Hi I would like to create a custom Layout like a Pizza Drawi

Question

Hi I would like to create a custom Layout like a Pizza Drawing is easy but I am not sure how to handle the tap gestures when the user taps a slice how can I know which slice was tapped I was hoping Compose may have some tools to help before I roll my sleeves up with computational geometry algo

romainguy · Answer

It s a feature I ve been wanting to add to `Path`

romainguy · Answer

but right now you d need to do it yourself

alexhelder · Answer

Thank you

romainguy · Answer

FWIW it s pretty easy in your case

romainguy · Answer

You will need to convert the x y touch coordinate to an angle which can be done with `atan2` and from that angle you can find the corresponding slice

romainguy · Answer

Something like this

romainguy · Answer

```const val RadToDeg = 180 0 PI toFloat val angleInRad = atan2 y x val angleInDeg = angleInRad RadToDeg```

romainguy · Answer

`angleRad` will be in the ` PI PI` range so you might want to account for that

romainguy · Answer

btw here I assume that `x` and `y` are offsets from the center of the pizza

alexhelder · Answer

Thanks Romain The Pizza was a simplification of my actual problem but your tips will help I am working on a goniophotometer like app the phone and illuminant rotate on same axis The UI rotates with the phone as samples are taken so that user always sees things level and can remove erroneous samples The UI looks like a starburst chart kinda pizza like D The actual sensor data is read from another device that is stationary

romainguy · Answer

Sounds like a fun project grinning

alexhelder · Answer

Ha thanks This is for an enthusiast community that tests flashlights A real integrating sphere is $$$$ Ideally there would be a spectrometer where the lux sensor is to get CCT dUV shift vs angle but I have not found an affordable semi accurate one yet Beaded TIRs solve most tint shift problems but it can be very pronounced with certain domed emitters + reflector setups The last part out of scope is flicker and driver dynamic range many flashlight drivers are unstable at their lowest settings but that also requires special hardware photosensors with fast response times

romainguy · Answer

I m familiar with stuff like this

alexhelder · Answer

I bet you are pretty famous in the photography circles not sure if you do any light painting photography but this fellow is pretty active in our circles <https www stephenknightphotography com >

romainguy · Answer

Oh nice I should check that out That said most of the lighting work I ve done was through building Filament and writing <https google github io filament Filament html>

romainguy · Answer

Got to spend a lot of quality time with light meters smile