qwt_picker.cpp

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/******************************************************************************
 * 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_picker.h"
#include "qwt_picker_machine.h"
#include "qwt_painter.h"
#include "qwt_math.h"
#include "qwt_widget_overlay.h"
#include "qwt_text.h"
 
#include <qevent.h>
#include <qpainter.h>
#include <qpainterpath.h>
#include <qcursor.h>
#include <qpointer.h>
#include <qmath.h>
 
static inline QRegion qwtMaskRegion( const QRect& r, int penWidth )
{
    const int pw = qMax( penWidth, 1 );
    const int pw2 = penWidth / 2;
 
    int x1 = r.left() - pw2;
    int x2 = r.right() + 1 + pw2 + ( pw % 2 );
 
    int y1 = r.top() - pw2;
    int y2 = r.bottom() + 1 + pw2 + ( pw % 2 );
 
    QRegion region;
 
    region += QRect( x1, y1, x2 - x1, pw );
    region += QRect( x1, y1, pw, y2 - y1 );
    region += QRect( x1, y2 - pw, x2 - x1, pw );
    region += QRect( x2 - pw, y1, pw, y2 - y1 );
 
    return region;
}
 
static inline QRegion qwtMaskRegion( const QLine& l, int penWidth )
{
    const int pw = qMax( penWidth, 1 );
    const int pw2 = penWidth / 2;
 
    QRegion region;
 
    if ( l.x1() == l.x2() )
    {
        region += QRect( l.x1() - pw2, l.y1(),
            pw, l.y2() ).normalized();
    }
    else if ( l.y1() == l.y2() )
    {
        region += QRect( l.x1(), l.y1() - pw2,
            l.x2(), pw ).normalized();
    }
 
    return region;
}
 
namespace
{
    class Rubberband QWT_FINAL : public QwtWidgetOverlay
    {
      public:
        Rubberband( QwtPicker* picker, QWidget* parent )
            : QwtWidgetOverlay( parent )
            , m_picker( picker )
        {
            setMaskMode( QwtWidgetOverlay::MaskHint );
        }
 
      protected:
        virtual void drawOverlay( QPainter* painter ) const QWT_OVERRIDE
        {
            painter->setPen( m_picker->rubberBandPen() );
            m_picker->drawRubberBand( painter );
        }
 
        virtual QRegion maskHint() const QWT_OVERRIDE
        {
            return m_picker->rubberBandMask();
        }
 
        QwtPicker* m_picker;
    };
 
    class Tracker QWT_FINAL : public QwtWidgetOverlay
    {
      public:
        Tracker( QwtPicker* picker, QWidget* parent )
            : QwtWidgetOverlay( parent )
            , m_picker( picker )
        {
            setMaskMode( QwtWidgetOverlay::MaskHint );
        }
 
      protected:
        virtual void drawOverlay( QPainter* painter ) const QWT_OVERRIDE
        {
            painter->setPen( m_picker->trackerPen() );
            m_picker->drawTracker( painter );
        }
 
        virtual QRegion maskHint() const QWT_OVERRIDE
        {
            return m_picker->trackerMask();
        }
 
        QwtPicker* m_picker;
    };
}
 
class QwtPicker::PrivateData
{
  public:
    PrivateData():
        enabled( false ),
        stateMachine( NULL ),
        resizeMode( QwtPicker::Stretch ),
        rubberBand( QwtPicker::NoRubberBand ),
        trackerMode( QwtPicker::AlwaysOff ),
        isActive( false ),
        trackerPosition( -1, -1 ),
        mouseTracking( false ),
        openGL( false )
    {
    }
 
    bool enabled;
 
    QwtPickerMachine* stateMachine;
 
    QwtPicker::ResizeMode resizeMode;
 
    QwtPicker::RubberBand rubberBand;
    QPen rubberBandPen;
 
    QwtPicker::DisplayMode trackerMode;
    QPen trackerPen;
    QFont trackerFont;
 
    QPolygon pickedPoints;
    bool isActive;
    QPoint trackerPosition;
 
    bool mouseTracking; // used to save previous value
 
    QPointer< Rubberband > rubberBandOverlay;
    QPointer< Tracker > trackerOverlay;
 
    bool openGL;
};
 
QwtPicker::QwtPicker( QWidget* parent ):
    QObject( parent )
{
    init( parent, NoRubberBand, AlwaysOff );
}
 
