From 7c8e11573b2ad85c3e46ff7c49e224a99f442e5c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=94=D0=B0=D0=BD=D0=B8=D1=97=D0=BB=20=D0=93=D1=80=D0=B8?=
 =?UTF-8?q?=D0=B3=D0=BE=D1=80=27=D1=94=D0=B2?= <dengr1065@gmail.com>
Date: Thu, 19 Jun 2025 23:11:30 +0300
Subject: [PATCH] Do not reuse canvas between savegame loads

Remove lastCanvas/lastContext cache for reusing canvas as creating a new
canvas does not cause performance issue. Additionaly, remove smoothing
classes and buffer registration as they are not used anywhere. Finally,
remove redundant stageDestroyed calls in the InGameState.
---
 src/js/game/core.js     | 46 ++++++-----------------------------------
 src/js/states/ingame.js | 18 +++++++---------
 2 files changed, 14 insertions(+), 50 deletions(-)

diff --git a/src/js/game/core.js b/src/js/game/core.js
index 3d9130e0..e349f5b2 100644
--- a/src/js/game/core.js
+++ b/src/js/game/core.js
@@ -2,7 +2,7 @@
 import { Application } from "../application";
 /* typehints:end */
 import { BufferMaintainer } from "../core/buffer_maintainer";
-import { getBufferStats, registerCanvas } from "../core/buffer_utils";
+import { getBufferStats } from "../core/buffer_utils";
 import { globalConfig } from "../core/config";
 import { getDeviceDPI, resizeHighDPICanvas } from "../core/dpi_manager";
 import { DrawParameters } from "../core/draw_parameters";
@@ -36,12 +36,6 @@ import { GameTime } from "./time/game_time";
 
 const logger = createLogger("ingame/core");
 
-// Store the canvas so we can reuse it later
-/** @type {HTMLCanvasElement} */
-let lastCanvas = null;
-/** @type {CanvasRenderingContext2D} */
-let lastContext = null;
-
 /**
  * The core manages the root and represents the whole game. It wraps the root, since
  * the root class is just a data holder.
@@ -208,51 +202,23 @@ export class GameCore {
      * Initializes the render canvas
      */
     internalInitCanvas() {
-        let canvas, context;
-        if (!lastCanvas) {
-            logger.log("Creating new canvas");
-            canvas = document.createElement("canvas");
-            canvas.id = "ingame_Canvas";
-            this.root.gameState.getDivElement().appendChild(canvas);
-            context = canvas.getContext("2d", { alpha: false });
-
-            lastCanvas = canvas;
-            lastContext = context;
-        } else {
-            logger.log("Reusing canvas");
-            if (lastCanvas.parentElement) {
-                lastCanvas.parentElement.removeChild(lastCanvas);
-            }
-            this.root.gameState.getDivElement().appendChild(lastCanvas);
-
-            canvas = lastCanvas;
-            context = lastContext;
-
-            lastContext.clearRect(0, 0, lastCanvas.width, lastCanvas.height);
-        }
-
-        canvas.classList.toggle("smoothed", globalConfig.smoothing.smoothMainCanvas);
-
-        // Oof, use :not() instead
-        canvas.classList.toggle("unsmoothed", !globalConfig.smoothing.smoothMainCanvas);
+        logger.log("Creating new canvas");
+        const canvas = document.createElement("canvas");
+        canvas.id = "ingame_Canvas";
+        this.root.gameState.getDivElement().appendChild(canvas);
+        const context = canvas.getContext("2d", { alpha: false });
 
         context.imageSmoothingEnabled = globalConfig.smoothing.smoothMainCanvas;
         context.imageSmoothingQuality = globalConfig.smoothing.quality;
 
         this.root.canvas = canvas;
         this.root.context = context;
-
-        registerCanvas(canvas, context);
     }
 
     /**
      * Destructs the root, freeing all resources
      */
     destruct() {
-        if (lastCanvas && lastCanvas.parentElement) {
-            lastCanvas.parentElement.removeChild(lastCanvas);
-        }
-
         this.root.destruct();
         delete this.root;
         this.root = null;
diff --git a/src/js/states/ingame.js b/src/js/states/ingame.js
index c48e27c3..34f4c1c9 100644
--- a/src/js/states/ingame.js
+++ b/src/js/states/ingame.js
@@ -1,15 +1,15 @@
-import { GameState } from "../core/game_state";
-import { logSection, createLogger } from "../core/logging";
-import { waitNextFrame } from "../core/utils";
 import { globalConfig } from "../core/config";
-import { GameLoadingOverlay } from "../game/game_loading_overlay";
-import { KeyActionMapper } from "../game/key_action_mapper";
-import { Savegame } from "../savegame/savegame";
+import { GameState } from "../core/game_state";
+import { createLogger, logSection } from "../core/logging";
+import { waitNextFrame } from "../core/utils";
 import { GameCore } from "../game/core";
-import { MUSIC } from "../platform/sound";
+import { GameLoadingOverlay } from "../game/game_loading_overlay";
 import { enumGameModeIds } from "../game/game_mode";
-import { MOD_SIGNALS } from "../mods/mod_signals";
 import { HUDModalDialogs } from "../game/hud/parts/modal_dialogs";
+import { KeyActionMapper } from "../game/key_action_mapper";
+import { MOD_SIGNALS } from "../mods/mod_signals";
+import { MUSIC } from "../platform/sound";
+import { Savegame } from "../savegame/savegame";
 import { T } from "../translations";
 
 const logger = createLogger("state/ingame");
@@ -194,7 +194,6 @@ export class InGameState extends GameState {
         }
         this.stageLeavingGame();
         this.doSave().then(() => {
-            this.stageDestroyed();
             this.moveToState(stateId, payload);
         });
     }
@@ -219,7 +218,6 @@ export class InGameState extends GameState {
     onInitializationFailure(err) {
         if (this.switchStage(GAME_LOADING_STATES.initFailed)) {
             logger.error("Init failure:", err);
-            this.stageDestroyed();
             this.moveToState("MainMenuState", { loadError: err });
         }
     }