I am poking around onPartialUpdate in a test watchface project. I am going watch model by model in the simulator and I am yet to find one that supports it (though I am checking AMOLED devices only). The code is:
var yes = (Toybox.WatchUi.WatchFace has :onPartialUpdate);
System.println(yes ? "Has it" : "Doesn't have it");
Building with the SDK 7.2.1.
I've gotta be missing something obvious here... is that that it's not supported on AMOLED watches?
It requires special display HW. Prior to the f5/935, MIP devices didn't support it either. The display needs to be addressable by row, and there is the limit where the average time onPartialUpdate…
Amoled devices probably don't have displays where you can limit the rows updated, as is available with recent MIP devices. And even if they did, you'd likely want to update more rows than on 280x280 MIP…
It's only on devices with an MIP display.
Here's the list of supported devices from the API Doc in the 7.3.0 SDK. It does seem to be missing some of the just announced f8 devices with a MIP display.
Supported Devices:
Charlie Delta PX Delta S Delta G1 / G1 Solar Mk1 Mk2 / Descent Mk2i Mk2 S 2
It looks like onPartialUpdate is withheld from AMOLED watches. That's a shame.
Yeah bc extending battery life and avoiding burn-in are paramount concerns for AMOLED displays. Burn-in isn't a factor for MIP, and MIP is less battery-hungry, so Garmin can get away with allowing the display to update every second, all the time (but still with limits when the user has not triggered high-power mode by turning their wrist.)
https://developer.garmin.com/connect-iq/user-experience-guidelines/watch-faces/
Low- and High-Power Modes
Connect IQ watch faces typically operate in a low-power state where the system requests updates every minute. When the user gestures to look at the watch, the system will request the watch face enter a high-power state. During this period, typically 10 seconds, the watch face can enable timers and play animations. Use this time to add some action to your watch faces.
Always Active
MIP watch faces by default update once a minute. High-power mode does allow drawing seconds or a second hand for a period of time, but sometimes the user wants that kind of information available the moment their eyes focus on the watch.
Always-active watch faces can perform a partial update of the screen every second. The update must operate under a 20 millisecond time frame, which does not allow updating the whole screen but can allow for an update on a small portion. For example, the seconds area of this watch face (highlighted in pink) could be updated once a second:
Always On (AMOLED)
Devices with AMOLED displays typically disable the display when not in use to save power, but they do allow the user to enable an always-on mode. Because long-term display use affects the battery life and can wear down the display, Connect IQ has special rules for AMOLED always-on mode. When the watch face enters always-on mode, the watch face will only update every minute, and each update is limited to using 10% of the available pixels of the display. In addition, a burn-in prevention mechanism will further guide the use of the display on some devices.
Many AMOLED devices have a setting to disable the gesture that returns the watch face to high power mode to save power. To avoid a poor user experience, it is expected that Connect IQ watch faces for AMOLED devices support always-on mode to keep and watch face visible in these cases.
https://forums.garmin.com/developer/connect-iq/b/news-announcements/posts/welcome-to-system-7
Always on Always
The original Venu was the first Connect IQ device with an AMOLED screen and introduced the heuristics to avoid screen burn-in. Newer devices allow watch faces to keep the screen on in “Always On” mode if the screen is using less than 10% of the display pixels.
With API level 5.0.0, we are updating the heuristic from one based on pixels to one based on luminance. Now the screen will stay on if the display is using less than 10% of the total luminance. This allows you to use more pixels.
