QwtPicker provides selections on a widget. More...

#include <qwt_picker.h>

Inheritance diagram for QwtPicker:

Classes
class	PrivateData
Public Types
enum	DisplayMode { AlwaysOff, AlwaysOn, ActiveOnly }
	Display mode. More...
enum	ResizeMode { Stretch, KeepSize }
enum	RubberBand { NoRubberBand = 0, HLineRubberBand, VLineRubberBand, CrossRubberBand, RectRubberBand, EllipseRubberBand, PolygonRubberBand, UserRubberBand = 100 }
Public Slots
void	setEnabled (bool)
	En/disable the picker.
Signals
void	activated (bool on)
void	appended (const QPoint &pos)
void	changed (const QPolygon &selection)
void	moved (const QPoint &pos)
void	removed (const QPoint &pos)
void	selected (const QPolygon &polygon)
Public Member Functions
virtual void	drawRubberBand (QPainter *) const
virtual void	drawTracker (QPainter *) const
virtual bool	eventFilter (QObject , QEvent )
	Event filter.
bool	isActive () const
bool	isEnabled () const
QWidget *	parentWidget ()
	Return the parent widget, where the selection happens.
const QWidget *	parentWidget () const
	Return the parent widget, where the selection happens.
virtual QPainterPath	pickArea () const
	QwtPicker (QWidget *parent)
	QwtPicker (RubberBand rubberBand, DisplayMode trackerMode, QWidget *)
ResizeMode	resizeMode () const
RubberBand	rubberBand () const
virtual QRegion	rubberBandMask () const
QPen	rubberBandPen () const
QPolygon	selection () const
void	setResizeMode (ResizeMode)
	Set the resize mode.
void	setRubberBand (RubberBand)
void	setRubberBandPen (const QPen &)
void	setStateMachine (QwtPickerMachine *)
void	setTrackerFont (const QFont &)
void	setTrackerMode (DisplayMode)
	Set the display mode of the tracker.
void	setTrackerPen (const QPen &)
const QwtPickerMachine *	stateMachine () const
QwtPickerMachine *	stateMachine ()
QFont	trackerFont () const
virtual QRegion	trackerMask () const
DisplayMode	trackerMode () const
QPen	trackerPen () const
QPoint	trackerPosition () const
virtual QRect	trackerRect (const QFont &) const
virtual QwtText	trackerText (const QPoint &pos) const
	Return the label for a position.
virtual	~QwtPicker ()
	Destructor.
Protected Member Functions
virtual bool	accept (QPolygon &) const
	Validate and fix up the selection.
virtual QPolygon	adjustedPoints (const QPolygon &) const
	Map the pickedPoints() into a selection()
virtual void	append (const QPoint &)
virtual void	begin ()
virtual bool	end (bool ok=true)
	Close a selection setting the state to inactive.
virtual void	move (const QPoint &)
const QPolygon &	pickedPoints () const
virtual void	remove ()
virtual void	reset ()
const QwtWidgetOverlay *	rubberBandOverlay () const
virtual void	stretchSelection (const QSize &oldSize, const QSize &newSize)
const QwtWidgetOverlay *	trackerOverlay () const
virtual void	transition (const QEvent *)
virtual void	updateDisplay ()
	Update the state of rubber band and tracker label.
virtual void	widgetEnterEvent (QEvent *)
virtual void	widgetKeyPressEvent (QKeyEvent *)
virtual void	widgetKeyReleaseEvent (QKeyEvent *)
virtual void	widgetLeaveEvent (QEvent *)
virtual void	widgetMouseDoubleClickEvent (QMouseEvent *)
virtual void	widgetMouseMoveEvent (QMouseEvent *)
virtual void	widgetMousePressEvent (QMouseEvent *)
virtual void	widgetMouseReleaseEvent (QMouseEvent *)
virtual void	widgetWheelEvent (QWheelEvent *)
Properties
bool	isEnabled
ResizeMode	resizeMode
RubberBand	rubberBand
QPen	rubberBandPen
QFont	trackerFont
DisplayMode	trackerMode
QPen	trackerPen
Private Member Functions
void	init (QWidget *, RubberBand rubberBand, DisplayMode trackerMode)
	Initialize the picker - used by the constructors.
void	setMouseTracking (bool)
Private Attributes
PrivateData *	d_data

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:

Nothing
QwtPickerTrackerMachine
Single points
QwtPickerClickPointMachine, QwtPickerDragPointMachine
Rectangles
QwtPickerClickRectMachine, QwtPickerDragRectMachine
Polygons
QwtPickerPolygonMachine

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 fix up 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 rubber band 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:

begin()
Activate/Initialize the selection.
append()
Add a new point
move()
Change the position of the last point.
remove()
Remove the last point.
end()
Terminate the selection and call accept to validate the picked points.

