TouchBackend: Clear old timeout in handleTopMoveStartDelay#3664
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raineorshine wants to merge 2 commits intoreact-dnd:mainfrom
Open
TouchBackend: Clear old timeout in handleTopMoveStartDelay#3664raineorshine wants to merge 2 commits intoreact-dnd:mainfrom
raineorshine wants to merge 2 commits intoreact-dnd:mainfrom
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@darthtrevino Ready for review! Thanks. |
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Problem
Normally,
delayTouchStartrequires that the user tap and hold the draggable element for a given delay before a drag is initiated. If there is a touchmove during this time, the drag is cancelled.However, if the user quickly touches the screen and then initiates a tap + move within
delayTouchStart, the drag will incorrectly start, ignoring the move that would have cancelled it.A real-world case is described in cybersemics/em#2967.
Cause
This occurs because the
handleTopMoveStarttimer is only cleared inhandleTopMove. WhenhandleTouchStartDelayis triggered in quick session (by two taps), then the second call tohandleTouchStartDelaywill overwrite the existing timer beforehandleTopMovehas the chance to clear it. Thus, whenhandleTopMovefires, it only clears the second timer, and the first incorrectly resolveshandleTouchStartthinking that the user has not moved their finger.Solution
This is fixed by clearing the old timer before setting the new timer.