Qwt User's Guide 5.2.2

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Public Types | Public Slots | Signals | Public Member Functions | Protected Member Functions

# QwtSlider Class Reference

The Slider Widget. More...

`#include <qwt_slider.h>`

Inheritance diagram for QwtSlider:
[legend]

List of all members.

## Public Types
enum | BGSTYLE { BgTrough = 0x1, BgSlot = 0x2, BgBoth = BgTrough | BgSlot }
enum | ScalePos { NoScale, LeftScale, RightScale, TopScale, BottomScale }
enum | ScrollMode { ScrNone, ScrMouse, ScrTimer, ScrDirect, ScrPage }
## Public Slots
virtual void | fitValue (double val)
virtual void | incValue (int steps)
virtual void | setReadOnly (bool)
virtual void | setValue (double val)
## Signals
void | sliderMoved (double value)
void | sliderPressed ()
void | sliderReleased ()
void | valueChanged (double value)
## Public Member Functions
bool | autoScale () const
BGSTYLE | bgStyle () const
int | borderWidth () const
virtual void | incPages (int)
bool | isReadOnly () const
bool | isValid () const
virtual double | mass () const
double | maxValue () const
virtual QSize | minimumSizeHint () const
double | minValue () const
Qt::Orientation | orientation () const
int | pageSize () const
bool | periodic () const
| QwtSlider (QWidget *parent, Qt::Orientation=Qt::Horizontal, ScalePos=NoScale, BGSTYLE bgStyle=BgTrough)
const QwtScaleDraw * | scaleDraw () const
const QwtScaleEngine * | scaleEngine () const
QwtScaleEngine * | scaleEngine ()
const QwtScaleMap & | scaleMap () const
int | scaleMaxMajor () const
int | scaleMaxMinor () const
ScalePos | scalePosition () const
void | setAutoScale ()
void | setBgStyle (BGSTYLE)
void | setBorderWidth (int bw)
void | setMargins (int x, int y)
virtual void | setMass (double val)
virtual void | setOrientation (Qt::Orientation)
void | setPeriodic (bool tf)
void | setRange (double vmin, double vmax, double vstep=0.0, int pagesize=1)
void | setScale (double vmin, double vmax, double step=0.0)
void | setScale (const QwtScaleDiv &s)
void | setScale (const QwtDoubleInterval &, double step=0.0)
void | setScaleDraw (QwtScaleDraw *)
void | setScaleEngine (QwtScaleEngine *)
void | setScaleMaxMajor (int ticks)
void | setScaleMaxMinor (int ticks)
void | setScalePosition (ScalePos s)
void | setStep (double)
void | setThumbLength (int l)
void | setThumbWidth (int w)
void | setTracking (bool enable)
void | setUpdateTime (int t)
void | setValid (bool valid)
virtual QSize | sizeHint () const
double | step () const
void | stopMoving ()
int | thumbLength () const
int | thumbWidth () const
double | value () const
## Protected Member Functions
const QwtAbstractScaleDraw * | abstractScaleDraw () const
QwtAbstractScaleDraw * | abstractScaleDraw ()
void | draw (QPainter *p, const QRect &update_rect)
virtual void | drawSlider (QPainter *p, const QRect &r)
virtual void | drawThumb (QPainter *p, const QRect &, int pos)
double | exactPrevValue () const
double | exactValue () const
virtual void | fontChange (const QFont &oldFont)
virtual void | getScrollMode (const QPoint &p, int &scrollMode, int &direction)
virtual double | getValue (const QPoint &p)
virtual void | keyPressEvent (QKeyEvent *e)
void | layoutSlider (bool update=true)
virtual void | mouseMoveEvent (QMouseEvent *e)
double | mouseOffset () const
virtual void | mousePressEvent (QMouseEvent *e)
virtual void | mouseReleaseEvent (QMouseEvent *e)
virtual void | paintEvent (QPaintEvent *e)
double | prevValue () const
virtual void | rangeChange ()
void | rescale (double vmin, double vmax, double step=0.0)
virtual void | resizeEvent (QResizeEvent *e)
virtual void | scaleChange ()
QwtScaleDraw * | scaleDraw ()
int | scrollMode () const
void | setAbstractScaleDraw (QwtAbstractScaleDraw *)
void | setMouseOffset (double)
virtual void | setPosition (const QPoint &)
virtual void | stepChange ()
virtual void | timerEvent (QTimerEvent *e)
virtual void | valueChange ()
virtual void | wheelEvent (QWheelEvent *e)
int | xyPosition (double v) const

## Detailed Description

The Slider Widget.

