtPlot::LegendPosition pos )
{
    setLegendPosition( pos, 0.0 );
}

QwtPlot::LegendPosition QwtPlotLayout::legendPosition() const
{
    return d_data->legendPos;
}

void QwtPlotLayout::setLegendRatio( double ratio )
{
    setLegendPosition( legendPosition(), ratio );
}

double QwtPlotLayout::legendRatio() const
{
    return d_data->legendRatio;
}

void QwtPlotLayout::setTitleRect( const QRectF &rect )
{
    d_data->titleRect = rect;
}

QRectF QwtPlotLayout::titleRect() const
{
    return d_data->titleRect;
}

void QwtPlotLayout::setFooterRect( const QRectF &rect )
{
    d_data->footerRect = rect;
}

QRectF QwtPlotLayout::footerRect() const
{
    return d_data->footerRect;
}

void QwtPlotLayout::setLegendRect( const QRectF &rect )
{
    d_data->legendRect = rect;
}

QRectF QwtPlotLayout::legendRect() const
{
    return d_data->legendRect;
}

void QwtPlotLayout::setScaleRect( int axis, const QRectF &rect )
{
    if ( axis >= 0 && axis < QwtPlot::axisCnt )
        d_data->scaleRect[axis] = rect;
}

QRectF QwtPlotLayout::scaleRect( int axis ) const
{
    if ( axis < 0 || axis >= QwtPlot::axisCnt )
    {
        static QRectF dummyRect;
        return dummyRect;
    }
    return d_data->scaleRect[axis];
}

void QwtPlotLayout::setCanvasRect( const QRectF &rect )
{
    d_data->canvasRect = rect;
}

QRectF QwtPlotLayout::canvasRect() const
{
    return d_data->canvasRect;
}

void QwtPlotLayout::invalidate()
{
    d_data->titleRect = d_data->footerRect
        = d_data->legendRect = d_data->canvasRect = QRect();

    for ( int axis = 0; axis < QwtPlot::axisCnt; axis++ )
        d_data->scaleRect[axis] = QRect();
}

QSize QwtPlotLayout::minimumSizeHint( const QwtPlot *plot ) const
{
    class ScaleData
    {
    public:
        ScaleData()
        {
            w = h = minLeft = minRight = tickOffset = 0;
        }

        int w;
        int h;
        int minLeft;
        int minRight;
        int tickOffset;
    } scaleData[QwtPlot::axisCnt];

    int canvasBorder[QwtPlot::axisCnt];

    int fw;
    plot->canvas()->getContentsMargins( &fw, NULL, NULL, NULL );

    int axis;
    for ( axis = 0; axis < QwtPlot::axisCnt; axis++ )
    {
        if ( plot->axisEnabled( axis ) )
        {
            const QwtScaleWidget *scl = plot->axisWidget( axis );
            ScaleData &sd = scaleData[axis];

            const QSize hint = scl->minimumSizeHint();
            sd.w = hint.width();
            sd.h = hint.height();
            scl->getBorderDistHint( sd.minLeft, sd.minRight );
            sd.tickOffset = scl->margin();
            if ( scl->scaleDraw()->hasComponent( QwtAbstractScaleDraw::Ticks ) )
                sd.tickOffset += qCeil( scl->scaleDraw()->maxTickLength() );
        }

        canvasBorder[axis] = fw + d_data->canvasMargin[axis] + 1;
    }


    for ( axis = 0; axis < QwtPlot::axisCnt; axis++ )
    {
        ScaleData &sd = scaleData[axis];
        if ( sd.w && ( axis == QwtPlot::xBottom || axis == QwtPlot::xTop ) )
        {
            if ( ( sd.minLeft > canvasBorder[QwtPlot::yLeft] )
                && scaleData[QwtPlot::yLeft].w )
            {
                int shiftLeft = sd.minLeft - canvasBorder[QwtPlot::yLeft];
                if ( shiftLeft > scaleData[QwtPlot::yLeft].w )
                    shiftLeft = scaleData[QwtPlot::yLeft].w;

                sd.w -= shiftLeft;
            }
            if ( ( sd.minRight > canvasBorder[QwtPlot::yRight] )
                && scaleData[QwtPlot::yRight].w )
            {
                int shiftRight = sd.minRight - canvasBorder[QwtPlot::yRight];
                if ( shiftRight > scaleData[QwtPlot::yRight].w )
                    shiftRight = scaleData[QwtPlot::yRight].w;

