source: ntrip/branches/BNC_2.11.0/qwt/qwt_picker.cpp@ 9961

/* -*- 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_picker.h"
#include "qwt_picker_machine.h"
#include "qwt_painter.h"
#include "qwt_math.h"
#include <qapplication.h>
#include <qevent.h>
#include <qpainter.h>
#include <qframe.h>
#include <qcursor.h>
#include <qbitmap.h>
#include <qpointer.h>
#include <qpaintengine.h>
#include <qmath.h>

class QwtPicker::PickerWidget: public QWidget
{
public:
    enum Type
    {
        RubberBand,
        Text
    };

    PickerWidget( QwtPicker *, QWidget *, Type );
    void updateMask();

    /*
       For a tracker text with a background we can use the background
       rect as mask. Also for "regular" Qt widgets >= 4.3.0 we
       don't need to mask the text anymore.
     */
    bool d_hasTextMask;

protected:
    virtual void paintEvent( QPaintEvent * );

    QwtPicker *d_picker;
    Type d_type;
};

class QwtPicker::PrivateData
{
public:
    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

    /*
      On X11 the widget below the picker widgets gets paint events
      with a region that is the bounding rect of the mask, if it is complex.
      In case of (f.e) a CrossRubberBand and a text this creates complete
      repaints of the widget. So we better use two different widgets.
     */

    QPointer<PickerWidget> rubberBandWidget;
    QPointer<PickerWidget> trackerWidget;
};

QwtPicker::PickerWidget::PickerWidget(
        QwtPicker *picker, QWidget *parent, Type type ):
    QWidget( parent ),
    d_hasTextMask( false ),
    d_picker( picker ),
    d_type( type )
{
    setAttribute( Qt::WA_TransparentForMouseEvents );
    setAttribute( Qt::WA_NoSystemBackground );
    setFocusPolicy( Qt::NoFocus );
}

void QwtPicker::PickerWidget::updateMask()
{
    QRegion mask;

    if ( d_type == RubberBand )
    {
        QBitmap bm( width(), height() );
        bm.fill( Qt::color0 );

        QPainter painter( &bm );
        QPen pen = d_picker->rubberBandPen();
        pen.setColor( Qt::color1 );
        painter.setPen( pen );

        d_picker->drawRubberBand( &painter );

        mask = QRegion( bm );
    }
    if ( d_type == Text )
    {
        d_hasTextMask = parentWidget()->testAttribute( Qt::WA_PaintOnScreen );

        if ( d_hasTextMask )
        {
            const QwtText label = d_picker->trackerText(
                d_picker->trackerPosition() );

            if ( label.testPaintAttribute( QwtText::PaintBackground )
                && label.backgroundBrush().style() != Qt::NoBrush )
            {
                if ( label.backgroundBrush().color().alpha() > 0 )
                {
                    // We don't need a text mask, when we have a background
                    d_hasTextMask = false;
                }
            }
        }

        if ( d_hasTextMask )
        {
            QBitmap bm( width(), height() );
            bm.fill( Qt::color0 );

            QPainter painter( &bm );
            painter.setFont( font() );

            QPen pen = d_picker->trackerPen();
            pen.setColor( Qt::color1 );
            painter.setPen( pen );

            d_picker->drawTracker( &painter );

            mask = QRegion( bm );
        }
        else
        {
            mask = d_picker->trackerRect( font() );
        }
    }

    QWidget *w = parentWidget();
    if ( w && !w->testAttribute( Qt::WA_PaintOnScreen ) )
    {
        // The parent widget gets an update for its complete rectangle
        // when the mask is changed in visible state.
        // With this hide/show we only get an update for the
        // previous mask.