QwtPicker::QwtPicker( RubberBand rubberBand,
    DisplayMode trackerMode, QWidget* parent ):
    QObject( parent )
{
    init( parent, rubberBand, trackerMode );
}
 
QwtPicker::~QwtPicker()
{
    setMouseTracking( false );
 
    delete m_data->stateMachine;
    delete m_data->rubberBandOverlay;
    delete m_data->trackerOverlay;
 
    delete m_data;
}
 
void QwtPicker::init( QWidget* parent,
    RubberBand rubberBand, DisplayMode trackerMode )
{
    m_data = new PrivateData;
 
    m_data->rubberBand = rubberBand;
 
    if ( parent )
    {
        if ( parent->focusPolicy() == Qt::NoFocus )
            parent->setFocusPolicy( Qt::WheelFocus );
 
        m_data->openGL = parent->inherits( "QGLWidget" );
        m_data->trackerFont = parent->font();
        m_data->mouseTracking = parent->hasMouseTracking();
 
        setEnabled( true );
    }
 
    setTrackerMode( trackerMode );
}
 
void QwtPicker::setStateMachine( QwtPickerMachine* stateMachine )
{
    if ( m_data->stateMachine != stateMachine )
    {
        reset();
 
        delete m_data->stateMachine;
        m_data->stateMachine = stateMachine;
 
        if ( m_data->stateMachine )
            m_data->stateMachine->reset();
    }
}
 
QwtPickerMachine* QwtPicker::stateMachine()
{
    return m_data->stateMachine;
}
 
const QwtPickerMachine* QwtPicker::stateMachine() const
{
    return m_data->stateMachine;
}
 
QWidget* QwtPicker::parentWidget()
{
    QObject* obj = parent();
    if ( obj && obj->isWidgetType() )
        return static_cast< QWidget* >( obj );
 
    return NULL;
}
 
const QWidget* QwtPicker::parentWidget() const
{
    QObject* obj = parent();
    if ( obj && obj->isWidgetType() )
        return static_cast< const QWidget* >( obj );
 
    return NULL;
}
 
void QwtPicker::setRubberBand( RubberBand rubberBand )
{
    m_data->rubberBand = rubberBand;
}
 
QwtPicker::RubberBand QwtPicker::rubberBand() const
{
    return m_data->rubberBand;
}
 
void QwtPicker::setTrackerMode( DisplayMode mode )
{
    if ( m_data->trackerMode != mode )
    {
        m_data->trackerMode = mode;
        setMouseTracking( m_data->trackerMode == AlwaysOn );
    }
}
 
QwtPicker::DisplayMode QwtPicker::trackerMode() const
{
    return m_data->trackerMode;
}
 
void QwtPicker::setResizeMode( ResizeMode mode )
{
    m_data->resizeMode = mode;
}
 
QwtPicker::ResizeMode QwtPicker::resizeMode() const
{
    return m_data->resizeMode;
}
 
void QwtPicker::setEnabled( bool enabled )
{
    if ( m_data->enabled != enabled )
    {
        m_data->enabled = enabled;
 
        QWidget* w = parentWidget();
        if ( w )
        {
            if ( enabled )
                w->installEventFilter( this );
            else
                w->removeEventFilter( this );
        }
 
        updateDisplay();
    }
}
 
bool QwtPicker::isEnabled() const
{
    return m_data->enabled;
}
 
void QwtPicker::setTrackerFont( const QFont& font )
{
    if ( font != m_data->trackerFont )
    {
        m_data->trackerFont = font;
        updateDisplay();
    }
}
 
QFont QwtPicker::trackerFont() const
{
    return m_data->trackerFont;
}
 
void QwtPicker::setTrackerPen( const QPen& pen )
{
    if ( pen != m_data->trackerPen )
    {
        m_data->trackerPen = pen;
        updateDisplay();
    }
}
 
QPen QwtPicker::trackerPen() const
{
    return m_data->trackerPen;
}
 
void QwtPicker::setRubberBandPen( const QPen& pen )
{
    if ( pen != m_data->rubberBandPen )
    {
        m_data->rubberBandPen = pen;
        updateDisplay();
    }
}
 
