Fix fling animation for fast scrolling gestures (#1616)

Fixes: https://youtrack.jetbrains.com/issue/CMP-6791

## Testing
- Check fast gesture for fling (see the issue description)
- Ensure that unintentional fling is not reproduced after the stop and
lift up gesture:
JetBrains/compose-multiplatform#3335

## Release Notes
### Fixes - iOS
- Fling animation works correctly for fast scrolling gestures

compose/ui/ui/src/androidMain/kotlin/androidx/compose/ui/input/pointer/util/VelocityTracker.android.kt

@@ -16,7 +16,6 @@
 
 package androidx.compose.ui.input.pointer.util
 
-internal actual const val AssumePointerMoveStoppedMilliseconds: Int = 40
 internal actual const val HistorySize: Int = 20
 
 /**
@@ -25,5 +24,6 @@ internal actual const val HistorySize: Int = 20
 internal actual fun VelocityTracker1D.shouldUseDataPoints(
     points: FloatArray,
     times: FloatArray,
-    count: Int
+    count: Int,
+    afterPointerStop: Boolean
 ): Boolean = true

compose/ui/ui/src/commonMain/kotlin/androidx/compose/ui/input/pointer/util/VelocityTracker.kt

@@ -30,7 +30,7 @@ import kotlin.math.abs
 import kotlin.math.sign
 import kotlin.math.sqrt
 
-internal expect val AssumePointerMoveStoppedMilliseconds: Int
+private const val AssumePointerMoveStoppedMilliseconds: Int = 40
 internal expect val HistorySize: Int
 
 // TODO(b/204895043): Keep value in sync with VelocityPathFinder.HorizonMilliSeconds
@@ -232,7 +232,7 @@ internal constructor(
         val newestSample: DataPointAtTime = samples[index] ?: return 0f
 
         var previousSample: DataPointAtTime = newestSample
-        var previousDirection: Boolean? = null
+        var afterPointerStop = false
 
         // Starting with the most recent PointAtTime sample, iterate backwards while
         // the samples represent continuous motion.
@@ -247,7 +247,11 @@ internal constructor(
                 } else {
                     newestSample
                 }
-            if (age > HorizonMilliseconds || delta > AssumePointerMoveStoppedMilliseconds) {
+            if (delta > AssumePointerMoveStoppedMilliseconds) {
+                afterPointerStop = true
+                break
+            }
+            if (age > HorizonMilliseconds) {
                 break
             }
 
@@ -258,7 +262,13 @@ internal constructor(
             sampleCount += 1
         } while (sampleCount < HistorySize)
 
-        if (sampleCount >= minSampleSize && shouldUseDataPoints(dataPoints, time, sampleCount)) {
+        if (sampleCount >= minSampleSize && shouldUseDataPoints(
+                dataPoints,
+                time,
+                sampleCount,
+                afterPointerStop
+            )
+        ) {
             // Choose computation logic based on strategy.
             return when (strategy) {
                 Strategy.Impulse -> {
@@ -351,7 +361,8 @@ private fun Array<DataPointAtTime?>.set(index: Int, time: Long, dataPoint: Float
 internal expect fun VelocityTracker1D.shouldUseDataPoints(
     points: FloatArray,
     times: FloatArray,
-    count: Int
+    count: Int,
+    afterPointerStop: Boolean
 ): Boolean
 
 

compose/ui/ui/src/notMobileMain/kotlin/androidx/compose/ui/input/pointer/util/VelocityTracker.notMobile.kt

@@ -16,7 +16,6 @@
 
 package androidx.compose.ui.input.pointer.util
 
-internal actual const val AssumePointerMoveStoppedMilliseconds: Int = 40
 internal actual const val HistorySize: Int = 20
 
 /**
@@ -25,5 +24,6 @@ internal actual const val HistorySize: Int = 20
 internal actual fun VelocityTracker1D.shouldUseDataPoints(
     points: FloatArray,
     times: FloatArray,
-    count: Int
+    count: Int,
+    afterPointerStop: Boolean
 ): Boolean = true

compose/ui/ui/src/uikitMain/kotlin/androidx/compose/ui/input/pointer/util/VelocityTracker.uikit.kt

@@ -18,7 +18,6 @@ package androidx.compose.ui.input.pointer.util
 
 import kotlin.math.abs
 
-internal actual const val AssumePointerMoveStoppedMilliseconds: Int = 100
 internal actual const val HistorySize: Int = 40 // Increased to store history on 120 Hz devices
 
 private const val MinimumGestureDurationMilliseconds: Int = 50
@@ -30,14 +29,15 @@ private const val MinimumGestureSpeed: Float = 1.0f // Minimum tracking speed, d
 internal actual fun VelocityTracker1D.shouldUseDataPoints(
     points: FloatArray,
     times: FloatArray,
-    count: Int
+    count: Int,
+    afterPointerStop: Boolean
 ): Boolean {
     if (count == 0) {
         return false
     }
 
     val timeDelta = abs(times[0] - times[count - 1])
-    if (timeDelta < MinimumGestureDurationMilliseconds) {
+    if (timeDelta < MinimumGestureDurationMilliseconds && afterPointerStop) {
         return false
     }