macOS: trackpad touch events

[shaunlebron]

Looking at adding access to macOS trackpad touch events. Some references to start:

• Magic: an example mac app that uses trackpad touch events for drawing
• docs on macos touch events
• edit: docs on web touch events
• edit: how SDL tracks touch events on macOS

[tonsky]

I think web api should be studied for this too

[shaunlebron]

setAcceptsTouchEvents:YES seems to be deprecated for allowedTouchTypes. I had to find a usage example on GitHub.

The acceptsTouchEvents property also seemed necessary. Does Apple have newer docs on this?

I confirmed that the touch events are being caught now (see 49a4483). I will look at logging the touch event data to the window.

[shaunlebron]

I added EventTrackpadTouch* events and the dashboard event panel is logging them successfully. I will look at drawing the touch points in a new trackpad panel.

[tonsky]

That would be cool!

[shaunlebron]

I put a trackpad panel next to the mouse panel:

CleanShot.2022-12-01.at.13.27.59.mp4

Problems so far:

1. The dashboard starts hiccuping when I move the touch points too quickly. Not sure what’s going on there.
2. Touch point state goes out of sync if you use a four-finger gesture that exits the view (swipe up, down, out or in). Not sure how to get external touch events to keep those in sync.