QwtSlider is a slider widget which operates on an interval of type double. QwtSlider supports different layouts as well as a scale.

See also:
  QwtAbstractSlider and QwtAbstractScale for the descriptions of the inherited members.

## Member Enumeration Documentation

enum QwtSlider::BGSTYLE

Background style.

See also:
  QwtSlider()

enum QwtSlider::ScalePos

Scale position. QwtSlider tries to enforce valid combinations of its orientation and scale position:

- Qt::Horizonal combines with NoScale, TopScale and BottomScale
- Qt::Vertical combines with NoScale, LeftScale and RightScale

See also:
  QwtSlider()

enum QwtAbstractSlider::ScrollMode`[inherited]`

Scroll mode

See also:
  getScrollMode()

## Constructor & Destructor Documentation

QwtSlider::QwtSlider | ( | QWidget * | parent,
|  | Qt::Orientation | orientation = `Qt::Horizontal`,
|  | ScalePos | scalePos = `NoScale`,
|  | BGSTYLE | bgStyle = `BgTrough`
| ) |  | `[explicit]`

Constructor.

Parameters:

  parent | parent widget
  orientation | Orientation of the slider. Can be Qt::Horizontal or Qt::Vertical. Defaults to Qt::Horizontal.
  scalePos | Position of the scale. Defaults to QwtSlider::NoScale.
  bgStyle | Background style. QwtSlider::BgTrough draws the slider button in a trough, QwtSlider::BgSlot draws a slot underneath the button. An or-combination of both may also be used. The default is QwtSlider::BgTrough.

QwtSlider enforces valid combinations of its orientation and scale position. If the combination is invalid, the scale position will be set to NoScale. Valid combinations are:

- Qt::Horizonal with NoScale, TopScale, or BottomScale;
- Qt::Vertical with NoScale, LeftScale, or RightScale.

## Member Function Documentation

const QwtAbstractScaleDraw * QwtAbstractScale::abstractScaleDraw | ( |  | ) | const`[protected, inherited]`

Returns:
  Scale draw

See also:
  setAbstractScaleDraw()

QwtAbstractScaleDraw * QwtAbstractScale::abstractScaleDraw | ( |  | ) | `[protected, inherited]`

Returns:
  Scale draw

See also:
  setAbstractScaleDraw()

bool QwtAbstractScale::autoScale | ( |  | ) | const`[inherited]`

Returns:
  `true` if autoscaling is enabled

QwtSlider::BGSTYLE QwtSlider::bgStyle | ( |  | ) | const

Returns:
  the background style.

int QwtSlider::borderWidth | ( |  | ) | const

Returns:
  the border width.

void QwtSlider::draw | ( | QPainter * | p,
|  | const QRect & | update_rect
| ) |  | `[protected]`

Draw the QwtSlider.

void QwtSlider::drawSlider | ( | QPainter * | painter,
|  | const QRect & | r
| ) |  | `[protected, virtual]`

Draw the slider into the specified rectangle.

Parameters:

  painter | Painter
  r | Rectangle

void QwtSlider::drawThumb | ( | QPainter * | painter,
|  | const QRect & | sliderRect,
|  | int | pos
| ) |  | `[protected, virtual]`

Draw the thumb at a position

Parameters:

  painter | Painter
  sliderRect | Bounding rectangle of the slider
  pos | Position of the slider thumb

double QwtDoubleRange::exactPrevValue | ( |  | ) | const`[protected, inherited]`

Returns the exact previous value.

double QwtDoubleRange::exactValue | ( |  | ) | const`[protected, inherited]`

Returns the exact value.

The exact value is the value which QwtDoubleRange::value would return if the value were not adjusted to the step raster. It differs from the current value only if QwtDoubleRange::fitValue or QwtDoubleRange::incValue have been used before. This function is intended for internal use in derived classes.

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

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

Parameters:

  value | Value

See also:
  setValue(), incValue()

Reimplemented from QwtDoubleRange.

void QwtSlider::fontChange | ( | const QFont & | oldFont | ) | `[protected, virtual]`

Notify change in font.

void QwtSlider::getScrollMode | ( | const QPoint & | p,
|  | int & | scrollMode,
|  | int & | direction
| ) |  | `[protected, virtual]`

Determine scrolling mode and direction.

