@apostel/node-canvas-core

@apostel/node-canvas-core

The core implementation of the @apostel/node-canvas framework.

Getting Started

Installation

# Using NPM
npm install @apostel/node-canvas-core

# Using Yarn
yarn add @apostel/node-canvas-core

# Using Bun
bun install @apostel/node-canvas-core

Additional dependencies

Make sure to also install the following packages:

# Using NPM
npm install rxjs zod

# Using Yarn
yarn add rxjs zod

# Using Bun
bun install rxjs zod

API

Node

Nodes are units that consists of inputs and outputs. They're conceptually very similar to functions, with the difference that outputs may be multiple, compared to a function's single return value.

An Addition Node may for instance have two inputs and a single output, which computes the sum of the inputs.

import { z } from 'zod';
import { Node, Input, Output, schema } from '@apostel/node-canvas-core';
import { combineLatest, map } from 'rxjs';

/** Declare a zod schema for value validation */
const NumberSchema = schema(z.number());

class Addition extends Node {
    name = 'Addition';

    inputs = {
        a: new Input({ name: 'A', type: NumberSchema, defaultValue: 0 }),
        b: new Input({ name: 'B', type: NumberSchema, defaultValue: 0 })
    };

    outputs = {
        output: new Output({
            name: 'Output',
            type: NumberSchema,
            observable: combineLatest([this.inputs.a, this.inputs.b]).pipe(
                map(inputs => inputs.reduce((sum, value) => sum + value), 0)
            )
        })
    };
}

Example

import { z } from 'zod';
import { Node, Input, Output, schema } from '@apostel/node-canvas-core';
import { combineLatest, map } from 'rxjs';

/** Declare a zod schema for value validation */
const NumberSchema = schema(z.number());

class Addition extends Node {
    name = 'Addition';

    inputs = {
        a: new Input({ name: 'A', type: NumberSchema, defaultValue: 0 }),
        b: new Input({ name: 'B', type: NumberSchema, defaultValue: 0 })
    };

    outputs = {
        output: new Output({
            name: 'Output',
            type: NumberSchema,
            observable: combineLatest([this.inputs.a, this.inputs.b]).pipe(
                map(inputs => inputs.reduce((sum, value) => sum + value), 0)
            )
        })
    };
}

/** Declare 3 addition nodes */
const additionNode1 = new Addition();
const additionNode2 = new Addition();
const additionNode3 = new Addition();

/** Connect them together */
additionNode1.outputs.output.connect(additionNode3.inputs.a);
additionNode2.outputs.output.connect(additionNode3.inputs.b);

/**
 * The output of AdditionNode3 will fire with a new sum
 * everytime the inputs of AdditionNode1 and AdditionNode2 changes
 */
additionNode3.outputs.output.subscribe(console.log);