QPen QwtPicker::rubberBandPen() const
{
    return m_data->rubberBandPen;
}
 
QwtText QwtPicker::trackerText( const QPoint& pos ) const
{
    QString label;
 
    switch ( rubberBand() )
    {
        case HLineRubberBand:
            label = QString::number( pos.y() );
            break;
        case VLineRubberBand:
            label = QString::number( pos.x() );
            break;
        default:
            label = QString::number( pos.x() ) + ", " + QString::number( pos.y() );
    }
    return label;
}
 
QRegion QwtPicker::trackerMask() const
{
    return trackerRect( m_data->trackerFont );
}
 
QRegion QwtPicker::rubberBandMask() const
{
    QRegion mask;
 
    if ( !isActive() || rubberBand() == NoRubberBand ||
        rubberBandPen().style() == Qt::NoPen )
    {
        return mask;
    }
 
    const QPolygon pa = adjustedPoints( m_data->pickedPoints );
 
    QwtPickerMachine::SelectionType selectionType =
        QwtPickerMachine::NoSelection;
 
    if ( m_data->stateMachine )
        selectionType = m_data->stateMachine->selectionType();
 
    const int pw = qCeil( rubberBandPen().widthF()
        * QwtPainter::devicePixelRatio( parentWidget() ) );
 
    switch ( selectionType )
    {
        case QwtPickerMachine::NoSelection:
        case QwtPickerMachine::PointSelection:
        {
            if ( pa.count() < 1 )
                return mask;
 
            const QPoint pos = pa[0];
 
            const QRect pRect = pickArea().boundingRect().toRect();
            switch ( rubberBand() )
            {
                case VLineRubberBand:
                {
                    mask += qwtMaskRegion( QLine( pos.x(), pRect.top(),
                        pos.x(), pRect.bottom() ), pw );
                    break;
                }
                case HLineRubberBand:
                {
                    mask += qwtMaskRegion( QLine( pRect.left(), pos.y(),
                        pRect.right(), pos.y() ), pw );
                    break;
                }
                case CrossRubberBand:
                {
                    mask += qwtMaskRegion( QLine( pos.x(), pRect.top(),
                        pos.x(), pRect.bottom() ), pw );
                    mask += qwtMaskRegion( QLine( pRect.left(), pos.y(),
                        pRect.right(), pos.y() ), pw );
                    break;
                }
                default:
                    break;
            }
            break;
        }
        case QwtPickerMachine::RectSelection:
        {
            if ( pa.count() < 2 )
                return mask;
 
            switch ( rubberBand() )
            {
                case RectRubberBand:
                {
                    const QRect r = QRect( pa.first(), pa.last() );
                    mask = qwtMaskRegion( r.normalized(), pw );
                    break;
                }
                case EllipseRubberBand:
                {
                    const QRect r = QRect( pa.first(), pa.last() );
                    mask += r.adjusted( -pw, -pw, pw, pw );
                    break;
                }
                default:
                    break;
            }
            break;
        }
        case QwtPickerMachine::PolygonSelection:
        {
            if ( pw <= 1 )
            {
                // because of the join style we better
                // return a mask for a pen width <= 1 only
 
                const int off = 2 * pw;
                const QRect r = pa.boundingRect();
                mask += r.adjusted( -off, -off, off, off );
            }
            break;
        }
        default:
            break;
    }
 
    return mask;
}
 
void QwtPicker::drawRubberBand( QPainter* painter ) const
{
    if ( !isActive() || rubberBand() == NoRubberBand ||
        rubberBandPen().style() == Qt::NoPen )
    {
        return;
    }
 
    const QPolygon pa = adjustedPoints( m_data->pickedPoints );
 
    QwtPickerMachine::SelectionType selectionType =
        QwtPickerMachine::NoSelection;
 
    if ( m_data->stateMachine )
        selectionType = m_data->stateMachine->selectionType();
 
    switch ( selectionType )
    {
        case QwtPickerMachine::NoSelection:
        case QwtPickerMachine::PointSelection:
        {
            if ( pa.count() < 1 )
                return;
 
            const QPoint pos = pa[0];
 