The picker is active (isActive()), between begin() and end(). In active state the rubber band 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.

Definition at line 95 of file qwt_picker.h.

Member Enumeration Documentation

enum QwtPicker::DisplayMode

Display mode.

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

Enumerator:

AlwaysOff	Display never.
AlwaysOn	Display always.
ActiveOnly	Display only when the selection is active.

Definition at line 153 of file qwt_picker.h.

enum QwtPicker::ResizeMode

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

The default value is QwtPicker::Stretch.

See also:: setResizeMode()

Enumerator:

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

Definition at line 173 of file qwt_picker.h.

enum QwtPicker::RubberBand

Rubber band style

The default value is QwtPicker::NoRubberBand.

See also:: setRubberBand(), rubberBand()

Enumerator:

NoRubberBand	No rubberband.
HLineRubberBand	A horizontal line ( only for QwtPickerMachine::PointSelection )
VLineRubberBand	A vertical line ( only for QwtPickerMachine::PointSelection )
CrossRubberBand	A crosshair ( only for QwtPickerMachine::PointSelection )
RectRubberBand	A rectangle ( only for QwtPickerMachine::RectSelection )
EllipseRubberBand	An ellipse ( only for QwtPickerMachine::RectSelection )
PolygonRubberBand	A polygon ( only for QwtPickerMachine::PolygonSelection )
UserRubberBand	Values >= UserRubberBand can be used to define additional rubber bands.

Definition at line 119 of file qwt_picker.h.

Constructor & Destructor Documentation

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

Constructor

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

Parameters:

parent Parent widget, that will be observed

Definition at line 180 of file qwt_picker.cpp.

QwtPicker::QwtPicker	(	RubberBand	rubberBand,
		DisplayMode	trackerMode,
		QWidget *	parent
	)		`[explicit]`

Constructor

Parameters:

rubberBand	Rubber band style
trackerMode	Tracker mode
parent	Parent widget, that will be observed

Definition at line 193 of file qwt_picker.cpp.

QwtPicker::~QwtPicker ( ) [virtual]

Destructor.

Definition at line 201 of file qwt_picker.cpp.

Member Function Documentation

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

Validate and fix up the selection.

Accepts all selections unmodified

Parameters:

selection Selection to validate and fix up

Returns:: true, when accepted, false otherwise

Reimplemented in QwtPlotZoomer, and PlotZoomer.

Definition at line 1394 of file qwt_picker.cpp.

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;
}

Parameters:

points Selected points

Returns:: Selected points unmodified

Definition at line 792 of file qwt_picker.cpp.

void QwtPicker::append ( const QPoint & pos ) [protected, virtual]

Append a point to the selection and update rubber band and tracker. The appended() signal is emitted.

Parameters:

pos	Additional point

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

Reimplemented in QwtPlotPicker.

Definition at line 1324 of file qwt_picker.cpp.

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.

Definition at line 1243 of file qwt_picker.cpp.

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 rubber band, depending on rubberBand()

Parameters:

painter Painter, initialized with a clip region

See also:: rubberBand(), RubberBand

Definition at line 649 of file qwt_picker.cpp.

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

Draw the tracker

Parameters:

painter Painter

See also:: trackerRect(), trackerText()

Definition at line 744 of file qwt_picker.cpp.

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 QwtPlotZoomer, and QwtPlotPicker.

Definition at line 1276 of file qwt_picker.cpp.

bool QwtPicker::eventFilter	(	QObject *	object,
		QEvent *	event
	)		`[virtual]`

Event filter.

When isEnabled() is 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 rubber band and tracker up to date.

Parameters:

object	Object to be filtered
event	Event

Returns:: Always false.

See also:: widgetEnterEvent(), widgetLeaveEvent(), widgetMousePressEvent(), widgetMouseReleaseEvent(), widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(), widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent(), QObject::installEventFilter(), QObject::event()

Definition at line 902 of file qwt_picker.cpp.

void QwtPicker::init	(	QWidget *	parent,
		RubberBand	rubberBand,
		DisplayMode	trackerMode
	)		`[private]`

Initialize the picker - used by the constructors.

Definition at line 213 of file qwt_picker.cpp.

bool QwtPicker::isActive ( ) const

A picker is active between begin() and end().

Returns:: true if the selection is active.

Definition at line 1404 of file qwt_picker.cpp.

bool QwtPicker::isEnabled ( ) const

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.

Definition at line 1344 of file qwt_picker.cpp.

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()

QWidget * QwtPicker::parentWidget ( )

Return the parent widget, where the selection happens.

Definition at line 274 of file qwt_picker.cpp.

const QWidget * QwtPicker::parentWidget ( ) const

Return the parent widget, where the selection happens.

