Basic save/load functionality

.gitignore

@@ -264,3 +264,6 @@ dmypy.json
 cython_debug/
 
 # End of https://www.toptal.com/developers/gitignore/api/python,jetbrains+all,macos
+
+# Don't save game saves to git!
+savegame.sav

engine.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+import lzma
+import pickle
 from typing import TYPE_CHECKING
 
 from tcod.console import Console
@@ -54,3 +56,9 @@ class Engine:
         )
 
         render_names_at_mouse_location(console, x=21, y=44, engine=self)
+
+    def save_as(self, filename: str) -> None:
+        """Save this Engine instance as a compressed file."""
+        save_data = lzma.compress(pickle.dumps(self))
+        with open(filename, "wb") as f:
+            f.write(save_data)

input_handlers.py

@@ -89,6 +89,33 @@ class BaseEventHandler(tcod.event.EventDispatch[ActionOrHandler]):
         raise SystemExit()
 
 
+class PopupMessage(BaseEventHandler):
+    """Display a popup text window."""
+
+    def __init__(self, parent_handler: BaseEventHandler, text: str):
+        self.parent = parent_handler
+        self.text = text
+
+    def on_render(self, console: tcod.Console) -> None:
+        """Render the parent and dim the result, then print the message on top."""
+        self.parent.on_render(console)
+        console.tiles_rgb["fg"] //= 8
+        console.tiles_rgb["bg"] //= 8
+
+        console.print(
+            console.width // 2,
+            console.height // 2,
+            self.text,
+            fg=color.white,
+            bg=color.black,
+            alignment=tcod.CENTER,
+        )
+
+    def ev_keydown(self, event: tcod.event.KeyDown) -> Optional[BaseEventHandler]:
+        """Any key returns to the parent handler."""
+        return self.parent
+
+
 class EventHandler(BaseEventHandler):
     def __init__(self, engine: Engine):
         self.engine = engine

main.py

@@ -1,31 +1,25 @@
 #!/usr/bin/env python3
-import copy
 import traceback
 
 import tcod
 
 import color
-from engine import Engine
-import entity_factories
 import exceptions
 import input_handlers
-from procgen import generate_dungeon
+import setup_game
+
+
+def save_game(handler: input_handlers.BaseEventHandler, filename: str) -> None:
+    """If the current event handler has an active Engine then save it."""
+    if isinstance(handler, input_handlers.EventHandler):
+        handler.engine.save_as(filename)
+        print("Game saved.")
 
 
 def main() -> None:
     screen_width = 80
     screen_height = 50
 
-    map_width = 80
-    map_height = 43
-
-    room_max_size = 10
-    room_min_size = 6
-    max_rooms = 30
-
-    max_monsters_per_room = 2
-    max_items_per_room = 2
-
     tileset = tcod.tileset.load_tilesheet(
         "dejavu10x10_gs_tc.png",
         32,
@@ -33,28 +27,7 @@ def main() -> None:
         tcod.tileset.CHARMAP_TCOD
     )
 
-    player = copy.deepcopy(entity_factories.player)
-
-    engine = Engine(player)
-
-    engine.game_map = generate_dungeon(
-        max_rooms,
-        room_min_size,
-        room_max_size,
-        map_width,
-        map_height,
-        max_monsters_per_room,
-        max_items_per_room,
-        engine,
-    )
-    engine.update_fov()
-
-    engine.message_log.add_message(
-        "Hello and welcome, adventurer, to yet another dungeon!",
-        color.welcome_text
-    )
-
-    handler: input_handlers.BaseEventHandler = input_handlers.MainGameEventHandler(engine)
+    handler: input_handlers.BaseEventHandler = setup_game.MainMenu()
 
     with tcod.context.new_terminal(
             screen_width,
@@ -67,25 +40,29 @@ def main() -> None:
         try:
             while True:
                 root_console.clear()
-                engine.event_handler.on_render(console=root_console)
+                handler.on_render(console=root_console)
                 context.present(root_console)
 
                 try:
                     for event in tcod.event.wait():
                         context.convert_event(event)
-                        engine.event_handler.handle_events(event)
+                        handler = handler.handle_events(event)
                 except Exception:  # Handle exceptions in game.
                     traceback.print_exc()  # Print error to stderr.
                     # Then print the error to the message log.
-                    engine.message_log.add_message(traceback.format_exc(), color.error)
+                    if isinstance(handler, input_handlers.EventHandler):
+                        handler.engine.message_log.add_message(
+                            traceback.format_exc(),
+                            color.error,
+                        )
 
         except exceptions.QuitWithoutSaving:
             raise
         except SystemExit:  # Save and quit.
-            # TODO: Add the save function here
+            save_game(handler, "savegame.sav")
             raise
         except BaseException:  # Save on any other unexpected exception.
-            # TODO: Add the save function here
+            save_game(handler, "savegame.sav")
             raise
 
