2024 06 10 user converting class components to hooks dealing with ref forwarding - bizkite-co/handterm GitHub Wiki

original file name: Codeium Chat - kDP2MeVdoorqUxPvTDPvQH25GenbUnUb.md summary: The chat began with the user wanting to convert their Hero.tsx and Zombie.tsx class components into functional components that use hooks such as useBaseCharacter. They needed to access the list of actions and the current sprite from these components in order to invoke the draw method on the current sprite from the TerminalGame component.

The chat then delved into utilizing forwardRef and useImperativeHandle to expose specific methods from the functional components to the parent component. The user encountered errors regarding returning JSX from the functional components and handling the possibility of baseCharacter being null.

Lastly, the user asked about the working of forwardRef in detail. The assistant explained that forwardRef allows the passing of a ref through a component to one of its children, enabling the access of child components' DOM nodes or instances from parent components. The steps and reasons behind using forwardRef in the context of the chat were outlined for better understanding. date: 2024-06-10T16:25

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 4:25 pm, Jun 10, 2024

I am in the process of converting my Hero.tsx and Zombie.tsx into functional components that use useBaseCharacter instead of classes that inherited from BaseCharacter class component, as they had done.

I need to get the list of Actions from the Hero and Zombie, and I need to get their current sprite, so that I can invoke the draw method on the current sprite from the TerminalGame.

How can the TerminalGame refer to these?

    <Hero
     ref={this.heroRef}
     currentActionType={this.props.heroAction}
     onGetSprites={this.onGetHeroSprites}
     onGetActions={this.onGetHeroActions}
    />
    <Zombie4
     ref={this.zombie4Ref}
     currentActionType={this.props.zombie4Action}
     onGetSprites={this.onGetZombie4Sprites}
    />

Codeium at 4:25 pm, Jun 10, 2024

Since you're using functional components for Hero and Zombie4, you should consider using React hooks such as useImperativeHandle in conjunction with forwardRef to expose specific methods to the parent TerminalGame component. The methods you expose can be used to get the list of actions and the current sprite.

Here's an example of how you might modify Hero and Zombie4 to use forwardRef and useImperativeHandle:

import React, { useImperativeHandle, forwardRef } from 'react';

// In Hero.tsx
export const Hero = forwardRef((props, ref) => {
  const baseCharacter = useBaseCharacter({
    // ...props and other setup
  });

  useImperativeHandle(ref, () => ({
    getCurrentSprite: () => baseCharacter.getCurrentSprite(),
    getActions: () => baseCharacter.getActions(),
  }));

  // ...rest of the component
});

// In Zombie4.tsx
export const Zombie4 = forwardRef((props, ref) => {
  const baseCharacter = useBaseCharacter({
    // ...props and other setup
  });

  useImperativeHandle(ref, () => ({
    getCurrentSprite: () => baseCharacter.getCurrentSprite(),
    getActions: () => baseCharacter.getActions(),
  }));

  // ...rest of the component
});

In the TerminalGame component, you can now call these methods:

// Assuming you've created refs using React.createRef()
const heroSprite = this.heroRef.current?.getCurrentSprite();
const heroActions = this.heroRef.current?.getActions();
const zombieSprite = this.zombie4Ref.current?.getCurrentSprite();
const zombieActions = this.zombie4Ref.current?.getActions();

// You can now use these in your game logic and call the draw method
heroSprite?.draw();
zombieSprite?.draw();

Please ensure that the useBaseCharacter hook provides getCurrentSprite and getActions methods that return the current sprite and the list of actions, respectively. Adjust the names and implementation details based on your actual code structure and naming conventions.

User at 4:49 pm, Jun 10, 2024

I am getting this error:

Argument of type '(props: ICharacterProps, ref: ForwardedRef<unknown>) => void' is not assignable to parameter of type 'ForwardRefRenderFunction<unknown, ICharacterProps>'.
  Type 'void' is not assignable to type 'ReactNode'.ts(2345)
Codeium: Explain Problem
⚠ Error (TS2345)  | 
Argument of type:(                             
  props: ICharacterProps,     
  ref: ForwardedRef<unknown>  
) => void                     
is not assignable to parameter of type  ForwardRefRenderFunction<unknown, ICharacterProps> 
 .   
Type  void 
 is not assignable to type  ReactNode 
 .
(alias) interface ICharacterProps
import ICharacterProps

on this code:

// Hero.tsx

import { useBaseCharacter } from "./useBaseCharacter";
import { HeroActions } from "./types/ActionTypes";
import { ICharacterProps } from "./ICharacterProps";
import { forwardRef, useImperativeHandle } from "react";

export const getActions = () => {
 return HeroActions;
}

export const Hero = forwardRef((props: ICharacterProps, ref) => {

 // Use the custom hook for shared logic with BaseCharacter
 const baseCharacter = useBaseCharacter({
  actions: HeroActions,
  currentActionType: props.currentActionType, // Replace with actual default action
  name: 'Hero',
  onGetSprites: props.onGetSprites,
 });

 useImperativeHandle(ref, () => ({
  getCurrentSprite: () => baseCharacter.getCurrentSprite(),
  getActions: () => baseCharacter.getActions(),
 }));

});

Codeium at 4:50 pm, Jun 10, 2024

The error is indicating that your Hero component is not returning anything (void), but it should return a valid React element (ReactNode). When using forwardRef, the component must return renderable JSX.

