Contents

• Public Types
• Properties
• Public Functions
• Public Slots
• Signals
• Protected Types
• Protected Functions
• Reimplemented Protected Functions
• Detailed Description

Detailed Description

TheQAbstractSlider class provides an integer value within a range.

The class is designed as a common super class for widgets likeQScrollBar,QSlider andQDial.

Here are the main properties of the class:

1. value: The bounded integer thatQAbstractSlider maintains.
2. minimum: The lowest possible value.
3. maximum: The highest possible value.
4. singleStep: The smaller of two natural steps that an abstract sliders provides and typically corresponds to the user pressing an arrow key.
5. pageStep: The larger of two natural steps that an abstract slider provides and typically corresponds to the user pressing PageUp or PageDown.
6. tracking: Whether slider tracking is enabled.
7. sliderPosition: The current position of the slider. Iftracking is enabled (the default), this is identical tovalue.

Unity (1) may be viewed as a third step size.setValue() lets you set the current value to any integer in the allowed range, not justminimum() +n *singleStep() for integer values ofn. Some widgets may allow the user to set any value at all; others may just provide multiples ofsingleStep() orpageStep().

QAbstractSlider emits a comprehensive set of signals:

QAbstractSlider provides a virtualsliderChange() function that is well suited for updating the on-screen representation of sliders. By callingtriggerAction(), subclasses trigger slider actions. Two helper functionsQStyle::sliderPositionFromValue() andQStyle::sliderValueFromPosition() help subclasses and styles to map screen coordinates to logical range values.

Member Type Documentation

enum QAbstractSlider::SliderAction

enum QAbstractSlider::SliderChange

Property Documentation

invertedAppearance :bool

This property holds whether or not a slider shows its values inverted.

If this property is false (the default), the minimum and maximum will be shown in its classic position for the inherited widget. If the value is true, the minimum and maximum appear at their opposite location.

Note: This property makes most sense for sliders and dials. For scroll bars, the visual effect of the scroll bar subcontrols depends on whether or not the styles understand inverted appearance; most styles ignore this property for scroll bars.

Access functions:

invertedControls :bool

This property holds whether or not the slider inverts its wheel and key events.

If this property is false, scrolling the mouse wheel "up" and using keys like page up will increase the slider's value towards its maximum. Otherwise pressing page up will move value towards the slider's minimum.

Access functions:

maximum :int

This property holds the slider's maximum value.

When setting this property, theminimum is adjusted if necessary to ensure that the range remains valid. Also the slider's current value is adjusted to be within the new range.

Access functions:

minimum :int

This property holds the sliders's minimum value.

When setting this property, themaximum is adjusted if necessary to ensure that the range remains valid. Also the slider's current value is adjusted to be within the new range.

Access functions:

orientation :Qt::Orientation

This property holds the orientation of the slider.

The orientation must beQt::Vertical (the default) orQt::Horizontal.

Access functions:

pageStep :int

This property holds the page step.

The larger of two natural steps that an abstract slider provides and typically corresponds to the user pressing PageUp or PageDown.

Access functions:

See alsosingleStep.

singleStep :int

This property holds the single step.

The smaller of two natural steps that an abstract sliders provides and typically corresponds to the user pressing an arrow key.

If the property is modified during an auto repeating key event, behavior is undefined.

Access functions:

See alsopageStep.

sliderDown :bool

This property holds whether the slider is pressed down.

The property is set by subclasses in order to let the abstract slider know whether or nottracking has any effect.

Changing the slider down property emits thesliderPressed() andsliderReleased() signals.

Access functions:

sliderPosition :int

This property holds the current slider position.

Iftracking is enabled (the default), this is identical tovalue.

Access functions:

Notifier signal:

tracking :bool

This property holds whether slider tracking is enabled.

If tracking is enabled (the default), the slider emits thevalueChanged() signal while the slider is being dragged. If tracking is disabled, the slider emits thevalueChanged() signal only when the user releases the slider.

Access functions:

See alsosliderDown.

value :int

This property holds the slider's current value.

The slider forces the value to be within the legal range:minimum <=value <=maximum.

Changing the value also changes thesliderPosition.

Access functions:

Notifier signal:

Member Function Documentation

QAbstractSlider::QAbstractSlider(QWidget * parent = 0)

Constructs an abstract slider.

Theparent argument is sent to theQWidget constructor.

Theminimum defaults to 0, themaximum to 99, with asingleStep size of 1 and apageStep size of 10, and an initialvalue of 0.

QAbstractSlider::~QAbstractSlider()

Destroys the slider.

[signal]void QAbstractSlider::actionTriggered(int action)

This signal is emitted when the slider actionaction is triggered. Actions areSliderSingleStepAdd,SliderSingleStepSub,SliderPageStepAdd,SliderPageStepSub,SliderToMinimum,SliderToMaximum, andSliderMove.

When the signal is emitted, thesliderPosition has been adjusted according to the action, but thevalue has not yet been propagated (meaning thevalueChanged() signal was not yet emitted), and the visual display has not been updated. In slots connected to this signal you can thus safely adjust any action by callingsetSliderPosition() yourself, based on both the action and the slider's value.

See alsotriggerAction().

[virtual protected]void QAbstractSlider::changeEvent(QEvent * ev)

Reimplemented fromQWidget::changeEvent().

[virtual protected]bool QAbstractSlider::event(QEvent * e)

Reimplemented fromQObject::event().

[virtual protected]void QAbstractSlider::keyPressEvent(QKeyEvent * ev)

Reimplemented fromQWidget::keyPressEvent().

[signal]void QAbstractSlider::rangeChanged(int min,int max)

This signal is emitted when the slider range has changed, withmin being the new minimum, andmax being the new maximum.

See alsominimum andmaximum.

[protected]SliderAction QAbstractSlider::repeatAction() const

Returns the current repeat action.

See alsosetRepeatAction().

void QAbstractSlider::setRange(int min,int max)

Sets the slider's minimum tomin and its maximum tomax.

Ifmax is smaller thanmin,min becomes the only legal value.

See alsominimum andmaximum.

[protected]void QAbstractSlider::setRepeatAction(SliderAction action,int thresholdTime = 500,int repeatTime = 50)

Sets actionaction to be triggered repetitively in intervals ofrepeatTime, after an initial delay ofthresholdTime.

See alsotriggerAction() andrepeatAction().

[virtual protected]void QAbstractSlider::sliderChange(SliderChange change)

Reimplement this virtual function to track slider changes such asSliderRangeChange,SliderOrientationChange,SliderStepsChange, orSliderValueChange. The default implementation only updates the display and ignores thechange parameter.

[signal]void QAbstractSlider::sliderPressed()

This signal is emitted when the user presses the slider with the mouse, or programmatically whensetSliderDown(true) is called.

See alsosliderReleased(),sliderMoved(), andisSliderDown().

[signal]void QAbstractSlider::sliderReleased()

This signal is emitted when the user releases the slider with the mouse, or programmatically whensetSliderDown(false) is called.

See alsosliderPressed(),sliderMoved(), andsliderDown.

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

Reimplemented fromQObject::timerEvent().

void QAbstractSlider::triggerAction(SliderAction action)

Triggers a slideraction. Possible actions areSliderSingleStepAdd,SliderSingleStepSub,SliderPageStepAdd,SliderPageStepSub,SliderToMinimum,SliderToMaximum, andSliderMove.

See alsoactionTriggered().

[virtual protected]void QAbstractSlider::wheelEvent(QWheelEvent * e)

Reimplemented fromQWidget::wheelEvent().