        hide();
    }
    setMask( mask );
    setVisible( !mask.isEmpty() );
}

void QwtPicker::PickerWidget::paintEvent( QPaintEvent *e )
{
    QPainter painter( this );
    painter.setClipRegion( e->region() );

    if ( d_type == RubberBand )
    {
        painter.setPen( d_picker->rubberBandPen() );
        d_picker->drawRubberBand( &painter );
    }

    if ( d_type == Text )
    {
        /*
           If we have a text mask we simply fill the region of
           the mask. This gives better results for antialiased fonts.
         */
        if ( d_hasTextMask )
        {
            painter.fillRect( e->rect(), 
                QBrush( d_picker->trackerPen().color() ) );
        }
        else
        {
            painter.setPen( d_picker->trackerPen() );
            d_picker->drawTracker( &painter );
        }
    }
}

/*!
  Constructor

  Creates an picker that is enabled, but without a state machine.
  rubberband and tracker are disabled.

  \param parent Parent widget, that will be observed
 */

QwtPicker::QwtPicker( QWidget *parent ):
    QObject( parent )
{
    init( parent, NoRubberBand, AlwaysOff );
}

/*!
  Constructor

  \param rubberBand Rubberband style
  \param trackerMode Tracker mode
  \param parent Parent widget, that will be observed
 */
QwtPicker::QwtPicker( RubberBand rubberBand,
        DisplayMode trackerMode, QWidget *parent ):
    QObject( parent )
{
    init( parent, rubberBand, trackerMode );
}

//! Destructor
QwtPicker::~QwtPicker()
{
    setMouseTracking( false );
    delete d_data->stateMachine;
    delete d_data->rubberBandWidget;
    delete d_data->trackerWidget;
    delete d_data;
}

//! Init the picker, used by the constructors
void QwtPicker::init( QWidget *parent,
    RubberBand rubberBand, DisplayMode trackerMode )
{
    d_data = new PrivateData;

    d_data->rubberBandWidget = NULL;
    d_data->trackerWidget = NULL;

    d_data->rubberBand = rubberBand;
    d_data->enabled = false;
    d_data->resizeMode = Stretch;
    d_data->trackerMode = AlwaysOff;
    d_data->isActive = false;
    d_data->trackerPosition = QPoint( -1, -1 );
    d_data->mouseTracking = false;

    d_data->stateMachine = NULL;

    if ( parent )
    {
        if ( parent->focusPolicy() == Qt::NoFocus )
            parent->setFocusPolicy( Qt::WheelFocus );

        d_data->trackerFont = parent->font();
        d_data->mouseTracking = parent->hasMouseTracking();
        setEnabled( true );
    }
    setTrackerMode( trackerMode );
}

/*!
  Set a state machine and delete the previous one

  \param stateMachine State machine
  \sa stateMachine()
*/
void QwtPicker::setStateMachine( QwtPickerMachine *stateMachine )
{
    if ( d_data->stateMachine != stateMachine )
    {
        reset();

        delete d_data->stateMachine;
        d_data->stateMachine = stateMachine;

        if ( d_data->stateMachine )
            d_data->stateMachine->reset();
    }
}

/*!
  \return Assigned state machine
  \sa setStateMachine()
*/
QwtPickerMachine *QwtPicker::stateMachine()
{
    return d_data->stateMachine;
}

/*!
  \return Assigned state machine
  \sa setStateMachine()
*/
const QwtPickerMachine *QwtPicker::stateMachine() const
{
    return d_data->stateMachine;
}

//! Return the parent widget, where the selection happens
QWidget *QwtPicker::parentWidget()
{
    QObject *obj = parent();
    if ( obj && obj->isWidgetType() )
        return static_cast<QWidget *>( obj );

    return NULL;
}

//! Return the parent widget, where the selection happens
const QWidget *QwtPicker::parentWidget() const
{
    QObject *obj = parent();
    if ( obj && obj->isWidgetType() )
        return static_cast< const QWidget *>( obj );

    return NULL;
}

/*!
  Set the rubberband style

  \param rubberBand Rubberband style
         The default value is NoRubberBand.

