2024 06 11 identifying memory leaks and performance issues in a react codebase - bizkite-co/handterm GitHub Wiki

original file name: Codeium Chat - rSeuCvH1sSeu2ThMI4ex9cAibD8yoMJX.md summary: The chat involved a user seeking assistance in identifying potential memory leaks and performance issues in their codebase, specifically focusing on the TerminalGame.tsx file that included a React component. The user shared the code with various methods, state properties, event handling, animation loops, timers, and more.

During the conversation, the assistant provided recommendations and identified possible areas of concern, such as managing animation frame requests, event listeners, timers, references to DOM elements, memory-intensive operations, and heavy rendering processes. Suggestions included optimizing event listener management, clearing timers properly, reusing objects efficiently, streamlining rendering operations, avoiding context state duplication, and being cautious with direct DOM manipulations.

The assistant also highlighted the importance of thoroughly reviewing the child components (Hero, Zombie4, etc.) for potential issues that could impact the parent component's memory management. date: 2024-06-11T09:40

Codeium Chat Conversation

Note: This is purely the output of the chat conversation and does not contain any raw data, codebase snippets, etc. used to generate the output.

User at 9:40 am, Jun 11, 2024

I am in the process of converting several components to functional components but I now have escalating memory usage, DOM Nodes, and event listeners.

I'm going to show you the files involved and I need your help checking for any code that might be causing memory leaks or performance issues.

The chat says that you have access or that you are "tracking" TerminalGame.tsx. Can you read the contents of that file, or I can copy it's text into this chat.

Codeium at 9:40 am, Jun 11, 2024

I don't have direct access to your files or the ability to "track" them, but I can definitely help you troubleshoot the memory leaks and performance issues based on the code snippets you provide here. Please paste the relevant sections of TerminalGame.tsx or any other files you suspect might be contributing to the problem, and I'll assist you in identifying potential issues.

User at 9:41 am, Jun 11, 2024

import React, { TouchEventHandler } from 'react';
import { Zombie4 } from './Zombie4';
import { Hero } from './Hero';
import { Action, ActionType } from './types/ActionTypes';
import { SpritePosition } from './types/Position';
import { getParallaxLayers, Level } from './Level';
import { drawParallaxLayer, IParallaxLayer } from './ParallaxBackground';
import { Sprite } from './sprites/Sprite';

interface ITerminalGameProps {
 canvasHeight: number
 canvasWidth: number
 isInPhraseMode: boolean
 heroAction: ActionType
 zombie4Action: ActionType
 onTouchStart: TouchEventHandler<HTMLDivElement>;
 onTouchEnd: TouchEventHandler<HTMLDivElement>;
}

interface ITerminalGameState {
 currentLevel: number;
 heroAction: ActionType;
 heroPosition: SpritePosition;
 heroReady: boolean;
 zombie4Action: ActionType;
 zombie4Position: SpritePosition;
 zombie4Ready: boolean;
 context: CanvasRenderingContext2D | null;
 idleStartTime: number | null; // in milliseconds
 backgroundOffsetX: number;
 isPhraseComplete: boolean;
 textScrollX: number;
 layers: IParallaxLayer[];
}

interface CharacterRefMethods {
 getCurrentSprite: () => Sprite | null;
 getActions: () => Record<ActionType, Action>;
 draw: (context: CanvasRenderingContext2D, position: SpritePosition) => void;
}

export class TerminalGame extends React.Component<ITerminalGameProps, ITerminalGameState> {

 private canvasRef = React.createRef<HTMLCanvasElement>();
 private gameTime: number = 0;
 private animationFrameIndex?: number;
 public context: CanvasRenderingContext2D | null = null;
 private heroXPercent: number = 0.3;
 isInScrollMode: boolean = true;
 zombie4DeathTimeout: NodeJS.Timeout | null = null;
 // Add a new field for the text animation
 private textScrollX: number = this.props.canvasWidth; // Start offscreen to the right
 private textToScroll: string = "Terminal Velocity!";
 private heroRef = React.createRef<CharacterRefMethods>();
 private zombie4Ref = React.createRef<CharacterRefMethods>();


 getInitState(props: ITerminalGameProps): ITerminalGameState {
  return {
   currentLevel: 1,
   heroAction: props.heroAction,
   heroPosition: { leftX: props.canvasWidth * this.heroXPercent, topY: 30 },
   heroReady: false,
   zombie4Action: props.zombie4Action,
   zombie4Position: { leftX: 50, topY: 0 },
   zombie4Ready: false,
   context: null as CanvasRenderingContext2D | null,
   idleStartTime: null,
   backgroundOffsetX: 0,
   isPhraseComplete: false,
   textScrollX: this.props.canvasWidth,
   layers: []
  };
 }

 public resetGame(): void {
  // TODO: Handle addListeners or subscrition before resetting state.
  // this.setState(this.getInitstate(this.props));
 }

 changeLevel = (newLevel: number) => {
  this.setState({ currentLevel: newLevel });
 }

 constructor(props: ITerminalGameProps) {
  super(props);
  this.state = this.getInitState(props);
 }

 componentDidMount() {
  const canvas = this.canvasRef.current;
  this.setParallaxLayers();
  if (canvas) {
   const context = canvas.getContext('2d');
   if (context) {
    this.setupCanvas();
   }
  }
 }


 componentDidUpdate(
  _prevProps: Readonly<ITerminalGameProps>,
  prevState: Readonly<ITerminalGameState>,
  _snapshot?: any
 ): void {
  if (this.state.currentLevel !== prevState.currentLevel) {
   this.setParallaxLayers();
  }
  this.startAnimationLoop(this.state.context!);
 }

 componentWillUnmount(): void {
  if (this.animationFrameIndex) {
   cancelAnimationFrame(this.animationFrameIndex);
  }

  this.stopAnimationLoop();
  if (this.zombie4DeathTimeout) {
   clearTimeout(this.zombie4DeathTimeout);
  }
 }

 // Call this method to update the background position
 updateBackgroundPosition(newOffsetX: number) {
  this.setState({ backgroundOffsetX: newOffsetX });
 }

 setupCanvas() {
  const canvas = this.canvasRef.current;
  if (canvas) {
   const context = canvas.getContext('2d');
   if (context instanceof CanvasRenderingContext2D) {
    // Set the context in the state instead of a class property
    this.setState({ context: context });

    // Load background images

   } else {
    console.error("Obtained context is not a CanvasRenderingContext2D instance.");
   }
  } else {
   console.error("Failed to get canvas element.");
  }
 }

 drawScrollingText(context: CanvasRenderingContext2D) {
  context.font = 'italic 60px Arial'; // Customize as needed
  context.fillStyle = 'lightgreen'; // Text color
  context.fillText(this.textToScroll, this.textScrollX, 85); // Adjust Y coordinate as needed

  // Update the X position for the next frame
  this.textScrollX -= 5; // Adjust speed as needed

  // Reset text position if it's fully offscreen to the left
  if (this.textScrollX < -context.measureText(this.textToScroll).width) {
   this.textScrollX = this.props.canvasWidth;
  }
 }

 // Call this method when the game is completed
 public completeGame() {
  this.setZombie4ToDeathThenResetPosition();
  this.textScrollX = this.props.canvasWidth; // Reset scroll position
  this.setState({
   isPhraseComplete: true,
   textScrollX: this.props.canvasWidth
  });
 }

 public setZombie4ToDeathThenResetPosition = (): void => {
  // Set the zombie action to 'Death'
  if (this.zombie4DeathTimeout) {
   clearTimeout(this.zombie4DeathTimeout);
   this.zombie4DeathTimeout = null;
  }

  this.setZombie4Action('Death');
  // After three seconds, reset the position
  this.zombie4DeathTimeout = setTimeout(() => {
   this.setState({
    zombie4Position: { topY: 0, leftX: -70 },
    isPhraseComplete: false,
    textScrollX: this.props.canvasWidth
   });

