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# QAbstractSlider Class Reference
[com.trolltech.qt.gui module]

The `QAbstractSlider` class provides an integer value within a range. More...

Inherits `QWidget`.

Inherited by `QDial`, `QScrollBar`, and `QSlider`.

## Detailed Description

The `QAbstractSlider` class provides an integer value within a range.

The class is designed as a common super class for widgets like `QScrollBar`, `QSlider` and `QDial`.

Here are the main properties of the class:

1. value: The bounded integer that `QAbstractSlider` 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. If tracking is enabled (the default), this is identical to value.

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 just `minimum` + n * `singleStep` for integer values of n. Some widgets may allow the user to set any value at all; others may just provide multiples of `singleStep` or `pageStep`.

`QAbstractSlider` emits a comprehensive set of signals:

Signal | Emitted when
--- | ---
`valueChanged` | the value has changed. The tracking determines whether this signal is emitted during user interaction.
`sliderPressed` | the user starts to drag the slider.
`sliderMoved` | the user drags the slider.
`sliderReleased` | the user releases the slider.
`actionTriggered` | a slider action was triggerd.
`rangeChanged` | a the range has changed.

`QAbstractSlider` provides a virtual `sliderChange` function that is well suited for updating the on-screen representation of sliders. By calling `triggerAction`, subclasses trigger slider actions. Two helper functions QStyle::sliderPositionFromValue() and QStyle::sliderValueFromPosition() help subclasses and styles to map screen coordinates to logical range values.

See also `QAbstractSpinBox`, `QSlider`, `QDial`, `QScrollBar`, and Sliders Example.