qwt_plot_layout.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
 *****************************************************************************/

// vim: expandtab

#include <qscrollbar.h>
#include "qwt_rect.h"
#include "qwt_text.h"
#include "qwt_text_label.h"
#include "qwt_plot_canvas.h"
#include "qwt_scale_widget.h"
#include "qwt_legend.h"
#include "qwt_plot_layout.h"

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

    struct t_legendData
    {
        int frameWidth;
        int vScrollBarWidth;
        int hScrollBarHeight;
        QSize hint;
    } legend;
    
    struct t_titleData
    {
        QwtText text;
        int frameWidth;
    } title;

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

    struct t_canvasData
    {
        int frameWidth;
    } canvas;
};

/*
  Extract all layout relevant data from the plot components
*/

void QwtPlotLayout::LayoutData::init(const QwtPlot *plot, const QRect &rect)
{
    // legend

    if ( plot->plotLayout()->legendPosition() != QwtPlot::ExternalLegend 
        && plot->legend() )
    {
        legend.frameWidth = plot->legend()->frameWidth();
        legend.vScrollBarWidth = 
            plot->legend()->verticalScrollBar()->sizeHint().width();
        legend.hScrollBarHeight = 
            plot->legend()->horizontalScrollBar()->sizeHint().height();

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

        int w = qwtMin(hint.width(), rect.width());
        int h = plot->legend()->heightForWidth(w);
        if ( h == 0 )
            h = hint.height();

        if ( h > rect.height() )
            w += legend.vScrollBarWidth;

        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();
    }

    // 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 += 
                    (int)scaleWidget->scaleDraw()->majTickLength();
            }

            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;
            scale[axis].dimWithoutTitle = 0;
        }
    }

    // canvas 

    canvas.frameWidth = plot->canvas()->frameWidth();
}

class QwtPlotLayout::PrivateData
{
public:
    PrivateData():
        margin(0),
        spacing(5),
        alignCanvasToScales(false)
    {
    }

    QRect titleRect;
    QRect legendRect;
    QRect scaleRect[QwtPlot::axisCnt];
    QRect canvasRect;

    QwtPlotLayout::LayoutData layoutData;

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

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

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

    invalidate();
}

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

void QwtPlotLayout::setMargin(int margin)
{
    if ( margin < 0 )
        margin = 0;
    d_data->margin = margin;
}

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

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 axis) const
{
    if ( axis < 0 || axis >= QwtPlot::axisCnt )
        return 0;

    return d_data->canvasMargin[axis];
}

void QwtPlotLayout::setAlignCanvasToScales(bool alignCanvasToScales)
{
    d_data->alignCanvasToScales = alignCanvasToScales;
}

bool QwtPlotLayout::alignCanvasToScales() const
{
    return d_data->alignCanvasToScales;
}

void QwtPlotLayout::setSpacing(int spacing)
{
    d_data->spacing = qwtMax(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;
        case QwtPlot::ExternalLegend:
            d_data->legendRatio = ratio; // meaningless
            d_data->legendPos = pos;
        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;
}

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

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

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

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

void QwtPlotLayout::invalidate()
{
    d_data->titleRect = 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 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 += scl->scaleDraw()->majTickLength();
        }

        canvasBorder[axis] = plot->canvas()->frameWidth() +
            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 QwtPlotCanvas *canvas = plot->canvas();
    const QSize minCanvasSize = canvas->minimumSize();

    int w = scaleData[QwtPlot::yLeft].w + scaleData[QwtPlot::yRight].w;
    int cw = qwtMax(scaleData[QwtPlot::xBottom].w, scaleData[QwtPlot::xTop].w)
        + 2 * (canvas->frameWidth() + 1);
    w += qwtMax(cw, minCanvasSize.width());

    int h = scaleData[QwtPlot::xBottom].h + scaleData[QwtPlot::xTop].h;
    int ch = qwtMax(scaleData[QwtPlot::yLeft].h, scaleData[QwtPlot::yRight].h)
        + 2 * (canvas->frameWidth() + 1);
    h += qwtMax(ch, minCanvasSize.height());

    const QwtTextLabel *title = plot->titleLabel();
    if (title && !title->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 titleW = w;
        if ( centerOnCanvas )
        {
            titleW -= scaleData[QwtPlot::yLeft].w 
                + scaleData[QwtPlot::yRight].w;
        }

