Export CanvasPattern and CanvasGradient

[cmdelatorre]

It'd be great if you exported CanvasPattern and CanvasGradient.

I have OpenLayers as a dependency. Internally, it's using CanvasPattern and CanvasGradient. I installed node-canvas for testing: I'm using mocha and jsdom to set a suitable DOM environment for the tests to run. So, in my tests configuration file I have something like:

const canvas = require('canvas');
// ...
global['CanvasRenderingContext2D'] = canvas.Context2d;

Now, some tests that use OpenLayers are failing because it is expecting CanvasPattern and CanvasGradient to be in the global scope.

I can see that you have such classes within your project but they are not public. Or maybe I don't know how to import/use them?

Environment

• canvas@1.6.6
• node v6.11.1 on Ubuntu 16.04.3 LTS

[zbjornson]

In 2.x, CanvasPattern is exposed. CanvasGradient isn't, but should be since it is in browsers.

2.x also exports "Context2d" with the correct name, so you could do something like this:

["CanvasRenderingContext2D", "CanvasPattern" /*, "CanvasGradient" */].forEach(obj => {
  global[obj] = canvas[obj]
})

Full list of exports in 2.x: https://github.com/Automattic/node-canvas/blob/master/index.js#L49
This is an easy fix. I can do it today, or if you want to open a PR, CanvasGradient: bindings.CanvasGradient just needs to be added to that exports object.

[cmdelatorre]

Awesome. Do you have an ETA for v2 to be in NPM?
I posted a PR, hopefully it is enough.

[zbjornson]

Linus has been publishing alpha versions regularly. The latest is 2.0.0-alpha.5 (npm i canvas@2.0.0-alpha.5).

[cmdelatorre]

Unlucky for me, I cannot move to v2 yet because of this: #978 (comment)

[zbjornson]

Here's a hack for 1.x if you need:

const Canvas = require("canvas");
const canvasBindings = require("canvas/lib/bindings");
Object.assign(Canvas, {
  CanvasGradient: canvasBindings.CanvasGradient,
  CanvasPattern: canvasBindings.CanvasPattern
});

[cmdelatorre]

Great. Taking this into account: #978 (comment)
I consider this issue closed. Thanks for the support.

[LinusU]

I'd be happy to merge a backport to 1.x if anyone needs it, feel free to open a PR