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Power consumption of clipping areas

topcaser
Hi, I am wondering whether the clipping area size matters regarding power consumption if only a few elements are changed. Or with other words: what's the main power driver?

Background: I have a watchface for a round watch and defined the lower quarter as my clipping area. Saying this a clipping are is a rectangle and this rectangle comprises:
1. areas which aren't physically on that watch (due to the rounding of the watch)
2. areas which aren't used by my watchface

Regarding the 2nd case I could (if it would help to save power) define two clipping areas (one after the other) which are optimized to match the rounding better.

What do you think?
  • The thing with the most impact on the power consumption (the power budget) is the number of rows involved, as the display updates by row. So, with 1/4 of the screen, that's still 1/2 the rows. That's why with an analog second hand, if you keep an eye on watchface diagnostics in the sim, you'll see things peak at 12 and 6, and get smallest at 3 and 9. It's the # of rows involved.

    If you use two cliping reasons, those are actually combined into a single one.

    So if for example, you have a small region at the very top of the display, and another small one at the bottom, it would be like a single large one, and chances are, you'll exceed the power budget
  • Hi Jim,

    thanks for sharing. My current clip looks like this:
    dc.setClip(37, 179, 166, 55);

    If I got you right, I could also write
    dc.setClip(0, 179, 240, 55);

    which makes no difference in power consumption?
  • There could be some impact, but the main thing is you want to make the area as small as possible, and if you have more than one area, as close together vertically as possible.

    Try it with View Watchface Diagnostics in the sim to see what changing the area does in your case.
  • Ok, thanks for that information. Any hints how to read the diagnostics window? Once you have written from a mean time of 30 ms per seconds but the window shows only current values, right?
  • Yes, the current values, so you just have to keep watching. Watch the total time, and especially watch for the max.