Efficient way to fill semi-circle

Let's say I have a watch with a circular screen with two data fields (upper semicircle and lower semicircle).

The simplest way to clear the screen for redrawing would be to just fill the entire screen using fillCircle().

But this will be inefficient if I only need to update one of the data field since I'd need to redraw both of the data fields.

Is this the correct assumption?

In this case, should I use Arc to clear out each data field instead?

6893645 over 2 years ago

And how would you fill semi-eclipse? Arc woudn't work in that case.

Remoh over 2 years ago

I am not 100% positive if this works, but I would try to use the WatchUi Layer

https://developer.garmin.com/connect-iq/api-docs/Toybox/WatchUi/Layer.html

Create for each data field an own layer and draw on it's dc. This way, you should be able to clear the layer with a dc.clear() call on the layer's dc.

jim_m_58 over 2 years ago in reply to 6893645

When onUpdate() is called you always what to redraw the entire screen. On some devices, the dc is cleared before onUpdate is called. If you only want to update part of the screen you do in in onPartialUpdate() and set a clip region.

jim_m_58 over 2 years ago in reply to jim_m_58

If you want to clear the top or bottom half of the screen, what you do is set the colors, then use dc.fillRectangle() with "y" being 0 or height/2, with the height of the rectangle being height/2.

The sim will not show you which devices clear the entire dc before onUpdate(). It never clears it before hand.

You'll not see things in the sim that mean you have to redraw everything like toasts and notifications, even if the dc isn't cleared before every time onUpdate() is called..