qwt_legend.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_legend.h"
#include "qwt_legend_label.h"
#include "qwt_dyngrid_layout.h"
#include "qwt_math.h"
#include "qwt_plot_item.h"
#include "qwt_painter.h"
#include <qapplication.h>
#include <qscrollbar.h>
#include <qscrollarea.h>
#include <qpainter.h>
#include <qstyle.h>
#include <qstyleoption.h>

class QwtLegendMap
{
public:
    inline bool isEmpty() const { return d_entries.isEmpty(); }

    void insert( const QVariant &, const QList<QWidget *> & );
    void remove( const QVariant & );

    void removeWidget( const QWidget * );

    QList<QWidget *> legendWidgets( const QVariant & ) const;
    QVariant itemInfo( const QWidget * ) const;

private:
    // we don't know anything about itemInfo and therefore don't have
    // any key that can be used for a map or hashtab.
    // But a simple linear list is o.k. here, as we will never have
    // more than a few entries.

    class Entry
    {
    public:
        QVariant itemInfo;
        QList<QWidget *> widgets;
    };

    QList< Entry > d_entries;
};

void QwtLegendMap::insert( const QVariant &itemInfo, 
    const QList<QWidget *> &widgets )
{
    for ( int i = 0; i < d_entries.size(); i++ )
    {
        Entry &entry = d_entries[i];
        if ( entry.itemInfo == itemInfo )
        {
            entry.widgets = widgets;
            return;
        }
    }

    Entry newEntry;
    newEntry.itemInfo = itemInfo;
    newEntry.widgets = widgets;

    d_entries += newEntry;
}

void QwtLegendMap::remove( const QVariant &itemInfo )
{
    for ( int i = 0; i < d_entries.size(); i++ )
    {
        Entry &entry = d_entries[i];
        if ( entry.itemInfo == itemInfo )
        {
            d_entries.removeAt( i );
            return;
        }
    }
}

void QwtLegendMap::removeWidget( const QWidget *widget )
{
    QWidget *w = const_cast<QWidget *>( widget );

    for ( int i = 0; i < d_entries.size(); i++ )
        d_entries[ i ].widgets.removeAll( w );
}

QVariant QwtLegendMap::itemInfo( const QWidget *widget ) const
{
    if ( widget != NULL )
    {
        QWidget *w = const_cast<QWidget *>( widget );

        for ( int i = 0; i < d_entries.size(); i++ )
        {
            const Entry &entry = d_entries[i];
            if ( entry.widgets.indexOf( w ) >= 0 )
                return entry.itemInfo;
        }
    }

    return QVariant();
}

QList<QWidget *> QwtLegendMap::legendWidgets( const QVariant &itemInfo ) const
{
    if ( itemInfo.isValid() )
    {
        for ( int i = 0; i < d_entries.size(); i++ )
        {
            const Entry &entry = d_entries[i];
            if ( entry.itemInfo == itemInfo )
                return entry.widgets;
        }
    }

    return QList<QWidget *>();
}

class QwtLegend::PrivateData
{
public:
    PrivateData():
        itemMode( QwtLegendData::ReadOnly ),
        view( NULL )
    {
    }

    QwtLegendData::Mode itemMode;
    QwtLegendMap itemMap;

    class LegendView;
    LegendView *view;
};

class QwtLegend::PrivateData::LegendView: public QScrollArea
{
public:
    explicit LegendView( QWidget *parent ):
        QScrollArea( parent )
    {
        contentsWidget = new QWidget( this );
        contentsWidget->setObjectName( "QwtLegendViewContents" );

        setWidget( contentsWidget );
        setWidgetResizable( false );

        viewport()->setObjectName( "QwtLegendViewport" );

        // QScrollArea::setWidget internally sets autoFillBackground to true
        // But we don't want a background.
        contentsWidget->setAutoFillBackground( false );
        viewport()->setAutoFillBackground( false );
    }

    virtual bool event( QEvent *event )
    {
        if ( event->type() == QEvent::PolishRequest )
        {
            setFocusPolicy( Qt::NoFocus );
        }

        if ( event->type() == QEvent::Resize )
        {
            // adjust the size to en/disable the scrollbars
            // before QScrollArea adjusts the viewport size

            const QRect cr = contentsRect();

            int w = cr.width();
            int h = contentsWidget->heightForWidth( cr.width() );
            if ( h > w )
            {
                w -= verticalScrollBar()->sizeHint().width();
                h = contentsWidget->heightForWidth( w );
            }

            contentsWidget->resize( w, h );
        }

        return QScrollArea::event( event );
    }

    virtual bool viewportEvent( QEvent *event )
    {
        bool ok = QScrollArea::viewportEvent( event );

        if ( event->type() == QEvent::Resize )
        {
            layoutContents();
        }
        return ok;
    }