Parameters:

  p | point
  scrollMode | Scrolling mode
  direction | Direction

Implements QwtAbstractSlider.

double QwtSlider::getValue | ( | const QPoint & | pos | ) | `[protected, virtual]`

Determine the value corresponding to a specified mouse location.

Parameters:

  pos | Mouse position

Implements QwtAbstractSlider.

void QwtDoubleRange::incPages | ( | int | nPages | ) | `[virtual, inherited]`

Increment the value by a specified number of pages.

Parameters:

  nPages | Number of pages to increment. A negative number decrements the value.

Warning:
  The Page size is specified in the constructor.

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

Increment the value by a specified number of steps.

Parameters:

  steps | number of steps

See also:
  setValue()

Reimplemented from QwtDoubleRange.

bool QwtAbstractSlider::isReadOnly | ( |  | ) | const`[inherited]`

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, inherited]`

See also:
  QwtDblRange::isValid()

Reimplemented from QwtDoubleRange.

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

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.

void QwtSlider::layoutSlider | ( | bool | update_geometry = `true` | ) | `[protected]`

Recalculate the slider's geometry and layout based on the current rect and fonts.

Parameters:

  update_geometry | notify the layout system and call update to redraw the scale

double QwtAbstractSlider::mass | ( |  | ) | const`[virtual, inherited]`

Returns:
  mass

See also:
  setMass()

Reimplemented in QwtWheel.

double QwtDoubleRange::maxValue | ( |  | ) | const`[inherited]`

Returns the value of the second border of the range.

maxValue returns the value which has been specified as the second parameter in QwtDoubleRange::setRange.

See also:
  setRange()

QSize QwtSlider::minimumSizeHint | ( |  | ) | const`[virtual]`

Return a minimum size hint.

Warning:
  The return value of QwtSlider::minimumSizeHint() depends on the font and the scale.

double QwtDoubleRange::minValue | ( |  | ) | const`[inherited]`

Returns the value at the first border of the range.

minValue returns the value which has been specified as the first parameter in setRange().

See also:
  setRange()

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

Mouse Move Event handler

Parameters:

  e | Mouse event

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

Mouse press event handler

Parameters:

  e | Mouse event

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

Mouse Release Event handler

Parameters:

  e | Mouse event

Qt::Orientation QwtAbstractSlider::orientation | ( |  | ) | const`[inherited]`

Returns:
  Orientation

See also:
  setOrientation()

int QwtDoubleRange::pageSize | ( |  | ) | const`[inherited]`

Returns the page size in steps.

void QwtSlider::paintEvent | ( | QPaintEvent * | event | ) | `[protected, virtual]`

Qt paint event

Parameters:

  event | Paint event

bool QwtDoubleRange::periodic | ( |  | ) | const`[inherited]`

Returns true if the range is periodic.

See also:
  setPeriodic()

double QwtDoubleRange::prevValue | ( |  | ) | const`[protected, inherited]`

Returns the previous value.

void QwtSlider::rangeChange | ( |  | ) | `[protected, virtual]`

Notify change of range.

Reimplemented from QwtDoubleRange.

void QwtAbstractScale::rescale | ( | double | vmin,
|  | double | vmax,
|  | double | stepSize = `0.0`
| ) |  | `[protected, inherited]`

Recalculate the scale division and update the scale draw.

Parameters:

  vmin | Lower limit of the scale interval
  vmax | Upper limit of the scale interval
  stepSize | Major step size

See also:
  scaleChange()

void QwtSlider::resizeEvent | ( | QResizeEvent * | e | ) | `[protected, virtual]`

Qt resize event.

void QwtSlider::scaleChange | ( |  | ) | `[protected, virtual]`

Notify changed scale.

Reimplemented from QwtAbstractScale.

const QwtScaleDraw * QwtSlider::scaleDraw | ( |  | ) | const

Returns:
  the scale draw of the slider

See also:
  setScaleDraw()

QwtScaleDraw * QwtSlider::scaleDraw | ( |  | ) | `[protected]`

Returns:
  the scale draw of the slider

See also:
  setScaleDraw()

const QwtScaleEngine * QwtAbstractScale::scaleEngine | ( |  | ) | const`[inherited]`

Returns:
  Scale engine

See also:
  setScaleEngine()

QwtScaleEngine * QwtAbstractScale::scaleEngine | ( |  | ) | `[inherited]`

Returns:
  Scale engine

See also:
  setScaleEngine()

const QwtScaleMap & QwtAbstractScale::scaleMap | ( |  | ) | const`[inherited]`

Returns:
  abstractScaleDraw()->scaleMap()

int QwtAbstractScale::scaleMaxMajor | ( |  | ) | const`[inherited]`

Returns:
  Max. number of major tick intervals The default value is 5.

int QwtAbstractScale::scaleMaxMinor | ( |  | ) | const`[inherited]`

Returns:
  Max. number of minor tick intervals The default value is 3.