            const QRect pRect = pickArea().boundingRect().toRect();
            switch ( rubberBand() )
            {
                case VLineRubberBand:
                {
                    QwtPainter::drawLine( painter, pos.x(),
                        pRect.top(), pos.x(), pRect.bottom() );
                    break;
                }
                case HLineRubberBand:
                {
                    QwtPainter::drawLine( painter, pRect.left(),
                        pos.y(), pRect.right(), pos.y() );
                    break;
                }
                case CrossRubberBand:
                {
                    QwtPainter::drawLine( painter, pos.x(),
                        pRect.top(), pos.x(), pRect.bottom() );
                    QwtPainter::drawLine( painter, pRect.left(),
                        pos.y(), pRect.right(), pos.y() );
                    break;
                }
                default:
                    break;
            }
            break;
        }
        case QwtPickerMachine::RectSelection:
        {
            if ( pa.count() < 2 )
                return;
 
            const QRect rect = QRect( pa.first(), pa.last() ).normalized();
            switch ( rubberBand() )
            {
                case EllipseRubberBand:
                {
                    QwtPainter::drawEllipse( painter, rect );
                    break;
                }
                case RectRubberBand:
                {
                    QwtPainter::drawRect( painter, rect );
                    break;
                }
                default:
                    break;
            }
            break;
        }
        case QwtPickerMachine::PolygonSelection:
        {
            if ( rubberBand() == PolygonRubberBand )
                painter->drawPolyline( pa );
            break;
        }
        default:
            break;
    }
}
 
void QwtPicker::drawTracker( QPainter* painter ) const
{
    const QRect textRect = trackerRect( painter->font() );
    if ( !textRect.isEmpty() )
    {
        const QwtText label = trackerText( m_data->trackerPosition );
        if ( !label.isEmpty() )
            label.draw( painter, textRect );
    }
}
 
QPolygon QwtPicker::adjustedPoints( const QPolygon& points ) const
{
    return points;
}
 
QPolygon QwtPicker::selection() const
{
    return adjustedPoints( m_data->pickedPoints );
}
 
QPoint QwtPicker::trackerPosition() const
{
    return m_data->trackerPosition;
}
 
QRect QwtPicker::trackerRect( const QFont& font ) const
{
    if ( trackerMode() == AlwaysOff ||
        ( trackerMode() == ActiveOnly && !isActive() ) )
    {
        return QRect();
    }
 
    if ( m_data->trackerPosition.x() < 0 || m_data->trackerPosition.y() < 0 )
        return QRect();
 
    QwtText text = trackerText( m_data->trackerPosition );
    if ( text.isEmpty() )
        return QRect();
 
    const QSizeF textSize = text.textSize( font );
 
    const int w = qwtCeil( textSize.width() );
    const int h = qwtCeil( textSize.height() );
 
    return trackerRect( QSize( w, h ) );
}
 
QRect QwtPicker::trackerRect( const QSize& size ) const
{
    const QPoint& pos = m_data->trackerPosition;
    QRect infoRect( 0, 0, size.width(), size.height() );
 
    int alignment = 0;
    if ( isActive() && m_data->pickedPoints.count() > 1
        && rubberBand() != NoRubberBand )
    {
        const QPoint last =
            m_data->pickedPoints[ m_data->pickedPoints.count() - 2 ];
 
        alignment |= ( pos.x() >= last.x() ) ? Qt::AlignRight : Qt::AlignLeft;
        alignment |= ( pos.y() > last.y() ) ? Qt::AlignBottom : Qt::AlignTop;
    }
    else
    {
        alignment = Qt::AlignTop | Qt::AlignRight;
    }
 
    const int margin = 5;
 
    int x = pos.x();
    if ( alignment & Qt::AlignLeft )
        x -= infoRect.width() + margin;
    else if ( alignment & Qt::AlignRight )
        x += margin;
 
    int y = pos.y();
    if ( alignment & Qt::AlignBottom )
        y += margin;
    else if ( alignment & Qt::AlignTop )
        y -= infoRect.height() + margin;
 
    infoRect.moveTopLeft( QPoint( x, y ) );
 
    const QRect pickRect = pickArea().boundingRect().toRect();
 
    int right = qMin( infoRect.right(), pickRect.right() - margin );
    int bottom = qMin( infoRect.bottom(), pickRect.bottom() - margin );
    infoRect.moveBottomRight( QPoint( right, bottom ) );
 
    int left = qMax( infoRect.left(), pickRect.left() + margin );
    int top = qMax( infoRect.top(), pickRect.top() + margin );
    infoRect.moveTopLeft( QPoint( left, top ) );
 
    return infoRect;
}
 
bool QwtPicker::eventFilter( QObject* object, QEvent* event )
{
    if ( object && object == parentWidget() )
    {
        switch ( event->type() )
        {
            case QEvent::Resize:
            {
                const QResizeEvent* re = static_cast< QResizeEvent* >( event );
 
