While working on my Pebble watchface “Future Time” I have encountered persistent annoying problem – watchface would run for a while and then crash – and not only crash, but actually restart the watch. What made this even more frustrating – after 3 restarts in a row Pebble would revert to recovery mode and complete firmware reinstall was required (did I accidentally write a Pebble virus?).
When I dug into device logs I found out that every restart was given reason: “Dangerous Stack Overflow”. Which is kinda strange – I don’t have any recursions nor deeply nested function calls nor large local variables. I tried lots of things – including extreme ones like declaring all local function variables as global or static – nothing helped.
Finally Christian form Pebble developers forum shed a light. He pointed out that I use a lot of GRect constructs which is basic rectangle building block for pretty much anything from defining layers to graphics functions. I used GRect inline directly inside function calls, which I thought wasn’t a big deal, after all “everybody does that” – including Pebble in its examples. Well, as Christian pointed out those GRects are kind of local variables, and either memory is not reclaimed fast enough when they go out of scope or they spring memory leak.
Keeping this in mind I created a global GRect variable and when needed to use a GRect in local function, first I’d assign it’s value to the variable and then use variable in the function.
So something like this:
I’ve recently updated code for Cobblestyle Pebble Watchface to take advantage of very cool geocoding service called Nominatim by Open Street Maps.
Nominatim is used in two places: Direct lookup is used in watchface’s config page to lookup coordinates of a place by its name for custom location setting; reverse lookup is used to lookup location name by its coordinates to display name on actual watchface.
It was working fine – on Pebble watches connected to Android phones. It was failing miserably on iOS, so iPhone Pebble users were getting neither location nor weather updates. And it was pretty puzzling for a while until I obtained logs from running watchface thanks to invaluable help from Robin.
Turned out iPhone Pebble app was plain simple blocked by Nominatim service, every attempt to retrieve location resulted in message being sent back “You have violated acceptable policy”. Which was kinda surprising since I just started using the service. When I contacted Nominatim support, they told me that apparently some Pebble app running from iPhone abused the service pretty badly, running hundreds of requests per second. And since the only way they can detect requesting app is by it’s User Agent string – all apps spotting iPhone Pebble UA were blocked.
Support suggested to set UA string specific to the app so it could be easily identifiable. Standard approach to set headers on xmlHttpRequest object is .setRequestHeader(..). Unfortunately by many browsers and clients it is considered unsafe to spoof UA via request headers. Fortunately iOS allows that, so all I have to do is catch and ignore errors in other clients. Basically this line of code solved the issue:
I’ve encountered a weird issue while working with EffectLayer Library (a visual effect library for Pebble smartwatch). In this particular watchface called Clean & Smart I used “invert” effect which inverts colors of the watchface should the user choose that option in settings. It was working fine when option changed when watchface was loaded/unload and behaved weirdly only in one particular scenario: when you would receive a notification (email, text etc.) and then dismiss it. Upon coming back from notification to watchface invert effect would only partially cover the watchface (as seen on the screenshot).
I don’t know exactly what was happening, but had a theory. Continue reading →
SDK 3.x for Pebble Time smartwatch offers cool and very convenient set of functions to create animation from your existing GIF or MP4 via APNG support. APNG is an obscure “Animated PNG” format (at the time of the post only Mozilla Firefox supports it) but it’s very powerful and can store animation in much more compressed format than traditional animated GIF, so Pebble chose it for a reason. So if you have a GIF, convert it to APNG with Gif2Apng (or if you have a video, convert MP4 to GIF first and then to APNG) and you’re ready to use it on Pebble Time. Just keep the size in check, since Pebble has to load entire APNG sequence in memory, try not to go overboard. The first video is showing animation from my “Vortex” watchface using this approach on Pebble Time.
But what about original classic Pebbles? Eventually they will get firmware 3.x and SDK 3.x support and with that APNG functions among other advantages, but at the time of this writing it is still hazy when this is going to happen. But where there’s a will there’s a way – you can still use your MP4/GIF source for animation it’s just a bit more tricky. Instead of dealing with a single APNG file as your resource and relying on Pebble firmware to draw the frames you will need to help it a little.
First you will need to split your source into individual frames, for example using this service. Yes, you will be dealing with individual frames, so don’t go creating a Hollywood blockbuster. But don’t fret, it’s a bit more manual work, but you won’t have to hand-crank the moving pictures all the way. Continue reading →
Pebble Time is latest and greatest smartwatch from Pebble corp. And one of the advantages it has over classic model is new epaper screen capable of supporting 64 colors. To test its capabilities I developed several color watchfaces. Some of them are the converted ones that originally were made for classic Pebble, some of them new. Click on the image to get redirected to Pebble appstore.
“Long Shadow” – inspired by stock LG G watchface, features large time and long colorful shadows. Config page allows customization of every color as well as shadow direction
“TV Time” – old-style TV displays time in cartoon format. Grid on the panel shows battery level
“Simple Striped – Large time in color-striped font. Thin line at the bottom shows battery level both in length and coior
“Rustic Slider” – Though not in full color, uses Pebble Time gray shades to create realistic blocks with customizable sliding animation
“Poochie” – spoof of Gucci luxury digital watch
“Meyer Objects” – Hour. minute and second hands are represented by wireframe design. Shake to display normal digital time. Configurable options
“3D Wedge” – Time displayed in diagonal skewed form along with date, time and battery percentage
Give them a try once you get your PT! Or, you can load them on your classic Pebble as B&W versions 🙂
Pebble Time timeline is a very cool user interface allowing you to see future and past events and act upon them right on your watch. Right out of the box Pebble Time supports calendar pins that shows your future and past appointments in the timeline as well as weather alerts. But the real power comes from 3rd party apps using timeline – they can add anything from sports scores to latest news to TV showtimes – limit is just your imagination.
Pebble has always had open SDK – this is one of its major strengths, and Timeline is not an exception. Timeline API is a very straightforward way to push your own pins to users of your app. There’re various examples and libraries including PHP and node.js on how to deal with the timeline, but I, being mostly a Microsoft developer by trade, decided to bring Timeline into .NET. This particular example is in ASP.NET – pin is pushed from Webpage when user clicks a button, but it’s just one of the possible scenarios.
In order to push timeline pins successfully you will need 2 pieces:
A watchapp that runs on Pebble. In fact after first run, that subscribes user to timeline, the app doesn’t have to be running on the watch anymore. It doesn’t even have to be on the watch. As long as it simple remains in your locker on the phone – you will continue to receive its pins
Your own server that sends calls to Pebble public Timeline API to control pins