Provided by: libqwt-doc_6.1.4-2_all 
NAME
QwtPicker - QwtPicker provides selections on a widget.
SYNOPSIS
#include <qwt_picker.h>
Inherits QObject, and QwtEventPattern.
Inherited by QwtPlotPicker.
Public Types
enum RubberBand { NoRubberBand = 0, HLineRubberBand, VLineRubberBand, CrossRubberBand,
RectRubberBand, EllipseRubberBand, PolygonRubberBand, UserRubberBand = 100 }
enum DisplayMode { AlwaysOff, AlwaysOn, ActiveOnly }
Display mode.
enum ResizeMode { Stretch, KeepSize }
Public Slots
void setEnabled (bool)
En/disable the picker.
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 ()
Destructor.
void setStateMachine (QwtPickerMachine *)
const QwtPickerMachine * stateMachine () const
QwtPickerMachine * stateMachine ()
void setRubberBand (RubberBand)
RubberBand rubberBand () const
void setTrackerMode (DisplayMode)
Set the display mode of the tracker.
DisplayMode trackerMode () const
void setResizeMode (ResizeMode)
Set the resize mode.
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 *)
Event filter.
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
virtual void drawRubberBand (QPainter *) const
virtual void drawTracker (QPainter *) const
virtual QRegion rubberBandMask () const
virtual QwtText trackerText (const QPoint &pos) const
Return the label for a position.
QPoint trackerPosition () const
virtual QRect trackerRect (const QFont &) const
QPolygon selection () const
Protected Member Functions
virtual QPolygon adjustedPoints (const QPolygon &) const
Map the pickedPoints() into a selection()
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)
Close a selection setting the state to inactive.
virtual bool accept (QPolygon &) const
Validate and fix up the selection.
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 ()
Update the state of rubber band and tracker label.
const QwtWidgetOverlay * rubberBandOverlay () const
const QwtWidgetOverlay * trackerOverlay () 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:
• 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.
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.
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.
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.
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
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
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.
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
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.
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 rubber band, depending on rubberBand()
Parameters:
painter Painter, initialized with a clip region
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 QwtPlotZoomer, and QwtPlotPicker.
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()
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()
QPainterPath QwtPicker::pickArea () const [virtual]
Find the area of the observed widget, where selection might happen.
Returns:
parentWidget()->contentsRect()
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
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.
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
QwtPicker::ResizeMode QwtPicker::resizeMode () const
Returns:
Resize mode
See also:
setResizeMode(), ResizeMode
QwtPicker::RubberBand QwtPicker::rubberBand () const
Returns:
Rubber band style
See also:
setRubberBand(), RubberBand, rubberBandPen()
QRegion QwtPicker::rubberBandMask () const [virtual]
Calculate the mask for the rubber band overlay
Returns:
Region for the mask
See also:
QWidget::setMask()
const QwtWidgetOverlay * QwtPicker::rubberBandOverlay () const [protected]
Returns:
Overlay displaying the rubber band
QPen QwtPicker::rubberBandPen () const
Returns:
Rubber band pen
See also:
setRubberBandPen(), 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 rubber band style
Parameters:
rubberBand Rubber band 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 Rubber band 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()
const QwtPickerMachine * QwtPicker::stateMachine () const
Returns:
Assigned state machine
See also:
setStateMachine()
QwtPickerMachine * QwtPicker::stateMachine ()
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
const QwtWidgetOverlay * QwtPicker::trackerOverlay () const [protected]
Returns:
Overlay displaying the tracker text
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 [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()
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.
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
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()
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
See also:
eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(),
widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(), widgetWheelEvent(),
widgetKeyReleaseEvent(), stateMachine(), QwtEventPattern::KeyPatternCode
Reimplemented in QwtPlotZoomer.
void QwtPicker::widgetKeyReleaseEvent (QKeyEvent * keyEvent) [protected], [virtual]
Handle a key release event for the observed widget.
Passes the event to the state machine.
Parameters:
keyEvent Key event
See also:
eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(),
widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(), widgetWheelEvent(),
widgetKeyPressEvent(), stateMachine()
void QwtPicker::widgetLeaveEvent (QEvent * event) [protected], [virtual]
Handle a leave event for the observed widget.
Parameters:
event Qt event
See also:
eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(),
widgetMouseDoubleClickEvent(), widgetWheelEvent(), widgetKeyPressEvent(),
widgetKeyReleaseEvent()
void QwtPicker::widgetMouseDoubleClickEvent (QMouseEvent * mouseEvent) [protected], [virtual]
Handle mouse double click event for the observed widget.
Parameters:
mouseEvent Mouse event
See also:
eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(),
widgetMouseMoveEvent(), widgetWheelEvent(), widgetKeyPressEvent(),
widgetKeyReleaseEvent()
void QwtPicker::widgetMouseMoveEvent (QMouseEvent * mouseEvent) [protected], [virtual]
Handle a mouse move event for the observed widget.
Parameters:
mouseEvent Mouse event
See also:
eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(),
widgetMouseDoubleClickEvent(), widgetWheelEvent(), widgetKeyPressEvent(),
widgetKeyReleaseEvent()
void QwtPicker::widgetMousePressEvent (QMouseEvent * mouseEvent) [protected], [virtual]
Handle a mouse press event for the observed widget.
Parameters:
mouseEvent Mouse event
See also:
eventFilter(), widgetMouseReleaseEvent(), widgetMouseDoubleClickEvent(),
widgetMouseMoveEvent(), widgetWheelEvent(), widgetKeyPressEvent(),
widgetKeyReleaseEvent()
void QwtPicker::widgetMouseReleaseEvent (QMouseEvent * mouseEvent) [protected], [virtual]
Handle a mouse release event for the observed widget.
Parameters:
mouseEvent Mouse event
See also:
eventFilter(), widgetMousePressEvent(), widgetMouseDoubleClickEvent(),
widgetMouseMoveEvent(), widgetWheelEvent(), widgetKeyPressEvent(),
widgetKeyReleaseEvent()
Reimplemented in QwtPlotZoomer.
void QwtPicker::widgetWheelEvent (QWheelEvent * wheelEvent) [protected], [virtual]
Handle a wheel event for the observed widget.
Move the last point of the selection in case of isActive() == true
Parameters:
wheelEvent Wheel event
See also:
eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(),
widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(), widgetKeyPressEvent(),
widgetKeyReleaseEvent()
Author
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