docs/src/widgets/slider.rst
.. _lv_slider:
Overview
The Slider Widget looks like a :ref:lv_bar supplemented with
a knob. The knob can be dragged to set the Slider's value. Like Bar, a Slider
can be vertical or horizontal.
.. _lv_slider_parts_and_styles:
Parts and Styles
LV_PART_MAIN The background of the Slider. Uses the
:ref:typical background style properties <typical bg props>. padding makes
the indicator smaller in the respective direction.LV_PART_INDICATOR The indicator that shows the current state of
the Slider; also uses the :ref:typical background style properties <typical bg props>.LV_PART_KNOB A rectangle (or circle) drawn at the current value;
also uses the :ref:typical background style properties <typical bg props> to
describe the knob(s). By default, the knob is round (radius-style can modify this)
with side length equal to the smaller dimension of the Slider. The knob can be
made larger with the padding values. Padding values can be asymmetric as well... _lv_slider_usage:
Usage
Once a Slider is created, it has:
LV_DPI_DEF),LV_DPI_DEF).To set different values use:
:cpp:expr:lv_slider_set_value(slider, new_value, LV_ANIM_ON/OFF) (animation time
is set by the styles' anim_time property);
:cpp:expr:lv_slider_set_range(slider, min , max); and
for orientation, width and height, simply set width and height properties;
:cpp:expr:lv_slider_set_orientation(slider, orientation) to override orientation
caused by width and height. Valid values for orientation are:
LV_SLIDER_ORIENTATION_AUTOLV_SLIDER_ORIENTATION_HORIZONTALLV_SLIDER_ORIENTATION_VERTICALThe default drawing direction is from left to right in horizontal orientation and bottom to top in vertical orientation. If the minimum value is set to be greater than the maximum value (e.g. [100..0]), the drawing direction is reversed.
The Slider can be in one of the following modes:
LV_SLIDER_MODE_NORMAL A normal Slider as described above (default)LV_SLIDER_SYMMETRICAL Draw the indicator from the zero value to
current value. Requires negative minimum range and positive maximum range.LV_SLIDER_RANGE Allows setting the start value as well by
:cpp:expr:lv_bar_set_start_value(slider, new_value, LV_ANIM_ON/OFF). The start
value must always be smaller than the end value.The mode can be changed with :cpp:expr:lv_slider_set_mode(slider, LV_SLIDER_MODE_...)
Normally, the Slider can be adjusted either by dragging the knob, or by
clicking on the Slider bar. In the latter case the knob moves to the
point clicked and the Slider value changes accordingly. In some cases it is
desirable to set the Slider to react on dragging the knob only. This
feature is enabled by adding the :cpp:enumerator:LV_OBJ_FLAG_ADV_HITTEST flag:
:cpp:expr:lv_obj_add_flag(slider, LV_OBJ_FLAG_ADV_HITTEST).
Any extended click area (set by :cpp:expr:lv_obj_set_ext_click_area(slider, value))
increases the knob's click area.
To get familiar with observers, subjects, and data bindings in general, visit the
:ref:Observer <observer_how_to_use> page.
This method of subscribing to an integer Subject affects a Slider Widget's integer value directly. Note that this is a two-way binding (Subject <===> Widget), so an end user's direct interaction with the Slider Widget updates the Subject's value and vice versa.
It supports integer and float subjects.
lv_slider_bind_value(slider, &subject).. _lv_slider_events:
Events
LV_EVENT_VALUE_CHANGED Sent while the Slider is being dragged or
changed with keys. The event is sent continuously while the Slider is
being dragged.LV_EVENT_RELEASED Sent once when Slider is released... admonition:: Further Reading
:ref:`Bar Events <lv_bar_events>`.
Learn more about :ref:`lv_obj_events` emitted by all Widgets.
Learn more about :ref:`events`.
.. _lv_slider_keys:
Keys
LV_KEY_UP/RIGHT Increment Slider's value by 1.LV_KEY_DOWN/LEFT Decrement Slider's value by 1... admonition:: Further Reading
Learn more about :ref:`indev_keys`.
.. _lv_slider_example:
Examples
.. include:: /examples/widgets/slider/index.rst
.. _lv_slider_api:
API