QwtAbstractSlider

Section: C Library Functions (3) Updated: 22 Mar 2009 Local index Up

NAME

QwtAbstractSlider - An abstract base class for slider widgets.

SYNOPSIS

#include <qwt_abstract_slider.h>

Inherits QwtDoubleRange.

Inherited by QwtDial, QwtKnob, QwtSlider, and QwtWheel.

Public Types

enum ScrollMode { ScrNone, ScrMouse, ScrTimer, ScrDirect, ScrPage }

Public Slots

virtual void setValue (double val)

virtual void fitValue (double val)

virtual void incValue (int steps)

virtual void setReadOnly (bool)

Signals

void valueChanged (double value)

void sliderPressed ()

void sliderReleased ()

void sliderMoved (double value)

Public Member Functions

QwtAbstractSlider (Qt::Orientation, QWidget *parent=NULL)

virtual ~QwtAbstractSlider ()

void setUpdateTime (int t)

void stopMoving ()

void setTracking (bool enable)

virtual void setMass (double val)

virtual double mass () const

virtual void setOrientation (Qt::Orientation o)

Qt::Orientation orientation () const

bool isReadOnly () const

bool isValid () const

void setValid (bool valid)

Protected Member Functions

virtual void setPosition (const QPoint &)

virtual void valueChange ()

virtual void timerEvent (QTimerEvent *e)

virtual void mousePressEvent (QMouseEvent *e)

virtual void mouseReleaseEvent (QMouseEvent *e)

virtual void mouseMoveEvent (QMouseEvent *e)

virtual void keyPressEvent (QKeyEvent *e)

virtual void wheelEvent (QWheelEvent *e)

virtual double getValue (const QPoint &p)=0

virtual void getScrollMode (const QPoint &p, int &scrollMode, int &direction)=0

void setMouseOffset (double)

double mouseOffset () const

int scrollMode () const

Detailed Description

An abstract base class for slider widgets.

QwtAbstractSlider is a base class for slider widgets. It handles mouse events and updates the slider's value accordingly. Derived classes only have to implement the getValue() and getScrollMode() members, and should react to a valueChange(), which normally requires repainting.

Member Enumeration Documentation

enum QwtAbstractSlider::ScrollMode

Scroll mode

See also:

: getScrollMode()

Constructor & Destructor Documentation

QwtAbstractSlider::QwtAbstractSlider (Qt::Orientation orientation, QWidget * parent = NULL) [explicit]

Constructor.

Parameters:

: orientation Orientation
parent Parent widget

QwtAbstractSlider::~QwtAbstractSlider () [virtual]

Destructor.

Member Function Documentation

void QwtAbstractSlider::fitValue (double value) [virtual, slot]

Set the slider's value to the nearest integer multiple of the step size.

Parameters:

: value Value

See also:

: setValue(), incValue()

Reimplemented from QwtDoubleRange.

virtual void QwtAbstractSlider::getScrollMode (const QPoint & p, int & scrollMode, int & direction) [protected, pure virtual]

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

This function is abstract and has to be implemented by derived classes. It is called on a mousePress event. The derived class can determine what should happen next in dependence of the position where the mouse was pressed by returning scrolling mode and direction. QwtAbstractSlider knows the following modes:

QwtAbstractSlider::ScrNone: Scrolling switched off. Don't change the value.
QwtAbstractSlider::ScrMouse: Change the value while the user keeps the button pressed and moves the mouse.
QwtAbstractSlider::ScrTimer: Automatic scrolling. Increment the value in the specified direction as long as the user keeps the button pressed.
QwtAbstractSlider::ScrPage: Automatic scrolling. Same as ScrTimer, but increment by page size.

Parameters:

: p point where the mouse was pressed

Return values:

: scrollMode The scrolling mode
direction direction: 1, 0, or -1.

Implemented in QwtDial, QwtSlider, and QwtWheel.

virtual double QwtAbstractSlider::getValue (const QPoint & p) [protected, pure virtual]

Determine the value corresponding to a specified poind.

This is an abstract virtual function which is called when the user presses or releases a mouse button or moves the mouse. It has to be implemented by the derived class.

Parameters:

: p point

Implemented in QwtDial, QwtSlider, and QwtWheel.

void QwtAbstractSlider::incValue (int steps) [virtual, slot]

Increment the value by a specified number of steps.