  \sa rubberBand(), RubberBand, setRubberBandPen()
*/
void QwtPicker::setRubberBand( RubberBand rubberBand )
{
    d_data->rubberBand = rubberBand;
}

/*!
  \return Rubberband style
  \sa setRubberBand(), RubberBand, rubberBandPen()
*/
QwtPicker::RubberBand QwtPicker::rubberBand() const
{
    return d_data->rubberBand;
}

/*!
  \brief Set the display mode of the tracker.

  A tracker displays information about current position of
  the cursor as a string. The display mode controls
  if the tracker has to be displayed whenever the observed
  widget has focus and cursor (AlwaysOn), never (AlwaysOff), or
  only when the selection is active (ActiveOnly).

  \param mode Tracker display mode

  \warning In case of AlwaysOn, mouseTracking will be enabled
           for the observed widget.
  \sa trackerMode(), DisplayMode
*/

void QwtPicker::setTrackerMode( DisplayMode mode )
{
    if ( d_data->trackerMode != mode )
    {
        d_data->trackerMode = mode;
        setMouseTracking( d_data->trackerMode == AlwaysOn );
    }
}

/*!
  \return Tracker display mode
  \sa setTrackerMode(), DisplayMode
*/
QwtPicker::DisplayMode QwtPicker::trackerMode() const
{
    return d_data->trackerMode;
}

/*!
  \brief Set the resize mode.

  The resize mode controls what to do with the selected points of an active
  selection when the observed widget is resized.

  Stretch means the points are scaled according to the new
  size, KeepSize means the points remain unchanged.

  The default mode is Stretch.

  \param mode Resize mode
  \sa resizeMode(), ResizeMode
*/
void QwtPicker::setResizeMode( ResizeMode mode )
{
    d_data->resizeMode = mode;
}

/*!
  \return Resize mode
  \sa setResizeMode(), ResizeMode
*/

QwtPicker::ResizeMode QwtPicker::resizeMode() const
{
    return d_data->resizeMode;
}

/*!
  \brief En/disable the picker

  When enabled is true an event filter is installed for
  the observed widget, otherwise the event filter is removed.

  \param enabled true or false
  \sa isEnabled(), eventFilter()
*/
void QwtPicker::setEnabled( bool enabled )
{
    if ( d_data->enabled != enabled )
    {
        d_data->enabled = enabled;

        QWidget *w = parentWidget();
        if ( w )
        {
            if ( enabled )
                w->installEventFilter( this );
            else
                w->removeEventFilter( this );
        }

        updateDisplay();
    }
}

/*!
  \return true when enabled, false otherwise
  \sa setEnabled(), eventFilter()
*/

bool QwtPicker::isEnabled() const
{
    return d_data->enabled;
}

/*!
  Set the font for the tracker

  \param font Tracker font
  \sa trackerFont(), setTrackerMode(), setTrackerPen()
*/
void QwtPicker::setTrackerFont( const QFont &font )
{
    if ( font != d_data->trackerFont )
    {
        d_data->trackerFont = font;
        updateDisplay();
    }
}

/*!
  \return Tracker font
  \sa setTrackerFont(), trackerMode(), trackerPen()
*/

QFont QwtPicker::trackerFont() const
{
    return d_data->trackerFont;
}

/*!
  Set the pen for the tracker

  \param pen Tracker pen
  \sa trackerPen(), setTrackerMode(), setTrackerFont()
*/
void QwtPicker::setTrackerPen( const QPen &pen )
{
    if ( pen != d_data->trackerPen )
    {
        d_data->trackerPen = pen;
        updateDisplay();
    }
}

/*!
  \return Tracker pen
  \sa setTrackerPen(), trackerMode(), trackerFont()
*/
QPen QwtPicker::trackerPen() const
{
    return d_data->trackerPen;
}

