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QwtPicker Class Reference

Inheritance diagram for QwtPicker:

QwtEventPattern QwtPlotPicker QwtPlotZoomer List of all members.

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 labels.

QwtPicker is useful for widgets where the event handlers canīt 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->setCursorLabelMode(QwtPicker::ActiveOnly);
connect(picker, SIGNAL(selected(const QPointArray &)), ...);

// 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 cursor label is visible in case of cursorLabelMode 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 cursorLabelMode() is AlwayOn.


Public Types

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

Public Member Functions

 QwtPicker (QWidget *, const char *name=0)
 QwtPicker (int selectionFlags, RubberBand rubberBand, DisplayMode cursorLabelMode, QWidget *, const char *name=0)
virtual ~QwtPicker ()
virtual void setSelectionFlags (int)
int selectionFlags () const
virtual void setRubberBand (RubberBand)
RubberBand rubberBand () const
virtual void setCursorLabelMode (DisplayMode)
DisplayMode cursorLabelMode () const
virtual void setResizeMode (ResizeMode)
ResizeMode resizeMode () const
virtual void setRubberBandPen (const QPen &)
QPen rubberBandPen () const
virtual void setCursorLabelPen (const QPen &)
QPen cursorLabelPen () const
virtual void setCursorLabelFont (const QFont &)
QFont cursorLabelFont () const
bool isEnabled () const
virtual void setEnabled (bool)
bool isActive () const
virtual bool event (QEvent *)
virtual bool eventFilter (QObject *, QEvent *)
QWidget * parentWidget ()
const QWidget * parentWidget () const
virtual QRect pickRect () const
const QPointArray & selection () const

Protected Member Functions

void selected (const QPointArray &pa)
void appended (const QPoint &pos)
void moved (const QPoint &pos)
void changed (const QPointArray &pa)
virtual bool accept (QPointArray &selection) const
virtual void transition (const QEvent *)
virtual void begin ()
virtual void append (const QPoint &)
virtual void move (const QPoint &)
virtual bool end (bool ok=TRUE)
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 drawRubberBand (const QRect &clipRect=QRect()) const
virtual void drawRubberBand (QPainter *, const QRect &rect, const QPointArray &) const
virtual void drawCursorLabel (const QRect &clipRect=QRect()) const
virtual void drawCursorLabel (QPainter *, const QRect &rect, const QPoint &, const QPointArray &) const
virtual void stretchSelection (const QSize &oldSize, const QSize &newSize)
virtual QString cursorLabel (const QPoint &pos) const
virtual QwtPickerMachinestateMachine (int) const


Member Enumeration Documentation

enum QwtPicker::DisplayMode
 

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

See also:
QwtPicker::setDisplayMode(), QwtPicker::displayMode(), QwtPicker::isActive()

enum QwtPicker::RectSelectionType
 

Selection subtype for RectSelection This enum type describes the type of rectangle selections. It can be orīd with QwtPicker::RectSelectionType and QwtPicker::SelectionMode and passed to QwtPicker::setSelectionFlags().

  • 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 orīd 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 orīd 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 cursor label.
  • 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,
const char *  name = 0
 

Constructor

Creates an picker that is enabled, but where selection flags s set to NoSelection, rubberband and cursor label are disabled.

Parameters:
parent Parent widget, that will be observed
name Object name

QwtPicker::QwtPicker int  selectionFlags,
RubberBand  rubberBand,
DisplayMode  cursorLabelMode,
QWidget *  parent,
const char *  name = 0
 

Constructor

Parameters:
selectionFlags Orīd value of SelectionType, RectSelectionType and SelectionMode
rubberBand Rubberband style
cursorLabelMode Cursor label mode
parent Parent widget, that will be observed
name Object name

QwtPicker::~QwtPicker  )  [virtual]
 

Destructor.


Member Function Documentation

bool QwtPicker::accept QPointArray &  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 cursor label. 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  )  [protected]
 

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 QPointArray &  pa  )  [protected]
 

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()

QString QwtPicker::cursorLabel const QPoint &  pos  )  const [protected, 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 ī, ī.

The format for the string conversion is "%d".

Parameters:
pos Position
Returns:
Converted position as string

Reimplemented in QwtPlotPicker.

QFont QwtPicker::cursorLabelFont  )  const
 

Returns:
Cursor label font
See also:
setCursorLabelFont(), cursorLabelMode(), cursorLabelPen()

QwtPicker::DisplayMode QwtPicker::cursorLabelMode  )  const
 

Returns:
Cursor label display mode
See also:
setCursorLabelMode(), DisplayMode

QPen QwtPicker::cursorLabelPen  )  const
 

Returns:
Cursor label pen
See also:
setCursorLabelPen(), cursorLabelMode(), cursorLabelFont()

void QwtPicker::drawCursorLabel QPainter *  painter,
const QRect &  pickRect,
const QPoint &  pos,
const QPointArray &  pa
const [protected, virtual]
 

Draw a cursor label.

