common: Make overlay support available to all widgets

This is the first step toward removing the underlay/overlay from
all item.style and item.layout and use the common implementation.

This will simplify the code a lot.

init.lua

@@ -35,28 +35,75 @@ local function set_menu(self,menu,button)
   return bt
 end
 
-local function _underlay_draw(self, context, cr, width, height)
+local function layer_draw_common(self, context, cr, width, height, typename)
   cr:save()
-  local udl = underlay.draw(self._underlay,{height=height,style = self._underlay_style,bg=self._underlay_color})
+
+  local udl  = underlay.draw(self["_"..typename], {
+      height = height,
+      style  = self["_"..typename.."_style"],
+      bg     = self["_"..typename.."_color"]
+    },
+    context
+  )
+
   cr:set_source_surface(udl,width-udl:get_width()-3)
-  cr:paint_with_alpha(self._underlay_alpha or beautiful.underlay_alpha or 0.7)
+  cr:paint_with_alpha(self["_"..typename.."_alpha"] or beautiful[typename.."_alpha"] or 0.7)
+
   cr:restore()
-  self._draw_underlay(self, context, cr, width, height)
 end
 
-local function set_underlay(self,udl,args)
-  local args = args or {}
-  if not self._draw_underlay then
-    self._draw_underlay = self.draw
-    self.draw = _underlay_draw
+local function draw_underlay(self, context, cr, width, height)
+  layer_draw_common(self, context, cr, width, height, "underlay")
+
+  if self._draw_original then
+    self._draw_original(self, context, cr, width, height)
   end
-  self._underlay = udl
-  self._underlay_style = args.style
-  self._underlay_alpha = args.alpha
-  self._underlay_color = args.color
+end
+
+local function draw_overlay(self, context, cr, width, height)
+  if self._draw_original then
+    self._draw_original(self, context, cr, width, height)
+  end
+
+  layer_draw_common(self, context, cr, width, height, "overlay")
+end
+
+local function set_layer_common(typename, self ,udl ,args)
+  local args = args or {}
+
+  if self.draw and not self._draw_original then
+    self._draw_original = self.draw
+
+    if typename == "underlay" then
+      self.draw = draw_underlay
+    elseif typename == "overlay" then
+      self.draw = draw_overlay
+    end
+
+  elseif typename == "underlay" then
+    self.before_draw_children = draw_underlay
+  elseif typename == "overlay" then
+    self.after_draw_children = draw_overlay
+  end
+
+
+  -- TODO detect if it is a Radical item and get those properties,
+  -- then, delete item.layout implementations
+  self["_"..typename          ] = udl
+  self["_"..typename.."_style"] = args.style
+  self["_"..typename.."_alpha"] = args.alpha
+  self["_"..typename.."_color"] = args.color
   self:emit_signal("widget::updated")
 end
 
+local function set_underlay(...)
+  set_layer_common("underlay",...)
+end
+
+local function set_overlay(...)
+  set_layer_common("overlay",...)
+end
+
 local function get_preferred_size(self, context, width, height)
   local context = context or 1
 
@@ -76,6 +123,7 @@ base.make_widget = function(...)
   ret.set_tooltip        = set_tooltip
   ret.set_menu           = set_menu
   ret.set_underlay       = set_underlay
+  ret.set_overlay        = set_overlay
 
   -- Textboxes already have it
   if not ret.get_preferred_size then

widgets/underlay.lua

@@ -51,11 +51,14 @@ function module.draw_arrow(cr,x,y,width,height,padding,args)
   cr:restore()
 end
 
-function module.fit(text,args)
+function module.fit(text, args, context)
+  local context = context or {}
   local args = args or {}
   local height = args.height or (beautiful.menu_height)
   local padding = height/4--beautiful.default_height/3
 
+  local dpi = context.dpi or beautiful.xresources.get_dpi(1)
+
   -- Get text height
   if not pango_l[height] then
     local pango_crx = pangocairo.font_map_get_default():create_context()
@@ -68,21 +71,26 @@ function module.fit(text,args)
     pango_l[height]:set_font_description(desc)
   end
 
+  local pango_layout = pango_l[height]
+
+  pango_layout:get_context():set_resolution(dpi)
+  pango_layout:context_changed()
+
   -- Compute full width
   local ret,full_width = {},0
   for k,v in ipairs(type(text) == "table" and text or {text}) do
-    pango_l[height].text = v
-    ret[k] = pango_l[height]:get_pixel_extents().width + height + padding
+    pango_layout.text = v
+    ret[k] = pango_layout:get_pixel_extents().width + height + padding
     full_width = full_width + ret[k]
   end
   return full_width,ret
 end
 
-function module.draw(text,args)
+function module.draw(text, args, context)
   local args = args or {}
   local height = args.height or (beautiful.menu_height)
   local padding = height/4--beautiful.default_height/3
-  local full_width,ret = module.fit(text,args)
+  local full_width,ret = module.fit(text, args, context)
 
   local img = cairo.ImageSurface.create(cairo.Format.ARGB32, full_width+(args.padding_right or 0), height+padding)
   cr = cairo.Context(img)