                /*
                   Adding/deleting additional event filters inside of an event filter
                   is not safe dues to the implementation in Qt ( changing a list while iterating ).
                   So we create the overlays in a way, that they don't install en event filter
                   ( parent set to NULL ) and do the resizing here.
                 */
                if ( m_data->trackerOverlay )
                    m_data->trackerOverlay->resize( re->size() );
 
                if ( m_data->rubberBandOverlay )
                    m_data->rubberBandOverlay->resize( re->size() );
 
                if ( m_data->resizeMode == Stretch )
                    stretchSelection( re->oldSize(), re->size() );
 
                updateDisplay();
                break;
            }
            case QEvent::Enter:
            {
                widgetEnterEvent( event );
                break;
            }
            case QEvent::Leave:
            {
                widgetLeaveEvent( event );
                break;
            }
            case QEvent::MouseButtonPress:
            {
                widgetMousePressEvent( static_cast< QMouseEvent* >( event ) );
                break;
            }
            case QEvent::MouseButtonRelease:
            {
                widgetMouseReleaseEvent( static_cast< QMouseEvent* >( event ) );
                break;
            }
            case QEvent::MouseButtonDblClick:
            {
                widgetMouseDoubleClickEvent( static_cast< QMouseEvent* >( event ) );
                break;
            }
            case QEvent::MouseMove:
            {
                widgetMouseMoveEvent( static_cast< QMouseEvent* >( event ) );
                break;
            }
            case QEvent::KeyPress:
            {
                widgetKeyPressEvent( static_cast< QKeyEvent* >( event ) );
                break;
            }
            case QEvent::KeyRelease:
            {
                widgetKeyReleaseEvent( static_cast< QKeyEvent* >( event ) );
                break;
            }
            case QEvent::Wheel:
            {
                widgetWheelEvent( static_cast< QWheelEvent* >( event ) );
                break;
            }
            default:
                break;
        }
    }
    return false;
}
 
void QwtPicker::widgetMousePressEvent( QMouseEvent* mouseEvent )
{
    transition( mouseEvent );
}
 
void QwtPicker::widgetMouseMoveEvent( QMouseEvent* mouseEvent )
{
    if ( pickArea().contains( mouseEvent->pos() ) )
        m_data->trackerPosition = mouseEvent->pos();
    else
        m_data->trackerPosition = QPoint( -1, -1 );
 
    if ( !isActive() )
        updateDisplay();
 
    transition( mouseEvent );
}
 
void QwtPicker::widgetEnterEvent( QEvent* event )
{
    transition( event );
}
 
void QwtPicker::widgetLeaveEvent( QEvent* event )
{
    transition( event );
 
    m_data->trackerPosition = QPoint( -1, -1 );
    if ( !isActive() )
        updateDisplay();
}
 
void QwtPicker::widgetMouseReleaseEvent( QMouseEvent* mouseEvent )
{
    transition( mouseEvent );
}
 
void QwtPicker::widgetMouseDoubleClickEvent( QMouseEvent* mouseEvent )
{
    transition( mouseEvent );
}
 
 
void QwtPicker::widgetWheelEvent( QWheelEvent* wheelEvent )
{
#if QT_VERSION < 0x050e00
    const QPoint wheelPos = wheelEvent->pos();
#else
    const QPoint wheelPos = wheelEvent->position().toPoint();
#endif
    if ( pickArea().contains( wheelPos ) )
        m_data->trackerPosition = wheelPos;
    else
        m_data->trackerPosition = QPoint( -1, -1 );
 
    updateDisplay();
 
    transition( wheelEvent );
}
 
void QwtPicker::widgetKeyPressEvent( QKeyEvent* keyEvent )
{
    int dx = 0;
    int dy = 0;
 
    int offset = 1;
    if ( keyEvent->isAutoRepeat() )
        offset = 5;
 
    if ( keyMatch( KeyLeft, keyEvent ) )
        dx = -offset;
    else if ( keyMatch( KeyRight, keyEvent ) )
        dx = offset;
    else if ( keyMatch( KeyUp, keyEvent ) )
        dy = -offset;
    else if ( keyMatch( KeyDown, keyEvent ) )
        dy = offset;
    else if ( keyMatch( KeyAbort, keyEvent ) )
    {
        reset();
    }
    else
        transition( keyEvent );
 
    if ( dx != 0 || dy != 0 )
    {
        const QRect rect = pickArea().boundingRect().toRect();
        const QPoint pos = parentWidget()->mapFromGlobal( QCursor::pos() );
 
        int x = pos.x() + dx;
        x = qMax( rect.left(), x );
        x = qMin( rect.right(), x );
 
        int y = pos.y() + dy;
        y = qMax( rect.top(), y );
        y = qMin( rect.bottom(), y );
 