To fix this, make sure you return some JSX from your Hero component. If the component doesn't render anything itself, you can return null or some placeholder. Here's an example fix:

// Hero.tsx

import React, { useBaseCharacter } from "./useBaseCharacter";
import { HeroActions } from "./types/ActionTypes";
import { ICharacterProps } from "./ICharacterProps";
import { forwardRef, useImperativeHandle } from "react";

export const getActions = () => {
  return HeroActions;
}

export const Hero = forwardRef((props: ICharacterProps, ref) => {

  // Use the custom hook for shared logic with BaseCharacter
  const baseCharacter = useBaseCharacter({
    actions: HeroActions,
    currentActionType: props.currentActionType,
    name: 'Hero',
    onGetSprites: props.onGetSprites,
  });

  useImperativeHandle(ref, () => ({
    getCurrentSprite: () => baseCharacter.getCurrentSprite(),
    getActions: () => baseCharacter.getActions(),
  }));

  // If the Hero component does not render anything, return null.
  return null;
});

This should resolve the TypeScript error you're encountering. Make sure your useBaseCharacter hook provides the getCurrentSprite and getActions methods and that they return the correct types.

User at 4:51 pm, Jun 10, 2024

I am also getting this error on the same code:

'baseCharacter' is possibly 'null'.ts(18047)
Codeium: Explain Problem
⚠ Error (TS18047) | 
baseCharacter is possibly  null 
 .
const baseCharacter: null
View Problem (Alt+F8)
No quick fixes available

Codeium at 4:52 pm, Jun 10, 2024

This error suggests that the useBaseCharacter hook might return null under certain conditions, and TypeScript is warning you that you're trying to access properties or methods on a value that could potentially be null.

To address this, you should ensure that baseCharacter is not null before trying to use it. You can add a guard to check if baseCharacter is not null before using it inside useImperativeHandle. Here's how you might adjust your code:

// Hero.tsx

// ... (other imports)
import { forwardRef, useImperativeHandle } from "react";

// ... (rest of your component)

export const Hero = forwardRef((props: ICharacterProps, ref) => {
  // Use the custom hook for shared logic with BaseCharacter
  const baseCharacter = useBaseCharacter({
    // ... (props setup)
  });

  useImperativeHandle(ref, () => ({
    getCurrentSprite: () => baseCharacter ? baseCharacter.getCurrentSprite() : null,
    getActions: () => baseCharacter ? baseCharacter.getActions() : null,
  }));

  // ... (rest of your component)

  return null; // or your JSX here
});

By using the ternary operator ? :, you're saying "if baseCharacter is not null, call the method, otherwise return null". This ensures that you're not trying to call a method on a null value.

Make sure to check the logic within useBaseCharacter to understand why it might return null and handle those cases appropriately within your component. If useBaseCharacter should never return null, you might need to refactor it to always return a valid object with the necessary methods.

User at 4:56 pm, Jun 10, 2024

How do I add getCurrentSprite to this?

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';

interface BaseCharacterProps {
 currentActionType: ActionType;
 actions: Record<ActionType, Action>;
 name: string;
 onGetSprites: () => Record<ActionType, Sprite>;
}

export const useBaseCharacter = (props: BaseCharacterProps) => {
 const [ sprite, 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 actionsRef = useRef<Record<ActionType, Action>>();
 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 onGetSprites = () => {
  // Just return the current sprite
  let spriteFromSprites = spritesRef.current[props.currentActionType];
  return spriteFromSprites;
 }

 // const draw(frameIndex: number, position: SpritePosition) {
 //  const sprite = spritesRef.current[props.currentActionType];
 //  // props.context.clearRect(position.leftX + 30, position.topY, 44, 80);
 //  if (sprite) {
 //   sprite.draw(
 //    props.context,
 //    frameIndex,
 //    position.leftX,
 //    position.topY,
 //    2
 //   );
 //  }
 // }

 return null;
};

Codeium at 4:56 pm, Jun 10, 2024

To add getCurrentSprite to your useBaseCharacter hook, you can simply define it as a function that retrieves the current sprite from the spritesRef based on props.currentActionType. Since you already have a similar function named onGetSprites, you can rename it to getCurrentSprite or use it as is.

