QwtPicker(3)

NAME
QwtPicker -

QwtPicker provides selections on a widget.

SYNOPSIS

#include <qwt_picker.h>

Inherits QwtEventPattern.

Inherited by QwtPlotPicker.

  Public Types
enum SelectionType { NoSelection = 0, PointSelection = 1, RectSelection = 2, PolygonSelection = 4 }
enum RectSelectionType { CornerToCorner = 64, CenterToCorner = 128, CenterToRadius = 256 }
enum SelectionMode { ClickSelection = 1024, DragSelection = 2048 }
enum RubberBand { NoRubberBand = 0, HLineRubberBand, VLineRubberBand, CrossRubberBand, RectRubberBand, EllipseRubberBand, PolygonRubberBand, UserRubberBand = 100 }
enum DisplayMode { AlwaysOff, AlwaysOn, ActiveOnly }
enum ResizeMode { Stretch, KeepSize }

  Signals
void selected (const QwtPolygon &pa)
void appended (const QPoint &pos)
void moved (const QPoint &pos)
void changed (const QwtPolygon &pa)

  Public Member Functions
QwtPicker (QWidget *parent)
QwtPicker (int selectionFlags, RubberBand rubberBand, DisplayMode trackerMode, QWidget *)
virtual ~QwtPicker ()
virtual void setSelectionFlags (int)
int selectionFlags () const
virtual void setRubberBand (RubberBand)
RubberBand rubberBand () const
virtual void setTrackerMode (DisplayMode)
DisplayMode trackerMode () const
virtual void setResizeMode (ResizeMode)
ResizeMode resizeMode () const
virtual void setRubberBandPen (const QPen &)
QPen rubberBandPen () const
virtual void setTrackerPen (const QPen &)
QPen trackerPen () const
virtual void setTrackerFont (const QFont &)
QFont trackerFont () const
bool isEnabled () const
virtual void setEnabled (bool)
bool isActive () const
virtual bool eventFilter (QObject *, QEvent *)
QWidget * parentWidget ()
const QWidget * parentWidget () const
virtual QRect pickRect () const
const QwtPolygon & selection () const
virtual void drawRubberBand (QPainter *) const
virtual void drawTracker (QPainter *) const
virtual QwtText trackerText (const QPoint &pos) const
QPoint trackerPosition () const
QRect trackerRect (const QFont &) const

  Protected Member Functions
virtual bool accept (QwtPolygon &selection) const
virtual void transition (const QEvent *)
virtual void begin ()
virtual void append (const QPoint &)
virtual void move (const QPoint &)
virtual bool end (bool ok=true)
virtual void reset ()
virtual void widgetMousePressEvent (QMouseEvent *)
virtual void widgetMouseReleaseEvent (QMouseEvent *)
virtual void widgetMouseDoubleClickEvent (QMouseEvent *)
virtual void widgetMouseMoveEvent (QMouseEvent *)
virtual void widgetWheelEvent (QWheelEvent *)
virtual void widgetKeyPressEvent (QKeyEvent *)
virtual void widgetKeyReleaseEvent (QKeyEvent *)
virtual void widgetLeaveEvent (QEvent *)
virtual void stretchSelection (const QSize &oldSize, const QSize &newSize)
virtual QwtPickerMachine * stateMachine (int) const
virtual void updateDisplay ()
const QWidget * rubberBandWidget () const
const QWidget * trackerWidget () const

Detailed Description

QwtPicker provides selections on a widget. QwtPicker filters all mouse and keyboard events of a widget and translates them into an array of selected points. Depending on the QwtPicker::SelectionType the selection might be a single point, a rectangle or a polygon. The selection process is supported by optional rubberbands (rubberband selection) and position trackers.

QwtPicker is useful for widgets where the event handlers can't be overloaded, like for components of composite widgets. It offers alternative handlers for mouse and key events.