 

setup_game.py

@@ -0,0 +1,119 @@
+"""Handle the loading and initialization of game sessions."""
+from __future__ import annotations
+
+import copy
+import lzma
+import pickle
+import traceback
+from typing import Optional
+
+import tcod
+
+import color
+from engine import Engine
+import entity_factories
+import input_handlers
+from procgen import generate_dungeon
+
+# Load the background image and remove the alpha channel.
+background_image = tcod.image.load("menu_background.png")[:, :, :3]
+
+
+def new_game() -> Engine:
+    """Return a brand new game session as an Engine instance."""
+    map_width = 80
+    map_height = 43
+
+    room_max_size = 10
+    room_min_size = 6
+    max_rooms = 30
+
+    max_monsters_per_room = 2
+    max_items_per_room = 2
+
+    player = copy.deepcopy(entity_factories.player)
+
+    engine = Engine(player)
+
+    engine.game_map = generate_dungeon(
+        max_rooms=max_rooms,
+        room_min_size=room_min_size,
+        room_max_size=room_max_size,
+        map_width=map_width,
+        map_height=map_height,
+        max_monsters_per_room=max_monsters_per_room,
+        max_items_per_room=max_items_per_room,
+        engine=engine,
+    )
+    engine.update_fov()
+
+    engine.message_log.add_message(
+        "Hello and welcome, adventurer, to yet another dungeon!",
+        color.welcome_text
+    )
+
+    return engine
+
+
+def load_game(filename: str) -> Engine:
+    """Load an engine instance from a file."""
+    with open(filename, "rb") as f:
+        engine = pickle.loads(lzma.decompress(f.read()))
+    assert isinstance(engine, Engine)
+
+    return engine
+
+
+class MainMenu(input_handlers.BaseEventHandler):
+    """Handle the main menu rendering and input."""
+
+    def on_render(self, console: tcod.Console) -> None:
+        """Render the main menu on a background image."""
+        console.draw_semigraphics(background_image, 0, 0)
+
+        console.print(
+            console.width // 2,
+            console.height // 2 - 4,
+            "TOMBS OF THE ANCIENT KINGS",
+            fg=color.menu_title,
+            alignment=tcod.CENTER,
+        )
+        console.print(
+            console.width // 2,
+            console.height - 2,
+            "By Timothy J. Warren",
+            fg=color.menu_title,
+            alignment=tcod.CENTER,
+        )
+
+        menu_width = 24
+        for i, text in enumerate([
+            "[N] Play a new game",
+            "[C] Continue last game",
+            "[Q] Quit"
+        ]):
+            console.print(
+                console.width // 2,
+                console.height // 2 - 2 + i,
+                text.ljust(menu_width),
+                fg=color.menu_text,
+                bg=color.black,
+                alignment=tcod.CENTER,
+                bg_blend=tcod.BKGND_ALPHA(64),
+            )
+
+    def ev_keydown(self, event: tcod.event.KeyDown) -> Optional[input_handlers.BaseEventHandler]:
+        if event.sym in (tcod.event.K_q, tcod.event.K_ESCAPE):
+            raise SystemExit()
+        elif event.sym == tcod.event.K_c:
+            try:
+                return input_handlers.MainGameEventHandler(load_game("savegame.sav"))
+            except FileNotFoundError:
+                return input_handlers.PopupMessage(self, "No saved game to load.")
+            except Exception as exc:
+                traceback.print_exc()  # Print to stderr.
+                return input_handlers.PopupMessage(self, f"Failed to load save:\n{exc}")
+        elif event.sym == tcod.event.K_n:
+            return input_handlers.MainGameEventHandler(new_game())
+
+        return None