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

            titleH = title->heightForWidth(titleW);
        }
        h += titleH + d_data->spacing;
    }

    // Compute the legend contribution

    const QwtLegend *legend = plot->legend();
    if ( d_data->legendPos != QwtPlot::ExternalLegend
        && 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->verticalScrollBar()->sizeHint().height();

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

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

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

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

    w += 2 * d_data->margin;
    h += 2 * d_data->margin;

    return QSize( w, h );
}

QRect QwtPlotLayout::layoutLegend(int options, 
    const QRect &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 = qwtMin(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.vScrollBarWidth;
            }
        }
    }
    else
    {
        dim = qwtMin(hint.height(), int(rect.height() * d_data->legendRatio));
        dim = qwtMax(dim, d_data->layoutData.legend.hScrollBarHeight);
    }

    QRect legendRect = rect;
    switch(d_data->legendPos)
    {
        case QwtPlot::LeftLegend:
            legendRect.setWidth(dim);
            break;
        case QwtPlot::RightLegend:
            legendRect.setX(rect.right() - dim + 1);
            legendRect.setWidth(dim);
            break;
        case QwtPlot::TopLegend:
            legendRect.setHeight(dim);
            break;
        case QwtPlot::BottomLegend:
            legendRect.setY(rect.bottom() - dim + 1);
            legendRect.setHeight(dim);
            break;
        case QwtPlot::ExternalLegend:
            break;
    }

    return legendRect;
}

QRect QwtPlotLayout::alignLegend(const QRect &canvasRect, 
    const QRect &legendRect) const
{
    QRect 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(int options, const QRect &rect, 
    int &dimTitle, int dimAxis[QwtPlot::axisCnt]) const
{
    dimTitle = 0;
    for ( int i = 0; i < QwtPlot::axisCnt; i++ )
        dimAxis[i] = 0;

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

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

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

            const struct LayoutData::t_scaleData &scaleData = 
                d_data->layoutData.scale[axis];

            if (scaleData.isEnabled)
            {
                int length;
                if ( axis == QwtPlot::xTop || axis == QwtPlot::xBottom )
                {
                    length = rect.width() - dimAxis[QwtPlot::yLeft] 
                        - dimAxis[QwtPlot::yRight];
                    length += qwtMin(dimAxis[QwtPlot::yLeft], 
                        scaleData.start - backboneOffset);
                    length += qwtMin(dimAxis[QwtPlot::yRight], 
                        scaleData.end - backboneOffset);
                }
                else // QwtPlot::yLeft, QwtPlot::yRight
                {
                    length = rect.height() - dimAxis[QwtPlot::xTop] 
                        - dimAxis[QwtPlot::xBottom];

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

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

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

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

void QwtPlotLayout::alignScales(int options,
    QRect &canvasRect, QRect scaleRect[QwtPlot::axisCnt]) const
{
    int axis;

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

    for (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;

        QRect &axisRect = scaleRect[axis];

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

            if ( scaleRect[QwtPlot::yLeft].isValid() )
            {
                int minLeft = scaleRect[QwtPlot::yLeft].left();
                int left = axisRect.left() + leftOffset;
                axisRect.setLeft(qwtMax(left, minLeft));
            }
            else
            {
                if ( d_data->alignCanvasToScales && leftOffset < 0 )
                {
                    canvasRect.setLeft(qwtMax(canvasRect.left(), 
                        axisRect.left() - leftOffset));
                }
                else
                {
                    if ( leftOffset > 0 )
                        axisRect.setLeft(axisRect.left() + leftOffset);
                }
            }

            const int rightOffset = backboneOffset[QwtPlot::yRight] - endDist;

