slider.lua

local core = require('gui.widgets.slide_core')

--------------------------------
-- Slider
--------------------------------

---@class widgets.Slider.attrs: widgets.Widget.attrs
---@field get_idx_fn? function
---@field on_change? fun(index: integer)
---@field is_single boolean


---@class widgets.Slider.attrs.partial: widgets.Slider.attrs

---@class widgets.Slider.initTable: widgets.Slider.attrs
---@field num_stops integer

---@class widgets.Slider: widgets.Widget, widgets.Slider.attrs
---@field super widgets.Widget
---@field ATTRS widgets.Slider.attrs|fun(attributes: widgets.Slider.attrs.partial)
---@overload fun(init_table: widgets.Slider.initTable): self
Slider = defclass(Slider, core)
Slider.ATTRS{
    get_idx_fn=DEFAULT_NIL,
    on_change=DEFAULT_NIL,
    num_stops=DEFAULT_NIL,
    is_single=true,
}

function Slider:get_width_per_idx()
    local min_value = (self.is_single) and 3 or 5  -- Single slider = 3, else 5
    return math.max(min_value, (self.frame_body.width-7) // (self.num_stops-1))
end

function Slider:onInput(keys)
    if not keys._MOUSE_L then return false end
    local x = self:getMousePos()
    if not x then return false end
    local left_idx, right_idx = self.get_idx_fn(), self.get_idx_fn()
    local width_per_idx = self:get_width_per_idx()
    local left_pos = width_per_idx*(left_idx-1)
    local right_pos = width_per_idx*(right_idx-1) + 4
    if x < left_pos then
        self.on_change(self:clamp_idx(self.get_idx_fn() - 1))
    elseif x < left_pos+3 then
        self.is_dragging_target = 'left'
        self.is_dragging_idx = x - left_pos
    elseif x < right_pos then
        self.is_dragging_target = 'both'
        self.is_dragging_idx = x - left_pos
    elseif x < right_pos+3 then
        self.is_dragging_target = 'right'
        self.is_dragging_idx = x - right_pos
    else
        self.on_change(self:clamp_idx(self.get_idx_fn() + 1))
    end
    return true
end

return Slider