   // Optionally reset the action if needed
   this.setZombie4Action('Walk'); // Or the default action you want to set
   this.zombie4DeathTimeout = null;
  }, 5000);
 };


 checkProximityAndSetAction() {
  // Constants to define "near"
  // TODO: Sprite image widths seem to be off by about 150.
  const ATTACK_THRESHOLD = 250; // pixels or appropriate unit for your game

  // Calculate the distance between the hero and zombie4
  const distance = this.state.heroPosition.leftX - this.state.zombie4Position.leftX;

  // If zombie4 is near the Hero, set its current action to Attack
  if (150 < distance && distance < ATTACK_THRESHOLD) {

   // Assuming zombie4 has a method to update its action
   this.setZombie4Action('Attack'); // Replace 'Attack' with actual ActionType for attacking
  } else {
   // Otherwise, set it back to whatever action it should be doing when not attacking
   if (this.state.zombie4Action === 'Attack') {
    this.setZombie4Action('Walk'); // Replace 'Walk' with actual ActionType for walking
   }
  }

  // Update the state or force a re-render if necessary, depending on how your animation loop is set up
  // this.setState({ ... }); or this.forceUpdate();
 }

 setZombie4Action(action: ActionType) {
  this.setState({ zombie4Action: action });
 }

 setParallaxLayers() {
  const layers = getParallaxLayers(this.state.currentLevel);
  this.setState({ layers });
 }

 updateCharacterAndBackground(_context: CanvasRenderingContext2D) {
  const canvasCenterX = this.props.canvasWidth * this.heroXPercent;
  const characterReachThreshold = canvasCenterX;


  // const heroDx
  //  = this.heroActions
  //   ? this.heroActions[this.state.heroAction].dx / 4
  //   : 0;

  let newBackgroundOffsetX = this.state.backgroundOffsetX;

  // Update character position as usual
  const newHeroPositionX = canvasCenterX;

  // Check if the hero reaches the threshold
  if (newHeroPositionX >= characterReachThreshold) {
   this.isInScrollMode = true;

   // Update the background offset
   // newBackgroundOffsetX += heroDx;

   this.setState({
    heroPosition: { ...this.state.heroPosition, leftX: characterReachThreshold },
    backgroundOffsetX: newBackgroundOffsetX, // Update background offset state
   });

   // this.updateBackgroundPosition(this.state.backgroundOffsetX + heroDx);
   // if (this.zombie4Actions) {
   //  const newX = this.state.zombie4Position.leftX - heroDx;
   //  this.setState({ zombie4Position: { ...this.state.zombie4Position, leftX: newX } });
   // }

  } else {
   this.setState({ heroPosition: { ...this.state.heroPosition, leftX: newHeroPositionX } });
  }
  if (this.heroRef.current && _context) {
   this.heroRef.current.draw(_context, this.state.heroPosition);
  }
  if (this.zombie4Ref.current && _context) {
   this.zombie4Ref.current.draw(_context, this.state.zombie4Position);
  }

 }

 startAnimationLoop(context: CanvasRenderingContext2D) {
  const image = new Image();
  const frameDelay = 100; // Delay in milliseconds (100ms for 10 FPS)
  let lastFrameTime = 0; // Time at which the last frame was processed

  const loop = (timestamp: number) => {
   if (!this.gameTime) {
    this.gameTime = timestamp; // Initialize gameTime on the first animation frame
    lastFrameTime = timestamp; // Initialize lastFrameTime on the first frame
   }

   // Calculate the time elapsed since the last frame
   const timeElapsed = timestamp - lastFrameTime;

   if (timeElapsed >= frameDelay) {
    // Update lastFrameTime to the current timestamp
    lastFrameTime = timestamp - (timeElapsed % frameDelay);

    // Get the parallax layers for the current level

    const layers = this.state.layers;
    // context.clearRect(0, 0, context.canvas.width, context.canvas.height);
    // Draw the parallax background layers
    context.save();
    layers.forEach(layer => {
     drawParallaxLayer(context, layer, this.state.backgroundOffsetX, this.props.canvasWidth, this.props.canvasHeight, image);
    });
    context.restore();

    if (this.state.isPhraseComplete) {
     this.drawScrollingText(context);
    }
    // Reset globalAlpha if other drawings should not be affected
    context.globalAlpha = 1.0;

    this.updateCharacterAndBackground(context);

    // Save the request ID to be able to cancel it
    this.checkProximityAndSetAction();
   };
    
   this.animationFrameIndex = requestAnimationFrame(loop);
  };

  // Start the animation loop
  this.animationFrameIndex = requestAnimationFrame(loop);
 }

 // Call this method when both characters are ready to draw
 maybeStartAnimationLoop() {
  if (this.state.context && this.state.heroReady && this.state.zombie4Ready) {
   this.startAnimationLoop(this.state.context);
  }
 }
 stopAnimationLoop() {
  if (this.animationFrameIndex) {
   cancelAnimationFrame(this.animationFrameIndex);
   this.animationFrameIndex = undefined;
   console.log("stopAnimationLoop");
  }
 }

 handleHeroPositionChange = (newPosition: SpritePosition) => {
  this.setState({ heroPosition: newPosition });
 };

 handleZombie4PositionChange = (newPosition: SpritePosition) => {
  this.setState({ zombie4Position: newPosition });
 }

 // Additional methods for calculating WPM, updating the progress bar, etc.
 render() {
  return (
   <>
    <canvas
     ref={this.canvasRef}
     width={this.props.canvasWidth}
     height={this.props.canvasHeight}>
    </canvas>
    <Level
     level={this.state.currentLevel}
     canvasWidth={this.props.canvasWidth}
     canvasHeight={this.props.canvasHeight}
     backgroundOffsetX={this.state.backgroundOffsetX}
     canvasRef={this.canvasRef}
    />
    <Hero
     ref={this.heroRef}
     currentActionType='Idle'
     scale={2}
    />
    <Zombie4
     ref={this.zombie4Ref}
     currentActionType='Walk'
     scale={2}
    />
   </>
  );
 }
}

Can you see any code that I may have left open to memory leaks?

Codeium at 9:42 am, Jun 11, 2024

Here are a few potential memory leak issues and performance considerations that I spotted in your TerminalGame.tsx component:

  1. Animation Frame Requests: You are correctly canceling the animation frame request in componentWillUnmount, but it seems like you are starting the animation loop again in componentDidUpdate without checking whether it's already running. This could lead to multiple loops running at the same time, stacking up unnecessary work.

    componentDidUpdate(
  _prevProps: Readonly<ITerminalGameProps>,
  prevState: Readonly<ITerminalGameState>,
  _snapshot?: any
): void {
  if (this.state.currentLevel !== prevState.currentLevel) {
    this.setParallaxLayers();
  }
  // Ensure no animation loop is already running
  if (!this.animationFrameIndex) {
    this.startAnimationLoop(this.state.context!);
  }
}

  2. Event Listeners: Ensure all event listeners added (especially in custom methods or lifecycle methods other than componentDidMount) are properly removed in componentWillUnmount. If you have any event listeners, add them in componentDidMount and remove them in componentWillUnmount.

  3. Timers: You have a timeout for zombie4DeathTimeout, which you clear on unmount, which is good. Just make sure that any other timers or intervals are also cleared on unmount to prevent them from trying to update the state of an unmounted component.

  4. References to DOM Elements: You are using refs to interact with DOM elements. Ensure that you're not holding onto these refs longer than necessary and that you're not manipulating the DOM directly in ways that could conflict with React's rendering lifecycle.