                sd.w -= shiftRight;
            }
        }

        if ( sd.h && ( axis == QwtPlot::yLeft || axis == QwtPlot::yRight ) )
        {
            if ( ( sd.minLeft > canvasBorder[QwtPlot::xBottom] ) &&
                scaleData[QwtPlot::xBottom].h )
            {
                int shiftBottom = sd.minLeft - canvasBorder[QwtPlot::xBottom];
                if ( shiftBottom > scaleData[QwtPlot::xBottom].tickOffset )
                    shiftBottom = scaleData[QwtPlot::xBottom].tickOffset;

                sd.h -= shiftBottom;
            }
            if ( ( sd.minLeft > canvasBorder[QwtPlot::xTop] ) &&
                scaleData[QwtPlot::xTop].h )
            {
                int shiftTop = sd.minRight - canvasBorder[QwtPlot::xTop];
                if ( shiftTop > scaleData[QwtPlot::xTop].tickOffset )
                    shiftTop = scaleData[QwtPlot::xTop].tickOffset;

                sd.h -= shiftTop;
            }
        }
    }

    const QWidget *canvas = plot->canvas();

    int left, top, right, bottom;
    canvas->getContentsMargins( &left, &top, &right, &bottom );

    const QSize minCanvasSize = canvas->minimumSize();

    int w = scaleData[QwtPlot::yLeft].w + scaleData[QwtPlot::yRight].w;
    int cw = qMax( scaleData[QwtPlot::xBottom].w, scaleData[QwtPlot::xTop].w )
        + left + 1 + right + 1;
    w += qMax( cw, minCanvasSize.width() );

    int h = scaleData[QwtPlot::xBottom].h + scaleData[QwtPlot::xTop].h;
    int ch = qMax( scaleData[QwtPlot::yLeft].h, scaleData[QwtPlot::yRight].h )
        + top + 1 + bottom + 1;
    h += qMax( ch, minCanvasSize.height() );

    const QwtTextLabel *labels[2];
    labels[0] = plot->titleLabel();
    labels[1] = plot->footerLabel();

    for ( int i = 0; i < 2; i++ )
    {
        const QwtTextLabel *label   = labels[i];
        if ( label && !label->text().isEmpty() )
        {
            // If only QwtPlot::yLeft or QwtPlot::yRight is showing,
            // we center on the plot canvas.
            const bool centerOnCanvas = !( plot->axisEnabled( QwtPlot::yLeft )
                && plot->axisEnabled( QwtPlot::yRight ) );

            int labelW = w;
            if ( centerOnCanvas )
            {
                labelW -= scaleData[QwtPlot::yLeft].w
                    + scaleData[QwtPlot::yRight].w;
            }

            int labelH = label->heightForWidth( labelW );
            if ( labelH > labelW ) // Compensate for a long title
            {
                w = labelW = labelH;
                if ( centerOnCanvas )
                {
                    w += scaleData[QwtPlot::yLeft].w
                        + scaleData[QwtPlot::yRight].w;
                }

                labelH = label->heightForWidth( labelW );
            }
            h += labelH + d_data->spacing;
        }
    }

    // Compute the legend contribution

    const QwtAbstractLegend *legend = plot->legend();
    if ( legend && !legend->isEmpty() )
    {
        if ( d_data->legendPos == QwtPlot::LeftLegend
            || d_data->legendPos == QwtPlot::RightLegend )
        {
            int legendW = legend->sizeHint().width();
            int legendH = legend->heightForWidth( legendW );

            if ( legend->frameWidth() > 0 )
                w += d_data->spacing;

            if ( legendH > h )
                legendW += legend->scrollExtent( Qt::Horizontal );

            if ( d_data->legendRatio < 1.0 )
                legendW = qMin( legendW, int( w / ( 1.0 - d_data->legendRatio ) ) );

            w += legendW + d_data->spacing;
        }
        else // QwtPlot::Top, QwtPlot::Bottom
        {
            int legendW = qMin( legend->sizeHint().width(), w );
            int legendH = legend->heightForWidth( legendW );

            if ( legend->frameWidth() > 0 )
                h += d_data->spacing;

            if ( d_data->legendRatio < 1.0 )
                legendH = qMin( legendH, int( h / ( 1.0 - d_data->legendRatio ) ) );

            h += legendH + d_data->spacing;
        }
    }

    return QSize( w, h );
}

QRectF QwtPlotLayout::layoutLegend( Options options,
    const QRectF &rect ) const
{
    const QSize hint( d_data->layoutData.legend.hint );

    int dim;
    if ( d_data->legendPos == QwtPlot::LeftLegend
        || d_data->legendPos == QwtPlot::RightLegend )
    {
        // We don't allow vertical legends to take more than
        // half of the available space.

