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Commit c1e7c48d authored by Jordan Demeulenaere's avatar Jordan Demeulenaere
Browse files

Avoid NPE when nested drag starts before enabling nestedDraggable() 

This CL fixes an NPE that was happening when a nested drag was started
right before enabling a nestedDraggable(), leading to a null
lastFirstDown.

Bug: 378470603
Test: atest NestedDraggableTest
Flag: EXEMPT NestedDraggable is not used yet
Change-Id: Ib7a4122b2815b1d1e1a664f04bcc5d6bd76bf2d8
parent be9d1529

packages/SystemUI/compose/core/src/com/android/compose/gesture/NestedDraggable.kt

+3 −2
Original line number Diff line number Diff line
@@ -549,9 +549,10 @@ private class NestedDraggableNode( 
            nestedScrollController == null &&

                // TODO(b/388231324): Remove this.

                !lastEventWasScrollWheel &&

                draggable.shouldConsumeNestedScroll(sign)

                draggable.shouldConsumeNestedScroll(sign) &&

                lastFirstDown != null

        ) {

            val startedPosition = checkNotNull(lastFirstDown) { "lastFirstDown is not set" }

            val startedPosition = checkNotNull(lastFirstDown)



            // TODO(b/382665591): Ensure that there is at least one pointer down.

            val pointersDownCount = pointersDown.size.coerceAtLeast(1)

packages/SystemUI/compose/core/tests/src/com/android/compose/gesture/NestedDraggableTest.kt

+23 −0
Original line number Diff line number Diff line
@@ -773,6 +773,29 @@ class NestedDraggableTest(override val orientation: Orientation) : OrientationAw 
        rule.onNodeWithTag(buttonTag).assertTextEquals("Count: 3")

    }



    @Test

    fun nestedDragNotStartedWhenEnabledAfterDragStarted() {

        val draggable = TestDraggable()

        var enabled by mutableStateOf(false)

        val touchSlop =

            rule.setContentWithTouchSlop {

                Box(

                    Modifier.fillMaxSize()

                        .nestedDraggable(draggable, orientation, enabled = enabled)

                        .scrollable(rememberScrollableState { 0f }, orientation)

                )

            }



        rule.onRoot().performTouchInput { down(center) }



        enabled = true

        rule.waitForIdle()



        rule.onRoot().performTouchInput { moveBy((touchSlop + 1f).toOffset()) }



        assertThat(draggable.onDragStartedCalled).isFalse()

    }



    private fun ComposeContentTestRule.setContentWithTouchSlop(

        content: @Composable () -> Unit

    ): Float {