  5. Memory Intensive Operations in the Animation Loop: Operations such as creating a new Image object on every call to startAnimationLoop can be memory-intensive. You should create such objects once and reuse them:

    startAnimationLoop(context: CanvasRenderingContext2D) {
  // Create image outside of the loop
  const image = new Image();
  const frameDelay = 100; // Delay in milliseconds (100ms for 10 FPS)
  let lastFrameTime = 0; // Time at which the last frame was processed
  
  // ... rest of the code
}

  6. Unused Properties and State: Review your component for any unused state properties or class properties that might be taking up memory without being used.

  7. Heavy Rendering Operations: Operations like drawParallaxLayer() and drawScrollingText() might be performance-intensive. Make sure they're optimized and not causing repaints or reflows more often than necessary.

  8. Context State Duplication: You are storing the context in both a class property (this.context) and the component state (this.state.context). This duplication is unnecessary and could lead to inconsistencies. Stick to one, preferably the state to leverage React's reactivity system.

  9. Direct DOM Manipulations: React is built on the principle of a virtual DOM for efficient updates. Directly manipulating the DOM or storing element references can sometimes lead to memory leaks. Make sure any direct manipulations are necessary and managed carefully.

Remember that memory leaks can also be introduced by the child components (Hero, Zombie4, etc.), so review their implementations as well. Profiling tools such as the Chrome DevTools can help you monitor memory usage and identify leaks by taking heap snapshots and observing memory timelines.

User at 9:57 am, Jun 11, 2024

Ok, I've fixed some of that, but you also referred to what might be happening in this code:

// ParallaxBackground.tsx
import React, { useEffect, useState } from 'react';

export interface IParallaxLayer {
  imageSrc: string;
  scale: number;
  movementRate: number;
}

export interface ParallaxBackgroundProps {
  layers: IParallaxLayer[];
  offset: number; // This prop is the backgroundOffsetX from your game state
  canvasWidth: number;
  canvasHeight: number;
  canvasRef: React.RefObject<HTMLCanvasElement>;
}

export const drawParallaxLayer = (
  context: CanvasRenderingContext2D,
  layer: IParallaxLayer,
  offset: number,
  canvasWidth: number,
  canvasHeight: number,
  image: HTMLImageElement
) => {
  const { imageSrc, scale, movementRate } = layer;
  // const image = new Image();
  image.src = imageSrc;

  // Wait for the image to load before drawing
  image.onload = () => {
    // Calculate the horizontal position based on the movement rate
    const x = -offset * movementRate;

    // Calculate the scaled dimensions of the image
    const scaledWidth = image.width * scale;
    const scaledHeight = image.height * scale;

    // Calculate how many times to draw the image to fill the canvas width
    const numImages = Math.ceil(canvasWidth / scaledWidth);

    // Draw the image as many times as needed to create the parallax effect
    for (let i = 0; i <= numImages; i++) {
      context.drawImage(
        image,
        x + i * scaledWidth % canvasWidth, // X position (looping the image)
        canvasHeight - scaledHeight,    // Y position (align to bottom)
        scaledWidth,           // Scaled width
        scaledHeight           // Scaled height
      );
    }
  };

  // If the image is already loaded (e.g., cached), draw it immediately
  if (image.complete) {
    const x = -offset * movementRate;
    const scaledWidth = image.width * scale;
    const scaledHeight = image.height * scale;
    const numImages = Math.ceil(canvasWidth / scaledWidth);
    for (let i = 0; i <= numImages; i++) {
      context.drawImage(
        image,
        x + i * scaledWidth % canvasWidth,
        canvasHeight - scaledHeight,
        scaledWidth,
        scaledHeight
      );
    }
  }
};

export const ParallaxBackground: React.FC<ParallaxBackgroundProps> = ({ layers, offset, canvasWidth, canvasHeight, canvasRef }) => {
  const [loadedImages, setLoadedImages] = useState<Map<string, HTMLImageElement>>(new Map());

  useEffect(() => {
    // Load the images when the layers change
    layers.forEach(layer => {
      if (!loadedImages.has(layer.imageSrc)) {
        const image = new Image();
        image.src = layer.imageSrc;
        image.onload = () => {
          setLoadedImages(prevLoadedImages => {
            const updatedLoadedImages = new Map(prevLoadedImages);
            updatedLoadedImages.set(layer.imageSrc, image);
            return updatedLoadedImages;
          });
        };
      }
    });
  }, [layers]);

  useEffect(() => {
    const canvas = canvasRef.current;
    const context = canvas?.getContext('2d');
    if (context) {
      // Clear the canvas before drawing the new frame
      context.clearRect(0, 0, canvasWidth, canvasHeight);

      // Draw each layer
      layers.forEach(layer => {
        const image = loadedImages.get(layer.imageSrc);
        if (image) {
          drawParallaxLayer(context, layer, offset, canvasWidth, canvasHeight, image)
        }
      });
    }
    console.log('ParallaxBackground rendered', layers, offset, canvasWidth, canvasHeight, canvasRef);
  }, [layers, offset, canvasWidth, canvasHeight, canvasRef]);

  // The canvas is rendered by the parent component (TerminalGame)
  return null;
};

Is there anything in there that could be improved?

Codeium at 9:58 am, Jun 11, 2024

The ParallaxBackground component in your code snippet looks generally well-structured for managing memory and preventing leaks. However, there are a couple of potential issues that you might want to address:

  1. Image Loading in useEffect: The useEffect hook that loads images is well-guarded with dependency on layers, so it should only run when layers change. However, if layers changes while images are still loading, you might end up with dangling event listeners on the old images that never get cleaned up. To prevent this, you could keep track of the loading state and abort the loading if layers change before the loading is complete.

  2. Redundant Image Loading: As per the current logic, every time the layers prop changes, you are setting up new onload handlers for all images, even if they are already present in loadedImages. It would be better to skip setting up the onload handler if the image is already loaded.

  3. Multiple onload Handlers: You're setting an onload handler within the drawParallaxLayer function, which can potentially create multiple handlers for the same image if it's called multiple times. This is unnecessary because you're already setting an onload handler when you load the images in the first useEffect. You should remove the onload handler from drawParallaxLayer to prevent this.

  4. Unnecessary Logging: The console.log at the end of the second useEffect could clutter your console in a production environment, and if the rendering happens frequently, it could slightly impact performance. Consider removing this log or guarding it with a development environment check.

  5. Returning null: While not a memory leak issue, returning null from a component that is supposed to render a canvas might be confusing. If the parent component TerminalGame is supposed to render the canvas, it might be better to move the canvas rendering logic into TerminalGame entirely, and use ParallaxBackground only for managing the parallax effect (i.e., calculating positions).

  6. Effect Cleanup: If you add any event listeners or timeouts within any useEffect, make sure to return a cleanup function that removes those event listeners or clears the timeouts.

Here's how you might improve the useEffect that loads the images:

useEffect(() => {
  const abortController = new AbortController(); // Create an abort controller for cleanup
  const signal = abortController.signal;

  layers.forEach(layer => {
    if (!loadedImages.has(layer.imageSrc)) {
      const image = new Image();
      image.src = layer.imageSrc;

      const onLoad = () => {
        if (!signal.aborted) { // Only proceed if the effect has not been aborted
          setLoadedImages(prevLoadedImages => {
            const updatedLoadedImages = new Map(prevLoadedImages);
            updatedLoadedImages.set(layer.imageSrc, image);
            return updatedLoadedImages;
          });
        }
      };

      image.onload = onLoad;
      // Add an event listener for aborting the image loading
      signal.addEventListener('abort', () => {
        image.onload = null; // Unset the onload handler if the effect is being cleaned up
      });
    }
  });

  // Cleanup function to abort loading if the component unmounts or layers change
  return () => {
    abortController.abort();
  };
}, [layers]);

This would help ensure that if the component is unmounted or layers changes, any ongoing image loading is aborted and won't cause a state update on an unmounted component.