Here's how you can add or rename the function:

export const useBaseCharacter = (props: BaseCharacterProps) => {
  // ... existing code ...

  const getCurrentSprite = () => {
    // Just return the current sprite
    let currentSprite = spritesRef.current[props.currentActionType];
    return currentSprite || null; // Return null if the sprite is not found
  };

  // ... rest of your hook ...

  // Instead of returning null, you return an object with the functions you want to expose
  return {
    getCurrentSprite, // Now this can be called from the component using this hook
    // ... any other values or functions you want to expose from this hook ...
  };
};

Now, components that use this hook can call getCurrentSprite to get the sprite for the current action type. Remember to include getCurrentSprite in the returned object from the hook, so it's accessible to the components.

When you use the hook in a component, like in your Hero component, you can now directly call baseCharacter.getCurrentSprite() to get the current sprite. Since you're returning an object from the hook, make sure to check for null to avoid trying to access properties on a null value in the component or when you expose methods through useImperativeHandle.

User at 5:01 pm, Jun 10, 2024

I have more questions but first, could you explain in detail what it is we did by adding forwardRef? How does that work, and how did it help us do what we are doing? It appears to be working, but I want to know all about why it is working.

Codeium at 5:02 pm, Jun 10, 2024

Certainly! forwardRef is a React feature that lets you pass a ref through a component to one of its children. This is useful when you need to access a child's DOM node or React instance directly from a parent component.

When you use forwardedRef, you're creating a higher-order component that can receive a ref as a parameter and then forward it to a child component. It's important to note that you cannot use the ref attribute on functional components because they don't have instances; forwardRef provides a way around this limitation.

Here's a step-by-step explanation of what we did with forwardRef and why it works:

  1. Creating a Ref Forwarding Component: We wrapped the Hero component with forwardRef. This allows the Hero component to receive a ref passed from a parent component, even though Hero is a functional component.

  2. Accessing the Ref Inside the Component: Inside the Hero component, we received this ref as the second argument of the component function. This ref can then be associated with a DOM element or used in useImperativeHandle.

  3. Exposing Specific Methods: We used the useImperativeHandle hook in conjunction with the ref to expose specific methods (getCurrentSprite and getActions) to the parent component. This is useful when you want the parent to access specific functionality of the child component but don't want to expose the entire instance.

  4. Using the Exposed Methods in the Parent Component: In the parent component (TerminalGame), when we render Hero, we can assign a ref (created by React.createRef() or useRef()). Thanks to forwardRef and useImperativeHandle, we can call the methods we exposed (ref.current.getCurrentSprite() and ref.current.getActions()) directly from the parent component.

The useImperativeHandle hook customizes the instance value that is exposed when using ref. Without useImperativeHandle, the ref would point to the default value, which is the DOM node in the case of DOM elements, or null for functional components. By using useImperativeHandle, you have control over what is exposed to the parent component, making it a powerful tool for parent-child interaction.

Here's a simplified example to illustrate the concept:

import React, { forwardRef, useImperativeHandle, useRef } from 'react';

const Child = forwardRef((props, ref) => {
  useImperativeHandle(ref, () => ({
    sayHello: () => {
      console.log('Hello from Child!');
    },
  }));

  return <div>Child Component</div>;
});

const Parent = () => {
  const childRef = useRef();

  const handleClick = () => {
    if (childRef.current) {
      childRef.current.sayHello();
    }
  };

  return (
    <>
      <Child ref={childInteract} />
      <button onClick={handleClick}>Call Child Method</button>
    </>
  );
};

In this example, Parent can call the sayHello method on Child, even though Child is a functional component without an instance. This is made possible by forwardRef and useImperativeHandle.

User at 5:44 pm, Jun 10, 2024

Ok, can you help me understand why this is giving me errors, then?

This is from TerminalGame

 private heroSprite = this.heroRef.current?.getCurrentSprite();
 private heroActions = this.heroRef.current?.getHeroActions();
 private zombieSprite = this.zombie4Ref.current?.getCurrentSprite();
 private zombieActions = this.zombie4Ref.current?.getActions();

which gives error: Property 'getCurrentSprite' does not exist on type '{}'.ts(2339) Codeium: Explain Problem ⚠ Error(TS2339)  |  Property getCurrentSprite does not exist on type {}.

And,

    <Hero
     ref={this.heroRef}
     currentActionType='Idle'
     onGetCurrentSprite={this.getCurrentHeroSprite}
     onGetActions={this.getHeroActions}
    />
    <Zombie4
     ref={this.zombie4Ref}
     currentActionType='Walk'
     onGetCurrentSprite={this.onGetZombie4Sprite}
     onGetActions={this.onGetZombie4Actions}
    />

Which gives error:

Property 'getCurrentSprite' does not exist on type '{}'.ts(2339) Codeium: Explain Problem ⚠ Error(TS2339)  |  Property getCurrentSprite does not exist on type {}. any

Codeium at 5:45 pm, Jun 10, 2024

The TypeScript errors you're encountering indicate that TypeScript doesn't know the specific type of object that heroRef.current and zombie4Ref.current are referring to. By default, ref.current is typed as {} (an empty object), which doesn't have the methods you're trying to call.

