Hezhou Air724UG LuatOS-Air LVGL API control-Slider

Slider

The slide bar looks somewhat similar to the progress bar, but the difference is that the slide bar can make numerical selections.

Sample code

-- 回调函数
slider_event_cb = function(obj, event)
    if event == lvgl.EVENT_VALUE_CHANGED then 
        local val = (lvgl.slider_get_value(obj) or "0").."%"
        lvgl.label_set_text(slider_label, val)
        lvgl.obj_align(slider_label, obj, lvgl.ALIGN_OUT_BOTTOM_MID, 0, 10)
    end
end

-- 创建滑动条
slider = lvgl.slider_create(lvgl.scr_act(), nil)
lvgl.obj_align(slider, nil, lvgl.ALIGN_CENTER, 0, 0)
lvgl.obj_set_event_cb(slider, slider_event_cb)

-- 创建标签
slider_label = lvgl.label_create(lvgl.scr_act(), nil)
lvgl.label_set_text(slider_label, "0%")
lvgl.obj_align(slider_label, slider, lvgl.ALIGN_OUT_BOTTOM_MID, 0, 10)

create

Sliders are  lvgl.slider_create created through functions.

slider = lvgl.slider_create(lvgl.scr_act(), nil)

After the slide bar is created, you can set the display position and operate it.

Set value

The use of sliders is still very similar to Bar. You can set the numerical value  lvgl.slider_set_valueand the display range.  lvgl.slider_set_range.

lvgl.slider_set_range(slider, 100, 200)
lvgl.slider_set_value(slider, 150, lvgl.ANIM_OFF)

type

The type of slider can be set. In addition to the ordinary single knob, you can also set two knobs, one for the starting position and one for the end position. The knobs in both positions can be slid. The slider type is  lvgl.slider_set_type set through a function. The types that can be selected are:

lvgl.SLIDER_TYPE_NORMAL -- 普通的默认类型
lvgl.SLIDER_TYPE_RANGE  -- 滑动条可以有两个旋钮

Let's take a look at the sliders of the two knobs.

lvgl.slider_set_type(slider, lvgl.SLIDER_TYPE_RANGE)

event

By setting a callback function for the slide bar, we can get the value set by the slide bar. The slide bar itself is an input control.

-- 回调函数
slider_event_cb = function(obj, event)
    if event == lvgl.EVENT_VALUE_CHANGED then 
        local val = (lvgl.slider_get_value(obj) or "0").."%"
        lvgl.label_set_text(slider_label, val)
        lvgl.obj_align(slider_label, obj, lvgl.ALIGN_OUT_BOTTOM_MID, 0, 10)
    end
end

-- 创建滑动条
slider = lvgl.slider_create(lvgl.scr_act())
lvgl.obj_align(slider, nil, lvgl.ALIGN_CENTER, 0, 0)
lvgl.obj_set_event_cb(slider, slider_event_cb)

-- 创建标签
slider_label = lvgl.label_create(lvgl.scr_act(), nil)
lvgl.label_set_text(slider_label, "0%")
lvgl.obj_align(slider_label, slider, lvgl.ALIGN_OUT_BOTTOM_MID, 0, 10)

Here, we set a callback function for the slider to listen for value change events. At the same time, we added a label to display the value of the slider. The display effect is as follows:

API

lvgl.slider_create

transfer	lvgl.slider_create(par, copy)
Function	Create a slider object
return	Pointer to the slider object
parameter
par	Pointer to the object that will be the parent of the new key object
copy	Pointer to the slider object from which the new object will be copied if not nil

lvgl.slider_set_value

transfer	lvgl.slider_set_value(slider, val, anim)
Function	Set the value of the slider
parameter
slider	Pointer to the slider object
val	The new value of the slider
anim	lvgl.ANIM_ON sets the value with animation. lvgl.ANIM_OFF changes value immediately

lvgl.slider_set_type

transfer	lvgl.slider_set_type(slider, type)
Function	Set the type of slider
parameter
slider	Pointer to the slider object
type	The type of slider is lvgl.SLIDER_TYPE_RANGE or lvgl.SLIDER_TYPE_NORMAL

lvgl.slider_set_range

transfer	lvgl.slider_set_range(slider, min, max)
Function	Set the minimum and maximum values ​​of the slider
parameter
slider	Pointer to the slider object
min	minimum value
max	maximum value

lvgl.slider_set_anim_time

transfer	lvgl.slider_set_anim_time(slider, anim_time)
Function	Set the animation time of the slider
parameter
slider	Pointer to the slider object
anim_time	Animation time in milliseconds.

lvgl.slider_get_value

transfer	lvgl.slider_get_value(slider)
Function	Get the setting value of the slider
return	Slider setting value
parameter
slider	Pointer to the slider object

lvgl.slider_get_left_value

transfer	lvgl.slider_get_left_value(slider)
Function	Get the left value of the slider
return	The left value of the slider
parameter
slider	Pointer to the slider object

lvgl.slider_get_min_value

transfer	lvgl.slider_get_min_value(slider)
Function	Get the minimum value of the slider
return	Minimum value of slider
parameter
slider	Pointer to the slider object

lvgl.slider_get_max_value

transfer	lvgl.slider_get_max_value(slider)
Function	Get the maximum value of the slider
return	The maximum value of the slider
parameter
slider	Pointer to the slider object

lvgl.slider_is_dragged

transfer	lvgl.slider_is_dragged(slider)
Function	Determine whether the Kuai has been dragged
return	true is being dragged, false is not being dragged
parameter
slider	Pointer to the slider object

lvgl.slider_get_anim_time

transfer	lvgl.slider_get_anim_time(slider, time)
Function	Get the animation time set by the slider
return	Slider animation time
parameter
slider	Pointer to the slider object