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[Android] Fix NPE when a touch cancel callback finishes the handler mid-transition #4584

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Merged
m-bert merged 1 commit into from
Oct 9, 2026
Merged

[Android] Fix NPE when a touch cancel callback finishes the handler mid-transition #4584

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12 changes: 9 additions & 3 deletions ...gesture-handler/android/src/main/java/com/swmansion/gesturehandler/core/GestureHandler.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -609,10 +609,14 @@ open class GestureHandler {
}

// if there are tracked pointers and the gesture is about to end, send event cancelling all pointers
if (trackedPointersCount > 0 &&
(newState == STATE_END || newState == STATE_CANCELLED || newState == STATE_FAILED)
) {
if (trackedPointersCount > 0 && isFinished(newState)) {
cancelPointers()

// `cancelPointers` dispatches the event synchronously and its callback may change the state
// (e.g. via `GestureStateManager.fail`), in which case the transition is already complete.
if (isFinished(state)) {
return
}
}

val oldState = state
Expand Down Expand Up @@ -998,6 +1002,8 @@ open class GestureHandler {
}

companion object {
fun isFinished(state: Int) = state == STATE_CANCELLED || state == STATE_FAILED || state == STATE_END
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j-piasecki marked this conversation as resolved.
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private const val DEFAULT_NEEDS_POINTER_DATA = false
private const val DEFAULT_MANUAL_ACTIVATION = false
private const val DEFAULT_SHOULD_CANCEL_WHEN_OUTSIDE = false
Expand Down
12 changes: 4 additions & 8 deletions ...ler/android/src/main/java/com/swmansion/gesturehandler/core/GestureHandlerOrchestrator.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -101,7 +101,7 @@ class GestureHandlerOrchestrator(

private fun cleanupFinishedHandlers() {
for (handler in gestureHandlers.asReversed()) {
if (isFinished(handler.state) && !handler.isAwaiting) {
if (GestureHandler.isFinished(handler.state) && !handler.isAwaiting) {
handler.reset()
handler.apply {
isActive = false
Expand All @@ -111,13 +111,13 @@ class GestureHandlerOrchestrator(
}
}

gestureHandlers.removeAll { isFinished(it.state) && !it.isAwaiting }
gestureHandlers.removeAll { GestureHandler.isFinished(it.state) && !it.isAwaiting }

finishedHandlersCleanupScheduled = false
}

private fun hasOtherHandlerToWaitFor(handler: GestureHandler) =
gestureHandlers.any { !isFinished(it.state) && shouldHandlerWaitForOther(handler, it) }
gestureHandlers.any { !GestureHandler.isFinished(it.state) && shouldHandlerWaitForOther(handler, it) }

private fun shouldBeCancelledByFinishedHandler(handler: GestureHandler) =
gestureHandlers.any { shouldHandlerWaitForOther(handler, it) && it.state == GestureHandler.STATE_END }
Expand Down Expand Up @@ -167,7 +167,7 @@ class GestureHandlerOrchestrator(
handler.isAwaiting = false
}

if (isFinished(newState)) {
if (GestureHandler.isFinished(newState)) {
// We have to loop through copy in order to avoid modifying collection
// while iterating over its elements
val currentlyAwaitingHandlers = awaitingHandlers.toList()
Expand Down Expand Up @@ -1027,9 +1027,5 @@ class GestureHandlerOrchestrator(
true
}
}

private fun isFinished(state: Int) = state == GestureHandler.STATE_CANCELLED ||
state == GestureHandler.STATE_FAILED ||
state == GestureHandler.STATE_END
}
}
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