[Flare] Add more functionality to Scroll event responder #16036
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Details of bundled changes.Comparing: 5cb8f6f...8a59925 react-events
Generated by 🚫 dangerJS |
necolas
approved these changes
Jul 2, 2019
| @@ -165,13 +230,19 @@ const ScrollResponder: ReactDOMEventResponder = { | |||
| state.pointerType = pointerType; | |||
| break; | |||
| } | |||
| case 'wheel': { | |||
| state.pointerType = 'mouse'; | |||
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Did you mention that trackPad fires both scroll and wheel events?
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I mentioned it in the summary of this PR. Did you mean for me to add a comment somewhere too?
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Is the pointerType going to be correct here if trackPad is the source of the wheel event?
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Unless I'm missing something. There's no way to know if it's a trackpad or not. Mouse events can trigger wheel events too.
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OK sounds like we'll just not have trackpad as a pointer type for scroll
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This PR adds more functionality to the
Scrollevent responder. Specifically:onScrollDragStartandonScrollDragEndonMomentumScrollStartandonMomentumScrollEndFlow prop types.I looked into how we might implement the momentum scroll events and ultimately decided it wasn't worth the logic to support. The issue is that trackpad events fire
wheelandscrollfor each bit of momentum and thus it's not possible to know if the user is doing this – or if it's a system setting (like on MacOS).Furthermore, working out the difference in delta between scrolls and mousewheels is one possibility (as other third party libraries try do), but the amount of code it requires and the complexity in handling edge cases makes it non-trivial. Adding support for touch based momentum is simpler but then this feature feels half-baked. I'd much rather leave it as a TODO for later work.