mirror of
https://github.com/lvgl/lvgl.git
synced 2025-01-14 06:42:58 +08:00
78 lines
2.2 KiB
ReStructuredText
78 lines
2.2 KiB
ReStructuredText
Roller (lv_roller)
|
|
==================
|
|
|
|
Overview
|
|
********
|
|
|
|
Roller allows you to simply select one option from a list by scrolling.
|
|
|
|
Parts and Styles
|
|
****************
|
|
|
|
- :cpp:enumerator:`LV_PART_MAIN` The background of the roller uses all the typical
|
|
background properties and text style properties.
|
|
``style_text_line_space`` adjusts the space between the options. When
|
|
the Roller is scrolled and doesn't stop exactly on an option it will
|
|
scroll to the nearest valid option automatically in ``anim_time``
|
|
milliseconds as specified in the style.
|
|
- :cpp:enumerator:`LV_PART_SELECTED` The selected option in the middle. Besides the
|
|
typical background properties it uses the text style properties to
|
|
change the appearance of the text in the selected area.
|
|
|
|
Usage
|
|
*****
|
|
|
|
Set options
|
|
-----------
|
|
|
|
Options are passed to the Roller as a string with
|
|
:cpp:expr:`lv_roller_set_options(roller, options, LV_ROLLER_MODE_NORMAL)`.
|
|
The options should be separated by ``\n``. For example:
|
|
``"First\nSecond\nThird"``.
|
|
|
|
:cpp:enumerator:`LV_ROLLER_MODE_INFINITE` makes the roller circular.
|
|
|
|
You can select an option manually with
|
|
:cpp:expr:`lv_roller_set_selected(roller, id, LV_ANIM_ON)`,
|
|
where *id* is the index of an option.
|
|
|
|
Get selected option
|
|
-------------------
|
|
|
|
To get the *index* of the currently selected option use :cpp:expr:`lv_roller_get_selected(roller)`.
|
|
|
|
:cpp:expr:`lv_roller_get_selected_str(roller, buf, buf_size)` will copy the name of the selected option to ``buf``.
|
|
|
|
Visible rows
|
|
------------
|
|
|
|
The number of visible rows can be adjusted with :cpp:expr:`lv_roller_set_visible_row_count(roller, num)`.
|
|
|
|
This function calculates the height with the current style. If the font,
|
|
line space, border width, etc. of the roller changes this function needs
|
|
to be called again.
|
|
|
|
Events
|
|
******
|
|
|
|
- :cpp:enumerator:`LV_EVENT_VALUE_CHANGED` Sent when a new option is selected.
|
|
|
|
See the events of the `Base object </widgets/obj>`__ too.
|
|
|
|
Learn more about :ref:`events`.
|
|
|
|
Keys
|
|
****
|
|
|
|
- ``LV_KEY_RIGHT/DOWN`` Select the next option
|
|
- ``LV_KEY_LEFT/UP`` Select the previous option
|
|
- :cpp:enumerator:`LY_KEY_ENTER` Apply the selected option (Send :cpp:enumerator:`LV_EVENT_VALUE_CHANGED` event)
|
|
|
|
Example
|
|
*******
|
|
|
|
.. include:: ../examples/widgets/roller/index.rst
|
|
|
|
API
|
|
***
|