Is it possible to override "getArrayBuffer" for offline usage/fallback?

[fnicollet]

Hello,

This is more of a question than an issue. I would like to have a fallback on local PBF files while offline, so basically instead of retrieving them via HTTP, override the behaviour and load a file from my hard drive. I can do this very easily in leaflet classic TMS layers with some code like:

L.TileLayer.Common = L.TileLayer.extend({
    getTileUrl: function (tilePoint, tile) {
    ... do something clever
    }
});

Works very well and I am very happy with that behaviour that allows me to override leaflet function without having to modify leaflet's core.
I would like to do the same with mapbox-gl-js but it seems like the way it is architectured makes it hard to override functions/behaviours because you can only see what's exported publicly, not the inside functions.

I found the part of the code that I need to override:

mapbox-gl-js/js/source/worker_tile.js

Line 32 in 0eb16da

WorkerTile.loading[source][id] = getArrayBuffer(url, function(err, data) {

Which calls "getArrayBuffer", which have been initialized as a local variable with

var getArrayBuffer = require('../util/ajax').getArrayBuffer;

From the outside, here is what the debugger can see:

Very little, only main objects and their prototype. I could modify util.getArrayBuffer but it is too late because Worker already "copied" it locally.

I am not so used to "require" and how it works but it looks like you can't access what's outside of the exports, so I can't "hack" very far.
Only solution I see is to modify the source code for getArrayBuffer and recompile my own version of mapbox-gl-js but i would rather not do that.

If there is some JS wizardry that would allow me to do it, i would be very interested :)

Thanks!

[jfirebaugh]

I think your best bet is to set the source URL to either a remote URL or file:// URL depending on offline status. We'll keep the offline use case in mind but allowing access to private implementation details of gl-js isn't something we're likely to do.

[fnicollet]

Thanks for the clarification :)

Fabien