Provided by: libqwt-doc_6.0.0-1.2_all 
NAME
QwtPicker -
QwtPicker provides selections on a widget.
SYNOPSIS
#include <qwt_picker.h>
Inherits QwtEventPattern.
Inherited by QwtPlotPicker.
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 QwtPickerMachine * stateMachine () const
QwtPickerMachine * stateMachine ()
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
virtual 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:
• 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 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:
• 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 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
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 Rubberband style
The default value is QwtPicker::NoRubberBand.
See also:
setRubberBand(), rubberBand()
Enumerator:
NoRubberBand
No rubberband.
HLineRubberBand
A horizontal line ( only for QwtPicker::PointSelection )
VLineRubberBand
A vertical line ( only for QwtPicker::PointSelection )
CrossRubberBand
A crosshair ( only for QwtPicker::PointSelection )
RectRubberBand
A rectangle ( only for QwtPicker::RectSelection )
EllipseRubberBand
An ellipse ( only for QwtPicker::RectSelection )
PolygonRubberBand
A polygon ( only for QwtPicker::&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. rubberband and tracker are disabled.
Parameters:
parent Parent widget, that will be observed
QwtPicker::QwtPicker (RubberBandrubberBand, DisplayModetrackerMode, 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 &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::activated (boolon) [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 (boolok = 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()
QWidget * QwtPicker::parentWidget ()
Return the parent widget, where the selection happens.
const QWidget * QwtPicker::parentWidget () const
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 (boolenabled) [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 (ResizeModemode)
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 (RubberBandrubberBand) 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 (DisplayModemode)
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
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.
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] Handle a enter event for the observed
widget.
See also:
eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(), widgetMouseDoubleClickEvent(),
widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()
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] 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.
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.
See also:
eventFilter(), widgetMouseReleaseEvent(), widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(),
widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()
void QwtPicker::widgetMouseReleaseEvent (QMouseEvent *e) [protected, virtual] Handle a mouse relase event for
the observed widget.
See also:
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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