Example .RS 4

#include <qwt_picker.h>
QwtPicker *picker = new QwtPicker(widget);
picker->setTrackerMode(QwtPicker::ActiveOnly);
connect(picker, SIGNAL(selected(const QwtPolygon &)), ...);
// emit the position of clicks on widget
picker->setSelectionFlags(QwtPicker::PointSelection | QwtPicker::ClickSelection);
    ...

// now select rectangles
picker->setSelectionFlags(QwtPicker::RectSelection | QwtPicker::DragSelection);
picker->setRubberBand(QwtPicker::RectRubberBand);

The selection process uses the commands begin(), append(), move() and end(). append() adds a new point to the selection, move() changes the position of the latest point.

The commands are initiated from a small state machine (QwtPickerMachine) that translates mouse and key events. There are a couple of predefined state machines for point, rect and polygon selections. The selectionFlags() control which one should be used. It is possible to use other machines by overloading stateMachine().

The picker is active (isActive()), between begin() and end(). In active state the rubberband is displayed, and the tracker is visible in case of trackerMode is ActiveOnly or AlwaysOn.

The cursor can be moved using the arrow keys. All selections can be aborted using the abort key. (QwtEventPattern::KeyPatternCode)

Warning:
    In case of QWidget::NoFocus the focus policy of the observed widget is set to QWidget::WheelFocus and mouse tracking will be manipulated for ClickSelection while the picker is active, or if trackerMode() is AlwayOn.

Member Enumeration Documentation

  enum QwtPicker::DisplayMode .IP • 2
AlwaysOff
 Display never.

•   AlwaysOn
     Display always.

•   ActiveOnly
     Display only when the selection is active.

See also:
    QwtPicker::setTrackerMode(), QwtPicker::trackerMode(), QwtPicker::isActive()

  enum QwtPicker::RectSelectionType

Selection subtype for RectSelection This enum type describes the type of rectangle selections. It can be or'd with QwtPicker::RectSelectionType and QwtPicker::SelectionMode and passed to QwtPicker::setSelectionFlags().

•   CornerToCorner
     The first and the second selected point are the corners of the rectangle.

•   CenterToCorner
     The first point is the center, the second a corner of the rectangle.

•   CenterToRadius
     The first point is the center of a quadrat, calculated by the maximum of the x- and y-distance.

The default value is CornerToCorner.

See also:
    QwtPicker::setSelectionFlags(), QwtPicker::selectionFlags()

  enum QwtPicker::ResizeMode Controls what to do with the selected points of an active selection when the observed widget is resized.

•   Stretch
     All points are scaled according to the new size,

•   KeepSize
     All points remain unchanged.

The default value is Stretch.

See also:
    QwtPicker::setResizeMode(), QwtPicker::resize()

  enum QwtPicker::RubberBand Rubberband style

•   NoRubberBand
     No rubberband.

•   HLineRubberBand & PointSelection
     A horizontal line.

•   VLineRubberBand & PointSelection
     A vertical line.

•   CrossRubberBand & PointSelection
     A horizontal and a vertical line.

•   RectRubberBand & RectSelection
     A rectangle.

•   EllipseRubberBand & RectSelection
     An ellipse.

•   PolygonRubberBand &PolygonSelection
     A polygon.

•   UserRubberBand
     Values >= UserRubberBand can be used to define additional rubber bands.

The default value is NoRubberBand.

See also:
    QwtPicker::setRubberBand(), QwtPicker::rubberBand()

  enum QwtPicker::SelectionMode Values of this enum type or'd together with a SelectionType value identifies which state machine should be used for the selection.

The default value is ClickSelection.

See also:
    stateMachine()

  enum QwtPicker::SelectionType This enum type describes the type of a selection. It can be or'd with QwtPicker::RectSelectionType and QwtPicker::SelectionMode and passed to QwtPicker::setSelectionFlags()

•   NoSelection
     Selection is disabled. Note this is different to the disabled state, as you might have a tracker.