/*!
  Set the pen for the rubberband

  \param pen Rubberband pen
  \sa rubberBandPen(), setRubberBand()
*/
void QwtPicker::setRubberBandPen( const QPen &pen )
{
    if ( pen != d_data->rubberBandPen )
    {
        d_data->rubberBandPen = pen;
        updateDisplay();
    }
}

/*!
  \return Rubberband pen
  \sa setRubberBandPen(), rubberBand()
*/
QPen QwtPicker::rubberBandPen() const
{
    return d_data->rubberBandPen;
}

/*!
   \brief Return the label for a position

   In case of HLineRubberBand the label is the value of the
   y position, in case of VLineRubberBand the value of the x position.
   Otherwise the label contains x and y position separated by a ',' .

   The format for the string conversion is "%d".

   \param pos Position
   \return Converted position as string
*/

QwtText QwtPicker::trackerText( const QPoint &pos ) const
{
    QString label;

    switch ( rubberBand() )
    {
        case HLineRubberBand:
            label.sprintf( "%d", pos.y() );
            break;
        case VLineRubberBand:
            label.sprintf( "%d", pos.x() );
            break;
        default:
            label.sprintf( "%d, %d", pos.x(), pos.y() );
    }
    return label;
}

/*!
   Draw a rubberband, depending on rubberBand()

   \param painter Painter, initialized with clip rect

   \sa rubberBand(), RubberBand
*/

void QwtPicker::drawRubberBand( QPainter *painter ) const
{
    if ( !isActive() || rubberBand() == NoRubberBand ||
        rubberBandPen().style() == Qt::NoPen )
    {
        return;
    }

    const QRect &pRect = pickRect();
    const QPolygon pa = adjustedPoints( d_data->pickedPoints );

    QwtPickerMachine::SelectionType selectionType =
        QwtPickerMachine::NoSelection;

    if ( d_data->stateMachine )
        selectionType = d_data->stateMachine->selectionType();

    switch ( selectionType )
    {
        case QwtPickerMachine::NoSelection:
        case QwtPickerMachine::PointSelection:
        {
            if ( pa.count() < 1 )
                return;

            const QPoint pos = pa[0];

            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 QPoint p1 = pa[0];
            const QPoint p2 = pa[int( pa.count() - 1 )];

            const QRect rect = QRect( p1, p2 ).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;
    }
}

/*!
   Draw the tracker

   \param painter Painter
   \sa trackerRect(), trackerText()
*/

void QwtPicker::drawTracker( QPainter *painter ) const
{
    const QRect textRect = trackerRect( painter->font() );
    if ( !textRect.isEmpty() )
    {
        const QwtText label = trackerText( d_data->trackerPosition );
        if ( !label.isEmpty() )
            label.draw( painter, textRect );
    }
}

/*!
   \brief Map the pickedPoints() into a selection()

   adjustedPoints() maps the points, that have been collected on
   the parentWidget() into a selection(). The default implementation
   simply returns the points unmodified.

   The reason, why a selection() differs from the picked points
   depends on the application requirements. F.e. :

   - A rectangular selection might need to have a specific aspect ratio only.\n
   - A selection could accept non intersecting polygons only.\n
   - ...\n

   The example below is for a rectangular selection, where the first
   point is the center of the selected rectangle.
  \par Example
  \verbatim QPolygon MyPicker::adjustedPoints(const QPolygon &points) const
{
    QPolygon adjusted;
    if ( points.size() == 2 )
    {
        const int width = qAbs(points[1].x() - points[0].x());
        const int height = qAbs(points[1].y() - points[0].y());

        QRect rect(0, 0, 2 * width, 2 * height);
        rect.moveCenter(points[0]);

        adjusted += rect.topLeft();
        adjusted += rect.bottomRight();
    }
    return adjusted;
}\endverbatim\n
*/
QPolygon QwtPicker::adjustedPoints( const QPolygon &points ) const
{
    return points;
}