        dim = qMin( hint.width(), int( rect.width() * d_data->legendRatio ) );

        if ( !( options & IgnoreScrollbars ) )
        {
            if ( hint.height() > rect.height() )
            {
                // The legend will need additional
                // space for the vertical scrollbar.

                dim += d_data->layoutData.legend.hScrollExtent;
            }
        }
    }
    else
    {
        dim = qMin( hint.height(), int( rect.height() * d_data->legendRatio ) );
        dim = qMax( dim, d_data->layoutData.legend.vScrollExtent );
    }

    QRectF legendRect = rect;
    switch ( d_data->legendPos )
    {
        case QwtPlot::LeftLegend:
            legendRect.setWidth( dim );
            break;
        case QwtPlot::RightLegend:
            legendRect.setX( rect.right() - dim );
            legendRect.setWidth( dim );
            break;
        case QwtPlot::TopLegend:
            legendRect.setHeight( dim );
            break;
        case QwtPlot::BottomLegend:
            legendRect.setY( rect.bottom() - dim );
            legendRect.setHeight( dim );
            break;
    }

    return legendRect;
}

QRectF QwtPlotLayout::alignLegend( const QRectF &canvasRect,
    const QRectF &legendRect ) const
{
    QRectF alignedRect = legendRect;

    if ( d_data->legendPos == QwtPlot::BottomLegend
        || d_data->legendPos == QwtPlot::TopLegend )
    {
        if ( d_data->layoutData.legend.hint.width() < canvasRect.width() )
        {
            alignedRect.setX( canvasRect.x() );
            alignedRect.setWidth( canvasRect.width() );
        }
    }
    else
    {
        if ( d_data->layoutData.legend.hint.height() < canvasRect.height() )
        {
            alignedRect.setY( canvasRect.y() );
            alignedRect.setHeight( canvasRect.height() );
        }
    }

    return alignedRect;
}

void QwtPlotLayout::expandLineBreaks( Options options, const QRectF &rect,
    int &dimTitle, int &dimFooter, int dimAxis[QwtPlot::axisCnt] ) const
{
    dimTitle = dimFooter = 0;
    for ( int axis = 0; axis < QwtPlot::axisCnt; axis++ )
        dimAxis[axis] = 0;

    int backboneOffset[QwtPlot::axisCnt];
    for ( int axis = 0; axis < QwtPlot::axisCnt; axis++ )
    {
        backboneOffset[axis] = 0;
        if ( !( options & IgnoreFrames ) )
            backboneOffset[axis] += d_data->layoutData.canvas.contentsMargins[ axis ];

        if ( !d_data->alignCanvasToScales[axis] )
            backboneOffset[axis] += d_data->canvasMargin[axis];
    }

    bool done = false;
    while ( !done )
    {
        done = true;

        // the size for the 4 axis depend on each other. Expanding
        // the height of a horizontal axis will shrink the height
        // for the vertical axis, shrinking the height of a vertical
        // axis will result in a line break what will expand the
        // width and results in shrinking the width of a horizontal
        // axis what might result in a line break of a horizontal
        // axis ... . So we loop as long until no size changes.

        if ( !( ( options & IgnoreTitle ) ||
            d_data->layoutData.title.text.isEmpty() ) )
        {
            double w = rect.width();

            if ( d_data->layoutData.scale[QwtPlot::yLeft].isEnabled
                != d_data->layoutData.scale[QwtPlot::yRight].isEnabled )
            {
                // center to the canvas
                w -= dimAxis[QwtPlot::yLeft] + dimAxis[QwtPlot::yRight];
            }

            int d = qCeil( d_data->layoutData.title.text.heightForWidth( w ) );
            if ( !( options & IgnoreFrames ) )
                d += 2 * d_data->layoutData.title.frameWidth;

            if ( d > dimTitle )
            {
                dimTitle = d;
                done = false;
            }
        }

        if ( !( ( options & IgnoreFooter ) ||
            d_data->layoutData.footer.text.isEmpty() ) )
        {
            double w = rect.width();