        QCursor::setPos( parentWidget()->mapToGlobal( QPoint( x, y ) ) );
    }
}
 
void QwtPicker::widgetKeyReleaseEvent( QKeyEvent* keyEvent )
{
    transition( keyEvent );
}
 
void QwtPicker::transition( const QEvent* event )
{
    if ( !m_data->stateMachine )
        return;
 
    const QList< QwtPickerMachine::Command > commandList =
        m_data->stateMachine->transition( *this, event );
 
    QPoint pos;
    switch ( event->type() )
    {
        case QEvent::MouseButtonDblClick:
        case QEvent::MouseButtonPress:
        case QEvent::MouseButtonRelease:
        case QEvent::MouseMove:
        {
            const QMouseEvent* me =
                static_cast< const QMouseEvent* >( event );
            pos = me->pos();
            break;
        }
        default:
            pos = parentWidget()->mapFromGlobal( QCursor::pos() );
    }
 
    for ( int i = 0; i < commandList.count(); i++ )
    {
        switch ( commandList[i] )
        {
            case QwtPickerMachine::Begin:
            {
                begin();
                break;
            }
            case QwtPickerMachine::Append:
            {
                append( pos );
                break;
            }
            case QwtPickerMachine::Move:
            {
                move( pos );
                break;
            }
            case QwtPickerMachine::Remove:
            {
                remove();
                break;
            }
            case QwtPickerMachine::End:
            {
                end();
                break;
            }
        }
    }
}
 
void QwtPicker::begin()
{
    if ( m_data->isActive )
        return;
 
    m_data->pickedPoints.clear();
    m_data->isActive = true;
    Q_EMIT activated( true );
 
    if ( trackerMode() != AlwaysOff )
    {
        if ( m_data->trackerPosition.x() < 0 || m_data->trackerPosition.y() < 0 )
        {
            QWidget* w = parentWidget();
            if ( w )
                m_data->trackerPosition = w->mapFromGlobal( QCursor::pos() );
        }
    }
 
    updateDisplay();
    setMouseTracking( true );
}
 
bool QwtPicker::end( bool ok )
{
    if ( m_data->isActive )
    {
        setMouseTracking( false );
 
        m_data->isActive = false;
        Q_EMIT activated( false );
 
        if ( trackerMode() == ActiveOnly )
            m_data->trackerPosition = QPoint( -1, -1 );
 
        if ( ok )
            ok = accept( m_data->pickedPoints );
 
        if ( ok )
            Q_EMIT selected( m_data->pickedPoints );
        else
            m_data->pickedPoints.clear();
 
        updateDisplay();
    }
    else
        ok = false;
 
    return ok;
}
 
void QwtPicker::reset()
{
    if ( m_data->stateMachine )
        m_data->stateMachine->reset();
 
    if ( isActive() )
        end( false );
}
 
void QwtPicker::append( const QPoint& pos )
{
    if ( m_data->isActive )
    {
        m_data->pickedPoints += pos;
 
        updateDisplay();
        Q_EMIT appended( pos );
    }
}
 
void QwtPicker::move( const QPoint& pos )
{
    if ( m_data->isActive && !m_data->pickedPoints.isEmpty() )
    {
        QPoint& point = m_data->pickedPoints.last();
        if ( point != pos )
        {
            point = pos;
 
            updateDisplay();
            Q_EMIT moved( pos );
        }
    }
}
 
void QwtPicker::remove()
{
    if ( m_data->isActive && !m_data->pickedPoints.isEmpty() )
    {
#if QT_VERSION >= 0x050100
        const QPoint pos = m_data->pickedPoints.takeLast();
#else
        const QPoint pos = m_data->pickedPoints.last();
        m_data->pickedPoints.resize( m_data->pickedPoints.count() - 1 );
#endif
 
