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QwtPicker(3) Qwt User's Guide QwtPicker(3)

NAME

QwtPicker -

SYNOPSIS

#include <qwt_picker.h>
Inherits QwtEventPattern.
Inherited by QwtPlotPicker.

Public Types


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

Signals


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

Public Member Functions


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

Protected Member Functions


virtual bool accept (QwtPolygon &selection) const
 
virtual void append (const QPoint &)
 
virtual void begin ()
 
virtual bool end (bool ok=true)
 
virtual void move (const QPoint &)
 
virtual void reset ()
 
const QWidget * rubberBandWidget () const
 
virtual QwtPickerMachine * stateMachine (int) const
 
virtual void stretchSelection (const QSize &oldSize, const QSize &newSize)
 
const QWidget * trackerWidget () const
 
virtual void transition (const QEvent *)
 
virtual void updateDisplay ()
 
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 *)
 

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 
#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

•
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(). .IP "•" 2 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 (intselectionFlags, RubberBandrubberBand, DisplayModetrackerMode, 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

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 (boolok = 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 QwtPlotZoomer, and QwtPlotPicker.

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()

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

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 (boolenabled) [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 ( ResizeModemode) [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 ( RubberBandrubberBand) [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 (intflags) [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 ( DisplayModemode) [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 (intflags) 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::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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Tue Nov 20 2012 Version 5.2.3