            if ( d_data->layoutData.scale[QwtPlot::yLeft].isEnabled
                != d_data->layoutData.scale[QwtPlot::yRight].isEnabled )
            {
                // center to the canvas
                w -= dimAxis[QwtPlot::yLeft] + dimAxis[QwtPlot::yRight];
            }

            int d = qCeil( d_data->layoutData.footer.text.heightForWidth( w ) );
            if ( !( options & IgnoreFrames ) )
                d += 2 * d_data->layoutData.footer.frameWidth;

            if ( d > dimFooter )
            {
                dimFooter = d;
                done = false;
            }
        }

        for ( int axis = 0; axis < QwtPlot::axisCnt; axis++ )
        {
            const struct LayoutData::t_scaleData &scaleData =
                d_data->layoutData.scale[axis];

            if ( scaleData.isEnabled )
            {
                double length;
                if ( axis == QwtPlot::xTop || axis == QwtPlot::xBottom )
                {
                    length = rect.width() - dimAxis[QwtPlot::yLeft]
                        - dimAxis[QwtPlot::yRight];
                    length -= scaleData.start + scaleData.end;

                    if ( dimAxis[QwtPlot::yRight] > 0 )
                        length -= 1;

                    length += qMin( dimAxis[QwtPlot::yLeft],
                        scaleData.start - backboneOffset[QwtPlot::yLeft] );
                    length += qMin( dimAxis[QwtPlot::yRight],
                        scaleData.end - backboneOffset[QwtPlot::yRight] );
                }
                else // QwtPlot::yLeft, QwtPlot::yRight
                {
                    length = rect.height() - dimAxis[QwtPlot::xTop]
                        - dimAxis[QwtPlot::xBottom];
                    length -= scaleData.start + scaleData.end;
                    length -= 1;

                    if ( dimAxis[QwtPlot::xBottom] <= 0 )
                        length -= 1;
                    if ( dimAxis[QwtPlot::xTop] <= 0 )
                        length -= 1;

                    if ( dimAxis[QwtPlot::xBottom] > 0 )
                    {
                        length += qMin(
                            d_data->layoutData.scale[QwtPlot::xBottom].tickOffset,
                            double( scaleData.start - backboneOffset[QwtPlot::xBottom] ) );
                    }
                    if ( dimAxis[QwtPlot::xTop] > 0 )
                    {
                        length += qMin(
                            d_data->layoutData.scale[QwtPlot::xTop].tickOffset,
                            double( scaleData.end - backboneOffset[QwtPlot::xTop] ) );
                    }

                    if ( dimTitle > 0 )
                        length -= dimTitle + d_data->spacing;
                }

                int d = scaleData.dimWithoutTitle;
                if ( !scaleData.scaleWidget->title().isEmpty() )
                {
                    d += scaleData.scaleWidget->titleHeightForWidth( qFloor( length ) );
                }


                if ( d > dimAxis[axis] )
                {
                    dimAxis[axis] = d;
                    done = false;
                }
            }
        }
    }
}

void QwtPlotLayout::alignScales( Options options,
    QRectF &canvasRect, QRectF scaleRect[QwtPlot::axisCnt] ) const
{
    int backboneOffset[QwtPlot::axisCnt];
    for ( int axis = 0; axis < QwtPlot::axisCnt; axis++ )
    {
        backboneOffset[axis] = 0;

        if ( !d_data->alignCanvasToScales[axis] )
        {
            backboneOffset[axis] += d_data->canvasMargin[axis];
        }

        if ( !( options & IgnoreFrames ) )
        {
            backboneOffset[axis] += 
                d_data->layoutData.canvas.contentsMargins[axis];
        }
    }

    for ( int axis = 0; axis < QwtPlot::axisCnt; axis++ )
    {
        if ( !scaleRect[axis].isValid() )
            continue;

        const int startDist = d_data->layoutData.scale[axis].start;
        const int endDist = d_data->layoutData.scale[axis].end;