•   PointSelection
     Select a single point.

•   RectSelection
     Select a rectangle.

•   PolygonSelection
     Select a polygon.

The default value is NoSelection.

See also:
    QwtPicker::setSelectionFlags(), QwtPicker::selectionFlags()

Constructor & Destructor Documentation

  QwtPicker::QwtPicker (QWidget * parent) [explicit] Constructor

Creates an picker that is enabled, but where selection flag is set to NoSelection, rubberband and tracker are disabled.

Parameters:
    parent Parent widget, that will be observed

  QwtPicker::QwtPicker (int selectionFlags, RubberBand rubberBand, DisplayMode trackerMode, QWidget * parent) [explicit] Constructor

Parameters:
    selectionFlags Or'd value of SelectionType, RectSelectionType and SelectionMode
    rubberBand Rubberband style
    trackerMode Tracker mode
    parent Parent widget, that will be observed

  QwtPicker::~QwtPicker () [virtual]

Destructor.

Member Function Documentation

  bool QwtPicker::accept (QwtPolygon & selection) const [protected, virtual]

Validate and fixup the selection. Accepts all selections unmodified

Parameters:
    selection Selection to validate and fixup

Returns:
    true, when accepted, false otherwise

Reimplemented in QwtPlotZoomer.

  void QwtPicker::append (const QPoint & pos) [protected, virtual] Append a point to the selection and update rubberband and tracker. The appended() signal is emitted.

Parameters:
    pos Additional point

See also:
    isActive(), begin(), end(), move(), appended()

Reimplemented in QwtPlotPicker.

  void QwtPicker::appended (const QPoint & pos) [signal] A signal emitted when a point has been appended to the selection

Parameters:
    pos Position of the appended point.

See also:
    append(). moved()

  void QwtPicker::begin () [protected, virtual] Open a selection setting the state to active

See also:
    isActive(), end(), append(), move()

Reimplemented in QwtPlotZoomer.

  void QwtPicker::changed (const QwtPolygon & pa) [signal] A signal emitted when the active selection has been changed. This might happen when the observed widget is resized.

Parameters:
    pa Changed selection

See also:
    stretchSelection()

  void QwtPicker::drawRubberBand (QPainter * painter) const [virtual] Draw a rubberband , depending on rubberBand() and selectionFlags()

Parameters:
    painter Painter, initialized with clip rect

See also:
    rubberBand(), RubberBand, selectionFlags()

  void QwtPicker::drawTracker (QPainter * painter) const [virtual] Draw the tracker

Parameters:
    painter Painter

See also:
    trackerRect(), trackerText()

  bool QwtPicker::end (bool ok = true) [protected, virtual]

Close a selection setting the state to inactive. The selection is validated and maybe fixed by QwtPicker::accept().

Parameters:
    ok If true, complete the selection and emit a selected signal otherwise discard the selection.

Returns:
    true if the selection is accepted, false otherwise

See also:
    isActive(), begin(), append(), move(), selected(), accept()

Reimplemented in QwtPlotPicker, and QwtPlotZoomer.

  bool QwtPicker::eventFilter (QObject * o, QEvent * e) [virtual]

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.

See also:
    event(), widgetMousePressEvent(), widgetMouseReleaseEvent(), widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(), widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()

  bool QwtPicker::isActive () const A picker is active between begin() and end().

Returns:
    true if the selection is active.

  bool QwtPicker::isEnabled () const Returns:
    true when enabled, false otherwise

See also:
    setEnabled(), eventFilter()

  void QwtPicker::move (const QPoint & pos) [protected, virtual] Move the last point of the selection The moved() signal is emitted.

Parameters:
    pos New position

See also:
    isActive(), begin(), end(), append()

Reimplemented in QwtPlotPicker.

  void QwtPicker::moved (const QPoint & pos) [signal] A signal emitted whenever the last appended point of the selection has been moved.

Parameters:
    pos Position of the moved last point of the selection.

