QwtPicker Class Reference

QwtPicker provides selections on a widget. More...

#include <qwt_picker.h>

Inheritance diagram for QwtPicker:
Inheritance graph
[legend]

List of all members.

Public Types

enum  RubberBand {
  NoRubberBand = 0,
  HLineRubberBand,
  VLineRubberBand,
  CrossRubberBand,
  RectRubberBand,
  EllipseRubberBand,
  PolygonRubberBand,
  UserRubberBand = 100
}
enum  DisplayMode {
  AlwaysOff,
  AlwaysOn,
  ActiveOnly
}
enum  ResizeMode {
  Stretch,
  KeepSize
}

Public Slots

void setEnabled (bool)

Signals

void activated (bool on)
void selected (const QPolygon &polygon)
void appended (const QPoint &pos)
void moved (const QPoint &pos)
void removed (const QPoint &pos)
void changed (const QPolygon &selection)

Public Member Functions

 QwtPicker (QWidget *parent)
 QwtPicker (RubberBand rubberBand, DisplayMode trackerMode, QWidget *)
virtual ~QwtPicker ()
void setStateMachine (QwtPickerMachine *)
const QwtPickerMachinestateMachine () const
QwtPickerMachinestateMachine ()
void setRubberBand (RubberBand)
RubberBand rubberBand () const
void setTrackerMode (DisplayMode)
DisplayMode trackerMode () const
void setResizeMode (ResizeMode)
ResizeMode resizeMode () const
void setRubberBandPen (const QPen &)
QPen rubberBandPen () const
void setTrackerPen (const QPen &)
QPen trackerPen () const
void setTrackerFont (const QFont &)
QFont trackerFont () const
bool isEnabled () const
bool isActive () const
virtual bool eventFilter (QObject *, QEvent *)
QWidget * parentWidget ()
const QWidget * parentWidget () const
virtual QRect pickRect () 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
QPolygon selection () const

Protected Member Functions

virtual QPolygon adjustedPoints (const QPolygon &) const
virtual void transition (const QEvent *)
virtual void begin ()
virtual void append (const QPoint &)
virtual void move (const QPoint &)
virtual void remove ()
virtual bool end (bool ok=true)
virtual bool accept (QPolygon &) const
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 widgetEnterEvent (QEvent *)
virtual void widgetLeaveEvent (QEvent *)
virtual void stretchSelection (const QSize &oldSize, const QSize &newSize)
virtual void updateDisplay ()
const QWidget * rubberBandWidget () const
const QWidget * trackerWidget () const
const QPolygon & pickedPoints () const

Detailed Description

QwtPicker provides selections on a widget.

QwtPicker filters all enter, leave, mouse and keyboard events of a widget and translates them into an array of selected points.

The way how the points are collected depends on type of state machine that is connected to the picker. Qwt offers a couple of predefined state machines for selecting:

While these state machines cover the most common ways to collect points it is also possible to implement individual machines as well.

QwtPicker translates the picked points into a selection using the adjustedPoints method. adjustedPoints is intended to be reimplemented to fixup the selection according to application specific requirements. (F.e. when an application accepts rectangles of a fixed aspect ratio only.)

Optionally QwtPicker support the process of collecting points by a rubberband and tracker displaying a text for the current mouse position.

Example
#include <qwt_picker.h>
#include <qwt_picker_machine.h>

QwtPicker *picker = new QwtPicker(widget);
picker->setStateMachine(new QwtPickerDragRectMachine);
picker->setTrackerMode(QwtPicker::ActiveOnly);
picker->setRubberBand(QwtPicker::RectRubberBand); 

The state machine triggers the following commands:

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 while the picker is active, or if trackerMode() is AlwayOn.

