layout: Add separator widget support to 3 layouts

The ratio, fixed and flex layout can now display a widget between
each layout elements.

The align layout was left out because it doesn't support spacing

lib/wibox/layout/fixed.lua

@@ -23,10 +23,15 @@ local fixed = {}
 function fixed:layout(context, width, height)
     local result = {}
     local pos,spacing = 0, self._private.spacing
+    local spacing_widget = self._private.spacing_widget
+    local is_y = self._private.dir == "y"
+    local is_x = not is_y
+    local abspace = math.abs(spacing)
+    local spoffset = spacing < 0 and 0 or spacing
 
     for k, v in pairs(self._private.widgets) do
         local x, y, w, h, _
-        if self._private.dir == "y" then
+        if is_y then
             x, y = 0, pos
             w, h = width, height - pos
             if k ~= #self._private.widgets or not self._private.fill_space then
@@ -42,10 +47,18 @@ function fixed:layout(context, width, height)
             pos = pos + w + spacing
         end
 
-        if (self._private.dir == "y" and pos-spacing > height) or
-            (self._private.dir ~= "y" and pos-spacing > width) then
+        if (is_y and pos-spacing > height) or
+            (is_x and pos-spacing > width) then
             break
         end
+
+        -- Add the spacing widget
+        if k > 1 and abspace > 0 and spacing_widget then
+            table.insert(result, base.place_widget_at(
+                spacing_widget, is_x and (x - spoffset) or x, is_y and (y - spoffset) or y,
+                is_x and abspace or w, is_y and abspace or h
+            ))
+        end
         table.insert(result, base.place_widget_at(v, x, y, w, h))
     end
     return result
@@ -194,6 +207,20 @@ function fixed:set(index, widget2)
     return true
 end
 
+--- The widget used to fill the spacing between the layout elements.
+--
+-- By default, no widget is used.
+--
+--@DOC_wibox_layout_fixed_spacing_widget_EXAMPLE@
+--
+-- @property spacing_widget
+-- @param widget
+
+function fixed:set_spacing_widget(wdg)
+    self._private.spacing_widget = base.make_widget_from_value(wdg)
+    self:emit_signal("widget::layout_changed")
+end
+
 --- Insert a new widget in the layout at position `index`
 -- **Signal:** widget::inserted The arguments are the widget and the index
 -- @tparam number index The position
@@ -308,7 +335,10 @@ function fixed.vertical(...)
     return get_layout("y", ...)
 end
 
---- Add spacing between each layout widgets
+--- Add spacing between each layout widgets.
+--
+--@DOC_wibox_layout_fixed_spacing_EXAMPLE@
+--
 -- @property spacing
 -- @tparam number spacing Spacing between widgets.
 

lib/wibox/layout/flex.lua

@@ -50,14 +50,35 @@ local flex = {}
 -- @name insert
 -- @class function
 
+--- The widget used to fill the spacing between the layout elements.
+--
+-- By default, no widget is used.
+--
+--@DOC_wibox_layout_flex_spacing_widget_EXAMPLE@
+--
+-- @property spacing_widget
+-- @param widget
+
+--- Add spacing between each layout widgets.
+--
+--@DOC_wibox_layout_flex_spacing_EXAMPLE@
+--
+-- @property spacing
+-- @tparam number spacing Spacing between widgets.
+
 function flex:layout(_, width, height)
     local result = {}
     local pos,spacing = 0, self._private.spacing
     local num = #self._private.widgets
     local total_spacing = (spacing*(num-1))
+    local spacing_widget = self._private.spacing_widget
+    local abspace = math.abs(spacing)
+    local spoffset = spacing < 0 and 0 or spacing
+    local is_y = self._private.dir == "y"
+    local is_x = not is_y
 
     local space_per_item
-    if self._private.dir == "y" then
+    if is_y then
         space_per_item = height / num - total_spacing/num
     else
         space_per_item = width / num - total_spacing/num
@@ -67,9 +88,9 @@ function flex:layout(_, width, height)
         space_per_item = math.min(space_per_item, self._private.max_widget_size)
     end
 
-    for _, v in pairs(self._private.widgets) do
+    for k, v in pairs(self._private.widgets) do
         local x, y, w, h
-        if self._private.dir == "y" then
+        if is_y then
             x, y = 0, gmath.round(pos)
             w, h = width, floor(space_per_item)
         else
@@ -81,10 +102,17 @@ function flex:layout(_, width, height)
 
         pos = pos + space_per_item + spacing
 
-        if (self._private.dir == "y" and pos-spacing >= height) or
-            (self._private.dir ~= "y" and pos-spacing >= width) then
+        if (is_y and pos-spacing >= height) or
+            (is_x and pos-spacing >= width) then
             break
         end
+
+        if k > 1 and spacing ~= 0 and spacing_widget then
+            table.insert(result, base.place_widget_at(
+                spacing_widget, is_x and (x - spoffset) or x, is_y and (y - spoffset) or y,
+                is_x and abspace or w, is_y and abspace or h
+            ))
+        end
     end
 
     return result

lib/wibox/layout/ratio.lua

@@ -22,6 +22,22 @@ local ratio = {}
 
 --@DOC_fixed_COMMON@
 
+--- The widget used to fill the spacing between the layout elements.
+--
+-- By default, no widget is used.
+--
+--@DOC_wibox_layout_ratio_spacing_widget_EXAMPLE@
+--
+-- @property spacing_widget
+-- @param widget
+
+--- Add spacing between each layout widgets.
+--
+--@DOC_wibox_layout_ratio_spacing_EXAMPLE@
+--
+-- @property spacing
+-- @tparam number spacing Spacing between widgets.
+
 -- Compute the sum of all ratio (ideally, it should be 1)
 local function gen_sum(self, i_s, i_e)
     local sum, new_w = 0,0
@@ -86,6 +102,11 @@ function ratio:layout(context, width, height)
     local has_stragety = strategy ~= "default"
     local to_redistribute, void_count = 0, 0
     local dir = self._private.dir or "x"
+    local spacing_widget = self._private.spacing_widget
+    local abspace = math.abs(spacing)
+    local spoffset = spacing < 0 and 0 or spacing
+    local is_y = self._private.dir == "y"
+    local is_x = not is_y
 
     for k, v in ipairs(self._private.widgets) do
         local space, is_void
@@ -150,7 +171,7 @@ function ratio:layout(context, width, height)
     -- Only the `justify` strategy changes the original widget size.
     to_redistribute = (strategy == "justify") and to_redistribute or 0
 
-    for _, entry in ipairs(preliminary_results) do
+    for k, entry in ipairs(preliminary_results) do
         local v, x, y, w, h, is_void = unpack(entry)
 
         -- Redistribute the space or move the widgets
@@ -167,6 +188,13 @@ function ratio:layout(context, width, height)
             end
         end
 
+        if k > 1 and abspace > 0 and spacing_widget then
+            table.insert(result, base.place_widget_at(
+                spacing_widget, is_x and (x - spoffset) or x, is_y and (y - spoffset) or y,
+                is_x and abspace or w, is_y and abspace or h
+            ))
+        end
+
         table.insert(result, base.place_widget_at(v, x, y, w, h))
     end