QwtAbstractSlider(3)

NAME
QwtAbstractSlider - An abstract base class for slider widgets with a scale.

SYNOPSIS

#include <qwt_abstract_slider.h>

Inherits QwtAbstractScale.

Inherited by QwtDial, QwtKnob, and QwtSlider.

  Public Slots
void setValue (double val)

  Signals
void valueChanged (double value)
Notify a change of value.
void sliderPressed ()
void sliderReleased ()
void sliderMoved (double value)

  Public Member Functions
QwtAbstractSlider (QWidget *parent=NULL)
Constructor.
virtual ~QwtAbstractSlider ()
Destructor.
void setValid (bool)
bool isValid () const
double value () const
Returns the current value.
void setWrapping (bool)
bool wrapping () const
void setTotalSteps (uint)
Set the number of steps.
uint totalSteps () const
void setSingleSteps (uint)
Set the number of steps for a single increment.
uint singleSteps () const
void setPageSteps (uint)
Set the number of steps for a page increment.
uint pageSteps () const
void setStepAlignment (bool)
Enable step alignment.
bool stepAlignment () const
void setTracking (bool)
Enables or disables tracking.
bool isTracking () const
void setReadOnly (bool)
bool isReadOnly () const
void setInvertedControls (bool)
bool invertedControls () const

  Protected Member Functions
virtual void mousePressEvent (QMouseEvent *)
virtual void mouseReleaseEvent (QMouseEvent *)
virtual void mouseMoveEvent (QMouseEvent *)
virtual void keyPressEvent (QKeyEvent *)
virtual void wheelEvent (QWheelEvent *)
virtual bool isScrollPosition (const QPoint &pos) const =0
Determine what to do when the user presses a mouse button.
virtual double scrolledTo (const QPoint &pos) const =0
Determine the value for a new position of the movable part of the slider.
void incrementValue (int numSteps)
virtual void scaleChange ()
virtual void sliderChange ()
Calling update()
double incrementedValue (double value, int stepCount) const

Detailed Description

An abstract base class for slider widgets with a scale. A slider widget displays a value according to a scale. The class is designed as a common super class for widgets like QwtKnob, QwtDial and QwtSlider.

When the slider is nor readOnly() its value can be modified by keyboard, mouse and wheel inputs.

The range of the slider is divided into a number of steps from which the value increments according to user inputs depend. Only for linear scales the number of steps correspond with a fixed step size.

Constructor & Destructor Documentation

  QwtAbstractSlider::QwtAbstractSlider (QWidget * parent = NULL) [explicit]

Constructor. The scale is initialized to [0.0, 100.0], the number of steps is set to 100 with 1 and 10 and single an page step sizes. Step alignment is enabled.

The initial value is invalid.

Parameters:
    parent Parent widget

Member Function Documentation

  double QwtAbstractSlider::incrementedValue (double value, int stepCount) const [protected]
Increment a value

Parameters:
    value Value
    stepCount Number of steps

Returns:
    Incremented value

  void QwtAbstractSlider::incrementValue (int stepCount) [protected]
Increment the slider

The step size depends on the number of totalSteps()

Parameters:
    stepCount Number of steps

See also:
    setTotalSteps(), incrementedValue()

  bool QwtAbstractSlider::invertedControls () const

Returns:
    True, when the controls are inverted

See also:
    setInvertedControls()

  bool QwtAbstractSlider::isReadOnly () const
In read only mode the slider can't be controlled by mouse or keyboard.

Returns:
    true if read only

See also:
    setReadOnly()

  virtual bool QwtAbstractSlider::isScrollPosition (const QPoint & pos) const [protected], [pure virtual]

Determine what to do when the user presses a mouse button.

Parameters:
    pos Mouse position

Return values:
    True,when pos is a valid scroll position

See also:
    scrolledTo()

Implemented in QwtKnob, QwtDial, and QwtSlider.

  bool QwtAbstractSlider::isTracking () const

Returns:
    True, when tracking has been enabled

See also:
    setTracking()

  bool QwtAbstractSlider::isValid () const

Returns:
    True, when the value is invalid

  void QwtAbstractSlider::keyPressEvent (QKeyEvent * event) [protected], [virtual]
Handles key events

QwtAbstractSlider handles the following keys:

•   Qt::Key_Left
     Add/Subtract singleSteps() in direction to lowerBound();

•   Qt::Key_Right
     Add/Subtract singleSteps() in direction to upperBound();

•   Qt::Key_Down
     Subtract singleSteps(), when invertedControls() is false

•   Qt::Key_Up
     Add singleSteps(), when invertedControls() is false

•   Qt::Key_PageDown
     Subtract pageSteps(), when invertedControls() is false

•   Qt::Key_PageUp
     Add pageSteps(), when invertedControls() is false

•   Qt::Key_Home
     Set the value to the minimum()

•   Qt::Key_End
     Set the value to the maximum()

Parameters:
    event Key event

See also:
    isReadOnly()

Reimplemented in QwtCompass.

  void QwtAbstractSlider::mouseMoveEvent (QMouseEvent * event) [protected], [virtual]
Mouse Move Event handler

Parameters:
    event Mouse event

  void QwtAbstractSlider::mousePressEvent (QMouseEvent * event) [protected], [virtual]
Mouse press event handler

Parameters:
    event Mouse event

Reimplemented in QwtSlider.

  void QwtAbstractSlider::mouseReleaseEvent (QMouseEvent * event) [protected], [virtual]
Mouse Release Event handler

Parameters:
    event Mouse event

Reimplemented in QwtSlider.

  uint QwtAbstractSlider::pageSteps () const

Returns:
    Number of steps

See also:
    setPageSteps(), totalSteps(), singleSteps()

  void QwtAbstractSlider::scaleChange () [protected], [virtual]
Update the slider according to modifications of the scale

Reimplemented from QwtAbstractScale.