/*!
  \return Selected points
  \sa pickedPoints(), adjustedPoints()
*/
QPolygon QwtPicker::selection() const
{
    return adjustedPoints( d_data->pickedPoints );
}

//! \return Current position of the tracker
QPoint QwtPicker::trackerPosition() const
{
    return d_data->trackerPosition;
}

/*!
   Calculate the bounding rectangle for the tracker text
   from the current position of the tracker

   \param font Font of the tracker text
   \return Bounding rectangle of the tracker text

   \sa trackerPosition()
*/
QRect QwtPicker::trackerRect( const QFont &font ) const
{
    if ( trackerMode() == AlwaysOff ||
        ( trackerMode() == ActiveOnly && !isActive() ) )
    {
        return QRect();
    }

    if ( d_data->trackerPosition.x() < 0 || d_data->trackerPosition.y() < 0 )
        return QRect();

    QwtText text = trackerText( d_data->trackerPosition );
    if ( text.isEmpty() )
        return QRect();

    const QSizeF textSize = text.textSize( font );
    QRect textRect( 0, 0, qCeil( textSize.width() ), qCeil( textSize.height() ) );

    const QPoint &pos = d_data->trackerPosition;

    int alignment = 0;
    if ( isActive() && d_data->pickedPoints.count() > 1
        && rubberBand() != NoRubberBand )
    {
        const QPoint last =
            d_data->pickedPoints[int( d_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 -= textRect.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 -= textRect.height() + margin;

    textRect.moveTopLeft( QPoint( x, y ) );

    int right = qMin( textRect.right(), pickRect().right() - margin );
    int bottom = qMin( textRect.bottom(), pickRect().bottom() - margin );
    textRect.moveBottomRight( QPoint( right, bottom ) );

    int left = qMax( textRect.left(), pickRect().left() + margin );
    int top = qMax( textRect.top(), pickRect().top() + margin );
    textRect.moveTopLeft( QPoint( left, top ) );

    return textRect;
}

/*!
  \brief Event filter

  When isEnabled() == true all events of the observed widget are filtered.
  Mouse and keyboard events are translated into widgetMouse- and widgetKey-
  and widgetWheel-events. Paint and Resize events are handled to keep
  rubberband and tracker up to date.

  \param object Object to be filtered
  \param event Event

  \sa widgetEnterEvent(), widgetLeaveEvent(),
      widgetMousePressEvent(), widgetMouseReleaseEvent(),
      widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(),
      widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent(),
      QObject::installEventFilter(), QObject::event()
*/
bool QwtPicker::eventFilter( QObject *object, QEvent *event )
{
    if ( object && object == parentWidget() )
    {
        switch ( event->type() )
        {
            case QEvent::Resize:
            {
                const QResizeEvent *re = ( QResizeEvent * )event;
                if ( d_data->resizeMode == Stretch )
                    stretchSelection( re->oldSize(), re->size() );

                if ( d_data->rubberBandWidget )
                    d_data->rubberBandWidget->resize( re->size() );

                if ( d_data->trackerWidget )
                    d_data->trackerWidget->resize( re->size() );
                break;
            }
            case QEvent::Enter:
                widgetEnterEvent( event );
                break;
            case QEvent::Leave:
                widgetLeaveEvent( event );
                break;
            case QEvent::MouseButtonPress:
                widgetMousePressEvent( ( QMouseEvent * )event );
                break;
            case QEvent::MouseButtonRelease:
                widgetMouseReleaseEvent( ( QMouseEvent * )event );
                break;
            case QEvent::MouseButtonDblClick:
                widgetMouseDoubleClickEvent( ( QMouseEvent * )event );
                break;
            case QEvent::MouseMove:
                widgetMouseMoveEvent( ( QMouseEvent * )event );
                break;
            case QEvent::KeyPress:
                widgetKeyPressEvent( ( QKeyEvent * )event );
                break;
            case QEvent::KeyRelease:
                widgetKeyReleaseEvent( ( QKeyEvent * )event );
                break;
            case QEvent::Wheel:
                widgetWheelEvent( ( QWheelEvent * )event );
                break;
            default:
                break;
        }
    }
    return false;
}

/*!
  Handle a mouse press event for the observed widget.