User at 10:07 am, Jun 11, 2024

Do I only need one useEffect then, like this:

export const ParallaxBackground: React.FC<ParallaxBackgroundProps> = ({ layers, offset, canvasWidth, canvasHeight }) => {
  const [loadedImages, setLoadedImages] = useState<Map<string, HTMLImageElement>>(new Map());

  useEffect(() => {
    const abortController = new AbortController(); // Create an abort controller for cleanup
    const signal = abortController.signal;

    layers.forEach(layer => {
      if (!loadedImages.has(layer.imageSrc)) {
        const image = new Image();
        image.src = layer.imageSrc;

        const onLoad = () => {
          if (!signal.aborted) { // Only proceed if the effect has not been aborted
            setLoadedImages(prevLoadedImages => {
              const updatedLoadedImages = new Map(prevLoadedImages);
              updatedLoadedImages.set(layer.imageSrc, image);
              return updatedLoadedImages;
            });
          }
        };

        image.onload = onLoad;
        // Add an event listener for aborting the image loading
        signal.addEventListener('abort', () => {
          image.onload = null; // Unset the onload handler if the effect is being cleaned up
        });
      }
    });

    // Cleanup function to abort loading if the component unmounts or layers change
    return () => {
      abortController.abort();
    };
  }, [layers]);

  // The canvas is rendered by the parent component (TerminalGame)
  return null;
};

Codeium at 10:07 am, Jun 11, 2024

No, you still need two separate useEffect hooks: one for loading images and another for drawing on the canvas. The reason for this is that these two hooks have different purposes and different dependencies.

  1. The first useEffect is for loading images and managing the loadedImages state. It runs whenever the layers prop changes. This is where you're using the abort controller to handle cleanup.

  2. The second useEffect is for drawing on the canvas. It should run whenever the loadedImages state, the offset, the canvasWidth, canvasHeight, or the canvasRef changes.

Here's how your component might look with both useEffect hooks properly set up:

export const ParallaxBackground: React.FC<ParallaxBackgroundProps> = ({ layers, offset, canvasWidth, canvasHeight, canvasRef }) => {
  const [loadedImages, setLoadedImages] = useState<Map<string, HTMLImageElement>>(new Map());

  useEffect(() => {
    // ... (Image loading logic from earlier)
  }, [layers]);

  useEffect(() => {
    const canvas = canvasRef.current;
    const context = canvas?.getContext('2d');
    if (context) {
      // Clear the canvas before drawing the new frame
      context.clearRect(0, 0, canvasWidth, canvasHeight);

      // Draw each layer
      layers.forEach(layer => {
        const image = loadedImages.get(layer.imageSrc);
        if (image) {
          drawParallaxLayer(context, layer, offset, canvasWidth, canvasHeight, image);
        }
      });
    }
  }, [loadedImages, offset, canvasWidth, canvasHeight, canvasRef]);

  // The canvas is rendered by the parent component (TerminalGame)
  return null;
};

In this setup, the second useEffect depends on loadedImages (among other things), which is the state that is updated by the first useEffect when images are loaded. This is why you need to keep them separate: the first useEffect manages image loading, and the second one handles the actual drawing on the canvas.

User at 10:40 am, Jun 11, 2024

Ok, I would like to review TerminalGame again.

We have greatly improved memory and CPU usage by checking the animationFrameIndex on componentDidUpdate, but I am still seeing slow expansion of DOM Nodes, and my Hero and Zombie4 characters are flickering between each render:

// TerminalGame.ts
import React, { TouchEventHandler } from 'react';
import { Zombie4 } from './Zombie4';
import { Hero } from './Hero';
import { Action, ActionType } from './types/ActionTypes';
import { SpritePosition } from './types/Position';
import { getParallaxLayers, Level } from './Level';
import { drawParallaxLayer, IParallaxLayer } from './ParallaxBackground';
import { Sprite } from './sprites/Sprite';

interface ITerminalGameProps {
 canvasHeight: number
 canvasWidth: number
 isInPhraseMode: boolean
 heroAction: ActionType
 zombie4Action: ActionType
 onTouchStart: TouchEventHandler<HTMLDivElement>;
 onTouchEnd: TouchEventHandler<HTMLDivElement>;
}

interface ITerminalGameState {
 currentLevel: number;
 heroAction: ActionType;
 heroPosition: SpritePosition;
 heroReady: boolean;
 zombie4Action: ActionType;
 zombie4Position: SpritePosition;
 zombie4Ready: boolean;
 context: CanvasRenderingContext2D | null;
 idleStartTime: number | null; // in milliseconds
 backgroundOffsetX: number;
 isPhraseComplete: boolean;
 textScrollX: number;
 layers: IParallaxLayer[];
}

interface CharacterRefMethods {
 getCurrentSprite: () => Sprite | null;
 getActions: () => Record<ActionType, Action>;
 draw: (context: CanvasRenderingContext2D, position: SpritePosition) => void;
}

export class TerminalGame extends React.Component<ITerminalGameProps, ITerminalGameState> {

 private canvasRef = React.createRef<HTMLCanvasElement>();
 private gameTime: number = 0;
 private animationFrameIndex?: number;
 public context: CanvasRenderingContext2D | null = null;
 private heroXPercent: number = 0.23;
 isInScrollMode: boolean = true;
 zombie4DeathTimeout: NodeJS.Timeout | null = null;
 // Add a new field for the text animation
 private textScrollX: number = this.props.canvasWidth; // Start offscreen to the right
 private textToScroll: string = "Terminal Velocity!";
 private heroRef = React.createRef<CharacterRefMethods>();
 private zombie4Ref = React.createRef<CharacterRefMethods>();
 private image = new Image();

 getInitState(props: ITerminalGameProps): ITerminalGameState {
  return {
   currentLevel: 1,
   heroAction: props.heroAction,
   heroPosition: { leftX: props.canvasWidth * this.heroXPercent, topY: 30 },
   heroReady: false,
   zombie4Action: props.zombie4Action,
   zombie4Position: { leftX: 50, topY: 0 },
   zombie4Ready: false,
   context: null as CanvasRenderingContext2D | null,
   idleStartTime: null,
   backgroundOffsetX: 0,
   isPhraseComplete: false,
   textScrollX: this.props.canvasWidth,
   layers: []
  };
 }

 public getLevel = () => {
  return this.state.currentLevel;
 }
 public setLevel = (newLevel: number) => {
  this.setState({ currentLevel: newLevel });
 }
 public resetGame(): void {
  // TODO: Handle addListeners or subscrition before resetting state.
  // this.setState(this.getInitstate(this.props));
 }

 changeLevel = (newLevel: number) => {
  this.setState({ currentLevel: newLevel });
 }

 constructor(props: ITerminalGameProps) {
  super(props);
  this.state = this.getInitState(props);
 }

 componentDidMount() {
  const canvas = this.canvasRef.current;
  this.setParallaxLayers();
  if (canvas) {
   const context = canvas.getContext('2d');
   if (context) {
    this.setupCanvas();
   }
  }
 }


 componentDidUpdate(
  _prevProps: Readonly<ITerminalGameProps>,
  prevState: Readonly<ITerminalGameState>,
  _snapshot?: any
 ): void {
  if (this.state.currentLevel !== prevState.currentLevel) {
   this.setParallaxLayers();
  }
  // Ensure no animation loop is already running
  if (!this.animationFrameIndex) {
   this.startAnimationLoop(this.state.context!);
  }
 }

 componentWillUnmount(): void {
  if (this.animationFrameIndex) {
   cancelAnimationFrame(this.animationFrameIndex);
  }

  this.stopAnimationLoop();
  if (this.zombie4DeathTimeout) {
   clearTimeout(this.zombie4DeathTimeout);
  }
 }

