[messagegui] Blank on task items with short titles

[randyheydon]

Affected hardware version

Bangle 2

Your firmware version

2v27

The bug

Certain notifications appear in the message UI with an almost-fully blank screen. When this happens to me, two of my widgets appear (widbatpc and widclk), but absolutely nothing else (not even the back button). After waiting for the message timeout, the display returns to the clock. Here's a screenshot of the blank notification:

This specifically happens for task notifications with short titles and no description. I use tasks.org on my phone, and my quick tests have shown:

• task title "Test" and no description gives the blank screen.
• task title "Test with longer title" displays as it should (with title in both the top and bottom spots).
• task title "Test" and description "Desc" displays as it should (with title on top and description below).

This bug has been happening for a while, so I can't narrow down exactly which update caused it. This bug did not occur back when I was on the previous firmware version (2v25?), but I think there was an update to messagegui around the same time, so I can't pinpoint which is the culprit.

Installed apps

widlock (0.08), notify (0.14), widalarm (0.02), reply (0.03), widmessages (0.07), widbatpc (0.20), quicklaunch (0.16), widgps (0.09), widbt_notify (0.18), delaylock (0.01), widclk (0.08), kbtouch (0.04), clkinfocal (0.05), widclkinfo (0.04), dtlaunch (0.28), bwclk (0.35), android (0.44), sched (0.33), messages (0.67), messageicons (0.09), boot (0.66), messagegui (0.88), clock_info (0.19)

[bobrippling]

I've seen similar widget behaviour when a screen doesn't render but not with messages (although I'm not a big messages user). Are you able to show those messages from tasks.org as they arrive?

If you do something like:

Bangle.on("message", (type, msg) => require("Storage").open("msgdbg.jsonl", "a").write(JSON.stringify({type, msg}) + "\n"));

in the IDE, then disconnect, connect your phone and send a few messages across, let's read out that msgdbg.jsonl file and see what's in it. Let me know if it doesn't do the trick or if you would like a bit more detail on debugging :)

[thyttan]

Just chiming in that I've seen similar behaviour with certain notifications. I think thay were shorter ones for me as well.

[randyheydon]

That console command didn't do what I hoped (no "msgdbg.jsonl" appeared in my Bangle's file browser), but I did get console output that pointed me in the right direction:

>Bangle.on("message", (type, msg) => require("Storage").open("msgdbg.jsonl", "a").write(JSON.stringify({type, msg}) + "\n"));
=undefined
>notify {
  "t": "notify",
  "id": 1754949095,
  "src": "Tasks",
  "title": "Test",
  "subject": "",
  "body": "",
  "sender": ""
}
Uncaught Error: Can't read property 'length' of undefined
    at showMessage (messagegui.app.js:32:102)
...16;linesPerRow=3;}if((lines.length+4.5)*lineHeight<Bangle.app...
                               ^
    at checkMessages (messagegui.app.js:33:368)
...Message(newMessages[0].id,false);if(global.BUZZ_ON_NEW_MESSAGE){g...
                                   ^
    at messagegui.app.js:34:1196
...te=="show"),dontStopBuzz:1});
                               ^
> 
{"t":"act","stp":0,"hrm":0,"mov":213,"act":"UNKNOWN"}

So the error is in messagegui/app.js, on line 439 from lines being undefined. The root cause looks to be that line 367 has if (body===undefined), while line 385 has if (body). With body being an empty string (rather than undefined), both lines evaluate to false. I think that changing the first one to if (!body) would fix this bug. The fact that longer titles work appears to be a coincidence as the lines variable is reused.

I also see another potential bug lurking in the odd case where both title and body are empty strings, which would leave lines undefined. It might be worth setting lines to an empty array by default.

[bobrippling]

Nice find and write up! I can put in a fix if you'd be willing to test, or I can let you have a go if you'd prefer?

[randyheydon]

Thanks @bobrippling , I just put in pull request #3972 for this.