Expose MotionEvent history

[rnikander]

Could we maybe put this behind a feature, or ?

Or could we just make that ndk_event field publicly accessible?

I think I need this for a drawing app. I say "think" since I haven't really experimented with the events yet, but I use the equivalent "coalesced touches" on iOS.

android-activity/android-activity/src/native_activity/input.rs

Lines 122 to 140 in 1652ebb

	/*
	XXX: Not currently supported with GameActivity so we don't currently expose for NativeActivity
	either, for consistency.
	/// Returns the size of the history contained in this event.
	///
	/// See [the NDK
	/// docs](https://developer.android.com/ndk/reference/group/input#amotionevent_gethistorysize)
	#[inline]
	pub fn history_size(&self) -> usize {
	self.ndk_event.history_size()
	}
	/// An iterator over the historical events contained in this event.
	#[inline]
	pub fn history(&self) -> HistoricalMotionEventsIter<'_> {
	self.ndk_event.history()
	}
	*/

[rib]

Since I first wrote that comment it looks like GameActivity does now have support for capturing historical axis values for motion events:

android-activity/android-activity/android-games-sdk/game-activity/prefab-src/modules/game-activity/src/game-activity/GameActivityEvents.cpp

Line 223 in 1652ebb

out_event->historySize = historySize;

The public API for this crate should try to avoid exposing the ndk_event since this should now be something that's possible to support consistently across both NativeActivity and GameActivity but ndk_event is an implementation detail that's specific to the NativeActivity backend.

That probably means we need to provide our own iterator that can wrap HistoricalMotionEventsIter in the NativeActivity backend and create a similar iterator in the GameActivity backend.

It looks like I also copy pasted a skeleton for implementing an iterator for the GameActivity backend here:

android-activity/android-activity/src/game_activity/input.rs

Line 344 in 1652ebb

/*

but I guess that's just the ndk code from before GameActivity added support for history.