The default position of the label is top-right of the cursor. In case of a rubberband the label is placed not to conflict with the rubberband.

Parameters:
painter Painter, initialized with clip rect, in Qt::XorROP mode of cursor label pen and background color of the observed widget.
pickRect Rectangle where selections can happen.
pos Cursor position
pa Current selection
See also:
rubberBand(), RubberBand, selectionFlags()

void QwtPicker::drawCursorLabel const QRect &  clipRect = QRect()  )  const [protected, virtual]
 

Draw the cursor label.

The cursor label is painted in Qt::XorROP mode, what means the first call paints the second erases the painted rubberband.

Parameters:
clipRect Clipping rectangle. If it is now valid the result of pickRect() is used instead.
See also:
pickRect(), QPainter::setRasterOp(), QPainter::setClipRect()

void QwtPicker::drawRubberBand QPainter *  painter,
const QRect &  pickRect,
const QPointArray &  pa
const [protected, virtual]
 

Draw a rubberband , depending on rubberBand() and selectionFlags()

Parameters:
painter Painter, initialized with clip rect, in Qt::XorROP mode of rubberband pen and background color of the observed widget.
pickRect Rectangle where selection can happen.
pa Current selection
See also:
rubberBand(), RubberBand, selectionFlags()

void QwtPicker::drawRubberBand const QRect &  clipRect = QRect()  )  const [protected, virtual]
 

Draw the rubberband.

The rubberband is painted in Qt::XorROP mode, what means the first call paints the second erases the painted rubberband.

Parameters:
clipRect Clipping rectangle. If it is now valid the result of pickRect() is used instead.
See also:
pickRect(), QPainter::setRasterOp(), QPainter::setClipRect()

bool QwtPicker::end bool  ok = 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 QwtPlotPicker, and QwtPlotZoomer.

bool QwtPicker::event QEvent *  e  )  [virtual]
 

Event Handler.

Paint events for the observed widgets require to repaint rubberband an cursor label too. To delay them until the widget is repainted the event filter sends a QEvent::Paint to the picker, that is handled here.

See also:
eventFilter(), drawRubberBand(), drawCursorLabel()

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 cursor label 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  )  [protected]
 

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()

const QWidget * QwtPicker::parentWidget  )  const
 

Return the parent widget, where the selection happens.

QWidget * QwtPicker::parentWidget  ) 
 

Return the parent widget, where the selection happens.

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.

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()

void QwtPicker::selected const QPointArray &  pa  )  [protected]
 

A signal emitting the selected points, at the end of a selection.

Parameters:
pa Selected points

const QPointArray & QwtPicker::selection  )  const
 

Return Selected points.

int QwtPicker::selectionFlags  )  const
 

Returns:
Selection flags, an Orīd value of SelectionType, RectSelectionType and SelectionMode.
See also:
setSelectionFlags(), SelectionType, RectSelectionType, SelectionMode

void QwtPicker::setCursorLabelFont const QFont &  font  )  [virtual]
 

Set the font for the cursor label

Parameters:
font Cursor label font
See also:
cursorLabelFont(), setCursorLabelMode(), setCursorLabelPen()

void QwtPicker::setCursorLabelMode DisplayMode  mode  )  [virtual]
 

Set the display mode of the cursor label.

A cursor label dispays the current position of the cursor as a string. The display mode controls if the label 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 Cursor label display mode
Warning:
In case of AlwaysOn, mouseTracking will be enabled for the observed widget.
See also:
cursorLabelMode(), DisplayMode

void QwtPicker::setCursorLabelPen const QPen &  pen  )  [virtual]
 

Set the pen for the cursor label

Parameters:
pen Cursor label pen
See also:
cursorLabelPen(), setCursorLabelMode(), setCursorLabelFont()

void QwtPicker::setEnabled bool  enabled  )  [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 ResizeMode  mode  )  [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 RubberBand  rubberBand  )  [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 int  flags  )  [virtual]
 

Set the selection flags

Parameters:
flags Orīd value of SelectionType, RectSelectionType and SelectionMode. The default value is NoSelection.
See also:
selectionFlags(), SelectionType, RectSelectionType, SelectionMode

Reimplemented in QwtPlotZoomer.

QwtPickerMachine * QwtPicker::stateMachine int  flags  )  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()

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::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()


Generated on Tue Nov 4 09:53:49 2003 for Qwt User's Guide by doxygen 1.3.4