[android] Direct device-to-device sharing of map files

[rtsisyk]

Problem

I am hearing countless complaints that the maps directory is not accessible anymore. Unfortunately, we have some technical limitation on Android 11+. There is no convenient way to use the shared storaged anymore.

Solution

The typical use-case is to transfer maps files from device to another without having the Internet connection. For example, you have a map downloaded, but your fellow traveler doesn't. Instead of thinking about raw access to the private storage, we can implement direct device-to-device sharing.

The workflow is the following:

1. Open the list of maps on your device
2. Select one particular map or entire country
3. Click "Share" button
4. Android will show the system sharing dialog with multiple options
5. On the second device, receive a file and open it via Organic Maps app
6. The app will open the map file and import it into the private storage

The beatify of this approach is that users will have numerous options to exchange maps files:

• Bluetooth
• Nearby Share
• Quick Share
• Save as file
• WhatsApp
• Telegram

Plus it provides a convenient method to test custom/new maps.

CC: @biodranik @vng

[biodranik]

I don't think that you named the main problem. From our users and from the past, the more actual problem was this one:

• There is no Internet access on the device (or it is very slow). Think about the Haiti disaster.
• APK is available and installed.
• Maps are downloaded manually on some PC using the mirror (or are brought on a USB stick).

The goal is to copy (import) pre-downloaded maps on the device somehow. Do you see any solutions for that?

[rtsisyk]

The goal is to copy (import) pre-downloaded maps on the device somehow. Do you see any solutions for that?

Sorry for the late answer. Sure, my proposal solves exactly this problem. Android supports numerous ways to share files via Sharing menu. Some of them don't require the Internet connection at all (e.g. Bluetooth and Nearby Sharing). You can transfer map files from one device to another easily without need to have the storage access.

[batyrmastyr]

Android to android sharing is very good start, but Android to iOS sharing is also needed. Use case: I have iPhone, my wife prefers Android and we usually forget to download some maps on one of the phones.

[biodranik]

That in theory could be done via a Bluetooth Sync.

[pastk]

Technically, another way to share map files will be by implementing a DocumentsProvider for them - hence the files will be visible and copiable via a file manager. Its just an assumption based on reading the docs so far :)

[RedAuburn]

For anyone trying to load mwms with root access, the maps are stored at /storage/emulated/0/Android/data/app.organicmaps/files/{6 numbers - map generation date}

[0709wiwiwi]

For anyone trying to load mwms with root access, the maps are stored at

Given Android is increasingly closing down access to data, apps like Cruiser & Locus offer alternative storage choices into media (internal or extsd). The access control drift in here still appears to be slightly more tolerant so far.
Example: /storage/1BA0-1D11/Android/media/gr.talent.cruiser/maps

[biodranik]

These apps have unsafe android.permission.WRITE_EXTERNAL_STORAGE permission. If you use external storage in OM settings, in most cases you usually are able to access maps using adb.

[0709wiwiwi]

Someone with too much fear of the outside world should already better not own any electronic device ?

Anyway @biodranik I wanted to know the ins and outs of it. I am not a dev so I have to inquire. The answer (cruiser) was.
Cruiser (and other apps like c:geo) declare the WRITE_EXTERNAL_STORAGE only for use up to Android 9 (Pie).
And this is only a requirement of "Android download manager" and only for old Android <= 9.
Cruiser does not need/use storage permissions at all because it uses app folders (data or media) or Android browser that do not require storage permissions.