QwtSlider::ScalePos QwtSlider::scalePosition | ( |  | ) | const

Return the scale position.

void QwtAbstractScale::setAbstractScaleDraw | ( | QwtAbstractScaleDraw * | scaleDraw | ) | `[protected, inherited]`

Set a scale draw.

scaleDraw has to be created with new and will be deleted in ~QwtAbstractScale or the next call of setAbstractScaleDraw.

void QwtAbstractScale::setAutoScale | ( |  | ) | `[inherited]`

Advise the widget to control the scale range internally.

Autoscaling is on by default.

See also:
  setScale(), autoScale()

void QwtSlider::setBgStyle | ( | BGSTYLE | st | ) |

Set the background style.

void QwtSlider::setBorderWidth | ( | int | bd | ) |

Change the slider's border width.

Parameters:

  bd | border width

void QwtSlider::setMargins | ( | int | xMargin,
|  | int | yMargin
| ) |  |

Set distances between the widget's border and internals.

Parameters:

  xMargin | Horizontal margin
  yMargin | Vertical margin

void QwtAbstractSlider::setMass | ( | double | val | ) | `[virtual, inherited]`

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 QwtSlider::setOrientation | ( | Qt::Orientation | o | ) | `[virtual]`

Set the orientation.

Parameters:

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

If the new orientation and the old scale position are an invalid combination, the scale position will be set to QwtSlider::NoScale.

See also:
  QwtAbstractSlider::orientation()

Reimplemented from QwtAbstractSlider.

void QwtDoubleRange::setPeriodic | ( | bool | tf | ) | `[inherited]`

Make the range periodic.

When the range is periodic, the value will be set to a point inside the interval such that

    point = value + n * width

if the user tries to set a new value which is outside the range. If the range is nonperiodic (the default), values outside the range will be clipped.

Parameters:

  tf | true for a periodic range

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

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

void QwtDoubleRange::setRange | ( | double | vmin,
|  | double | vmax,
|  | double | vstep = `0.0`,
|  | int | pageSize = `1`
| ) |  | `[inherited]`

Specify range and step size.

Parameters:

  vmin | lower boundary of the interval
  vmax | higher boundary of the interval
  vstep | step width
  pageSize | page size in steps

Warning:
  - A change of the range changes the value if it lies outside the new range. The current value will *not* be adjusted to the new step raster.
  - vmax < vmin is allowed.
  - If the step size is left out or set to zero, it will be set to 1/100 of the interval length.
  - If the step size has an absurd value, it will be corrected to a better one.

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

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 QwtAbstractScale::setScale | ( | const QwtDoubleInterval & | interval,
|  | double | stepSize = `0.0`
| ) |  | `[inherited]`

Specify a scale.

Disable autoscaling and define a scale by an interval and a step size

Parameters:

  interval | Interval
  stepSize | major step size

See also:
  setAutoScale()

void QwtAbstractScale::setScale | ( | double | vmin,
|  | double | vmax,
|  | double | stepSize = `0.0`
| ) |  | `[inherited]`

Specify a scale.

Disable autoscaling and define a scale by an interval and a step size

Parameters:

  vmin | lower limit of the scale interval
  vmax | upper limit of the scale interval
  stepSize | major step size

See also:
  setAutoScale()

void QwtAbstractScale::setScale | ( | const QwtScaleDiv & | scaleDiv | ) | `[inherited]`

Specify a scale.

Disable autoscaling and define a scale by a scale division

Parameters:

  scaleDiv | Scale division

See also:
  setAutoScale()

void QwtSlider::setScaleDraw | ( | QwtScaleDraw * | scaleDraw | ) |

Set a scale draw.

For changing the labels of the scales, it is necessary to derive from QwtScaleDraw and overload QwtScaleDraw::label().

Parameters:

  scaleDraw | ScaleDraw object, that has to be created with new and will be deleted in ~QwtSlider or the next call of setScaleDraw().

void QwtAbstractScale::setScaleEngine | ( | QwtScaleEngine * | scaleEngine | ) | `[inherited]`

Set a scale engine.

