[typescript] wrong types on getContext()

[doritosxxx]

Issue

Possibly part of #1656

getContext() returns type NodeCanvasRenderingContext2D. NodeCanvasRenderingContext2D extends CanvasRenderingContext2D, which has the canvas field.

canvas field has type HTMLCanvasElement. But as far as i know this library doesn't work with DOM. Furthermore HTMLCanvasElement can't be explicitly converted to Canvas.

Steps to Reproduce

import { Canvas } from 'canvas'

const canvas = new Canvas(100, 100)
const ctx = canvas.getContext("2d")

// cts.canvas is HTMLCanvasElement accoring to typings.
// but it should be Canvas.
// HTMLCanvasElement has the "toBlob" method

// TypeError: ctx.canvas.toBlob is not a function
ctx.canvas.toBlob(()=>{})

// This one won't compile.
ctx.canvas.toBuffer()

// This one works fine.
;(ctx.canvas as unknown as Canvas).toBuffer()

Your Environment

• [email protected]
• [email protected]
• node v14.15.4 on Windows10 20H2

[zbjornson]

Yeah, for the sake of simplicity I had just extended CanvasRenderingContext2D, but as you found in #1656, that turned out to be problematic.

Happy to review a PR if you want to work on this. Meanwhile I'm going to close this as a duplicate of #1656.