  \param mouseEvent Mouse event

  \sa eventFilter(), widgetMouseReleaseEvent(),
      widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(),
      widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()
*/
void QwtPicker::widgetMousePressEvent( QMouseEvent *mouseEvent )
{
    transition( mouseEvent );
}

/*!
  Handle a mouse move event for the observed widget.

  \param mouseEvent Mouse event

  \sa eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(),
      widgetMouseDoubleClickEvent(),
      widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()
*/
void QwtPicker::widgetMouseMoveEvent( QMouseEvent *mouseEvent )
{
    if ( pickRect().contains( mouseEvent->pos() ) )
        d_data->trackerPosition = mouseEvent->pos();
    else
        d_data->trackerPosition = QPoint( -1, -1 );

    if ( !isActive() )
        updateDisplay();

    transition( mouseEvent );
}

/*!
  Handle a enter event for the observed widget.

  \param event Qt event

  \sa eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(),
      widgetMouseDoubleClickEvent(),
      widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()
*/
void QwtPicker::widgetEnterEvent( QEvent *event )
{
    transition( event );
}

/*!
  Handle a leave event for the observed widget.

  \param event Qt event

  \sa eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(),
      widgetMouseDoubleClickEvent(),
      widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()
*/
void QwtPicker::widgetLeaveEvent( QEvent *event )
{
    transition( event );

    d_data->trackerPosition = QPoint( -1, -1 );
    if ( !isActive() )
        updateDisplay();
}

/*!
  Handle a mouse relase event for the observed widget.

  \param mouseEvent Mouse event

  \sa eventFilter(), widgetMousePressEvent(),
      widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(),
      widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()
*/
void QwtPicker::widgetMouseReleaseEvent( QMouseEvent *mouseEvent )
{
    transition( mouseEvent );
}

/*!
  Handle mouse double click event for the observed widget.

  \param mouseEvent Mouse event

  \sa eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(),
      widgetMouseMoveEvent(),
      widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()
*/
void QwtPicker::widgetMouseDoubleClickEvent( QMouseEvent *mouseEvent )
{
    transition( mouseEvent );
}


/*!
  Handle a wheel event for the observed widget.

  Move the last point of the selection in case of isActive() == true

  \param wheelEvent Wheel event

  \sa eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(),
      widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(),
      widgetKeyPressEvent(), widgetKeyReleaseEvent()
*/
void QwtPicker::widgetWheelEvent( QWheelEvent *wheelEvent )
{
    if ( pickRect().contains( wheelEvent->pos() ) )
        d_data->trackerPosition = wheelEvent->pos();
    else
        d_data->trackerPosition = QPoint( -1, -1 );

    updateDisplay();

    transition( wheelEvent );
}

/*!
  Handle a key press event for the observed widget.

  Selections can be completely done by the keyboard. The arrow keys
  move the cursor, the abort key aborts a selection. All other keys
  are handled by the current state machine.

  \param keyEvent Key event

  \sa eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(),
      widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(),
      widgetWheelEvent(), widgetKeyReleaseEvent(), stateMachine(),
      QwtEventPattern::KeyPatternCode
*/
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 = pickRect();
        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 ) ) );
    }
}

/*!
  Handle a key release event for the observed widget.

  Passes the event to the state machine.

  \param keyEvent Key event

  \sa eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(),
      widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(),
      widgetWheelEvent(), widgetKeyPressEvent(), stateMachine()
*/
void QwtPicker::widgetKeyReleaseEvent( QKeyEvent *keyEvent )
{
    transition( keyEvent );
}

/*!
  Passes an event to the state machine and executes the resulting
  commands. Append and Move commands use the current position
  of the cursor (QCursor::pos()).