To resolve these errors, you need to define an interface that includes the methods you're adding via useImperativeHandle and then use that interface as the type for your refs. Here's how you can do it:

  1. Define an interface that describes the methods you want to call on the ref:
// Define an interface for the ref methods
interface CharacterRefMethods {
  getCurrentSprite: () => Sprite | null;
  getActions: () => Record<ActionType, Action>;
}

// Update your ref definitions with the correct type
private heroRef = React.createRef<CharacterRefMethods>();
private zombie4Ref = React.createRef<CharacterRefMethods>();
  1. Now, when you use these refs, TypeScript will know that heroRef.current and zombie4Ref.current will either be null or an object with the getCurrentSprite and getActions methods, preventing the error.

Regarding the second part, the props onGetCurrentSprite and onGetActions you're trying to pass to Hero and Zombie4 components don't seem to match the expected props defined in ICharacterProps. If you intend to pass callback functions to these components, you should first ensure that ICharacterProps includes these callback properties. If you're trying to call methods on the child components (which seems to be the case), you don't need to pass them as props since you're already using ref to call methods on the child instances.

Here's what the ICharacterProps interface should look like if you want to pass callbacks:

interface ICharacterProps {
  currentActionType: ActionType;
  // Add callback types if necessary
  onGetCurrentSprite?: () => Sprite | null;
  onGetActions?: () => Record<ActionType, Action>;
  // ... other properties
}

But given the context, it seems you're not supposed to pass callbacks, but rather you should use the ref to call methods on the child components directly. So your Hero and Zombie4 usages would be like this:

// You don't need to pass onGetCurrentSprite and onGetActions as props
<Hero
  ref={this.heroRef}
  currentActionType='Idle'
/>
<Zombie4
  ref={this.zombie4Ref}
  currentActionType='Walk'
/>

And you would call getCurrentSprite and getActions elsewhere in your TerminalGame component, probably in a lifecycle method or an event handler after the component has mounted and the refs have been populated.

User at 6:22 pm, Jun 10, 2024

If I want to access these variables in TerminalGame, shouldn't I load them in componentDidMount?

 private heroSprite = this.heroRef.current?.getCurrentSprite();
 private heroActions = this.heroRef.current?.getActions();
 private zombieSprite = this.zombie4Ref.current?.getCurrentSprite();
 private zombieActions = this.zombie4Ref.current?.getActions();

Codeium at 6:22 pm, Jun 10, 2024

Yes, you're correct. Accessing the refs immediately in the constructor or during the initial render will not work because the child components have not been mounted yet, and thus the refs are not populated. To access the methods getCurrentSprite and getActions from the refs, you should do so in the componentDidMount lifecycle method or in a useEffect hook if you were using functional components with hooks.

Here's how you could modify your TerminalGame class component to access these methods in componentDidMount:

class TerminalGame extends React.Component<ITerminalGameProps, ITerminalGameState> {
  private heroRef = React.createRef<CharacterRefMethods>();
  private zombie4Ref = React.createRef<CharacterRefMethods>();

  private heroSprite: Sprite | null = null;
  private heroActions: Record<ActionType, Action> | null = null;
  private zombieSprite: Sprite | null = null;
  private zombieActions: Record<ActionType, Action> | null = null;

  componentDidMount() {
    this.heroSprite = this.heroRef.current?.getCurrentSprite();
    this.heroActions = this.heroRef.current?.getActions();
    this.zombieSprite = this.zombie4Ref.current?.getCurrentSprite();
    this.zombieActions = this.zombie4Ref.current?.getActions();

    // Now you can use this.heroSprite, this.heroActions, etc.
    // Just make sure to check if they are not null before using
  }

  // ... rest of your component ...
}

By moving the assignments to componentDidMount, you ensure that the child components (Hero and Zombie4) have been mounted and that their refs are set. Remember that you might need to handle updates to these properties if the child components update their sprites or actions. In such cases, you would also use the componentDidUpdate lifecycle method to keep these properties in sync.

This pattern assumes that the sprites and actions are not changing frequently. If they do change often, it might be better to call the ref methods (getCurrentSprite and getActions) directly where you need the current sprite and actions, rather than storing them as properties on the TerminalGame class.