    QSize viewportSize( int w, int h ) const
    {
        const int sbHeight = horizontalScrollBar()->sizeHint().height();
        const int sbWidth = verticalScrollBar()->sizeHint().width();

        const int cw = contentsRect().width();
        const int ch = contentsRect().height();

        int vw = cw;
        int vh = ch;

        if ( w > vw )
            vh -= sbHeight;

        if ( h > vh )
        {
            vw -= sbWidth;
            if ( w > vw && vh == ch )
                vh -= sbHeight;
        }
        return QSize( vw, vh );
    }

    void layoutContents()
    {
        const QwtDynGridLayout *tl = qobject_cast<QwtDynGridLayout *>(
            contentsWidget->layout() );
        if ( tl == NULL )
            return;

        const QSize visibleSize = viewport()->contentsRect().size();

        const int minW = int( tl->maxItemWidth() ) + 2 * tl->margin();

        int w = qMax( visibleSize.width(), minW );
        int h = qMax( tl->heightForWidth( w ), visibleSize.height() );

        const int vpWidth = viewportSize( w, h ).width();
        if ( w > vpWidth )
        {
            w = qMax( vpWidth, minW );
            h = qMax( tl->heightForWidth( w ), visibleSize.height() );
        }

        contentsWidget->resize( w, h );
    }

    QWidget *contentsWidget;
};

QwtLegend::QwtLegend( QWidget *parent ):
    QwtAbstractLegend( parent )
{
    setFrameStyle( NoFrame );

    d_data = new QwtLegend::PrivateData;

    d_data->view = new QwtLegend::PrivateData::LegendView( this );
    d_data->view->setObjectName( "QwtLegendView" );
    d_data->view->setFrameStyle( NoFrame );

    QwtDynGridLayout *gridLayout = new QwtDynGridLayout(
        d_data->view->contentsWidget );
    gridLayout->setAlignment( Qt::AlignHCenter | Qt::AlignTop );

    d_data->view->contentsWidget->installEventFilter( this );

    QVBoxLayout *layout = new QVBoxLayout( this );
    layout->setContentsMargins( 0, 0, 0, 0 );
    layout->addWidget( d_data->view );
}

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

void QwtLegend::setMaxColumns( uint numColums )
{
    QwtDynGridLayout *tl = qobject_cast<QwtDynGridLayout *>(
        d_data->view->contentsWidget->layout() );
    if ( tl )
        tl->setMaxColumns( numColums );
}

uint QwtLegend::maxColumns() const
{
    uint maxCols = 0;

    const QwtDynGridLayout *tl = qobject_cast<const QwtDynGridLayout *>(
        d_data->view->contentsWidget->layout() );
    if ( tl )
        maxCols = tl->maxColumns();

    return maxCols;
}

void QwtLegend::setDefaultItemMode( QwtLegendData::Mode mode )
{
    d_data->itemMode = mode;
}

QwtLegendData::Mode QwtLegend::defaultItemMode() const
{
    return d_data->itemMode;
}

QWidget *QwtLegend::contentsWidget()
{
    return d_data->view->contentsWidget;
}

QScrollBar *QwtLegend::horizontalScrollBar() const
{
    return d_data->view->horizontalScrollBar();
}

QScrollBar *QwtLegend::verticalScrollBar() const
{
    return d_data->view->verticalScrollBar();
}

const QWidget *QwtLegend::contentsWidget() const
{
    return d_data->view->contentsWidget;
}

void QwtLegend::updateLegend( const QVariant &itemInfo, 
    const QList<QwtLegendData> &data )
{
    QList<QWidget *> widgetList = legendWidgets( itemInfo );

    if ( widgetList.size() != data.size() )
    {
        QLayout *contentsLayout = d_data->view->contentsWidget->layout();

        while ( widgetList.size() > data.size() )
        {
            QWidget *w = widgetList.takeLast();

            contentsLayout->removeWidget( w );

            // updates might be triggered by signals from the legend widget
            // itself. So we better don't delete it here.