Definition at line 284 of file qwt_picker.cpp.

QPainterPath QwtPicker::pickArea ( ) const [virtual]

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

Returns:: parentWidget()->contentsRect()

Definition at line 1487 of file qwt_picker.cpp.

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

Definition at line 1414 of file qwt_picker.cpp.

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

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

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

Definition at line 1368 of file qwt_picker.cpp.

void QwtPicker::removed ( const QPoint & pos ) [signal]

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

Parameters:

pos	Position of the point, that has been removed

See also:: remove(), appended()

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

Reset the state machine and terminate ( end(false) ) the selection

Definition at line 1307 of file qwt_picker.cpp.

ResizeMode QwtPicker::resizeMode ( ) const

RubberBand QwtPicker::rubberBand ( ) const

QRegion QwtPicker::rubberBandMask ( ) const [virtual]

Calculate the mask for the rubber band overlay

Returns:: Region for the mask

See also:: QWidget::setMask()

Definition at line 537 of file qwt_picker.cpp.

const QwtWidgetOverlay * QwtPicker::rubberBandOverlay ( ) const [protected]

Returns:: Overlay displaying the rubber band

Definition at line 1594 of file qwt_picker.cpp.

QPen QwtPicker::rubberBandPen ( ) const

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()

Definition at line 801 of file qwt_picker.cpp.

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()

Definition at line 387 of file qwt_picker.cpp.

void QwtPicker::setMouseTracking ( bool enable ) [private]

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.

Definition at line 1465 of file qwt_picker.cpp.

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

Definition at line 363 of file qwt_picker.cpp.

void QwtPicker::setRubberBand ( RubberBand rubberBand )

Set the rubber band style

Parameters:

rubberBand Rubber band style The default value is NoRubberBand.

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

Definition at line 301 of file qwt_picker.cpp.

void QwtPicker::setRubberBandPen ( const QPen & pen )

Set the pen for the rubberband

Parameters:

pen	Rubber band pen

See also:: rubberBandPen(), setRubberBand()

Definition at line 471 of file qwt_picker.cpp.

void QwtPicker::setStateMachine ( QwtPickerMachine * stateMachine )

Set a state machine and delete the previous one

Parameters:

stateMachine State machine

See also:: stateMachine()

Definition at line 241 of file qwt_picker.cpp.

void QwtPicker::setTrackerFont ( const QFont & font )

Set the font for the tracker

Parameters:

font	Tracker font

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

Definition at line 422 of file qwt_picker.cpp.

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

Definition at line 331 of file qwt_picker.cpp.

void QwtPicker::setTrackerPen ( const QPen & pen )

Set the pen for the tracker

Parameters:

pen	Tracker pen

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

Definition at line 447 of file qwt_picker.cpp.

const QwtPickerMachine * QwtPicker::stateMachine ( ) const

Returns:: Assigned state machine

See also:: setStateMachine()

Definition at line 268 of file qwt_picker.cpp.

QwtPickerMachine * QwtPicker::stateMachine ( )

Returns:: Assigned state machine

See also:: setStateMachine()

Definition at line 259 of file qwt_picker.cpp.

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()

Definition at line 1428 of file qwt_picker.cpp.

QFont QwtPicker::trackerFont ( ) const

QRegion QwtPicker::trackerMask ( ) const [virtual]

Calculate the mask for the tracker overlay

Returns:: Region with one rectangle: trackerRect( trackerFont() );

See also:: QWidget::setMask(), trackerRect()

Definition at line 526 of file qwt_picker.cpp.

DisplayMode QwtPicker::trackerMode ( ) const

const QwtWidgetOverlay * QwtPicker::trackerOverlay ( ) const [protected]

Returns:: Overlay displaying the tracker text

Definition at line 1600 of file qwt_picker.cpp.

QPen QwtPicker::trackerPen ( ) const

QPoint QwtPicker::trackerPosition ( ) const

Returns:: Current position of the tracker

Definition at line 807 of file qwt_picker.cpp.

QRect QwtPicker::trackerRect ( const QFont & font ) const [virtual]

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()

Definition at line 821 of file qwt_picker.cpp.

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.

Definition at line 502 of file qwt_picker.cpp.

void QwtPicker::transition ( const QEvent * event ) [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:

event Event

Definition at line 1180 of file qwt_picker.cpp.

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

Update the state of rubber band and tracker label.

Definition at line 1499 of file qwt_picker.cpp.

void QwtPicker::widgetEnterEvent ( QEvent * event ) [protected, virtual]

Handle a enter event for the observed widget.

Parameters:

event Qt event

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

Definition at line 1027 of file qwt_picker.cpp.

void QwtPicker::widgetKeyPressEvent ( QKeyEvent * keyEvent ) [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.

Parameters:

keyEvent Key event