mirror of
https://github.com/facebook/react-native.git
synced 2025-11-01 09:14:26 +00:00
Luna WeiandFacebook GitHub Bot
1e53f88b72
Summary: Changelog: [Internal] Support hovering in/out of root views Prior to this change, we did not have signal when an input device moved out of the root view and so our internal state would not be aware and we would not trigger enter/leave events. This diff starts listening to `HOVER_EXIT` events as dispatched from `onInterceptHoverEvent` and assumes that's the right event to signal a cursor has moved out of the root view. We dispatch the relevant leave events for this case and update our internal state to ensure the next `HOVER_MOVE` in our rootview, will properly dispatch the enter events. ## Investigation for creating this diff Determining the signal for when an inputDevice enters/exits our rootview wasn't straight-forward. From my understanding Android event dispatching follows a similar capture, bubbling phase as web. With `onIntercept..` handlers to swallow events. See this explanation: https://suragch.medium.com/how-touch-events-are-delivered-in-android-eee3b607b038 and this video talk: https://youtu.be/EZAoJU-nUyI?t=929 However when trying to understand hover enter/exit events on the root view, my understanding of this logic broke down. Here's what confused me: * When moving a cursor from inside to outside the root view, I would receive `HOVER_ENTER/EXIT` MotionEvents on `onInterceptHoverEvent` and since we did not swallow them, we'd receive those same events on the bubble up in `onHover`. That makes sense. * However, when I hovered from the rootview into a child view, I would receive MotionEvents of `HOVER_ENTER/HOVER_EXIT` in the `onHoverEvent` handler of the rootview without having seen them in the `onInterceptHoverEvent` (re: capture phase down). This was confusing, where was the capture down? * What tips me off that these events (`HOVER_ENTER/EXIT`) don't follow the classic capture, bubbling model as explained in the linked article, is that I don't receive `HOVER_ENTER/HOVER_EXIT` events for each child view in the root view's `onInterceptHoverEvent`. * Like when a cursor moves from root -> child, I'd expect to motion events 1. exit for the rootview, 2. enter for the child view. But I never receive the 2. from the root view -- * I also wonder if the wording for `HOVER_EXIT` events mean that these events are directly dispatched to the view? Re: ["This action is always delivered to the window or view that was previously under the pointer."](https://developer.android.com/reference/android/view/MotionEvent#ACTION_HOVER_ENTER) * There also seems to be some optimizations around the dispatch path as mentioned in this video at this timestamp: https://youtu.be/EZAoJU-nUyI?t=929 for the UP gesture.. so maybe there's some optimization happening with hover events? I'm not sure how hover events are account for in gesture handling for Android. Reviewed By: vincentriemer Differential Revision: D42817315 fbshipit-source-id: 412c971c1d1e7afc0d67fadcc4417189967fe48c
Building React Native for Android
See the Building from Source guide on the React Native website.
Running tests
When you submit a pull request CircleCI will automatically run all tests. To run tests locally, see Testing guide on the React Native website.