        QRectF &axisRect = scaleRect[axis];

        if ( axis == QwtPlot::xTop || axis == QwtPlot::xBottom )
        {
            const QRectF &leftScaleRect = scaleRect[QwtPlot::yLeft];
            const int leftOffset =
                backboneOffset[QwtPlot::yLeft] - startDist;

            if ( leftScaleRect.isValid() )
            {
                const double dx = leftOffset + leftScaleRect.width();
                if ( d_data->alignCanvasToScales[QwtPlot::yLeft] && dx < 0.0 )
                {
                    /*
                      The axis needs more space than the width
                      of the left scale.
                     */
                    const double cLeft = canvasRect.left(); // qreal -> double
                    canvasRect.setLeft( qMax( cLeft, axisRect.left() - dx ) );
                }
                else
                {
                    const double minLeft = leftScaleRect.left();
                    const double left = axisRect.left() + leftOffset;
                    axisRect.setLeft( qMax( left, minLeft ) );
                }
            }
            else
            {
                if ( d_data->alignCanvasToScales[QwtPlot::yLeft] && leftOffset < 0 )
                {
                    canvasRect.setLeft( qMax( canvasRect.left(),
                        axisRect.left() - leftOffset ) );
                }
                else
                {
                    if ( leftOffset > 0 )
                        axisRect.setLeft( axisRect.left() + leftOffset );
                }
            }

            const QRectF &rightScaleRect = scaleRect[QwtPlot::yRight];
            const int rightOffset =
                backboneOffset[QwtPlot::yRight] - endDist + 1;

            if ( rightScaleRect.isValid() )
            {
                const double dx = rightOffset + rightScaleRect.width();
                if ( d_data->alignCanvasToScales[QwtPlot::yRight] && dx < 0 )
                {
                    /*
                      The axis needs more space than the width
                      of the right scale.
                     */
                    const double cRight = canvasRect.right(); // qreal -> double
                    canvasRect.setRight( qMin( cRight, axisRect.right() + dx ) );
                }   

                const double maxRight = rightScaleRect.right();
                const double right = axisRect.right() - rightOffset;
                axisRect.setRight( qMin( right, maxRight ) );
            }
            else
            {
                if ( d_data->alignCanvasToScales[QwtPlot::yRight] && rightOffset < 0 )
                {
                    canvasRect.setRight( qMin( canvasRect.right(),
                        axisRect.right() + rightOffset ) );
                }
                else
                {
                    if ( rightOffset > 0 )
                        axisRect.setRight( axisRect.right() - rightOffset );
                }
            }
        }
        else // QwtPlot::yLeft, QwtPlot::yRight
        {
            const QRectF &bottomScaleRect = scaleRect[QwtPlot::xBottom];
            const int bottomOffset =
                backboneOffset[QwtPlot::xBottom] - endDist + 1;

            if ( bottomScaleRect.isValid() )
            {
                const double dy = bottomOffset + bottomScaleRect.height();
                if ( d_data->alignCanvasToScales[QwtPlot::xBottom] && dy < 0 )
                {
                    /*
                      The axis needs more space than the height
                      of the bottom scale.
                     */
                    const double cBottom = canvasRect.bottom(); // qreal -> double
                    canvasRect.setBottom( qMin( cBottom, axisRect.bottom() + dy ) );
                }
                else
                {
                    const double maxBottom = bottomScaleRect.top() +
                        d_data->layoutData.scale[QwtPlot::xBottom].tickOffset;
                    const double bottom = axisRect.bottom() - bottomOffset;
                    axisRect.setBottom( qMin( bottom, maxBottom ) );
                }
            }
            else
            {
                if ( d_data->alignCanvasToScales[QwtPlot::xBottom] && bottomOffset < 0 )
                {
                    canvasRect.setBottom( qMin( canvasRect.bottom(),
                        axisRect.bottom() + bottomOffset ) );
                }
                else
                {
                    if ( bottomOffset > 0 )
                        axisRect.setBottom( axisRect.bottom() - bottomOffset );
                }
            }

            const QRectF &topScaleRect = scaleRect[QwtPlot::xTop];
            const int topOffset = backboneOffset[QwtPlot::xTop] - startDist;

            if ( topScaleRect.isValid() )
            {
                const double dy = topOffset + topScaleRect.height();
                if ( d_data->alignCanvasToScales[QwtPlot::xTop] && dy < 0 )
                {
                    /*
                      The axis needs more space than the height
                      of the top scale.
                     */
                    const double cTop = canvasRect.top(); // qreal -> double
                    canvasRect.setTop( qMax( cTop, axisRect.top() - dy ) );
                }
                else
                {
                    const double minTop = topScaleRect.bottom() -
                        d_data->layoutData.scale[QwtPlot::xTop].tickOffset;
                    const double top = axisRect.top() + topOffset;
                    axisRect.setTop( qMax( top, minTop ) );
                }
            }
            else
            {
                if ( d_data->alignCanvasToScales[QwtPlot::xTop] && topOffset < 0 )
                {
                    canvasRect.setTop( qMax( canvasRect.top(),
                        axisRect.top() - topOffset ) );
                }
                else
                {
                    if ( topOffset > 0 )
                        axisRect.setTop( axisRect.top() + topOffset );
                }
            }
        }
    }

