Name: 2pi Pulse Halo
Rating: 4.9 (32 reviews)
Author: secretsciencelab

A minimal + fast watchface that draws your heartrate history as a radial chart.
Data is beautiful. Turn your pulse data into personal art on your watchface. You’re the artist.
A reminder that time is not a straight line. But a dimension with no beginning and no end.   
As the chart sweeps around the clock, new data erases old data. Nothing is forever and tomorrow's a new adventure.
The watchface is powered by your pulse. It comes to life when you put it on. When your pulse stops, it stops too. 


FEATURES
- Low power & optimized. (Under 1 ms per update on Fenix 6 pro.)
- Similar power consumption as a stock watchface.
- As responsive as a stock watchface when pressing buttons or switching screens. No sacrificing function for form.
- 12-hour radial heart chart that shows both average and max.
- Customizable segment resolution per hour (1-3).
- Customizable colors.
- Customizable line widths.
- Option to draw heart chart's bars inward or outward.
- 3 text data fields (Default layout: top = heart rate, bottom-left = date, bottom-right = next Sunrise/Sunset) 
- Option to enable up to 4 "progress" data lines above & below the time (E.g., daily steps %, battery %, body battery %, move bar %)
- Option to disable all data fields, leaving a super-clean time face. 
- Less frequent updates during sleep time to save power.

DESIGN DETAILS
- Our watches are round so it seems natural to draw a round chart.
- Try to present data in a natural uncluttered graphic, instead of typical watchface data barf.
- Every pixel has a purpose; no superfluous lines.
- High-viz time because it's a watch's primary function.
- Organic decay of older chart segments to resemble a comet’s tail.
- Heart rate range is determined from your User Profile.
- Based on Fenix 6's minimal 3-datafield stock watchface that I liked for battery life and responsiveness. Had an itch to add a cool complication (while preserving battery life & snappiness).

TECHNICAL DETAILS
- Each screen element is redrawn independently (only when there's a change) and cached as a BufferedBitmap.
- Heavy circle trigonometry math to draw chart lines are pre-computed and cached.
- Chart lines are cached for 1 quadrant only to save memory; reflected to the other 3 quadrants at runtime. 
- drawLine used instead of drawArc for performance and because short arcs looked worse.
- New heart data is fetched incrementally. Only fresh data is processed. No cycles wasted on old data.
- Sunrise/Sunset time uses the latest GPS location. The latest location is then saved to Application.Storage as a fallback in case no new live location is available.
- anti-burn-in is auto-enabled for AMOLED devices. In Always-On-Display mode, a checkerboard overlay is applied to reduce active pixels to 10% and ensure no pixel is on for more than 3 minutes.

PERMISSIONS
- GPS permission needed to get the last GPS location for Sunrise/Sunset Time (but GPS is never activated).
- Garmin Connect fitness profile permission needed to get your heart rate range for drawing the radial chart.
- Sensor History permission needed to read your body battery and stress level data.

NOTE: The watchface auto-refreshes when you change Settings. But if it's asleep, please wake it with the wrist gesture to pick up the latest changes.