            w->hide();
            w->deleteLater();
        }

        for ( int i = widgetList.size(); i < data.size(); i++ )
        {
            QWidget *widget = createWidget( data[i] );

            if ( contentsLayout )
                contentsLayout->addWidget( widget );

            if ( isVisible() )
            {
                // QLayout does a delayed show, with the effect, that
                // the size hint will be wrong, when applications
                // call replot() right after changing the list
                // of plot items. So we better do the show now.

                widget->setVisible( true );
            }

            widgetList += widget;
        }

        if ( widgetList.isEmpty() )
        {
            d_data->itemMap.remove( itemInfo );
        }
        else
        {
            d_data->itemMap.insert( itemInfo, widgetList );
        }

        updateTabOrder();
    }
    
    for ( int i = 0; i < data.size(); i++ )
        updateWidget( widgetList[i], data[i] );
}

QWidget *QwtLegend::createWidget( const QwtLegendData &data ) const
{
    Q_UNUSED( data );

    QwtLegendLabel *label = new QwtLegendLabel();
    label->setItemMode( defaultItemMode() );

    connect( label, SIGNAL( clicked() ), SLOT( itemClicked() ) );
    connect( label, SIGNAL( checked( bool ) ), SLOT( itemChecked( bool ) ) );

    return label;
}

void QwtLegend::updateWidget( QWidget *widget, const QwtLegendData &data )
{
    QwtLegendLabel *label = qobject_cast<QwtLegendLabel *>( widget );
    if ( label )
    {
        label->setData( data );
        if ( !data.value( QwtLegendData::ModeRole ).isValid() )
        {
            // use the default mode, when there is no specific
            // hint from the legend data

            label->setItemMode( defaultItemMode() );
        }
    }
}

void QwtLegend::updateTabOrder()
{
    QLayout *contentsLayout = d_data->view->contentsWidget->layout();
    if ( contentsLayout )
    {
        // set tab focus chain

        QWidget *w = NULL;

        for ( int i = 0; i < contentsLayout->count(); i++ )
        {
            QLayoutItem *item = contentsLayout->itemAt( i );
            if ( w && item->widget() )
                QWidget::setTabOrder( w, item->widget() );

            w = item->widget();
        }
    }
}

QSize QwtLegend::sizeHint() const
{
    QSize hint = d_data->view->contentsWidget->sizeHint();
    hint += QSize( 2 * frameWidth(), 2 * frameWidth() );

    return hint;
}

int QwtLegend::heightForWidth( int width ) const
{
    width -= 2 * frameWidth();

    int h = d_data->view->contentsWidget->heightForWidth( width );
    if ( h >= 0 )
        h += 2 * frameWidth();

    return h;
}


bool QwtLegend::eventFilter( QObject *object, QEvent *event )
{
    if ( object == d_data->view->contentsWidget )
    {
        switch ( event->type() )
        {
            case QEvent::ChildRemoved:
            {
                const QChildEvent *ce = 
                    static_cast<const QChildEvent *>(event);
                if ( ce->child()->isWidgetType() )
                {
                    QWidget *w = static_cast< QWidget * >( ce->child() );
                    d_data->itemMap.removeWidget( w );
                }
                break;
            }
            case QEvent::LayoutRequest:
            {
                d_data->view->layoutContents();

                if ( parentWidget() && parentWidget()->layout() == NULL )
                {
                    /*
                       We want the parent widget ( usually QwtPlot ) to recalculate
                       its layout, when the contentsWidget has changed. But
                       because of the scroll view we have to forward the LayoutRequest
                       event manually.

                       We don't use updateGeometry() because it doesn't post LayoutRequest
                       events when the legend is hidden. But we want the
                       parent widget notified, so it can show/hide the legend
                       depending on its items.
                     */
                    QApplication::postEvent( parentWidget(),
                        new QEvent( QEvent::LayoutRequest ) );
                }                
                break;
            }
            default:
                break;
        }
    }

    return QwtAbstractLegend::eventFilter( object, event );
}

void QwtLegend::itemClicked()
{
    QWidget *w = qobject_cast<QWidget *>( sender() );
    if ( w )
    {
        const QVariant itemInfo = d_data->itemMap.itemInfo( w );
        if ( itemInfo.isValid() )
        {
            const QList<QWidget *> widgetList =
                d_data->itemMap.legendWidgets( itemInfo );

