renamed Slider to RangeSlider, and added draft of Lua API.rst entry

docs/changelog.txt

@@ -49,7 +49,7 @@ changelog.txt uses a syntax similar to RST, with a few special sequences:
 ## API
 
 ## Lua
-- ``widgets``: "Slider" class has been moved from ``filterselection.lua`` into ``widgets.lua``
+- ``widgets``: "Slider" class has been moved from ``filterselection.lua`` into ``widgets.lua`` and renamed to "RangeSlider"
 
 ## Removed
 

docs/dev/Lua API.rst

@@ -5130,6 +5130,17 @@ widget does not require direct usage of ``Tab``.
            usage of ``Tab`` in ``TabBar:init()`` for an example. See the default value of ``active_tab_pens`` or ``inactive_tab_pens``
            in ``TabBar`` for an example of how to construct pens.
 
+RangeSlider class
+-----------------
+
+This widget implements a mouse-interactable range-slider. The user can move its two handles to set minimum and maximum values to define a range.
+
+:num_stops: Specifies the amount of "notches" in the range slider, the places where handles can stop.
+:get_left_idx_fn: The function used by the RangeSlider to determine what value to display on its left handle.
+:get_right_idx_fn: The function used by the RangeSlider to determine what value to display on its right handle.
+:on_left_change: Callback executed when a handle is moved leftwards.
+:on_right_change: Callback executed when a handle is moved rightwards.
+
 .. _lua-plugins:
 
 =======

library/lua/gui/widgets.lua

@@ -2294,11 +2294,11 @@ function TabBar:onInput(keys)
 end
 
 --------------------------------
--- Slider
+-- RangeSlider
 --
 
-Slider = defclass(Slider, Widget)
-Slider.ATTRS{
+RangeSlider = defclass(RangeSlider, Widget)
+RangeSlider.ATTRS{
     num_stops=DEFAULT_NIL,
     get_left_idx_fn=DEFAULT_NIL,
     get_right_idx_fn=DEFAULT_NIL,
@@ -2306,27 +2306,27 @@ Slider.ATTRS{
     on_right_change=DEFAULT_NIL,
 }
 
-function Slider:preinit(init_table)
+function RangeSlider:preinit(init_table)
     init_table.frame = init_table.frame or {}
     init_table.frame.h = init_table.frame.h or 1
 end
 
-function Slider:init()
-    if self.num_stops < 2 then error('too few Slider stops') end
+function RangeSlider:init()
+    if self.num_stops < 2 then error('too few RangeSlider stops') end
     self.is_dragging_target = nil -- 'left', 'right', or 'both'
     self.is_dragging_idx = nil -- offset from leftmost dragged tile
 end
 
-local function slider_get_width_per_idx(self)
+local function rangeslider_get_width_per_idx(self)
     return math.max(5, (self.frame_body.width-7) // (self.num_stops-1))
 end
 
-function Slider:onInput(keys)
+function RangeSlider:onInput(keys)
     if not keys._MOUSE_L_DOWN then return false end
     local x = self:getMousePos()
     if not x then return false end
     local left_idx, right_idx = self.get_left_idx_fn(), self.get_right_idx_fn()
-    local width_per_idx = slider_get_width_per_idx(self)
+    local width_per_idx = rangeslider_get_width_per_idx(self)
     local left_pos = width_per_idx*(left_idx-1)
     local right_pos = width_per_idx*(right_idx-1) + 4
     if x < left_pos then
@@ -2346,7 +2346,7 @@ function Slider:onInput(keys)
     return true
 end
 
-local function slider_do_drag(self, width_per_idx)
+local function rangeslider_do_drag(self, width_per_idx)
     local x = self.frame_body:localXY(dfhack.screen.getMousePos())
     local cur_pos = x - self.is_dragging_idx
     cur_pos = math.max(0, cur_pos)
@@ -2383,9 +2383,9 @@ local SLIDER_TAB_LEFT = to_pen{ch=60, fg=COLOR_BLACK, bg=COLOR_YELLOW}
 local SLIDER_TAB_CENTER = to_pen{ch=9, fg=COLOR_BLACK, bg=COLOR_YELLOW}
 local SLIDER_TAB_RIGHT = to_pen{ch=62, fg=COLOR_BLACK, bg=COLOR_YELLOW}
 
-function Slider:onRenderBody(dc, rect)
+function RangeSlider:onRenderBody(dc, rect)
     local left_idx, right_idx = self.get_left_idx_fn(), self.get_right_idx_fn()
-    local width_per_idx = slider_get_width_per_idx(self)
+    local width_per_idx = rangeslider_get_width_per_idx(self)
     -- draw track
     dc:seek(1,0)
     dc:char(nil, SLIDER_LEFT_END)
@@ -2422,7 +2422,7 @@ function Slider:onRenderBody(dc, rect)
     dc:char(nil, SLIDER_TAB_RIGHT)
     -- manage dragging
     if self.is_dragging_target then
-        slider_do_drag(self, width_per_idx)
+        rangeslider_do_drag(self, width_per_idx)
     end
     if df.global.enabler.mouse_lbut == 0 then
         self.is_dragging_target = nil

plugins/lua/buildingplan/filterselection.lua

@@ -191,7 +191,7 @@ function QualityAndMaterialsPage:init()
                     enabled=enable_item_quality,
                     on_change=function(val) self:set_max_quality(val+1) end,
                 },
-                widgets.Slider{
+                widgets.RangeSlider{
                     frame={l=0, t=6},
                     num_stops=7,
                     get_left_idx_fn=function()