Reimplemented in QwtDial, and QwtSlider.

  virtual double QwtAbstractSlider::scrolledTo (const QPoint & pos) const [protected], [pure virtual]

Determine the value for a new position of the movable part of the slider.

Parameters:
    pos Mouse position

Returns:
    Value for the mouse position

See also:
    isScrollPosition()

Implemented in QwtKnob, QwtDial, and QwtSlider.

  void QwtAbstractSlider::setInvertedControls (bool on)
Invert wheel and key events

Usually scrolling the mouse wheel 'up' and using keys like page up will increase the slider's value towards its maximum. When invertedControls() is enabled the value is scrolled towards its minimum.

Inverting the controls might be f.e. useful for a vertical slider with an inverted scale ( decreasing from top to bottom ).

Parameters:
    on Invert controls, when true

See also:
    invertedControls(), keyEvent(), wheelEvent()

  void QwtAbstractSlider::setPageSteps (uint stepCount)

Set the number of steps for a page increment. The range of the slider is divided into a number of steps from which the value increments according to user inputs depend.

Parameters:
    stepCount Number of steps

See also:
    pageSteps(), setTotalSteps(), setSingleSteps()

  void QwtAbstractSlider::setReadOnly (bool on)
En/Disable read only mode

In read only mode the slider can't be controlled by mouse or keyboard.

Parameters:
    on Enables in case of true

See also:
    isReadOnly()

Warning:
    The focus policy is set to Qt::StrongFocus or Qt::NoFocus

  void QwtAbstractSlider::setSingleSteps (uint stepCount)

Set the number of steps for a single increment. The range of the slider is divided into a number of steps from which the value increments according to user inputs depend.

Parameters:
    stepCount Number of steps

See also:
    singleSteps(), setTotalSteps(), setPageSteps()

  void QwtAbstractSlider::setStepAlignment (bool on)

Enable step alignment. When step alignment is enabled values resulting from slider movements are aligned to the step size.

Parameters:
    on Enable step alignment when true

See also:
    stepAlignment()

  void QwtAbstractSlider::setTotalSteps (uint stepCount)

Set the number of steps. The range of the slider is divided into a number of steps from which the value increments according to user inputs depend.

The default setting is 100.

Parameters:
    stepCount Number of steps

See also:
    totalSteps(), setSingleSteps(), setPageSteps()

  void QwtAbstractSlider::setTracking (bool on)

Enables or disables tracking. If tracking is enabled, the slider emits the valueChanged() signal while the movable part of the slider is being dragged. If tracking is disabled, the slider emits the valueChanged() signal only when the user releases the slider.

Tracking is enabled by default.

Parameters:
    on true (enable) or false (disable) tracking.

See also:
    isTracking(), sliderMoved()

  void QwtAbstractSlider::setValid (bool on)
Set the value to be valid/invalid

Parameters:
    on When true, the value is invalidated

See also:
    setValue()

  void QwtAbstractSlider::setValue (double value) [slot]
Set the slider to the specified value

Parameters:
    value New value

See also:
    setValid(), sliderChange(), valueChanged()

  void QwtAbstractSlider::setWrapping (bool on)
If wrapping is true stepping up from upperBound() value will take you to the minimum() value and vice versa.

Parameters:
    on En/Disable wrapping

See also:
    wrapping()

  uint QwtAbstractSlider::singleSteps () const

Returns:
    Number of steps

See also:
    setSingleSteps(), totalSteps(), pageSteps()

  void QwtAbstractSlider::sliderMoved (double value) [signal]
This signal is emitted when the user moves the slider with the mouse.

Parameters:
    value New value

See also:
    valueChanged()

  void QwtAbstractSlider::sliderPressed () [signal]
This signal is emitted when the user presses the movable part of the slider.

  void QwtAbstractSlider::sliderReleased () [signal]
This signal is emitted when the user releases the movable part of the slider.

  bool QwtAbstractSlider::stepAlignment () const

Returns:
    True, when step alignment is enabled

See also:
    setStepAlignment()

  uint QwtAbstractSlider::totalSteps () const

Returns:
    Number of steps

See also:
    setTotalSteps(), singleSteps(), pageSteps()

  void QwtAbstractSlider::valueChanged (double value) [signal]

Notify a change of value. When tracking is enabled (default setting), this signal will be emitted every time the value changes.

Parameters:
    value New value

See also:
    setTracking(), sliderMoved()

  void QwtAbstractSlider::wheelEvent (QWheelEvent * event) [protected], [virtual]
Wheel Event handler

In/decreases the value by s number of steps. The direction depends on the invertedControls() property.

When the control or shift modifier is pressed the wheel delta ( divided by 120 ) is mapped to an increment according to pageSteps(). Otherwise it is mapped to singleSteps().

Parameters:
    event Wheel event

Reimplemented in QwtDial.

  bool QwtAbstractSlider::wrapping () const

Returns:
    True, when wrapping is set

See also:
    setWrapping()

Author

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