User language and LTR/RTL text-direction

[mapmeld]

I was testing out the a RTL locale (dv) in Firefox on the OpenStreetMap site. In Firefox or Chrome, you can see the same results in Arabic (ar).

• When my browser's top language is Dhivehi or Arabic, I get RTL layout, but English text (bad)
• When I add "dv" or "ar" to my languages in OpenStreetMap user preferences, I get RTL layout and Dhivehi text, regardless of browser setting (good)

I think that I missed this earlier because I was testing the locale / browser-detection code, not knowing that the text language preference can be coming from OSM user preferences. Any idea where the locale text and direction are getting mixed up?

[bhousel]

Yeah the locale handoff from the OpenStreetMap Rails site to iD is tricky.. I think what is supposed to happen is

1. Rails calls context.locale(), with your OSM language preference:

https://github.com/openstreetmap/iD/blob/b2eb982044c682656e101889d4b009eada8c0fbe/modules/core/context.js#L383-L388

2. Rails calls id.ui()(container) to render iD into something:

https://github.com/openstreetmap/iD/blob/b2eb982044c682656e101889d4b009eada8c0fbe/modules/ui/init.js#L343-L355

3. which calls context.loadLocale() to actually load the desired language file:

https://github.com/openstreetmap/iD/blob/b2eb982044c682656e101889d4b009eada8c0fbe/modules/core/context.js#L393-L398

4. After it is loaded, the callback calls setLocale(), which sets the currentLocale variable. It's exported and used many places (kind of like a global variable):

https://github.com/openstreetmap/iD/blob/b2eb982044c682656e101889d4b009eada8c0fbe/modules/util/locale.js#L6-L12

5. The callback also calls utilDetect(true) to redetect all the things.. It is supposed to use that currentLocale variable to override whatever iD detected from your browser. It's also supposed to lock in LTR or RTL:

https://github.com/openstreetmap/iD/blob/b2eb982044c682656e101889d4b009eada8c0fbe/modules/util/detect.js#L84-L100

6. All those things should happen before the iD interface starts drawing itself into the container (see 2.). I'll have to test a bit, but I'm sure we can figure out where it is getting thrown off...

[mapmeld]

I wonder if setTextDirection should happen in setLocale then?