The scale engine is responsible for calculating the scale division, and in case of auto scaling how to align the scale.

scaleEngine has to be created with new and will be deleted in ~QwtAbstractScale or the next call of setScaleEngine.

void QwtAbstractScale::setScaleMaxMajor | ( | int | ticks | ) | `[inherited]`

Set the maximum number of major tick intervals.

The scale's major ticks are calculated automatically such that the number of major intervals does not exceed ticks. The default value is 5.

Parameters:

  ticks | maximal number of major ticks.

See also:
  QwtAbstractScaleDraw

void QwtAbstractScale::setScaleMaxMinor | ( | int | ticks | ) | `[inherited]`

Set the maximum number of minor tick intervals.

The scale's minor ticks are calculated automatically such that the number of minor intervals does not exceed ticks. The default value is 3.

Parameters:

  ticks |

See also:
  QwtAbstractScaleDraw

void QwtSlider::setScalePosition | ( | ScalePos | s | ) |

Change the scale position (and slider orientation).

Parameters:

  s | Position of the scale.

A valid combination of scale position and orientation is enforced:

- if the new scale position is Left or Right, the scale orientation will become Qt::Vertical;
- if the new scale position is Bottom or Top the scale orientation will become Qt::Horizontal;
- if the new scale position is QwtSlider::NoScale, the scale orientation will not change.

void QwtDoubleRange::setStep | ( | double | vstep | ) | `[inherited]`

Change the step raster.

Parameters:

  vstep | new step width

Warning:
  The value will not be adjusted to the new step raster.

Reimplemented in QwtCounter.

void QwtSlider::setThumbLength | ( | int | thumbLength | ) |

Set the slider's thumb length.

Parameters:

  thumbLength | new length

void QwtSlider::setThumbWidth | ( | int | w | ) |

Change the width of the thumb.

Parameters:

  w | new width

void QwtAbstractSlider::setTracking | ( | bool | enable | ) | `[inherited]`

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 | ) | `[inherited]`

Specify the update interval for automatic scrolling.

Parameters:

  t | update interval in milliseconds

See also:
  getScrollMode()

void QwtAbstractSlider::setValid | ( | bool | valid | ) | `[inline, inherited]`

Parameters:

  valid | true/false

See also:
  QwtDblRange::isValid()

Reimplemented from QwtDoubleRange.

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

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.

QSize QwtSlider::sizeHint | ( |  | ) | const`[virtual]`

Returns:
  QwtSlider::minimumSizeHint()

void QwtAbstractSlider::sliderMoved | ( | double | value | ) | `[signal, inherited]`

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

Parameters:

  value | new value

void QwtAbstractSlider::sliderPressed | ( |  | ) | `[signal, inherited]`

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

void QwtAbstractSlider::sliderReleased | ( |  | ) | `[signal, inherited]`

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

double QwtDoubleRange::step | ( |  | ) | const`[inherited]`

Returns:
  the step size

See also:
  setStep(), setRange()

Reimplemented in QwtCounter.

void QwtDoubleRange::stepChange | ( |  | ) | `[protected, virtual, inherited]`

Notify a change of the step size.

This virtual function is called whenever the step size changes. The default implementation does nothing.

void QwtAbstractSlider::stopMoving | ( |  | ) | `[inherited]`

Stop updating if automatic scrolling is active.

int QwtSlider::thumbLength | ( |  | ) | const

Returns:
  the thumb length.

int QwtSlider::thumbWidth | ( |  | ) | const

Returns:
  the thumb width.

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

Qt timer event

Parameters:

  e | Timer event

double QwtDoubleRange::value | ( |  | ) | const`[inherited]`

Returns the current value.

Reimplemented in QwtCounter.

void QwtSlider::valueChange | ( |  | ) | `[protected, virtual]`

Notify change of value.

Reimplemented from QwtAbstractSlider.

void QwtAbstractSlider::valueChanged | ( | double | value | ) | `[signal, inherited]`

Notify a change of value.

In the default setting (tracking enabled), this signal will be emitted every time the value changes ( see setTracking() ).

Parameters:

  value | new value

void QwtAbstractSlider::wheelEvent | ( | QWheelEvent * | e | ) | `[protected, virtual, inherited]`

Wheel Event handler

Parameters:

  e | Whell event

int QwtSlider::xyPosition | ( | double | value | ) | const`[protected]`

Find the x/y position for a given value v

Parameters:

  value | Value