    /*
      The canvas has been aligned to the scale with largest
      border distances. Now we have to realign the other scale.
     */


    for ( int axis = 0; axis < QwtPlot::axisCnt; axis++ )
    {
        QRectF &sRect = scaleRect[axis];

        if ( !sRect.isValid() )
            continue;

        if ( axis == QwtPlot::xBottom || axis == QwtPlot::xTop )
        {
            if ( d_data->alignCanvasToScales[QwtPlot::yLeft] )
            {
                double y = canvasRect.left() - d_data->layoutData.scale[axis].start;
                if ( !( options & IgnoreFrames ) )
                    y += d_data->layoutData.canvas.contentsMargins[ QwtPlot::yLeft ];

                sRect.setLeft( y );
            }
            if ( d_data->alignCanvasToScales[QwtPlot::yRight] )
            {
                double y = canvasRect.right() - 1 + d_data->layoutData.scale[axis].end;
                if ( !( options & IgnoreFrames ) )
                    y -= d_data->layoutData.canvas.contentsMargins[ QwtPlot::yRight ];

                sRect.setRight( y );
            }

            if ( d_data->alignCanvasToScales[ axis ] )
            {
                if ( axis == QwtPlot::xTop )
                    sRect.setBottom( canvasRect.top() );
                else
                    sRect.setTop( canvasRect.bottom() );
            }
        }
        else
        {
            if ( d_data->alignCanvasToScales[QwtPlot::xTop] )
            {
                double x = canvasRect.top() - d_data->layoutData.scale[axis].start;
                if ( !( options & IgnoreFrames ) )
                    x += d_data->layoutData.canvas.contentsMargins[ QwtPlot::xTop ];

                sRect.setTop( x );
            }
            if ( d_data->alignCanvasToScales[QwtPlot::xBottom] )
            {
                double x = canvasRect.bottom() - 1 + d_data->layoutData.scale[axis].end;
                if ( !( options & IgnoreFrames ) )
                    x -= d_data->layoutData.canvas.contentsMargins[ QwtPlot::xBottom ];

                sRect.setBottom( x );
            }

            if ( d_data->alignCanvasToScales[ axis ] )
            {
                if ( axis == QwtPlot::yLeft )
                    sRect.setRight( canvasRect.left() );
                else
                    sRect.setLeft( canvasRect.right() );
            }
        }
    }
}

void QwtPlotLayout::activate( const QwtPlot *plot,
    const QRectF &plotRect, Options options )
{
    invalidate();

    QRectF rect( plotRect );  // undistributed rest of the plot rect

    // We extract all layout relevant parameters from the widgets,
    // and save them to d_data->layoutData.

    d_data->layoutData.init( plot, rect );

    if ( !( options & IgnoreLegend )
        && plot->legend() && !plot->legend()->isEmpty() )
    {
        d_data->legendRect = layoutLegend( options, rect );

        // subtract d_data->legendRect from rect

        const QRegion region( rect.toRect() );
        rect = region.subtracted( d_data->legendRect.toRect() ).boundingRect();

        switch ( d_data->legendPos )
        {
            case QwtPlot::LeftLegend:
                rect.setLeft( rect.left() + d_data->spacing );
                break;
            case QwtPlot::RightLegend:
                rect.setRight( rect.right() - d_data->spacing );
                break;
            case QwtPlot::TopLegend:
                rect.setTop( rect.top() + d_data->spacing );
                break;
            case QwtPlot::BottomLegend:
                rect.setBottom( rect.bottom() - d_data->spacing );
                break;
        }
    }

    /*
     +---+-----------+---+
     |       Title       |
     +---+-----------+---+
     |   |   Axis    |   |
     +---+-----------+---+
     | A |           | A |
     | x |  Canvas   | x |
     | i |           | i |
     | s |           | s |
     +---+-----------+---+
     |   |   Axis    |   |
     +---+-----------+---+
     |      Footer       |
     +---+-----------+---+
    */