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

            if ( scaleRect[QwtPlot::xBottom].isValid() )
            {
                int maxBottom = scaleRect[QwtPlot::xBottom].top() + 
                    d_data->layoutData.scale[QwtPlot::xBottom].tickOffset;

                int bottom = axisRect.bottom() - bottomOffset;
                axisRect.setBottom(qwtMin(bottom, maxBottom));
            }
            else
            {
                if ( d_data->alignCanvasToScales && bottomOffset < 0 )
                {
                    canvasRect.setBottom(qwtMin(canvasRect.bottom(), 
                        axisRect.bottom() + bottomOffset));
                }
                else
                {
                    if ( bottomOffset > 0 )
                        axisRect.setBottom(axisRect.bottom() - bottomOffset);
                }
            }
        
            const int topOffset = backboneOffset[QwtPlot::xTop] - startDist;

            if ( scaleRect[QwtPlot::xTop].isValid() )
            {
                int minTop = scaleRect[QwtPlot::xTop].bottom() -
                    d_data->layoutData.scale[QwtPlot::xTop].tickOffset;

                int top = axisRect.top() + topOffset;
                axisRect.setTop(qwtMax(top, minTop));
            }
            else
            {
                if ( d_data->alignCanvasToScales && topOffset < 0 )
                {
                    canvasRect.setTop(qwtMax(canvasRect.top(), 
                        axisRect.top() - topOffset));
                }
                else
                {
                    if ( topOffset > 0 )
                        axisRect.setTop(axisRect.top() + topOffset);
                }
            }
        }
    }

    if ( d_data->alignCanvasToScales )
    {
        /*
          The canvas has been aligned to the scale with largest
          border distances. Now we have to realign the other scale.
         */

        if ( scaleRect[QwtPlot::xBottom].isValid() && 
            scaleRect[QwtPlot::xTop].isValid() )
        {
            for ( int axis = QwtPlot::xBottom; axis <= QwtPlot::xTop; axis++ )
            {
                scaleRect[axis].setLeft(canvasRect.left() + 1 
                    - d_data->layoutData.scale[axis].start);
                scaleRect[axis].setRight(canvasRect.right() - 1 
                    + d_data->layoutData.scale[axis].end);
            }
        }

        if ( scaleRect[QwtPlot::yLeft].isValid() && 
            scaleRect[QwtPlot::yRight].isValid() )
        {
            for ( int axis = QwtPlot::yLeft; axis <= QwtPlot::yRight; axis++ )
            {
                scaleRect[axis].setTop(canvasRect.top() + 1 
                    - d_data->layoutData.scale[axis].start);
                scaleRect[axis].setBottom(canvasRect.bottom() - 1 
                    + d_data->layoutData.scale[axis].end);
            }
        }
    }
}

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

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

    if ( !(options & IgnoreMargin) )
    {
        // subtract the margin

        rect.setRect(
            rect.x() + d_data->margin, 
            rect.y() + d_data->margin,
            rect.width() - 2 * d_data->margin, 
            rect.height() - 2 * d_data->margin
        );
    }

    // We extract all layout relevant data from the widgets,
    // filter them through pfilter and save them to d_data->layoutData.

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

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

        // subtract d_data->legendRect from rect

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

        if ( d_data->layoutData.legend.frameWidth && 
            !(options & IgnoreFrames ) )
        {
            // In case of a frame we have to insert a spacing.
            // Otherwise the leading of the font separates
            // legend and scale/canvas

            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;
                case QwtPlot::ExternalLegend:
                    break; // suppress compiler warning
            }
        }
    }

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


    // axes and title 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 and axes
    // including all line breaks.

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

    if (dimTitle > 0 )
    {
        d_data->titleRect = QRect(rect.x(), rect.y(),
            rect.width(), dimTitle);

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

        // subtract title 
        rect.setTop(rect.top() + dimTitle + d_data->spacing);
    }

    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];
            QRect &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() + 1);
                    scaleRect.setWidth(dim);
                    break;
                case QwtPlot::xBottom:
                    scaleRect.setY(d_data->canvasRect.bottom() + 1);
                    scaleRect.setHeight(dim);
                    break;
                case QwtPlot::xTop:
                    scaleRect.setY(d_data->canvasRect.top() - dim);
                    scaleRect.setHeight(dim);
                    break;
            }
#if QT_VERSION < 0x040000
            scaleRect = scaleRect.normalize();
#else
            scaleRect = scaleRect.normalized();
#endif
        }
    }

    // +---+-----------+---+
    // |  <-   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);
    }
}

---