User at 7:10 pm, Jun 10, 2024

While I was implementing that, I think I figured out that the TerminalGame doesn't need to know abou the list of character actions or the current sprite if it just calls the draw method exposed by the useBaseCharacter which calls the draw method on the Sprite, which will have the animation information, as long as I pass it the canvas context and the position.

useBaseCharacter:

 const draw = (
  context: CanvasRenderingContext2D, 
  position: SpritePosition
 ) =>{
  const sprite = spritesRef.current[props.currentActionType];
  // props.context.clearRect(position.leftX + 30, position.topY, 44, 80);
  if (sprite) {
   sprite.draw(
    context,
    frameIndexRef.current,
    position.leftX,
    position.topY,
    2
   );
  }
 }

 return {
  getCurrentSprite,
  draw
 };

However, when I try to do this in TerminalGame in the animation loop after the background renders:

  if(this.heroRef.current && this.context) {
   this.heroRef.current.draw(this.context, this.state.heroPosition);
  }
  if(this.zombie4Ref.current && this.context) {
   this.zombie4Ref.current.draw(this.context, this.state.zombie4Position);
  }

The browser tells me:


TerminalGame.tsx:309  
Uncaught TypeError: this.heroRef.current.draw is not a function
    at TerminalGame.updateCharacterAndBackground (TerminalGame.tsx:309:28)
    at loop (TerminalGame.tsx:329:12)

TerminalGame.tsx:309  
Uncaught TypeError: this.heroRef.current.draw is not a function
    at TerminalGame.updateCharacterAndBackground (TerminalGame.tsx:309:28)
    at loop (TerminalGame.tsx:329:12)

Codeium at 7:10 pm, Jun 10, 2024

The error message you're encountering indicates that the draw function is not being correctly exposed to the TerminalGame component via the ref. To ensure that the draw function is accessible, you need to include it in the object returned by useImperativeHandle within your Hero and Zombie4 components.

Here's how you should be using useImperativeHandle in your Hero and Zombie4 components to expose the draw function:

import React, { useImperativeHandle, forwardRef } from 'react';

// Inside your Hero component
const Hero = forwardRef((props, ref) => {
  const { draw, getCurrentSprite } = useBaseCharacter({
    // Props passed to useBaseCharacter
  });

  useImperativeHandle(ref, () => ({
    draw,
    getCurrentSprite,
    // ... any other methods you want to expose
  }));

  // ... rest of the Hero component
  return <div>Hero Component</div>;
});

// The Zombie4 component would have a similar structure

Make sure that you're exposing the draw function in both your Hero and Zombie4 components. Also, ensure that you've updated the CharacterRefMethods interface to include the draw method:

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

After doing this, when you call this.heroRef.current.draw or this.zombie4Ref.current.draw in your TerminalGame component, it should correctly call the draw function provided by the useBaseCharacter hook.

Remember to bind these methods to this or use arrow functions to ensure that the correct this context is used when the methods are called. This is especially important if the methods inside useBaseCharacter rely on this to access other properties or methods of the hook. If you're using arrow functions, as shown in the example above, the context (this) is automatically bound.

User at 7:40 pm, Jun 10, 2024

My app seems to be creating about 1000 DOM Nodes per second now, and not doing much else.

This concerns me.

Codeium at 7:41 pm, Jun 10, 2024

Creating a large number of DOM nodes at such a rate is a red flag for a memory leak or a performance issue, often due to unnecessary re-renders or improper DOM manipulation. Here's a general approach to troubleshoot and address this:

  1. Verify Component Updates: Ensure components are only updating when necessary. Use React.memo for functional components or PureComponent for class components to prevent unnecessary re-renders.

  2. Check for Imperative DOM Manipulations: If you're manipulating the DOM directly (outside of React's rendering cycle), ensure that you properly clean up created nodes. For instance, if you create DOM nodes in a useEffect without cleaning them up, they can accumulate.

  3. Use Keys in Lists: When rendering lists, always use unique and stable keys for each item to help React identify which items have changed, are added, or are removed.

  4. Inspect useEffect and Event Listeners: Make sure any useEffect hooks have correct dependency arrays to avoid them running more than necessary. Also, ensure you clean up event listeners when components unmount.

  5. Profile the Application: Use the React Developer Tools to profile the application. Look for components that mount and unmount frequently or update excessively.

  6. Check for State Updates in a Loop: Ensure there are no unintended continuous state updates that could cause a component to re-render in a loop.

  7. Audit External Libraries: If you're using external libraries for DOM manipulation or animations, ensure they're not the source of the issue.

Given your specific context of using refs and canvas drawing in a game loop, you should ensure that:

  • The game loop is not creating new components or elements in each iteration.
  • State updates within the loop are batched or minimized to prevent re-renders.
  • Any time you create DOM nodes (like canvases), you remove them during cleanup.

If you're still unable to identify the source of the issue, please provide more details or code snippets related to where you suspect the DOM nodes are being created, and I can offer more targeted advice.

User at 8:45 pm, Jun 10, 2024

Every time I cycle through the animation loop I get 10 new DOM nodes and 7 new event listeners.