  \param event Event
*/
void QwtPicker::transition( const QEvent *event )
{
    if ( !d_data->stateMachine )
        return;

    const QList<QwtPickerMachine::Command> commandList =
        d_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;
            }
        }
    }
}

/*!
  Open a selection setting the state to active

  \sa isActive(), end(), append(), move()
*/
void QwtPicker::begin()
{
    if ( d_data->isActive )
        return;

    d_data->pickedPoints.resize( 0 );
    d_data->isActive = true;
    Q_EMIT activated( true );

    if ( trackerMode() != AlwaysOff )
    {
        if ( d_data->trackerPosition.x() < 0 || d_data->trackerPosition.y() < 0 )
        {
            QWidget *w = parentWidget();
            if ( w )
                d_data->trackerPosition = w->mapFromGlobal( QCursor::pos() );
        }
    }

    updateDisplay();
    setMouseTracking( true );
}

/*!
  \brief Close a selection setting the state to inactive.

  The selection is validated and maybe fixed by accept().

  \param ok If true, complete the selection and emit a selected signal
            otherwise discard the selection.
  \return true if the selection is accepted, false otherwise
  \sa isActive(), begin(), append(), move(), selected(), accept()
*/
bool QwtPicker::end( bool ok )
{
    if ( d_data->isActive )
    {
        setMouseTracking( false );

        d_data->isActive = false;
        Q_EMIT activated( false );

        if ( trackerMode() == ActiveOnly )
            d_data->trackerPosition = QPoint( -1, -1 );

        if ( ok )
            ok = accept( d_data->pickedPoints );

        if ( ok )
            Q_EMIT selected( d_data->pickedPoints );
        else
            d_data->pickedPoints.resize( 0 );

        updateDisplay();
    }
    else
        ok = false;

    return ok;
}

/*!
   Reset the state machine and terminate (end(false)) the selection
*/
void QwtPicker::reset()
{
    if ( d_data->stateMachine )
        d_data->stateMachine->reset();

    if ( isActive() )
        end( false );
}

/*!
  Append a point to the selection and update rubberband and tracker.
  The appended() signal is emitted.

  \param pos Additional point

  \sa isActive(), begin(), end(), move(), appended()
*/
void QwtPicker::append( const QPoint &pos )
{
    if ( d_data->isActive )
    {
        const int idx = d_data->pickedPoints.count();
        d_data->pickedPoints.resize( idx + 1 );
        d_data->pickedPoints[idx] = pos;

        updateDisplay();
        Q_EMIT appended( pos );
    }
}

/*!
  Move the last point of the selection
  The moved() signal is emitted.

  \param pos New position
  \sa isActive(), begin(), end(), append()
*/
void QwtPicker::move( const QPoint &pos )
{
    if ( d_data->isActive )
    {
        const int idx = d_data->pickedPoints.count() - 1;
        if ( idx >= 0 )
        {
            if ( d_data->pickedPoints[idx] != pos )
            {
                d_data->pickedPoints[idx] = pos;

                updateDisplay();
                Q_EMIT moved( pos );
            }
        }
    }
}

/*!
  Remove the last point of the selection
  The removed() signal is emitted.