Member Enumeration Documentation

Display mode

  • AlwaysOff
    Display never.
  • AlwaysOn
    Display always.
  • ActiveOnly
    Display only when the selection is active.
See also:
setTrackerMode(), trackerMode(), isActive()

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()

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:
setRubberBand(), rubberBand()

Constructor & Destructor Documentation

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

Constructor

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

Parameters:
parent Parent widget, that will be observed
QwtPicker::QwtPicker ( RubberBand  rubberBand,
DisplayMode  trackerMode,
QWidget *  parent 
) [explicit]

Constructor

Parameters:
rubberBand Rubberband style
trackerMode Tracker mode
parent Parent widget, that will be observed
QwtPicker::~QwtPicker (  )  [virtual]

Destructor.


Member Function Documentation

bool QwtPicker::accept ( QPolygon &   )  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::activated ( bool  on  )  [signal]

A signal indicating, when the picker has been activated. Together with setEnabled() it can be used to implement selections with more than one picker.

Parameters:
on True, when the picker has been activated
QPolygon QwtPicker::adjustedPoints ( const QPolygon &  points  )  const [protected, virtual]

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.
  • A selection could accept non intersecting polygons only.
  • ...

The example below is for a rectangular selection, where the first point is the center of the selected rectangle.

Example
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;
}

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 QPolygon &  selection  )  [signal]

A signal emitted when the active selection has been changed. This might happen when the observed widget is resized.

Parameters:
selection Changed selection
See also:
stretchSelection()
void QwtPicker::drawRubberBand ( QPainter *  painter  )  const [virtual]

Draw a rubberband, depending on rubberBand()

Parameters:
painter Painter, initialized with clip rect
See also:
rubberBand(), RubberBand
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 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(), widgetEnterEvent(), widgetLeaveEvent(), 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.

const QPolygon & QwtPicker::pickedPoints (  )  const [protected]

Return the points, that have been collected so far. The selection() is calculated from the pickedPoints() in adjustedPoints().

Returns:
Picked points
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::remove (  )  [protected, virtual]

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

See also:
isActive(), begin(), end(), append(), move()
void QwtPicker::removed ( const QPoint &  pos  )  [signal]

A signal emitted whenever the last appended point of the selection has been removed.

See also:
remove(), appended()
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 QPolygon &  polygon  )  [signal]

A signal emitting the selected points, at the end of a selection.

Parameters:
polygon Selected points
QPolygon QwtPicker::selection (  )  const
Returns:
Selected points
See also:
pickedPoints(), adjustedPoints()
void QwtPicker::setEnabled ( bool  enabled  )  [slot]

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  ) 

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  ) 

Set the rubberband style

Parameters:
rubberBand Rubberband style The default value is NoRubberBand.
See also:
rubberBand(), RubberBand, setRubberBandPen()
void QwtPicker::setRubberBandPen ( const QPen &  pen  ) 

Set the pen for the rubberband

Parameters:
pen Rubberband pen
See also:
rubberBandPen(), setRubberBand()
void QwtPicker::setStateMachine ( QwtPickerMachine stateMachine  ) 

Set a state machine and delete the previous one

Parameters:
stateMachine State machine
See also:
stateMachine()
void QwtPicker::setTrackerFont ( const QFont &  font  ) 

Set the font for the tracker

Parameters:
font Tracker font
See also:
trackerFont(), setTrackerMode(), setTrackerPen()
void QwtPicker::setTrackerMode ( DisplayMode  mode  ) 

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  ) 

Set the pen for the tracker

Parameters:
pen Tracker pen
See also:
trackerPen(), setTrackerMode(), setTrackerFont()
QwtPickerMachine * QwtPicker::stateMachine (  ) 
Returns:
Assigned state machine
See also:
setStateMachine()
const QwtPickerMachine * QwtPicker::stateMachine (  )  const
Returns:
Assigned state machine
See also:
setStateMachine()
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::widgetEnterEvent ( QEvent *  event  )  [protected, virtual]
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:
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 *  event  )  [protected, virtual]
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]
void QwtPicker::widgetMousePressEvent ( QMouseEvent *  e  )  [protected, virtual]
void QwtPicker::widgetMouseReleaseEvent ( QMouseEvent *  e  )  [protected, virtual]
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()
Generated on Sun Nov 21 12:01:38 2010 for Qwt User's Guide by  doxygen 1.6.3