 // Call this method to update the background position
 updateBackgroundPosition(newOffsetX: number) {
  this.setState({ backgroundOffsetX: newOffsetX });
 }

 setupCanvas() {
  const canvas = this.canvasRef.current;
  if (canvas) {
   const context = canvas.getContext('2d');
   if (context instanceof CanvasRenderingContext2D) {
    // Set the context in the state instead of a class property
    this.setState({ context: context });

    // Load background images

   } else {
    console.error("Obtained context is not a CanvasRenderingContext2D instance.");
   }
  } else {
   console.error("Failed to get canvas element.");
  }
 }

 drawScrollingText(context: CanvasRenderingContext2D) {
  context.font = 'italic 60px Arial'; // Customize as needed
  context.fillStyle = 'lightgreen'; // Text color
  context.fillText(this.textToScroll, this.textScrollX, 85); // Adjust Y coordinate as needed

  // Update the X position for the next frame
  this.textScrollX -= 5; // Adjust speed as needed

  // Reset text position if it's fully offscreen to the left
  if (this.textScrollX < -context.measureText(this.textToScroll).width) {
   this.textScrollX = this.props.canvasWidth;
  }
 }

 // Call this method when the game is completed
 public completeGame() {
  this.setZombie4ToDeathThenResetPosition();
  this.textScrollX = this.props.canvasWidth; // Reset scroll position
  this.setState({
   isPhraseComplete: true,
   textScrollX: this.props.canvasWidth
  });
 }

 public setZombie4ToDeathThenResetPosition = (): void => {
  // Set the zombie action to 'Death'
  if (this.zombie4DeathTimeout) {
   clearTimeout(this.zombie4DeathTimeout);
   this.zombie4DeathTimeout = null;
  }

  this.setZombie4Action('Death');
  // After three seconds, reset the position
  this.zombie4DeathTimeout = setTimeout(() => {
   this.setState({
    zombie4Position: { topY: 0, leftX: -70 },
    isPhraseComplete: false,
    textScrollX: this.props.canvasWidth
   });

   // Optionally reset the action if needed
   this.setZombie4Action('Walk'); // Or the default action you want to set
   this.zombie4DeathTimeout = null;
  }, 5000);
 };


 checkProximityAndSetAction() {
  // Constants to define "near"
  // TODO: Sprite image widths seem to be off by about 150.
  const ATTACK_THRESHOLD = 250; // pixels or appropriate unit for your game

  // Calculate the distance between the hero and zombie4
  const distance = this.state.heroPosition.leftX - this.state.zombie4Position.leftX;

  // If zombie4 is near the Hero, set its current action to Attack
  if (150 < distance && distance < ATTACK_THRESHOLD) {

   // Assuming zombie4 has a method to update its action
   this.setZombie4Action('Attack'); // Replace 'Attack' with actual ActionType for attacking
  } else {
   // Otherwise, set it back to whatever action it should be doing when not attacking
   if (this.state.zombie4Action === 'Attack') {
    this.setZombie4Action('Walk'); // Replace 'Walk' with actual ActionType for walking
   }
  }

  // Update the state or force a re-render if necessary, depending on how your animation loop is set up
  // this.setState({ ... }); or this.forceUpdate();
 }

 setZombie4Action(action: ActionType) {
  this.setState({ zombie4Action: action });
 }

 setParallaxLayers() {
  const layers = getParallaxLayers(this.state.currentLevel);
  this.setState({ layers });
 }

 updateCharacterAndBackground(_context: CanvasRenderingContext2D) {
  const canvasCenterX = this.props.canvasWidth * this.heroXPercent;
  const characterReachThreshold = canvasCenterX;

  // const heroDx
  //  = this.heroActions
  //   ? this.heroActions[this.state.heroAction].dx / 4
  //   : 0;

  let newBackgroundOffsetX = this.state.backgroundOffsetX;

  // Update character position as usual
  const newHeroPositionX = canvasCenterX;

  // Check if the hero reaches the threshold
  if (newHeroPositionX >= characterReachThreshold) {
   this.isInScrollMode = true;

   // Update the background offset
   // newBackgroundOffsetX += heroDx;

   this.setState({
    heroPosition: { ...this.state.heroPosition, leftX: characterReachThreshold },
    backgroundOffsetX: newBackgroundOffsetX, // Update background offset state
   });

   // this.updateBackgroundPosition(this.state.backgroundOffsetX + heroDx);
   // if (this.zombie4Actions) {
   //  const newX = this.state.zombie4Position.leftX - heroDx;
   //  this.setState({ zombie4Position: { ...this.state.zombie4Position, leftX: newX } });
   // }

  } else {
   this.setState({ heroPosition: { ...this.state.heroPosition, leftX: newHeroPositionX } });
  }
  if (this.heroRef.current && _context) {
   this.heroRef.current.draw(_context, this.state.heroPosition);
  }
  if (this.zombie4Ref.current && _context) {
   this.zombie4Ref.current.draw(_context, this.state.zombie4Position);
  }

 }

 startAnimationLoop(context: CanvasRenderingContext2D) {
  const frameDelay = 100; // Delay in milliseconds (100ms for 10 FPS)
  let lastFrameTime = 0; // Time at which the last frame was processed

  const loop = (timestamp: number) => {
   if (!this.gameTime) {
    this.gameTime = timestamp; // Initialize gameTime on the first animation frame
    lastFrameTime = timestamp; // Initialize lastFrameTime on the first frame
   }

   // Calculate the time elapsed since the last frame
   const timeElapsed = timestamp - lastFrameTime;

   if (timeElapsed >= frameDelay) {
    // Update lastFrameTime to the current timestamp
    lastFrameTime = timestamp - (timeElapsed % frameDelay);

    // Get the parallax layers for the current level

    // Draw the parallax background layers
    // context.save();
    context.clearRect(0, 0, this.props.canvasWidth, this.props.canvasHeight);
     
    this.state.layers.forEach(layer => {
     drawParallaxLayer(context, layer, this.state.backgroundOffsetX, this.props.canvasWidth, this.props.canvasHeight, this.image);
    });

    if (this.state.isPhraseComplete) {
     this.drawScrollingText(context);
    }
    // Reset globalAlpha if other drawings should not be affected
    context.globalAlpha = 1.0;

    this.updateCharacterAndBackground(context);
    // context.restore();

    // Save the request ID to be able to cancel it
    this.checkProximityAndSetAction();
   };

   this.animationFrameIndex = requestAnimationFrame(loop);
  };

  // Start the animation loop
  this.animationFrameIndex = requestAnimationFrame(loop);
 }

 // Call this method when both characters are ready to draw
 maybeStartAnimationLoop() {
  if (this.state.context && this.state.heroReady && this.state.zombie4Ready) {
   this.startAnimationLoop(this.state.context);
  }
 }
 stopAnimationLoop() {
  if (this.animationFrameIndex) {
   cancelAnimationFrame(this.animationFrameIndex);
   this.animationFrameIndex = undefined;
   console.log("stopAnimationLoop");
  }
 }

 handleHeroPositionChange = (newPosition: SpritePosition) => {
  this.setState({ heroPosition: newPosition });
 };

 handleZombie4PositionChange = (newPosition: SpritePosition) => {
  this.setState({ zombie4Position: newPosition });
 }

 // Additional methods for calculating WPM, updating the progress bar, etc.
 render() {
  return (
   <>
    <canvas
     ref={this.canvasRef}
     width={this.props.canvasWidth}
     height={this.props.canvasHeight}>
    </canvas>
    <Level
     level={this.state.currentLevel}
     canvasWidth={this.props.canvasWidth}
     canvasHeight={this.props.canvasHeight}
     backgroundOffsetX={this.state.backgroundOffsetX}
     canvasRef={this.canvasRef}
    />
    <Hero
     ref={this.heroRef}
     currentActionType='Idle'
     scale={2}
    />
    <Zombie4
     ref={this.zombie4Ref}
     currentActionType='Walk'
     scale={2}
    />
   </>
  );
 }
}

Codeium at 10:40 am, Jun 11, 2024

Given the code snippet for TerminalGame.tsx, the flickering of Hero and Zombie4 characters and the slow expansion of DOM Nodes could likely be attributed to a few potential issues:

  1. Unnecessary Renders and Reconciliation: The Hero and Zombie4 components are being rendered within TerminalGame's render method. If these components internally manage their own state or have side effects that cause them to re-render independently of TerminalGame, this could cause flickering. Ensure that the props passed to Hero and Zombie4 do not change unnecessarily between renders, triggering unwanted updates.

