place: Split internal logic to be reusable.

This will become the base class of a new "tile" container.

I also fixed a bug which could cause the output to be blurry for
some widget sizes.

lib/wibox/container/place.lua

@@ -23,13 +23,8 @@ local align_fct = {
 }
 align_fct.top, align_fct.bottom = align_fct.left, align_fct.right
 
--- Layout this layout
-function place:layout(context, width, height)
-
-    if not self._private.widget then
-        return
-    end
-
+-- Shared with some subclasses like the `tiled` and `scaled` modules.
+function place:_layout(context, width, height)
     local w, h = base.fit_widget(self, context, self._private.widget, width, height)
 
     if self._private.content_fill_horizontal then
@@ -45,6 +40,21 @@ function place:layout(context, width, height)
 
     local x, y = align_fct[halign](w, width), align_fct[valign](h, height)
 
+    -- Sub pixels makes everything blurry. This is now what people expect.
+    x, y = math.floor(x), math.floor(y)
+
+    return x, y, w, h
+end
+
+-- Layout this layout
+function place:layout(context, width, height)
+
+    if not self._private.widget then
+        return
+    end
+
+    local x, y, w, h = self:_layout(context, width, height)
+
     return { base.place_widget_at(self._private.widget, x, y, w, h) }
 end