Qwt User's Guide  6.0.2
Public Types | Public Slots | Signals | Public Member Functions | Protected Member Functions
QwtPicker Class Reference

#include <qwt_picker.h>

Inheritance diagram for QwtPicker:
Inheritance graph
[legend]

List of all members.

Public Types

enum  DisplayMode {
  AlwaysOff,
  AlwaysOn,
  ActiveOnly
}
enum  ResizeMode {
  Stretch,
  KeepSize
}
enum  RubberBand {
  NoRubberBand = 0,
  HLineRubberBand,
  VLineRubberBand,
  CrossRubberBand,
  RectRubberBand,
  EllipseRubberBand,
  PolygonRubberBand,
  UserRubberBand = 100
}
- Public Types inherited from QwtEventPattern
enum  KeyPatternCode {
  KeySelect1,
  KeySelect2,
  KeyAbort,
  KeyLeft,
  KeyRight,
  KeyUp,
  KeyDown,
  KeyRedo,
  KeyUndo,
  KeyHome,
  KeyPatternCount
}
enum  MousePatternCode {
  MouseSelect1,
  MouseSelect2,
  MouseSelect3,
  MouseSelect4,
  MouseSelect5,
  MouseSelect6,
  MousePatternCount
}

Public Slots

void setEnabled (bool)

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

 QwtPicker (QWidget *parent)
 QwtPicker (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
QPolygon selection () const
void setResizeMode (ResizeMode)
void setRubberBand (RubberBand)
void setRubberBandPen (const QPen &)
void setStateMachine (QwtPickerMachine *)
void setTrackerFont (const QFont &)
void setTrackerMode (DisplayMode)
void setTrackerPen (const QPen &)
const QwtPickerMachinestateMachine () const
QwtPickerMachinestateMachine ()
QFont trackerFont () const
DisplayMode trackerMode () const
QPen trackerPen () const
QPoint trackerPosition () const
virtual QRect trackerRect (const QFont &) const
virtual QwtText trackerText (const QPoint &pos) const
- Public Member Functions inherited from QwtEventPattern
 QwtEventPattern ()
virtual ~QwtEventPattern ()
void initKeyPattern ()
void initMousePattern (int numButtons)
bool keyMatch (uint pattern, const QKeyEvent *) const
const QVector< KeyPattern > & keyPattern () const
QVector< KeyPattern > & keyPattern ()
bool mouseMatch (uint pattern, const QMouseEvent *) const
const QVector< MousePattern > & mousePattern () const
QVector< MousePattern > & mousePattern ()
void setKeyPattern (uint pattern, int key, int state=Qt::NoButton)
void setKeyPattern (const QVector< KeyPattern > &)
void setMousePattern (uint pattern, int button, int state=Qt::NoButton)
void setMousePattern (const QVector< MousePattern > &)

Protected Member Functions

virtual bool accept (QPolygon &) const
virtual QPolygon adjustedPoints (const QPolygon &) const
virtual void append (const QPoint &)
virtual void begin ()
virtual bool end (bool ok=true)
virtual void move (const QPoint &)
const QPolygon & pickedPoints () const
virtual void remove ()
virtual void reset ()
const QWidget * rubberBandWidget () const
virtual void stretchSelection (const QSize &oldSize, const QSize &newSize)
const QWidget * trackerWidget () const
virtual void transition (const QEvent *)
virtual void updateDisplay ()
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 *)
- Protected Member Functions inherited from QwtEventPattern
virtual bool keyMatch (const KeyPattern &, const QKeyEvent *) const
virtual bool mouseMatch (const MousePattern &, const QMouseEvent *) 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.

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

Display never.

AlwaysOn 

Display always.

ActiveOnly 

Display only when the selection is active.

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.

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:
parentParent widget, that will be observed
QwtPicker::QwtPicker ( RubberBand  rubberBand,
DisplayMode  trackerMode,
QWidget *  parent 
)
explicit

Constructor

Parameters:
rubberBandRubberband style
trackerModeTracker mode
parentParent widget, that will be observed

Member Function Documentation

bool QwtPicker::accept ( QPolygon &  selection) const
protectedvirtual

Validate and fixup the selection.