See also:
    move(), appended()

  const QWidget * QwtPicker::parentWidget () const

Return the parent widget, where the selection happens.

  QWidget * QwtPicker::parentWidget ()

Return the parent widget, where the selection happens.

  QRect QwtPicker::pickRect () const [virtual] Find the area of the observed widget, where selection might happen.

Returns:
    QFrame::contentsRect() if it is a QFrame, QWidget::rect() otherwise.

  void QwtPicker::reset () [protected, virtual] Reset the state machine and terminate (end(false)) the selection

  QwtPicker::ResizeMode QwtPicker::resizeMode () const Returns:
    Resize mode

See also:
    setResizeMode(), ResizeMode

  QwtPicker::RubberBand QwtPicker::rubberBand () const Returns:
    Rubberband style

See also:
    setRubberBand(), RubberBand, rubberBandPen()

  QPen QwtPicker::rubberBandPen () const Returns:
    Rubberband pen

See also:
    setRubberBandPen(), rubberBand()

  const QWidget * QwtPicker::rubberBandWidget () const [protected] Returns:
    Widget displaying the rubberband

  void QwtPicker::selected (const QwtPolygon & pa) [signal] A signal emitting the selected points, at the end of a selection.

Parameters:
    pa Selected points

  const QwtPolygon & QwtPicker::selection () const

Return Selected points.

  int QwtPicker::selectionFlags () const Returns:
    Selection flags, an Or'd value of SelectionType, RectSelectionType and SelectionMode.

See also:
    setSelectionFlags(), SelectionType, RectSelectionType, SelectionMode

  void QwtPicker::setEnabled (bool enabled) [virtual]

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

Parameters:
    enabled true or false

See also:
    isEnabled(), eventFilter()

  void QwtPicker::setResizeMode (ResizeMode mode) [virtual]

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.

Parameters:
    mode Resize mode

See also:
    resizeMode(), ResizeMode

  void QwtPicker::setRubberBand (RubberBand rubberBand) [virtual] Set the rubberband style

Parameters:
    rubberBand Rubberband style The default value is NoRubberBand.

See also:
    rubberBand(), RubberBand, setRubberBandPen()

  void QwtPicker::setRubberBandPen (const QPen & pen) [virtual] Set the pen for the rubberband

Parameters:
    pen Rubberband pen

See also:
    rubberBandPen(), setRubberBand()

  void QwtPicker::setSelectionFlags (int flags) [virtual] Set the selection flags

Parameters:
    flags Or'd value of SelectionType, RectSelectionType and SelectionMode. The default value is NoSelection.

See also:
    selectionFlags(), SelectionType, RectSelectionType, SelectionMode

Reimplemented in QwtPlotZoomer.

  void QwtPicker::setTrackerFont (const QFont & font) [virtual] Set the font for the tracker

Parameters:
    font Tracker font

See also:
    trackerFont(), setTrackerMode(), setTrackerPen()

  void QwtPicker::setTrackerMode (DisplayMode mode) [virtual]

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).

Parameters:
    mode Tracker display mode

Warning:
    In case of AlwaysOn, mouseTracking will be enabled for the observed widget.

See also:
    trackerMode(), DisplayMode

  void QwtPicker::setTrackerPen (const QPen & pen) [virtual] Set the pen for the tracker

Parameters:
    pen Tracker pen

See also:
    trackerPen(), setTrackerMode(), setTrackerFont()

  QwtPickerMachine * QwtPicker::stateMachine (int flags) const [protected, virtual] Create a state machine depending on the selection flags.

•   PointSelection | ClickSelection
     QwtPickerClickPointMachine()

•   PointSelection | DragSelection
     QwtPickerDragPointMachine()

•   RectSelection | ClickSelection
     QwtPickerClickRectMachine()

•   RectSelection | DragSelection
     QwtPickerDragRectMachine()

•   PolygonSelection
     QwtPickerPolygonMachine()

See also:
    setSelectionFlags()

  void QwtPicker::stretchSelection (const QSize & oldSize, const QSize & newSize) [protected, virtual] Scale the selection by the ratios of oldSize and newSize The changed() signal is emitted.