    // title, footer and axes include text labels. The height of each
    // label depends on its line breaks, that depend on the width
    // for the label. A line break in a horizontal text will reduce
    // the available width for vertical texts and vice versa.
    // expandLineBreaks finds the height/width for title, footer and axes
    // including all line breaks.

    int dimTitle, dimFooter, dimAxes[QwtPlot::axisCnt];
    expandLineBreaks( options, rect, dimTitle, dimFooter, dimAxes );

    if ( dimTitle > 0 )
    {
        d_data->titleRect.setRect(
            rect.left(), rect.top(), rect.width(), dimTitle );

        rect.setTop( d_data->titleRect.bottom() + d_data->spacing );

        if ( d_data->layoutData.scale[QwtPlot::yLeft].isEnabled !=
            d_data->layoutData.scale[QwtPlot::yRight].isEnabled )
        {
            // if only one of the y axes is missing we align
            // the title centered to the canvas

            d_data->titleRect.setX( rect.left() + dimAxes[QwtPlot::yLeft] );
            d_data->titleRect.setWidth( rect.width()
                - dimAxes[QwtPlot::yLeft] - dimAxes[QwtPlot::yRight] );
        }
    }

    if ( dimFooter > 0 )
    {
        d_data->footerRect.setRect(
            rect.left(), rect.bottom() - dimFooter, rect.width(), dimFooter );

        rect.setBottom( d_data->footerRect.top() - d_data->spacing );

        if ( d_data->layoutData.scale[QwtPlot::yLeft].isEnabled !=
            d_data->layoutData.scale[QwtPlot::yRight].isEnabled )
        {
            // if only one of the y axes is missing we align
            // the footer centered to the canvas

            d_data->footerRect.setX( rect.left() + dimAxes[QwtPlot::yLeft] );
            d_data->footerRect.setWidth( rect.width()
                - dimAxes[QwtPlot::yLeft] - dimAxes[QwtPlot::yRight] );
        }
    }

    d_data->canvasRect.setRect(
        rect.x() + dimAxes[QwtPlot::yLeft],
        rect.y() + dimAxes[QwtPlot::xTop],
        rect.width() - dimAxes[QwtPlot::yRight] - dimAxes[QwtPlot::yLeft],
        rect.height() - dimAxes[QwtPlot::xBottom] - dimAxes[QwtPlot::xTop] );

    for ( int axis = 0; axis < QwtPlot::axisCnt; axis++ )
    {
        // set the rects for the axes

        if ( dimAxes[axis] )
        {
            int dim = dimAxes[axis];
            QRectF &scaleRect = d_data->scaleRect[axis];

            scaleRect = d_data->canvasRect;
            switch ( axis )
            {
                case QwtPlot::yLeft:
                    scaleRect.setX( d_data->canvasRect.left() - dim );
                    scaleRect.setWidth( dim );
                    break;
                case QwtPlot::yRight:
                    scaleRect.setX( d_data->canvasRect.right() );
                    scaleRect.setWidth( dim );
                    break;
                case QwtPlot::xBottom:
                    scaleRect.setY( d_data->canvasRect.bottom() );
                    scaleRect.setHeight( dim );
                    break;
                case QwtPlot::xTop:
                    scaleRect.setY( d_data->canvasRect.top() - dim );
                    scaleRect.setHeight( dim );
                    break;
            }
            scaleRect = scaleRect.normalized();
        }
    }

    // +---+-----------+---+
    // |  <-   Axis   ->   |
    // +-^-+-----------+-^-+
    // | | |           | | |
    // |   |           |   |
    // | A |           | A |
    // | x |  Canvas   | x |
    // | i |           | i |
    // | s |           | s |
    // |   |           |   |
    // | | |           | | |
    // +-V-+-----------+-V-+
    // |   <-  Axis   ->   |
    // +---+-----------+---+

    // The ticks of the axes - not the labels above - should
    // be aligned to the canvas. So we try to use the empty
    // corners to extend the axes, so that the label texts
    // left/right of the min/max ticks are moved into them.

    alignScales( options, d_data->canvasRect, d_data->scaleRect );

    if ( !d_data->legendRect.isEmpty() )
    {
        // We prefer to align the legend to the canvas - not to
        // the complete plot - if possible.

        d_data->legendRect = alignLegend( d_data->canvasRect, d_data->legendRect );
    }
}