acid-drop

- Hacking the planet from a LilyGo T-Deck using custom firmware
git clone git://git.acid.vegas/acid-drop.git
slider.md (3467B)
      1 ```eval_rst
      2 .. include:: /header.rst
      3 :github_url: |github_link_base|/widgets/core/slider.md
      4 ```
      5 # Slider (lv_slider)
      6 
      7 ## Overview
      8 
      9 The Slider object looks like a [Bar](/widgets/core/bar) supplemented with a knob. The knob can be dragged to set a value. Just like Bar, Slider can be vertical or horizontal.
     10 
     11 
     12 ## Parts and Styles
     13 - `LV_PART_MAIN` The background of the slider. Uses all the typical background style properties. `padding` makes the indicator smaller in the respective direction.
     14 - `LV_PART_INDICATOR` The indicator that shows the current state of the slider. Also uses all the typical background style properties.
     15 - `LV_PART_KNOB` A rectangle (or circle) drawn at the current value. Also uses all the typical background properties to describe the knob(s). By default, the knob is square (with an optional corner radius) with side length equal to the smaller side of the slider. The knob can be made larger with the `padding` values. Padding values can be asymmetric too.
     16 
     17 ## Usage
     18 
     19 ### Value and range
     20 To set an initial value use `lv_slider_set_value(slider, new_value, LV_ANIM_ON/OFF)`.  The animation time is set by the styles' `anim_time` property.
     21 
     22 To specify the range (min, max values), `lv_slider_set_range(slider, min , max)` can be used.
     23 
     24 ### Modes
     25 The slider can be one of the following modes:
     26 - `LV_SLIDER_MODE_NORMAL` A normal slider as described above
     27 - `LV_SLIDER_SYMMETRICAL` Draw the indicator form the zero value to current value. Requires negative minimum range and positive maximum range.
     28 - `LV_SLIDER_RANGE` Allows setting the start value too by `lv_bar_set_start_value(bar, new_value, LV_ANIM_ON/OFF)`. The start value has to be always smaller than the end value.
     29 
     30 The mode can be changed with `lv_slider_set_mode(slider, LV_SLIDER_MODE_...)`
     31 
     32 ### Knob-only mode
     33 Normally, the slider can be adjusted either by dragging the knob, or by clicking on the slider bar.
     34 In the latter case the knob moves to the point clicked and 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 `LV_OBJ_FLAG_ADV_HITTEST`: `lv_obj_add_flag(slider, LV_OBJ_FLAG_ADV_HITTEST)`.
     35 
     36 The extended click area (set by `lv_obj_set_ext_click_area(slider, value)`) increases to knob's click area.
     37 
     38 ## Events
     39 - `LV_EVENT_VALUE_CHANGED` Sent while the slider is being dragged or changed with keys.
     40 The event is sent continuously while the slider is dragged and once when released. Use `lv_slider_is_dragged` to determine whether the Slider is still being dragged or has just been released.
     41 - `LV_EVENT_DRAW_PART_BEGIN` and `LV_EVENT_DRAW_PART_END` are sent for the following parts.
     42     - `LV_SLIDER_DRAW_PART_KNOB` The main (right) knob of the slider
     43         - `part`: `LV_PART_KNOB`
     44         - `draw_area`: area of the indicator
     45         - `rect_dsc`
     46         - `id`: 0
     47     - `LV_SLIDER_DRAW_PART_KNOB`  The left knob of the slider
     48         - `part`: `LV_PART_KNOB`
     49         - `draw_area`: area of the indicator
     50         - `rect_dsc`
     51         - `id`: 1
     52 
     53 See the events of the [Bar](/widgets/core/bar) too.
     54 
     55 Learn more about [Events](/overview/event).
     56 
     57 ## Keys
     58 - `LV_KEY_UP/RIGHT` Increment the slider's value by 1
     59 - `LV_KEY_DOWN/LEFT` Decrement the slider's value by 1
     60 
     61 Learn more about [Keys](/overview/indev).
     62 
     63 ## Example
     64 
     65 ```eval_rst
     66 
     67 .. include:: ../../../examples/widgets/slider/index.rst
     68 
     69 ```
     70 
     71 ## API
     72 
     73 ```eval_rst
     74 
     75 .. doxygenfile:: lv_slider.h
     76   :project: lvgl
     77 
     78 ```