  2. Canvas State Management: You are manipulating the canvas directly within your animation loop and other methods like drawScrollingText. Direct manipulation of canvas should be done with care to ensure it's not causing flickering. Flickering can occur if the canvas is being cleared (context.clearRect) or drawn to in a way that doesn't align with the browser's repaint cycle.

  3. Animation Loop Control: Make sure the animation loop is properly managed. It looks like you are correctly starting and stopping the animation loop in componentDidMount, componentDidUpdate, and componentWillUnmount. However, if there are any conditions where startAnimationLoop could be called multiple times without the previous loop being canceled, it could result in overlapping animation frames, which might cause flickering.

  4. Image Loading and Drawing: You're using a single Image instance (this.image) for all the layers in drawParallaxLayer. If drawParallaxLayer is called before an image is loaded, it could cause flickering or missing images as they load asynchronously. You should ensure that images are fully loaded before they are drawn to the canvas.

  5. DOM Nodes Expansion: If you are noticing a continuous increase in the number of DOM nodes, it could be due to components being mounted without a corresponding unmount, or due to memory leaks where references to DOM nodes are not released. Use the browser's developer tools to inspect the DOM and see if components are being duplicated or if nodes are not being cleaned up properly.

  6. Component Update Performance: If Hero and Zombie4 components are complex and take significant time to render, consider optimizing their rendering or using React.memo to prevent unnecessary re-renders.

  7. Proper Cleanup in Effects/Hooks: Ensure that any effects or hooks in Hero, Zombie4, or any other child components have proper cleanup to prevent memory leaks or unintended behavior.

Without the code for Hero and Zombie4, it's difficult to pinpoint the exact cause of the flickering, but reviewing the above points and considering how these components interact with TerminalGame should help identify the problem. Use profiling tools available in the browser's developer tools to analyze performance and rendering bottlenecks.

User at 11:18 am, Jun 11, 2024

I would like to address each of those issues which apply.

Item 1. Each character passes it's draw function down to the Sprite.draw function, but I don't think it is updating any other state that needs to be rerendered, but I am new to React so I could be wrong.

import { useEffect, useRef, useState } from 'react';
import { Sprite } from './sprites/Sprite';
import { SpriteAnimation } from './types/SpriteTypes';
import { Action, ActionType } from './types/ActionTypes';
import { SpriteManager } from './sprites/SpriteManager';
import { SpritePosition } from './types/Position';

interface BaseCharacterProps {
 currentActionType: ActionType;
 actions: Record<ActionType, Action>;
 name: string;
 scale: number;
}

export const useBaseCharacter = (props: BaseCharacterProps) => {
 const [, setSprite] = useState<Sprite | null>(null);
 const spriteManager = new SpriteManager();
 const animationFrameId = useRef<number | null>(null);
 const previousActionTypeRef = useRef<ActionType>(props.currentActionType);
 const frameIndexRef = useRef<number>(0);
 const spritesRef = useRef<Record<ActionType, Sprite | undefined>>({} as Record<ActionType, Sprite | undefined>);

 const loadSprite = async (actionKey: ActionType, animationData: SpriteAnimation) => {
  const loadedSprite = await spriteManager.loadSprite(animationData);
  if (loadedSprite) {
   // Update the sprites ref with the new loaded sprite
   spritesRef.current[actionKey] = loadedSprite;
   // If the actionKey is still the current action, update the sprite state
   if (actionKey === props.currentActionType) {
    setSprite(loadedSprite);
   }
  }
 };

 const loadActions = () => {
  Object.entries(props.actions).forEach(([actionKey, actionData]) => {
   loadSprite(actionKey as ActionType, actionData.animation);
  });
 };

 useEffect(() => {
  loadActions();
  // Assuming you need to handle animation
  // startAnimation();
  return () => {
   if (animationFrameId.current !== null) {
    cancelAnimationFrame(animationFrameId.current);
   }
  };
  // Did-mount and will-unmount only
  // TODO: Clean up animation frame, etc.

 }, []);

 useEffect(() => {
  // Update the sprite for the current action type
  const currentSprite = spritesRef.current[props.currentActionType];
  if (currentSprite) {
   // If the sprite is already loaded, use it
   setSprite(currentSprite);
  } else {
   // If the sprite is not loaded, load it and update the ref
   loadSprite(props.currentActionType, props.actions[props.currentActionType].animation);
  }
 }, [props.currentActionType, props.actions]);

 useEffect(() => {
  // Set the current action type
  if (props.name.toLocaleLowerCase() === 'hero')
   setCurrentActionType(props.currentActionType);

  // Specify how to clean up after this effect
  return () => {
   console.log('BaseCharacter Cleanup called');
  };
 }, [props.currentActionType]);

 useEffect(() => {
  const sprite = spritesRef.current[props.currentActionType];
  if (sprite && sprite.frameCount) {
   if (props.currentActionType !== previousActionTypeRef.current) {
    frameIndexRef.current = 0;
   } else {
    incrementFrameIndex();
   }
  }

  // Remember the previous action type for the next call
  previousActionTypeRef.current = props.currentActionType;

  // This effect should run every time the action type changes or the sprite animation needs to be updated
 }, [props.currentActionType, props.actions]);

 const setCurrentActionType = (newActionType: ActionType) => {
  if (props.currentActionType === newActionType) return
  // Update the current action
  props.currentActionType = newActionType;
  frameIndexRef.current = 0;
  // Update the current sprite to match the new action
  const sprite = spritesRef.current[newActionType];
  if (sprite) {
   setSprite(sprite);
  } else {
   console.error(`Sprite not found for action type: ${newActionType}`);
  }
 }

 const incrementFrameIndex = () => {
  const sprite = spritesRef.current[props.currentActionType];
  if (sprite) {
   const nextFrameIndex = (frameIndexRef.current + 1) % sprite.frameCount;
   frameIndexRef.current = nextFrameIndex; // Update the ref's current value
  }
 };

 const draw = (
  context: CanvasRenderingContext2D, 
  position: SpritePosition, 
  scale: number | null
 ) =>{
  const sprite = spritesRef.current[props.currentActionType];
  incrementFrameIndex();
  // if(props.name.toLocaleLowerCase() === 'zombie4') console.log("zombie4", frameIndexRef.current)
  if (sprite) {
   sprite.draw(
    context,
    frameIndexRef.current,
    position.leftX,
    position.topY,
    scale ?? props.scale
   );
  }
 }

 return {
  draw
 };
};

Maybe instead of passing the draw requtest down, I could pass the image up and let the game loop render it, but I don't know if that would help.

Codeium at 11:18 am, Jun 11, 2024

The useBaseCharacter hook manages sprite loading and animation frame updates without directly causing re-renders of your Hero and Zombie4 components. The draw function is called to render the current sprite on the canvas, and it's not a typical cause for React re-renders since it doesn't affect React's virtual DOM.

Here are a few considerations and suggestions that might help:

  1. React State Updates: The useState hook is used to store the current sprite, but the setter (setSprite) is only called when a new sprite is loaded or when the action type changes. This should not cause unnecessary re-renders if the action type isn't changing often.

