better on_activate for canvas

init.lua

@@ -107,17 +107,12 @@ picent = {
   end,
 
   on_activate = function(self, staticdata)
-    local pos = self.object:getpos()
-    local meta = minetest.env:get_meta(pos)
-    local data = meta:get_string("painting:picturedata")
+    self.grid = minetest.deserialize(staticdata) or initgrid()
+    self.object:set_properties({textures = { to_imagestring(self.grid) }})
+  end,
 
-    if data == "" then
-      self.grid = initgrid()
-    else
-      data = minetest.deserialize(data)
-      data = to_imagestring(data)
-      self.object:set_properties({textures = { data }})
-    end
+  get_staticdata = function(self)
+    return minetest.serialize(self.grid)
   end
 }