        updateDisplay();
        Q_EMIT removed( pos );
    }
}
 
bool QwtPicker::accept( QPolygon& selection ) const
{
    Q_UNUSED( selection );
    return true;
}
 
bool QwtPicker::isActive() const
{
    return m_data->isActive;
}
 
const QPolygon& QwtPicker::pickedPoints() const
{
    return m_data->pickedPoints;
}
 
void QwtPicker::stretchSelection( const QSize& oldSize, const QSize& newSize )
{
    if ( oldSize.isEmpty() )
    {
        // avoid division by zero. But scaling for small sizes also
        // doesn't make much sense, because of rounding losses. TODO ...
        return;
    }
 
    const double xRatio = double( newSize.width() ) / double( oldSize.width() );
    const double yRatio = double( newSize.height() ) / double( oldSize.height() );
 
    for ( int i = 0; i < m_data->pickedPoints.count(); i++ )
    {
        QPoint& p = m_data->pickedPoints[i];
        p.setX( qRound( p.x() * xRatio ) );
        p.setY( qRound( p.y() * yRatio ) );
 
        Q_EMIT changed( m_data->pickedPoints );
    }
}
 
void QwtPicker::setMouseTracking( bool enable )
{
    QWidget* widget = parentWidget();
    if ( !widget )
        return;
 
    if ( enable )
    {
        m_data->mouseTracking = widget->hasMouseTracking();
        widget->setMouseTracking( true );
    }
    else
    {
        widget->setMouseTracking( m_data->mouseTracking );
    }
}
 
QPainterPath QwtPicker::pickArea() const
{
    QPainterPath path;
 
    const QWidget* widget = parentWidget();
    if ( widget )
        path.addRect( widget->contentsRect() );
 
    return path;
}
 
void QwtPicker::updateDisplay()
{
    QWidget* w = parentWidget();
 
    bool showRubberband = false;
    bool showTracker = false;
 
    if ( w && w->isVisible() && m_data->enabled )
    {
        if ( rubberBand() != NoRubberBand && isActive() &&
            rubberBandPen().style() != Qt::NoPen )
        {
            showRubberband = true;
        }
 
        if ( trackerMode() == AlwaysOn ||
            ( trackerMode() == ActiveOnly && isActive() ) )
        {
            if ( trackerPen() != Qt::NoPen
                && !trackerRect( QFont() ).isEmpty() )
            {
                showTracker = true;
            }
        }
    }
 
    QPointer< Rubberband >& rw = m_data->rubberBandOverlay;
    if ( showRubberband )
    {
        if ( rw.isNull() )
        {
            rw = new Rubberband( this, NULL ); // NULL -> no extra event filter
            rw->setObjectName( "PickerRubberBand" );
            rw->setParent( w );
            rw->resize( w->size() );
        }
 
        if ( m_data->rubberBand <= RectRubberBand )
            rw->setMaskMode( QwtWidgetOverlay::MaskHint );
        else
            rw->setMaskMode( QwtWidgetOverlay::AlphaMask );
 
        rw->updateOverlay();
    }
    else
    {
        if ( m_data->openGL )
        {
            // Qt 4.8 crashes for a delete
            if ( !rw.isNull() )
            {
                rw->hide();
                rw->deleteLater();
                rw = NULL;
            }
        }
        else
        {
            delete rw;
        }
    }
 
    QPointer< Tracker >& tw = m_data->trackerOverlay;
    if ( showTracker )
    {
        if ( tw.isNull() )
        {
            tw = new Tracker( this, NULL ); // NULL -> no extra event filter
            tw->setObjectName( "PickerTracker" );
            tw->setParent( w );
            tw->resize( w->size() );
        }
        tw->setFont( m_data->trackerFont );
        tw->updateOverlay();
    }
    else
    {
        if ( m_data->openGL )
        {
            // Qt 4.8 crashes for a delete
            if ( !tw.isNull() )
            {
                tw->hide();
                tw->deleteLater();
                tw = NULL;
            }
        }
        else
        {
            delete tw;
        }
    }
}
 
const QwtWidgetOverlay* QwtPicker::rubberBandOverlay() const
{
    return m_data->rubberBandOverlay;
}
 
const QwtWidgetOverlay* QwtPicker::trackerOverlay() const
{
    return m_data->trackerOverlay;
}
 
#if QWT_MOC_INCLUDE
#include "moc_qwt_picker.cpp"
#endif