OpenCPN on Android 11 - Chart Directories

[CaptTom]

Moving to Android 11 on a tablet, using OpenCPN paid version.

On Windows and on my old Android device, I maintain directories of current vector and raster charts. I've been able to "add" those directories to OpenCPN.

On my new Samsung tablet running Android 11, OpenCPN can't seem to navigate to the folder on my SD card containing the charts.

When I tap SD card, it shows the current directory OpenCPN created and a "Charts" sub-directory, but I can't navigate "up" the tree to the SD card, nor can I type in the name of the directory where my charts are.

Am I missing something?

[bdbcat]

Capt Tom...
Nope, you are not missing anything.
Android/11 has significantly reduced the utility of SDCards by creating something called "scoped storage". In this policy, the SDCard root directory (and the internal memory root e.g. "/storage/emulated/0" as well) is no longer accessible to applications. All app data must be stored in an app-specific directory, accessible to that app and no other. This was done by Google in the interest of user data security. Nobody likes it much....



There is a migration utility built into OpenCPN for Android, which will help you move your charts to the proper private location.


Search this forum for the word "scoped" for more information.



Dave

[CaptTom]

Thanks Dave. I was afraid this was going to be the answer.

I noticed there is a permission some apps have called "Allow management of all files." I'm guessing the Google Gods aren't allowing you to use this?

I guess I'll just copy the charts to the directory structure OCPN has available, instead of using the naming conventions I use everywhere else.

I'm beginning to see why nobody is buying Android tablets any more. Once it's as locked down as an iPad, it becomes easier to just follow the herd and buy one of those, instead.

[bdbcat]

CaptTom...
"Allow management of all files."
This appears to be reserved for things like virus checkers, and traditional file managers. Not available for fixed function apps like OCPN.
Astute comment re: Android vs iPad.


btw, I have found that the free app called xPlore does a moderately good job as a file manager for A11, at least for internal storage. Not so good for SDCard. Some users resort to using an SDCard adapter for their PC to do file management on SDCard.


Dave

[sv_pelagia]

Originally Posted by CaptTom

I'm beginning to see why nobody is buying Android tablets any more

Huh?

Yes, this new chart management situation for Android OpenCPN IS a pain and stupid.

BUT the OpenCPN migration assistant seems to work fine. (So much so, a non-computer-saavy friend "accidentally" updated his app and the charts were migrated seamlessly without him knowing it. He loves his OpenCPN on his new android tablet.)

FYI: I hook my androids up to my PC laptop for easy file management for OpenCPN.

[CaptTom]

Originally Posted by sv_pelagia

...FYI: I hook my androids up to my PC laptop for easy file management for OpenCPN.

That's what I'm doing right now. I'm about 75% through copying all the charts to the OCPN directory. Hopefully the correct one. There's really only one other app I use which still allows me to use the free NOAA charts I've downloaded. Things like Navionics insist on downloading their own charts anyway. Storage is cheaper these days, so even though it's a pain maintaining two current copies, I can do that.

[fgd3]

I don't understand how scoped storage works. If OpenCPN is installed in internal storage can you have an app specific directory on an SD card? Can you install OpenCPN on an SD card? If you do that can you put app specific directories on the SD card? How do you designate a directory as specific to an app?


I take it scoped storag is a little more complicated than simply having the data reside in the ap's directory or below.

[Hakan]

Originally Posted by fgd3

How do you designate a directory as specific to an app?

You can't. That's where Android is locating the app during install.
For OCPN it's normally: ./storage/emulated/0/Android/data/org.opencpn.opencpn/
See the OCPN tool "About OpenCPN" ([?]) to find the log file's directory.

So a normal chart directory on A 11 and up would be:
./storage/emulated/0/Android/data/org.opencpn.opencpn/files/Charts/

Support for external SD-card would probably end in future. It may be Google think new gadgets would have enough internal memory?

[bdbcat]

fgd3,


1. If OpenCPN is installed in internal storage can you have an app specific directory on an SD card?

Yes, one is automatically created for you, by migration utility. You will not be happy with App performance using this mode, due to the significant overhead of Android scoped file system.



2. Can you install OpenCPN on an SD card?
Not sure about that in Android/11. Many modern devices no longer offer that option.


3. If you do that can you put app specific directories on the SD card?
This is done for you automatically. You may not create directories on the SDCard that do not belong to the App.


4. How do you designate a directory as specific to an app?
As above, automatically created. One does not designate an arbitrary directory as belonging to an app. As Hakan notes, the naming convention is very specific.


All said, the utility value of SDcard storage is being squeezed away, step by step.


Sorry
Dave

[rehogan]

Dave,

This string highlights some of the considerations for using OpenCPN on android operating systems. I'd be interested in hearing any guidance you may have regarding robustness, ease of installation/maintenance, etc that might be useful for folks who are considering putting together an OpenCPN system in the future. Would you comment on the following options for putting together a system from scratch (or point us to a source of similar information)? Seems to me the choices fall along the following

1 - ios on ipad or phones
2 - android on tablets or phones
3 - windows on pcs, nucs, or tablets
4 - linux on raspberry pi
5 - arduino ?

Any insight to these options for a new, from-scratch system would be appreciated. I'm sure everyone will have differing experiences, but what would you build starting with a clean plate?

Thank you!

Roy

[tenchiki]

I've had this argument with the Android devs before. They just don't seem to get the logical difference between "app data" and "user data". Their attitude seems to be something like "if an App touches it, it is app data". And since you can't do anything (without hooking to an outside computer) without an app, they claim everything. There also seems to be a "we know better than the users what to do with their data" attitude.

[bdbcat]

tenchiki...
"we know better than the users what to do with their data".


The rub is this: There are more than 2.5 billion(!) android devices in the wild. And for 99+%, that statement is probably correct. Pictures, videos, contact lists, music,SMS.

And that's about it.


For the sub-1% who use an Android device as a general purpose handheld computer with a good UI, useful wireless interfaces, and reliable geolocation hardware: We adapt as best we can, within the limits of the O/S. I don't expect much relief going forward. I expect more squeeze.



Dave