Parameters:
    oldSize Previous size
    newSize Current size

See also:
    ResizeMode, setResizeMode(), resizeMode()

  QFont QwtPicker::trackerFont () const Returns:
    Tracker font

See also:
    setTrackerFont(), trackerMode(), trackerPen()

  QwtPicker::DisplayMode QwtPicker::trackerMode () const Returns:
    Tracker display mode

See also:
    setTrackerMode(), DisplayMode

  QPen QwtPicker::trackerPen () const Returns:
    Tracker pen

See also:
    setTrackerPen(), trackerMode(), trackerFont()

  QPoint QwtPicker::trackerPosition () const Returns:
    Current position of the tracker

  QRect QwtPicker::trackerRect (const QFont & font) const Calculate the bounding rectangle for the tracker text from the current position of the tracker

Parameters:
    font Font of the tracker text

Returns:
    Bounding rectangle of the tracker text

See also:
    trackerPosition()

  QwtText QwtPicker::trackerText (const QPoint & pos) const [virtual]

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'.

Parameters:
    pos Position

Returns:
    Converted position as string

Reimplemented in QwtPlotPicker.

  const QWidget * QwtPicker::trackerWidget () const [protected] Returns:
    Widget displaying the tracker text

  void QwtPicker::transition (const QEvent * e) [protected, virtual] 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()).

Parameters:
    e Event

  void QwtPicker::updateDisplay () [protected, virtual]

Update the state of rubberband and tracker label.

  void QwtPicker::widgetKeyPressEvent (QKeyEvent * ke) [protected, virtual] 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.

See also:
    QwtPicker, selectionFlags()

    eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(), widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(), widgetWheelEvent(), widgetKeyReleaseEvent(), stateMachine(), QwtEventPattern::KeyPatternCode

Reimplemented in QwtPlotZoomer.

  void QwtPicker::widgetKeyReleaseEvent (QKeyEvent * ke) [protected, virtual] Handle a key release event for the observed widget.

Passes the event to the state machine.

See also:
    eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(), widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(), widgetWheelEvent(), widgetKeyPressEvent(), stateMachine()

  void QwtPicker::widgetLeaveEvent (QEvent *) [protected, virtual] Handle a leave event for the observed widget.

See also:
    eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(), widgetMouseDoubleClickEvent(), widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()

  void QwtPicker::widgetMouseDoubleClickEvent (QMouseEvent * me) [protected, virtual] Handle mouse double click event for the observed widget.

Empty implementation, does nothing.

See also:
    eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(), widgetMouseMoveEvent(), widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()

  void QwtPicker::widgetMouseMoveEvent (QMouseEvent * e) [protected, virtual] Handle a mouse move event for the observed widget.

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

See also:
    eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(), widgetMouseDoubleClickEvent(), widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()

  void QwtPicker::widgetMousePressEvent (QMouseEvent * e) [protected, virtual] Handle a mouse press event for the observed widget.

Begin and/or end a selection depending on the selection flags.

See also:
    QwtPicker, selectionFlags()

    eventFilter(), widgetMouseReleaseEvent(), widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(), widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()

  void QwtPicker::widgetMouseReleaseEvent (QMouseEvent * e) [protected, virtual] Handle a mouse relase event for the observed widget.

End a selection depending on the selection flags.

See also:
    QwtPicker, selectionFlags()

    eventFilter(), widgetMousePressEvent(), widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(), widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()

Reimplemented in QwtPlotZoomer.

  void QwtPicker::widgetWheelEvent (QWheelEvent * e) [protected, virtual] Handle a wheel event for the observed widget.

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

See also:
    eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(), widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()

Author

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