The life view is now a menu attached to the game.

It means that its callbacks on_draw, on_key_pressed, on_update, etc. are
now called automatically.
Other HUD elements will do the same.

quests/zsdx/data/hud/hearts.lua

@@ -18,6 +18,8 @@ function hearts:initialize(game)
   self.game = game
   self.surface = sol.surface.create(90, 18)
   self.surface:set_transparency_color{0, 0, 0}
+  self.dst_x = 0
+  self.dst_y = 0
   self.empty_heart_sprite = sol.sprite.create("hud/empty_heart")
   self.nb_max_hearts_displayed = game:get_max_life() / 4
   self.nb_current_hearts_displayed = game:get_life()
@@ -132,7 +134,21 @@ function hearts:rebuild_surface()
   end
 end
 
-function hearts:draw(dst_surface, x, y)
+function hearts:set_dst_position(x, y)
+  self.dst_x = x
+  self.dst_y = y
+end
+
+function hearts:on_draw(dst_surface)
+
+  local x, y = self.dst_x, self.dst_y
+  local width, height = dst_surface:get_size()
+  if x < 0 then
+    x = width + x
+  end
+  if y < 0 then
+    y = height + y
+  end
 
   -- Everything was already drawn on self.surface.
   self.surface:draw(dst_surface, x, y)

quests/zsdx/data/play_game.lua

@@ -7,25 +7,27 @@ function game:on_started()
   -- Set up the HUD.
   self.hud = {}
   self.hud.hearts = hearts_class:new(self)
+  self.hud.hearts:set_dst_position(-104, 6)
   self:set_hud_enabled(true)
 end
 
-function game:on_post_draw(surface)
-  -- Draw the hud after the game is drawn.
-  if game:is_hud_enabled() then
-    local width, height = surface:get_size()
-    self.hud.hearts:draw(surface, width - 104, 6)
-  end
-end
-
 -- Useful functions for this quest.
 
 function game:is_hud_enabled()
   return self.hud_enabled
 end
 
 function game:set_hud_enabled(hud_enabled)
-  game.hud_enabled = hud_enabled
+
+  if hud_enabled ~= game.hud_enabled then
+    game.hud_enabled = hud_enabled
+
+    if hud_enabled then
+      sol.menu.start(self, self.hud.hearts)
+    else
+      sol.menu.stop(self.hud.hearts)
+    end
+  end
 end
 
 -- Returns the item name of a bottle with the specified content, or nil.

quests/zsdx/data/screens/savegames.lua

@@ -161,7 +161,8 @@ function savegame_menu:draw_savegame(slot_index)
   slot.player_name_text:draw(self.surface, 87, 61 + slot_index * 27)
 
   if slot.hearts_view ~= nil then
-    slot.hearts_view:draw(self.surface, 168, 51 + slot_index * 27)
+    slot.hearts_view:set_dst_position(168, 51 + slot_index * 27)
+    slot.hearts_view:on_draw(self.surface)
   end
 end