            const int index = widgetList.indexOf( w );
            if ( index >= 0 )
                Q_EMIT clicked( itemInfo, index );
        }
    }
}

void QwtLegend::itemChecked( bool on )
{
    QWidget *w = qobject_cast<QWidget *>( sender() );
    if ( w )
    {
        const QVariant itemInfo = d_data->itemMap.itemInfo( w );
        if ( itemInfo.isValid() )
        {
            const QList<QWidget *> widgetList =
                d_data->itemMap.legendWidgets( itemInfo );

            const int index = widgetList.indexOf( w );
            if ( index >= 0 )
                Q_EMIT checked( itemInfo, on, index );
        }
    }
}

void QwtLegend::renderLegend( QPainter *painter, 
    const QRectF &rect, bool fillBackground ) const
{
    if ( d_data->itemMap.isEmpty() )
        return;

    if ( fillBackground )
    {
        if ( autoFillBackground() ||
            testAttribute( Qt::WA_StyledBackground ) )
        {
            QwtPainter::drawBackgound( painter, rect, this );
        }
    }

    const QwtDynGridLayout *legendLayout = 
        qobject_cast<QwtDynGridLayout *>( contentsWidget()->layout() );
    if ( legendLayout == NULL )
        return;

    int left, right, top, bottom;
    getContentsMargins( &left, &top, &right, &bottom );

    QRect layoutRect; 
    layoutRect.setLeft( qCeil( rect.left() ) + left );
    layoutRect.setTop( qCeil( rect.top() ) + top );
    layoutRect.setRight( qFloor( rect.right() ) - right );
    layoutRect.setBottom( qFloor( rect.bottom() ) - bottom );

    uint numCols = legendLayout->columnsForWidth( layoutRect.width() );
    QList<QRect> itemRects =
        legendLayout->layoutItems( layoutRect, numCols );

    int index = 0;

    for ( int i = 0; i < legendLayout->count(); i++ )
    {
        QLayoutItem *item = legendLayout->itemAt( i );
        QWidget *w = item->widget();
        if ( w )
        {
            painter->save();

            painter->setClipRect( itemRects[index], Qt::IntersectClip );
            renderItem( painter, w, itemRects[index], fillBackground );

            index++;
            painter->restore();
        }
    }
}

void QwtLegend::renderItem( QPainter *painter, 
    const QWidget *widget, const QRectF &rect, bool fillBackground ) const
{
    if ( fillBackground )
    {
        if ( widget->autoFillBackground() ||
            widget->testAttribute( Qt::WA_StyledBackground ) )
        {
            QwtPainter::drawBackgound( painter, rect, widget );
        }
    }

    const QwtLegendLabel *label = qobject_cast<const QwtLegendLabel *>( widget );
    if ( label )
    {
        // icon

        const QwtGraphic &icon = label->data().icon();
        const QSizeF sz = icon.defaultSize();

        const QRectF iconRect( rect.x() + label->margin(),
            rect.center().y() - 0.5 * sz.height(), 
            sz.width(), sz.height() );

        icon.render( painter, iconRect, Qt::KeepAspectRatio );

        // title

        QRectF titleRect = rect;
        titleRect.setX( iconRect.right() + 2 * label->spacing() );

        painter->setFont( label->font() );
        painter->setPen( label->palette().color( QPalette::Text ) );
        const_cast< QwtLegendLabel *>( label )->drawText( painter, titleRect );
    }
}

QList<QWidget *> QwtLegend::legendWidgets( const QVariant &itemInfo ) const
{
    return d_data->itemMap.legendWidgets( itemInfo );
}

QWidget *QwtLegend::legendWidget( const QVariant &itemInfo ) const
{
    const QList<QWidget *> list = d_data->itemMap.legendWidgets( itemInfo );
    if ( list.isEmpty() )
        return NULL;

    return list[0];
}

QVariant QwtLegend::itemInfo( const QWidget *widget ) const
{
    return d_data->itemMap.itemInfo( widget );
}

bool QwtLegend::isEmpty() const
{
    return d_data->itemMap.isEmpty();
}

int QwtLegend::scrollExtent( Qt::Orientation orientation ) const
{
    int extent = 0;

    if ( orientation == Qt::Horizontal )
        extent = verticalScrollBar()->sizeHint().width();
    else
        extent = horizontalScrollBar()->sizeHint().height();

    return extent;
}