@netless/canvas-polyfill

@netless/canvas-polyfill is a polyfill for resetTransform,ellipse,getTransform. It is inspired by canvas-5-polyfill, canvas-currentTransform.

This polyfill can work in Android 19 WebView and iOS 10 WKWebView.

different from these

canvas-5-polyfill implement polyfill for Path2D objects and ellipse() on CanvasRenderingContext2D which doesn't implement getTransform. @netless/canvas-polyfill doesn't implement Path2D, but implement getTransform.

canvas-currentTransform 's setTransform has some problem. @netless/canvas-polyfill just fix it and canvas-currentTransform not implement getTransform. But the currentTransform 's getter is same as getTransform.

Installation

yarn install @netless/canvas-polyfill
# or
npm install @netless/canvas-polyfill

Use:

import "@netless/canvas-polyfill";

Publish

npm publish --access public

the implement for getTransform

The matrix calculation is just copy from canvas-currentTransform for currentTransform. I just fix setTransform method which has two forms of parameters:

interface CanvasTransform {
    setTransform(a: number, b: number, c: number, d: number, e: number, f: number): void;
    setTransform(transform?: DOMMatrix2DInit): void;
}