Codeium at 8:45 pm, Jun 10, 2024

The DOM nodes and event listeners increasing with each animation loop cycle suggest that something within your animation loop is causing React components to mount without unmounting previous instances, or you're adding event listeners without removing them later. Here are steps to debug and resolve this issue:

  1. Review Animation Loop Code: Look at the code inside your animation loop. Ensure that it doesn't contain any React component rendering or DOM manipulation logic that inadvertently creates new elements or mounts components.

  2. Inspect Event Listeners: If you're adding event listeners in the animation loop or in a component that's part of the loop, make sure to remove them. Event listeners should typically be added in componentDidMount or useEffect with an empty dependency array, and removed in componentWillUnmount or the cleanup function of useEffect.

  3. Check Component Mounting: Ensure that components involved in the animation are not being remounted on each loop iteration. Components should only mount once and then update if needed.

  4. Canvas Drawing: If you're using canvas and manipulating it through React, make sure you're not creating new canvases or context objects in each frame. You should create a single canvas and then just update its context in the loop.

  5. Use key Prop Correctly: If you're rendering lists of elements within the loop, ensure each element has a unique key prop to prevent unnecessary re-rendering and element creation.

  6. Profiling: Use the React DevTools profiler to see which components are mounting, updating, and unmounting. It can help you identify unexpected behavior.

  7. Check for Memory Leaks: Look for any closures that might be capturing large objects or a large number of objects, leading to memory leaks.

  8. Optimize State Updates: If your loop involves updating the state, make sure that you're doing so optimally. Unnecessary state updates can lead to unexpected component behavior.

If you could share more specific code from your animation loop, especially the parts where you suspect the issue might be occurring, I could provide more detailed assistance.

User at 8:51 pm, Jun 10, 2024

I am going to show you the few files that are involved with the changes that result in DOM Node explosion.

Here is one. Do you see anything of concern?

// Level.tsx
import React from 'react';
import {ParallaxBackground, IParallaxLayer } from './ParallaxBackground';

interface ILevelProps {
 level: number;
 backgroundOffsetX: number;
 canvasWidth: number;
 canvasHeight: number;
 canvasRef: React.RefObject<HTMLCanvasElement>;
}

export const getParallaxLayers = (level: number): IParallaxLayer[] => {
 const layers: IParallaxLayer[][] = [
  // Level 1 layers
  [
   { imageSrc: '/images/parallax-industrial-pack/parallax-industrial-pack/layers/skill-desc_0002_far-buildings.png', scale: 0.8, movementRate: 0.4 },
   { imageSrc: '/images/parallax-industrial-pack/parallax-industrial-pack/layers/skill-desc_0001_buildings.png', scale: 0.6, movementRate: 0.6 },
   { imageSrc: '/images/parallax-industrial-pack/parallax-industrial-pack/layers/skill-desc_0000_foreground.png', scale: 0.6, movementRate: 1 },
  ],
  // Level 2 layers
  [
   { imageSrc: '/images/cyberpunk-street-files/cyberpunk-street-files/PNG/layers/far-buildings.png', scale: 0.6, movementRate: 0.4 },
   { imageSrc: '/images/cyberpunk-street-files/cyberpunk-street-files/PNG/layers/back-buildings.png', scale: 0.8, movementRate: 0.6 },
   { imageSrc: '/images/cyberpunk-street-files/cyberpunk-street-files/PNG/layers/foreground.png', scale: 1, movementRate: 1 },
  ],
  // Add more levels as needed
 ];

 console.log('getParallaxLayers called with level:', level);
 // Ensure the level index is within bounds, defaulting to level 1 if out of bounds
 const levelIndex = level - 1; // Adjust for zero-based index
 return layers[levelIndex] || layers[0];
};

export const Level: React.FC<ILevelProps> = ({ level, backgroundOffsetX, canvasWidth, canvasHeight, canvasRef }) => {
 const layers = React.useMemo(() => {

  // Function to get parallax layers based on the level
  // Use getParallaxLayers to get the layers for the current level
  return getParallaxLayers(level);
 }, [level]);

 return (
  <>
   <ParallaxBackground
    layers={layers}
    offset={backgroundOffsetX}
    canvasWidth={canvasWidth}
    canvasHeight={canvasHeight}
    canvasRef={canvasRef}
   />
   {/* Render your characters and other level elements here */}
  </>
 );
};

Codeium at 8:51 pm, Jun 10, 2024

The Level component itself doesn't appear to be the direct cause of the DOM node increase. It's a functional component that uses useMemo to memoize the parallax layers, and it renders the ParallaxBackground component with the correct props. There are no obvious signs of issues like DOM manipulation or event listener registration that would cause the symptoms you're describing.

