Watchface: BufferedBitmap vs. Clipping

Former Member over 4 years ago

Hi, unfortunately there seems to be no tool to measure resource usage (cpu usage, processing time -> battery usage) on development. So: Is it more efficient to “copy a BufferedBitmap to Screen(dc)” or to use “setClip” and draw the second arm while “onPartialUpdate()” resp. “onUpdate() in 1 Hz Mode” for an area of about 50x50 pixel on a 240x240 pixel (Fenix 6S) screen?

Thx, Armin

0 jim_m_58 over 4 years ago

It's not really an "or". For an analog WF with an always on second hand, you'll want to do something like save the screen in onUpdate to a buffered bit map, then in onPartialUpdate, set the clip region for the second hand (include the old location, and then use the buffered bitmap to redraw the background in the clip region, and then draw the new second hand.

Have you looked at the analog sample in the SDK?

0 Former Member over 4 years ago in reply to jim_m_58

Thank you!

0 markdotai over 4 years ago in reply to Former Member

So really the buffered bitmap is an alternative to drawing the hour & minute hands (every second), and then in addition you always draw the second hand.

The buffered bitmap will perform as one draw, whereas drawing the hour hand + minute hand + anything else will probably be at least 2 draws. So the buffered bitmap could be cheaper in some ways.

Although if you created a single polygon which draws both the hour and minute hand in one draw call then who knows which would be cheaper