Accepts all selections unmodified

Parameters:
selectionSelection 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:
onTrue, when the picker has been activated
QPolygon QwtPicker::adjustedPoints ( const QPolygon &  points) const
protectedvirtual

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)
protectedvirtual

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

Parameters:
posAdditional 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:
posPosition of the appended point.
See also:
append(). moved()
void QwtPicker::begin ( )
protectedvirtual

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:
selectionChanged selection
See also:
stretchSelection()
void QwtPicker::drawRubberBand ( QPainter *  painter) const
virtual

Draw a rubberband, depending on rubberBand()

Parameters:
painterPainter, initialized with clip rect
See also:
rubberBand(), RubberBand
void QwtPicker::drawTracker ( QPainter *  painter) const
virtual

Draw the tracker

Parameters:
painterPainter
See also:
trackerRect(), trackerText()
bool QwtPicker::end ( bool  ok = true)
protectedvirtual

Close a selection setting the state to inactive.

The selection is validated and maybe fixed by accept().

Parameters:
okIf 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 *  object,
QEvent *  event 
)
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.

Parameters:
objectObject to be filtered
eventEvent
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)
protectedvirtual

Move the last point of the selection The moved() signal is emitted.

Parameters:
posNew 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:
posPosition of the moved last point of the selection.
See also:
move(), appended()
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:
parentWidget()->contentsRect()
void QwtPicker::remove ( )
protectedvirtual

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 ( )
protectedvirtual

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:
polygonSelected 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:
enabledtrue 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:
modeResize mode
See also:
resizeMode(), ResizeMode
void QwtPicker::setRubberBand ( RubberBand  rubberBand)

Set the rubberband style

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

Set the pen for the rubberband

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

Set a state machine and delete the previous one

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

Set the font for the tracker

Parameters:
fontTracker 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:
modeTracker 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:
penTracker 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 
)
protectedvirtual

Scale the selection by the ratios of oldSize and newSize The changed() signal is emitted.

Parameters:
oldSizePrevious size
newSizeCurrent 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:
fontFont 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:
posPosition
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 *  event)
protectedvirtual

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:
eventEvent
void QwtPicker::widgetEnterEvent ( QEvent *  event)
protectedvirtual
void QwtPicker::widgetKeyPressEvent ( QKeyEvent *  keyEvent)
protectedvirtual

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:
keyEventKey event
See also:
eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(), widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(), widgetWheelEvent(), widgetKeyReleaseEvent(), stateMachine(), QwtEventPattern::KeyPatternCode

Reimplemented in QwtPlotZoomer.

void QwtPicker::widgetKeyReleaseEvent ( QKeyEvent *  keyEvent)
protectedvirtual

Handle a key release event for the observed widget.

Passes the event to the state machine.

Parameters:
keyEventKey event
See also:
eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(), widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(), widgetWheelEvent(), widgetKeyPressEvent(), stateMachine()
void QwtPicker::widgetLeaveEvent ( QEvent *  event)
protectedvirtual
void QwtPicker::widgetMouseDoubleClickEvent ( QMouseEvent *  mouseEvent)
protectedvirtual

Handle mouse double click event for the observed widget.

Parameters:
mouseEventMouse event
See also:
eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(), widgetMouseMoveEvent(), widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()
void QwtPicker::widgetMouseMoveEvent ( QMouseEvent *  mouseEvent)
protectedvirtual

Handle a mouse move event for the observed widget.

Parameters:
mouseEventMouse event
See also:
eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(), widgetMouseDoubleClickEvent(), widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()
void QwtPicker::widgetMousePressEvent ( QMouseEvent *  mouseEvent)
protectedvirtual

Handle a mouse press event for the observed widget.

Parameters:
mouseEventMouse event
See also:
eventFilter(), widgetMouseReleaseEvent(), widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(), widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()
void QwtPicker::widgetMouseReleaseEvent ( QMouseEvent *  mouseEvent)
protectedvirtual

Handle a mouse relase event for the observed widget.

Parameters:
mouseEventMouse event
See also:
eventFilter(), widgetMousePressEvent(), widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(), widgetWheelEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()

Reimplemented in QwtPlotZoomer.

void QwtPicker::widgetWheelEvent ( QWheelEvent *  wheelEvent)
protectedvirtual

Handle a wheel event for the observed widget.

Move the last point of the selection in case of isActive() == true

Parameters:
wheelEventWheel event
See also:
eventFilter(), widgetMousePressEvent(), widgetMouseReleaseEvent(), widgetMouseDoubleClickEvent(), widgetMouseMoveEvent(), widgetKeyPressEvent(), widgetKeyReleaseEvent()