Parameters:

: steps number of steps

See also:

: setValue()

Reimplemented from QwtDoubleRange.

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()

bool QwtAbstractSlider::isValid () const [inline]

See also:

: QwtDblRange::isValid()

Reimplemented from QwtDoubleRange.

void QwtAbstractSlider::keyPressEvent (QKeyEvent * e) [protected, virtual]

Handles key events

•: Key_Down, KeyLeft

Decrement by 1
•: Key_Up, Key_Right

Increment by 1

Parameters:

: e Key event

See also:

: isReadOnly()

Reimplemented in QwtCompass, and QwtDial.

double QwtAbstractSlider::mass () const [virtual]

Returns:

: mass

See also:

: setMass()

Reimplemented in QwtWheel.

void QwtAbstractSlider::mouseMoveEvent (QMouseEvent * e) [protected, virtual]

Mouse Move Event handler

Parameters:

: e Mouse event

void QwtAbstractSlider::mousePressEvent (QMouseEvent * e) [protected, virtual]

Mouse press event handler

Parameters:

: e Mouse event

void QwtAbstractSlider::mouseReleaseEvent (QMouseEvent * e) [protected, virtual]

Mouse Release Event handler

Parameters:

: e Mouse event

Qt::Orientation QwtAbstractSlider::orientation () const

Returns:

: Orientation

See also:

: setOrientation()

void QwtAbstractSlider::setMass (double val) [virtual]

Set the slider's mass for flywheel effect.

If the slider's mass is greater then 0, it will continue to move after the mouse button has been released. Its speed decreases with time at a rate depending on the slider's mass. A large mass means that it will continue to move for a long time.

Derived widgets may overload this function to make it public.

Parameters:

: val New mass in kg

See also:

: mass()

Reimplemented in QwtWheel.

void QwtAbstractSlider::setOrientation (Qt::Orientation o) [virtual]

Set the orientation.

Parameters:

: o Orientation. Allowed values are Qt::Horizontal and Qt::Vertical.

Reimplemented in QwtSlider, and QwtWheel.

void QwtAbstractSlider::setPosition (const QPoint & p) [protected, virtual]

Move the slider to a specified point, adjust the value and emit signals if necessary.

void QwtAbstractSlider::setReadOnly (bool readOnly) [virtual, slot]

En/Disable read only mode

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

Parameters:

: readOnly Enables in case of true

See also:

: isReadOnly()

void QwtAbstractSlider::setTracking (bool enable)

Enables or disables tracking.

If tracking is enabled, the slider emits a valueChanged() signal whenever its value changes (the default behaviour). If tracking is disabled, the value changed() signal will only be emitted if:

•: the user releases the mouse button and the value has changed or
•: at the end of automatic scrolling.

Tracking is enabled by default.

Parameters:

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

void QwtAbstractSlider::setUpdateTime (int t)

Specify the update interval for automatic scrolling.

Parameters:

: t update interval in milliseconds

See also:

: getScrollMode()

void QwtAbstractSlider::setValid (bool valid) [inline]

Parameters:

: valid true/false

See also:

: QwtDblRange::isValid()

Reimplemented from QwtDoubleRange.

void QwtAbstractSlider::setValue (double val) [virtual, slot]

Move the slider to a specified value.

This function can be used to move the slider to a value which is not an integer multiple of the step size.

Parameters:

: val new value

See also:

: fitValue()

Reimplemented from QwtDoubleRange.

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

This signal is emitted when the user moves the slider with the mouse.

Parameters:

: value new value

void QwtAbstractSlider::sliderPressed () [signal]

This signal is emitted when the user presses the movable part of the slider (start ScrMouse Mode).

void QwtAbstractSlider::sliderReleased () [signal]

This signal is emitted when the user releases the movable part of the slider.

void QwtAbstractSlider::stopMoving ()

Stop updating if automatic scrolling is active.

void QwtAbstractSlider::timerEvent (QTimerEvent * e) [protected, virtual]

Qt timer event

Parameters:

: e Timer event

void QwtAbstractSlider::valueChange () [protected, virtual]

Notify change of value

This function can be reimplemented by derived classes in order to keep track of changes, i.e. repaint the widget. The default implementation emits a valueChanged() signal if tracking is enabled.

Reimplemented from QwtDoubleRange.

Reimplemented in QwtDial, QwtSlider, and QwtWheel.