VERY Simple sample of a watch face with a background process.

This one really doesn't do much. It displays the time, an indication if it's on a device that supports background processes (you can see how that's checked in the App Class), The count of the times the background process has run, and the data returned from the background. It does cache data in the object store, so after the first time the background runs, it will have data.

The background process is a Temporal event, and runs every 5 minutes. All the background does is return a string with a time stamp (HH:MM). There are a number of Sys.println() calls to see what's going on. If you have a watch that supports background processes (f5's,chronos,935,735,va-hr), create a <myapp>.txt in logs to catch the println() calls, as you see kind of a neat thing where those that come from the background are marked as such!

This runs in the sim can you can use the code to build a sideload. In addition to devices that support background processes, I included the fenix 3 as a target so you can see how it works on a watch that doesn't.

if you have questions about the code, just ask!

Top Replies

Bodya over 4 years ago +2

For some reasons I can’t find source code of your example. Could you help me with it? Thank you!
jim_m_58 over 4 years ago in reply to Bodya +2

The original sample was posted before the forum SW changed last April, but here it is again. (I've probably changed it slightly since then )

6735.vsbgwf.zip
jim_m_58 over 4 years ago in reply to thoms +2

looks like it might have.

Here's close to what I first posted.

7750.vsbgwf.zip

All Replies

jim_m_58 over 4 years ago in reply to Bodya

The original sample was posted before the forum SW changed last April, but here it is again. (I've probably changed it slightly since then )

6735.vsbgwf.zip

Bodya over 4 years ago in reply to jim_m_58

appreciate it, thank you

thecubical over 4 years ago in reply to jim_m_58

is there a chance something has changed, ive tried other apps and also your sample app here and I'm no longer seeing the "count" update after waiting 5 minutes (or more), the only way to get an update to be triggered is if I go into a menu or something else and come back to the watch face then the latest count will be shown.

This is on a fenix 6, various firmwares (including which was the last 9.x firmware, the current 10.x release firmware and evne the 10.75 beta firmware).

From debugging myself it seems that after background.exit is called the onbackgroundata call is never called until I interact with the watch.

I also have a vivoactive 3 which is not exhibiting this behaviour, any ideas?

jim_m_58 over 4 years ago in reply to thecubical

It'[s a FW bug on the f6.

See https://forums.garmin.com/developer/connect-iq/i/bug-reports/fenix-6-with-background-app-watchface-doesn-t-update

thecubical over 4 years ago in reply to jim_m_58

damn that was my bug report, was hoping it was something else

Fsallstrom over 4 years ago

i Jim, I used the example to create my own data field with a background process (to do makewebrequest) a long while ago (it helped me a lot). Now when I return to my code I wonder if I really need to use app properties to pass data from the bg to the main application or if I could use a global variable in my app class instead? thanks!

jim_m_58 over 4 years ago in reply to Fsallstrom

You can not write to app properties from a background process (unless something has changed and I missed. it

The background returns data to the main app using Background.exit()

Globals are not what you think when using backgrounding.

Say you have a global

var abc=0;

in the background you can access it and change it to 123.

The main app still sees 0.

The main app and the background have their own copy of a global. Recall the background can run even if the main app isn't running

Fsallstrom over 4 years ago in reply to jim_m_58

Ah, I see now. Thank you for the explanation.

This is what I have in my existing data field implementation, that works: (I think this is based on your example)

//global vars
var OSDATA="osdata";

// function declared in my app class, to receive data from the BG process
function onBackgroundData(data) {
    App.getApp().setProperty(OSDATA,data);

I thought this meant I shared data between the bg and main process through an app property. Another thing I havent been able to figure out is if "osdata" is some sort of a special property, or could I use any name I'd like?

jim_m_58 over 4 years ago in reply to Fsallstrom

Nothing special. It's just a sting with the key.

thoms over 4 years ago

Thanks @jim_m_58

I am not sure it is me or an actual bug, but was the zip file deleted?