Fix GeckoView tile loading android assets folder

[jwoodwardtfx]

Fixes #4451

[HarelM]

What about ajax.ts usage of file?

[jwoodwardtfx]

No other changes are required. "file://" isn't referenced anywhere else in the code base, and, it's only this check that is causing an issue.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 87.65%. Comparing base (c00a30b) to head (fbc8846).
Report is 3 commits behind head on main.

Files	Patch %	Lines
src/util/actor.ts	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4478      +/-   ##
==========================================
- Coverage   87.84%   87.65%   -0.20%     
==========================================
  Files         246      246              
  Lines       33421    33421              
  Branches     2219     2205      -14     
==========================================
- Hits        29359    29295      -64     
- Misses       3043     3124      +81     
+ Partials     1019     1002      -17     

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[HarelM]

See here:

maplibre-gl-js/src/util/ajax.ts

Line 140 in 04e39c5

const isFileURL = url => /^file:/.test(url) || (/^file:/.test(getReferrer()) && !/^\w+:/.test(url));

I'll be surprised if this wouldn't need a patch as well...

[jwoodwardtfx]

See here:

maplibre-gl-js/src/util/ajax.ts

Line 140 in 04e39c5

const isFileURL = url => /^file:/.test(url) || (/^file:/.test(getReferrer()) && !/^\w+:/.test(url));

I'll be surprised if this wouldn't need a patch as well...

You are right, I was just looking at that line. However, if I just patch the one line in the commit, it all springs into life. I'll do a bit more digging. Thanks.

[jwoodwardtfx]

See here:

maplibre-gl-js/src/util/ajax.ts

Line 140 in 04e39c5

const isFileURL = url => /^file:/.test(url) || (/^file:/.test(getReferrer()) && !/^\w+:/.test(url));

I'll be surprised if this wouldn't need a patch as well...

You are right, I was just looking at that line. However, if I just patch the one line in the commit, it all springs into life. I'll do a bit more digging. Thanks.

It looks like the code is trying to avoid using the Fetch API when using "file://" and instead drop back to the legacy XMLHttpRequest.

It's not clear to me why, as I can't find anything in Mozilla Fetch API documentation (https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API) or Chrome documentation (https://web.dev/articles/introduction-to-fetch) that states that the Fetch API can't work with a "file://" request (or "resource://android" in my case).

I've done some tests an using GeckoView on Android and both the Fetch API and XMLHttpRequest successfully load the fonts and glyphs.

I've had a quick look at Chromium on Windows too using "file://" and this is the same, both Fetch API and XMLHttpRequest seem to work fine.

So, I think this check is redundant, though, I'm not keen to back it out, even if not needed, as I assume it was added for an older browser than may not support "file://" access via the Fetch API? Removing it may cause a breakage for someone else, but, with a modern browser, it doesn't appear to be needed anymore.

[HarelM]

I can find old articles about fetch not supporting file protocol:
JakeChampion/fetch#92 (comment)
https://stackoverflow.com/questions/55133723/does-will-the-fetch-api-support-other-protocols-than-http

It might be that this is no longer relevant, IDK...

[jwoodwardtfx]

If you agree, maybe the best option for now is to apply this fix for GeckoView, and the use of the Fetch API vs XMLHttpRequest can be looked at at a later point? A change to ajax.ts isn't needed to resolve the specific issue for GeckoView :)

[HarelM]

Sure, why not.