However, the real cause might be hidden in the details of how the ParallaxBackground component is implemented or how the Level component is used within the rest of your application. Here are some things to consider:

  • ParallaxBackground Implementation: Look into the ParallaxBackground component to see if it's creating new DOM elements or adding event listeners without proper cleanup.
  • Re-rendering: Verify how often the Level component re-renders. If it's re-rendering too often, it could be triggering re-renders down the component tree, which might cause issues if children are not optimized.
  • Use of canvasRef: Check how the canvasRef is being used. If new canvases are created on each render without removing the previous ones, it could lead to a buildup of DOM nodes.
  • Console Logging: The console.log in getParallaxLayers will execute every time the component re-renders and the level prop changes. While this isn't a direct cause of the DOM increase, excessive logging can clutter your console and obscure real issues.
  • Component Usage: Look at all places where Level is used in your application. Ensure that it's not being unmounted and remounted repeatedly, as this could cause issues if the Level component or its children have side effects that are not cleaned up properly.

If you don't find the issue within this component, it would be helpful to inspect the ParallaxBackground component, the parent components that render Level, and any other components rendered alongside or within Level for potential causes of the DOM node increase.

User at 8:53 pm, Jun 10, 2024

The ParallaxBackground is here:

// ParallaxBackground.tsx
import React, { useEffect } 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
) => {
  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 }) => {

  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 => drawParallaxLayer(context, layer, offset, canvasWidth, canvasHeight));
    }
    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;
};

Codeium at 8:53 pm, Jun 10, 2024

The ParallaxBackground component is designed to update a canvas element using a ref. The actual drawing occurs in the drawParallaxLayer function. There is nothing in the ParallaxBackground component itself that would cause an increase in DOM nodes, as the component returns null and does not render any DOM elements directly.

However, the drawParallaxLayer function creates a new Image object for each layer every time it's called. If this function is being called repeatedly in a tight loop, the creation of Image objects could be the cause of your performance issues, even though they are not DOM nodes themselves.

Each Image object may be registering event listeners for the load event. If drawParallaxLayer is being called very frequently, those event listeners might not be getting a chance to be garbage collected, especially if the images are large and take a while to load. This could contribute to a seeming increase in event listeners and memory usage.

To mitigate this, you could optimize drawParallaxLayer in a few ways:

  1. Cache Images: Instead of creating a new Image object every time, cache the images so that each one is only loaded once. You can store them in a state or ref and reuse them for drawing.
  2. Load Images Separately: You could load all the images when the component mounts or when the layers prop changes, instead of loading them on every draw call.
  3. Cleanup: Ensure that any resources created during the drawing process are properly cleaned up if they're no longer needed.

Here's an example of how you might cache the images:

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

  useEffect(() => {
    // Load the images when the layers change
    const newLoadedImages = new Map();
    layers.forEach(layer => {
      if (!loadedImages.has(layer.imageSrc)) {
        const image = new Image();
        image.src = layer.imageSrc;
        image.onload = () => {
          newLoadedImages.set(layer.imageSrc, image);
          setLoadedImages(newLoadedImages);
        };
      }
    });
  }, [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 using the cached images
      layers.forEach(layer => {
        const image = loadedImages.get(layer.imageSrc);
        if (image) {
          drawParallaxLayer(context, layer, offset, canvasWidth, canvasHeight, image);
        }
      });
    }
  }, [layers, offset, canvasWidth, canvasHeight, canvasRef, loadedImages]);

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

// Update drawParallaxLayer to accept an HTMLImageElement instead of creating a new Image
function drawParallaxLayer(
  context: CanvasRenderingContext2D,
  layer: IParallaxLayer,
  offset: number,
  canvasWidth: number,
  canvasHeight: number,
  image: HTMLImageElement
) {
  // Existing drawing logic...
}

This change ensures each image is only loaded once and then reused for drawing. Remember to handle cases where images may fail to load and provide a fallback or retry mechanism if necessary.

User at 9:12 pm, Jun 10, 2024

That looks very helpful. I should only have to load different parallax background images when a level changes. The rest of the time they should be cached.

When exactly in the code is the image loaded from the image file? What is the role of the HTML new Image() if the image is drawn to the canvas?

Codeium at 9:12 pm, Jun 10, 2024

The new Image() constructor in JavaScript is used to create a new HTMLImageElement, which is an in-memory representation of an image. This element is not automatically part of the DOM and will not be visible on the page until you explicitly add it to the DOM or draw it onto a canvas.

Here's the process of loading and using an image in the context of your ParallaxBackground component:

  1. Image Creation: When you call new Image(), a new HTMLImageElement is created. At this point, it does not yet contain any image data.

  2. Setting src Attribute: You then set the src attribute of this image element to the URL of the image file you want to load (image.src = imageSrc;). This action initiates the loading of the image from the server.

  3. Loading: The browser requests the image from the server using the URL provided. The loading happens asynchronously in the background.

  4. Onload Event: Once the image is fully loaded and ready to use, the onload event is fired. This is where you can safely draw the image onto the canvas since you know the image data is fully available.