  2. Animation Frame Management: You have an animationFrameId ref that is used to keep track of the request animation frame ID. Make sure that startAnimation (which is commented out) correctly uses this ref to prevent multiple animation loops from running concurrently, which could cause flickering.

  3. Sprite Loading: The loadSprite function is called asynchronously within useEffect hooks. Ensure that the loaded sprites are cached and not reloaded unnecessarily, which could cause flickering as images load.

  4. Separation of Concerns: The draw function provided by useBaseCharacter is responsible for drawing the character, which is typical in canvas-based rendering. Passing the image up to the game loop wouldn't necessarily help with rendering performance or flickering, as the draw method is the appropriate place for this logic. However, you should ensure that the canvas drawing operations are synchronized with the browser's repaint cycles to prevent flickering.

  5. Props Stability: Verify that the props passed to Hero and Zombie4 are stable between renders. If these props are causing the components to re-render unnecessarily, it could contribute to flickering. Consider using React.memo for functional components or shouldComponentUpdate for class components to avoid unnecessary updates.

  6. Canvas Context Management: Ensure that the canvas context (context) is not being modified unnecessarily between frames. Also, check that global canvas state changes (like context.globalAlpha) are properly reset after each draw call to prevent unexpected state carryover.

  7. Debugging Flickering: If the characters are flickering, you can try commenting out parts of your rendering code to isolate the cause. For example, you can temporarily remove the parallax background rendering to see if the issue persists with just the characters being rendered.

Regarding memory usage and DOM node expansion, since the canvas drawing operations don't interact with the DOM directly, the issue may lie elsewhere in your application. If you're creating new elements or components without removing them properly, that could lead to a continuous increase in DOM nodes. Use the browser's developer tools to inspect the DOM and monitor the memory usage over time.

Remember that in a complex React application, performance issues and flickering can be caused by a combination of factors, so you might need to consider a holistic review of your app's rendering logic and optimize accordingly.

User at 11:24 am, Jun 11, 2024

I believe the SpriteManager is using cached images:

import { Sprite } from './Sprite';
import { SpriteAnimation } from '../types/SpriteTypes';

export class SpriteManager {
  private spriteCache = new Map<string, Sprite>();

  public async loadSprite(animationData: SpriteAnimation): Promise<Sprite> {
    if (this.spriteCache.has(animationData.imagePath)) {
      const cachedSprite = this.spriteCache.get(animationData.imagePath);
      if (cachedSprite !== undefined) {
        return cachedSprite;
      }
    }

    const sprite = new Sprite(animationData.imagePath, animationData.frameCount, animationData.frameWidth, animationData.frameHeight, animationData.framePositions);
    await this.waitForManagerImageLoad(sprite.image);

    this.spriteCache.set(animationData.imagePath, sprite);
    return sprite;
  }

  private waitForManagerImageLoad(image: HTMLImageElement): Promise<void> {
    return new Promise((resolve) => {
      const onLoad = () => {
        // Cleanup: Remove both event listeners
        image.removeEventListener('load', onLoad);
        image.removeEventListener('error', onError);
        resolve();
      };

      const onError = () => {
        // Cleanup: Remove both event listeners
        image.removeEventListener('load', onLoad);
        image.removeEventListener('error', onError);
        console.error('Image failed to load: ' + image.src);
        // reject(new Error(`Image failed to load: ${image.src}`));
      };

      // Attach the event listeners
      image.addEventListener('load', onLoad);
      image.addEventListener('error', onError);
    });
  }
}

I don't know if it is doing that optimally, since I've made many changes since creating this.

Codeium at 11:25 am, Jun 11, 2024

The SpriteManager class you've provided does appear to implement caching for images:

  1. It checks for the existence of a Sprite in spriteCache using the imagePath as a key.
  2. If a cached Sprite is found, it is returned immediately without loading the image again.
  3. If the Sprite is not found in the cache, it creates a new Sprite, waits for the image to load, and then stores it in the spriteCache.

This approach should help to prevent unnecessary network requests and image loading, which can improve performance. However, there are a couple of things to consider for further optimization and correctness:

  • Memory Management: Depending on the number of different sprites and the size of their images, you might want to be mindful of memory usage. If the game uses a large number of sprites, you might eventually run into memory pressure. Consider implementing a cache eviction strategy if memory usage becomes a concern.

  • Error Handling: The onError function logs an error to the console, but it doesn't reject the promise returned by waitForManagerImageLoad. This means that if an image fails to load, the promise will neither resolve nor reject, potentially leaving the loadSprite function hanging indefinitely. You should uncomment the reject line or handle the error in a way that doesn't leave the promise in limbo.

Here's a suggestion to handle errors properly:

private waitForManagerImageLoad(image: HTMLImageElement): Promise<void> {
  return new Promise((resolve, reject) => {
    const onLoad = () => {
      // Cleanup: Remove both event listeners
      image.removeEventListener('load', onLoad);
      image.removeEventListener('error', onError);
      resolve();
    };

    const onError = () => {
      // Cleanup: Remove both event listeners
      image.removeEventListener('load', onLoad);
      image.removeEventListener('error', onError);
      console.error('Image failed to load: ' + image.src);
      reject(new Error(`Image failed to load: ${image.src}`)); // Reject the promise on error
    };

    // Attach the event listeners
    image.addEventListener('load', onLoad);
    image.addEventListener('error', onError);
  });
}

By rejecting the promise on error, you allow the calling code to handle the failure appropriately, such as by retrying the load or providing a fallback image. It's also important to ensure that loadSprite properly handles the promise rejection to avoid unhandled promise rejections.

Overall, your SpriteManager seems to be set up well for caching and reusing sprites, which should help to prevent flickering caused by repeated image loading.

User at 11:27 am, Jun 11, 2024

How would I do this recommendation of yours?

"However, you should ensure that the canvas drawing operations are synchronized with the browser's repaint cycles to prevent flickering."

Codeium at 11:28 am, Jun 11, 2024

To ensure that canvas drawing operations are synchronized with the browser's repaint cycles, you should use the requestAnimationFrame (rAF) API. This method tells the browser that you wish to perform an animation and requests that the browser call a specified function to update an animation before the next repaint.

Your code snippet already uses requestAnimationFrame within the startAnimationLoop method, which is the correct approach. Here are some tips to ensure that it is used effectively:

  1. Single rAF Call per Frame: Ensure that you only have one call to requestAnimationFrame per frame. Multiple calls can lead to multiple frames being scheduled, which could cause flickering or performance issues.

  2. Update Logic Inside rAF Callback: Perform your drawing and state update logic inside the rAF callback. This ensures that your updates are timed with the browser's repaint cycle.

  3. Timing Control: For games or animations that do not need to run at 60 FPS (the typical refresh rate that rAF targets), you can control the timing by calculating the elapsed time since the last frame and only updating the visuals when necessary. Your startAnimationLoop method already includes logic for this using frameDelay.

  4. Proper Cleanup: When the component unmounts or you need to stop the animation for any reason, use cancelAnimationFrame to cancel the animation frame request. This prevents the callback from being called after the component is no longer in use.

  5. Minimize Work Per Frame: Keep the amount of work done in each frame to a minimum to ensure that drawing operations can complete quickly and do not cause delays.

  6. Avoid Unnecessary State Changes: Any state changes that trigger re-renders of React components should be minimized during the animation. Use refs to store values that change frequently between frames instead of state if they do not need to trigger re-renders.