  \sa isActive(), begin(), end(), append(), move()
*/
void QwtPicker::remove()
{
    if ( d_data->isActive )
    {
        const int idx = d_data->pickedPoints.count() - 1;
        if ( idx > 0 )
        {
            const int idx = d_data->pickedPoints.count();

            const QPoint pos = d_data->pickedPoints[idx - 1];
            d_data->pickedPoints.resize( idx - 1 );

            updateDisplay();
            Q_EMIT removed( pos );
        }
    }
}

/*!
  \brief Validate and fixup the selection

  Accepts all selections unmodified

  \param selection Selection to validate and fixup
  \return true, when accepted, false otherwise
*/
bool QwtPicker::accept( QPolygon &selection ) const
{
    Q_UNUSED( selection );
    return true;
}

/*!
  A picker is active between begin() and end().
  \return true if the selection is active.
*/
bool QwtPicker::isActive() const
{
    return d_data->isActive;
}

/*!
  Return the points, that have been collected so far. The selection()
  is calculated from the pickedPoints() in adjustedPoints().
  \return Picked points
*/
const QPolygon &QwtPicker::pickedPoints() const
{
    return d_data->pickedPoints;
}

/*!
  Scale the selection by the ratios of oldSize and newSize
  The changed() signal is emitted.

  \param oldSize Previous size
  \param newSize Current size

  \sa ResizeMode, setResizeMode(), resizeMode()
*/
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 < int( d_data->pickedPoints.count() ); i++ )
    {
        QPoint &p = d_data->pickedPoints[i];
        p.setX( qRound( p.x() * xRatio ) );
        p.setY( qRound( p.y() * yRatio ) );

        Q_EMIT changed( d_data->pickedPoints );
    }
}

/*!
  Set mouse tracking for the observed widget.

  In case of enable is true, the previous value
  is saved, that is restored when enable is false.

  \warning Even when enable is false, mouse tracking might be restored
           to true. When mouseTracking for the observed widget
           has been changed directly by QWidget::setMouseTracking
           while mouse tracking has been set to true, this value can't
           be restored.
*/

void QwtPicker::setMouseTracking( bool enable )
{
    QWidget *widget = parentWidget();
    if ( !widget )
        return;

    if ( enable )
    {
        d_data->mouseTracking = widget->hasMouseTracking();
        widget->setMouseTracking( true );
    }
    else
    {
        widget->setMouseTracking( d_data->mouseTracking );
    }
}

/*!
  Find the area of the observed widget, where selection might happen.

  \return parentWidget()->contentsRect() 
*/
QRect QwtPicker::pickRect() const
{
    const QWidget *widget = parentWidget();
    if ( widget )
        return widget->contentsRect();

    return QRect();
}

//! Update the state of rubberband and tracker label
void QwtPicker::updateDisplay()
{
    QWidget *w = parentWidget();

    bool showRubberband = false;
    bool showTracker = false;
    if ( w && w->isVisible() && d_data->enabled )
    {
        if ( rubberBand() != NoRubberBand && isActive() &&
            rubberBandPen().style() != Qt::NoPen )
        {
            showRubberband = true;
        }

        if ( trackerMode() == AlwaysOn ||
            ( trackerMode() == ActiveOnly && isActive() ) )
        {
            if ( trackerPen() != Qt::NoPen )
                showTracker = true;
        }
    }

    QPointer<PickerWidget> &rw = d_data->rubberBandWidget;
    if ( showRubberband )
    {
        if ( rw.isNull() )
        {
            rw = new PickerWidget( this, w, PickerWidget::RubberBand );
            rw->resize( w->size() );
        }
        rw->updateMask();
        rw->update(); // Needed, when the mask doesn't change
    }
    else
        delete rw;

    QPointer<PickerWidget> &tw = d_data->trackerWidget;
    if ( showTracker )
    {
        if ( tw.isNull() )
        {
            tw = new PickerWidget( this, w, PickerWidget::Text );
            tw->resize( w->size() );
        }
        tw->setFont( d_data->trackerFont );
        tw->updateMask();
        tw->update(); // Needed, when the mask doesn't change
    }
    else
        delete tw;
}

//! \return Widget displaying the rubberband
const QWidget *QwtPicker::rubberBandWidget() const
{
    return d_data->rubberBandWidget;
}

//! \return Widget displaying the tracker text
const QWidget *QwtPicker::trackerWidget() const
{
    return d_data->trackerWidget;
}