  5. Drawing to Canvas: Using context.drawImage(), you can then draw the loaded image onto a canvas element. The image is rendered onto the canvas based on the parameters you provide, such as the position and size.

The role of the HTML new Image() is to provide a way to programmatically load images and use them in JavaScript, which is particularly useful when working with the canvas API. By drawing an image onto the canvas, you're effectively rendering that image within the canvas's pixel grid, allowing for complex graphical operations, animations, and effects.

In the context of your game, you'd typically want to load the parallax background images once per level, draw them onto the canvas to create the visual background, and then simply shift their positions or redraw as needed to achieve the parallax scrolling effect as the player moves through the level. Caching these images, as previously discussed, avoids unnecessary network requests and performance issues by reusing the already loaded images.

User at 9:37 pm, Jun 10, 2024

Yes. the parallax images are tiles of the background, so they only need to be loaded once per level change.

Is that what we're doing?

We are creating an additional image in here:

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

Codeium at 9:37 pm, Jun 10, 2024

Yes, that's the intention of the code within the useEffect. However, there's a mistake in the logic that could lead to images being reloaded unnecessarily. The issue is that newLoadedImages is a new Map created on each execution of useEffect, and since loadedImages is not a dependency of this useEffect, it will always be an empty map when this effect runs. This means the condition !loadedImages.has(layer.imageSrc) will always be true, and the image will be loaded again, even if it's already in the state.

The setLoadedImages(newLoadedImages) call inside the image.onload callback will update the component's state, causing the component to re-render, which could lead to a new execution of this useEffect and potentially create a loop if layers changes as a result.

To fix this and ensure that each image is only loaded once, you should modify the logic as follows:

  1. Initialize loadedImages with an empty Map and update it only when images are loaded.
  2. Remove loadedImages from the dependency array of the useEffect that loads images to avoid it triggering on every state update.
  3. Use a functional state update to ensure you're adding to the current state rather than overwriting it.

Here's an updated version of the code:

useEffect(() => {
  // This effect runs once on mount and whenever 'layers' changes.
  layers.forEach(layer => {
    if (!loadedImages.has(layer.imageSrc)) {
      const image = new Image();
      image.src = layer.imageSrc;
      image.onload = () => {
        // Use a functional update to correctly merge with the existing map
        setLoadedImages(prevLoadedImages => {
          const updatedLoadedImages = new Map(prevLoadedImages);
          updatedLoadedImages.set(layer.imageSrc, image);
          return updatedLoadedImages;
        });
      };
    }
  });
  // We only want to run this effect when 'layers' changes, not 'loadedImages'.
}, [layers]);

With this updated code, images are loaded only once when the layers prop changes, which should happen when you change levels. Each Image object is added to the loadedImages map, and because we use a functional update for setting state, we ensure that we're always working with the current state. This should prevent unnecessary image reloads and avoid the creation of extraneous Image objects, which should help with the performance issues you're experiencing.

User at 8:00 am, Jun 11, 2024

I seem to have lost the frameDelay in the animation loop.

 startAnimationLoop(context: CanvasRenderingContext2D) {
  const image = new Image();
  const loop = (timestamp: number) => {
   if (!this.gameTime) {
    this.gameTime = timestamp; // Initialize gameTime on the first animation frame
   }
   this.gameTime = timestamp; // Update gameTime for the next frame

   // 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.animationFrameIndex = requestAnimationFrame(loop);
   this.checkProximityAndSetAction();
  };

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

What is the best way to have the loop run only once per 100 milliseconds?

Codeium at 8:00 am, Jun 11, 2024

To adjust your startAnimationLoop function so that the loop runs once per 100 milliseconds, you would need to incorporate a frameDelay mechanism that keeps track of the time since the last update and only continues with the rest of the function if the delay has been met or exceeded.

Here's a modified version of your startAnimationLoop function that includes a frameDelay:

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);

      // Your drawing and update logic here

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

      // Additional drawing logic...
      if (this.state.isPhraseComplete) {
        this.drawScrollingText(context);
      }
      context.globalAlpha = 1.0;

      this.updateCharacterAndBackground(context);
      this.checkProximityAndSetAction();
    }

    // Request the next frame, continuing the loop
    this.animationFrameIndex = requestAnimationFrame(loop);
  };

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

In this version, lastFrameTime keeps track of when the last frame was processed. On each call to loop, the function checks if the timeElapsed since the last frame is greater than or equal to frameDelay. If so, it proceeds with the drawing and update logic. The modulo operation (timeElapsed % frameDelay) is used to adjust lastFrameTime to maintain a stable frame rate even if requestAnimationFrame calls loop more frequently than every 100 milliseconds.

The requestAnimationFrame method typically runs at 60 frames per second (approximately every 16.67 milliseconds), so using a frameDelay of 100 milliseconds will effectively limit your loop to 10 frames per second.

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