Here's a simplified example of using requestAnimationFrame:

startAnimationLoop(context: CanvasRenderingContext2D) {
  let lastFrameTime = performance.now(); // use performance.now() for higher accuracy

  const loop = () => {
    const now = performance.now();
    const deltaTime = now - lastFrameTime;

    if (deltaTime >= frameDelay) { // Control the frame rate
      lastFrameTime = now - (deltaTime % frameDelay);

      // Clear the canvas
      context.clearRect(0, 0, this.props.canvasWidth, this.props.canvasHeight);

      // Update game state and draw
      this.updateGameState();
      this.drawGame(context);
    }

    this.animationFrameIndex = requestAnimationFrame(loop); // Schedule the next frame
  };

  this.animationFrameIndex = requestAnimationFrame(loop); // Start the loop
}

By following these guidelines, you can help ensure that your animation is smooth and flicker-free.

User at 2:22 pm, Jun 11, 2024

Can I create two canvases and place one in fronte of the other. so the background could be a different canvas?

Codeium at 2:22 pm, Jun 11, 2024

Yes, you can use multiple canvases layered on top of each other to separate different parts of your scene, such as foreground and background. This technique is often used for optimization because it allows you to redraw only the parts of the scene that change frequently, leaving the rest static.

To layer canvases, you can position them absolutely within a relative container, ensuring they overlap perfectly. Here's a simple example of how you can structure your HTML to layer two canvases:

<div style="position: relative;">
  <canvas id="backgroundCanvas" style="position: absolute; left: 0; top: 0; z-index: 1;"></canvas>
  <canvas id="foregroundCanvas" style="position: absolute; left: 0; top: 0; z-index: 2;"></canvas>
</div>

In your React component, it might look something like this:

render() {
  return (
    <div style={{ position: 'relative' }}>
      <canvas
        ref={this.backgroundCanvasRef}
        width={this.props.canvasWidth}
        height={this.props.canvasHeight}
        style={{ position: 'absolute', left: 0, top: 0, zIndex: 1 }}
      />
      <canvas
        ref={this.foregroundCanvasRef}
        width={this.props.canvasWidth}
        height={this.props.canvasHeight}
        style={{ position: 'absolute', left: 0, top: 0, zIndex: 2 }}
      />
      {/* Other components */}
    </div>
  );
}

And in your React component class, you would have:

private backgroundCanvasRef = React.createRef<HTMLCanvasElement>();
private foregroundCanvasRef = React.createRef<HTMLCanvasElement>();

With this setup, you can draw the background once (or only when necessary) on the backgroundCanvas. The foregroundCanvas can be used for elements that change often, such as characters, UI elements, or animations.

Using multiple canvases can be beneficial for performance, but it's important to remember that each additional canvas does consume more memory. Therefore, you should balance the number of canvases with the needs of your application.

User at 2:35 pm, Jun 11, 2024

ok, now I am wondering why, in all this dicussion of helping me optimize the rendering of the background and the foreground elements, you never mentioned multiple canvases.

Did that seem to be beyond the scope of the discussion to you?

I am asking so that I might be able to inprove my questions in the future so that we have more fruitfull discussions and hopefully avoid these days-long detours.

Codeium at 2:35 pm, Jun 11, 2024

My apologies for not mentioning the use of multiple canvases earlier. The conversation initially focused on specific issues such as flickering and performance concerns within the single canvas setup you were using. The discussion aimed to address those direct concerns with the existing structure of your application.

Multiple canvases can indeed be a useful optimization technique, and it's a valid approach to consider when designing or refactoring a game's rendering architecture. The reason it wasn't brought up initially could be due to the focus on addressing the immediate concerns you presented with the current single-canvas implementation. The intent was to help optimize and troubleshoot within the given context before suggesting a structural change to the rendering approach.

For future discussions, if you're open to broader architectural changes or optimizations, it can be helpful to indicate that in your questions. For example, you could ask, "Are there alternative rendering strategies, such as using multiple canvases, that could help optimize my game's performance?" This signals that you're open to considering more fundamental changes beyond fixing issues within the current approach.

Again, I apologize for any oversight. It's always my goal to provide the most useful and relevant information based on your questions and the context of the conversation. If you have further questions or need assistance with implementing multiple canvases or any other aspect of your project, please feel free to ask.

User at 2:43 pm, Jun 11, 2024

I didn't know about the multiple canvas option, so it would be unlikely that I would have mentioned it.

I can see from the converstaion history that it appears I was probably leading the conversation design decisions and I could probably try to invite more architectural-level analysis.

Codeium at 2:43 pm, Jun 11, 2024

Absolutely, it's a collaborative process, and I'm here to assist with both detailed technical issues and broader architectural discussions. When tackling complex projects like game development, it's common to start with specific questions that lead to deeper exploration of various solutions.

In future discussions, feel free to ask open-ended questions that invite architectural-level analysis. You could ask questions like:

  • "Are there any design patterns or architectural improvements you recommend for my game's rendering engine?"
  • "What are some performance optimization strategies for canvas-based games in React?"
  • "Could you suggest best practices for structuring a game loop in a React application?"

By framing your questions to allow for a wider range of suggestions, you'll likely receive a broader set of options to consider, including ones you may not be aware of, like using multiple canvases.

Remember, there's always a trade-off between refining the current approach and considering new architectural changes. Both are valid strategies, and sometimes it takes a bit of back-and-forth discussion to arrive at the best solution.

If you have any more questions or need further clarification on any topic, whether it's specific or architectural, please don't hesitate to ask. I'm here to help guide you through the decision-making process to find the best solutions for your project's needs.

User at 7:58 pm, Jun 11, 2024

The background canvas idea is now making me wonder if it might not be more efficient to make each layer of the parallax background a different canvas, or to make the background a simple <div> element with repeating x-dimmension.

Is there any reason to believe one of theose options might be more efficient?

Codeium at 7:59 pm, Jun 11, 2024

The decision to use multiple canvases versus CSS and <div> elements for a parallax background largely depends on the complexity of your background, the performance characteristics you need, and the ease of development. Here are some considerations for each approach:

Multiple Canvases

  • Pros:

    • Canvases are great for complex animations and interactive graphics.
    • They offer fine-grained control over every pixel, which can be necessary for certain visual effects.
    • Canvases can handle dynamic drawing and transformations more efficiently than DOM manipulation.

  • Cons:

    • Each canvas element may consume more memory and CPU resources, especially if many canvases are used.
    • Managing multiple canvases can add complexity to your code.
    • Canvases don't benefit from hardware acceleration in the same way CSS does.

CSS and <div> Elements

  • Pros:

    • CSS is optimized for layout and rendering performance and can take advantage of hardware acceleration.
    • Simple to implement, especially for static or repeating images.
    • More efficient memory usage when dealing with static elements or images.
    • The browser's layout engine can handle complex compositions with less manual work.

  • Cons:

    • Less control over pixel-level details compared to canvas.
    • Not suitable for complex animations that require redrawing many elements frequently.
    • Overuse of layered elements and transparency can lead to performance issues on some devices.

Which is more efficient?

For static or slowly moving backgrounds, using CSS and <div> elements with background images can be more efficient and easier to manage. This is because the browser can optimize the rendering of these elements, and you can benefit from hardware acceleration for smooth animations.

If your parallax background consists of simple repeating images, CSS with background images set to background-repeat: repeat-x; could be a very efficient solution. This approach is also responsive and can adapt to different screen sizes with relative ease.

However, if you need more dynamic, interactive, or complex animations within your parallax layers, using separate canvases for each layer might be the better choice. You can then redraw only the canvases that need updates, which can be more efficient than redrawing a single canvas with all the content.

Conclusion

Before deciding, consider testing both approaches to see which performs better for your specific scenario. Use browser profiling tools to measure memory usage, CPU load, and rendering performance. Efficiency can vary based on the number of elements, the complexity of animations, and the browsers or devices you are targeting.

In summary, for a simple parallax background with static or repeating images, CSS and <div> elements are often more efficient. For more complex or interactive backgrounds, multiple canvases may offer the necessary control and performance. Always profile and test to make the best decision for your project.

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