Fix scroll animation when system animation is disabled (#7509)

app/src/main/java/eu/kanade/presentation/util/Scrollable.kt

@@ -0,0 +1,60 @@
+package eu.kanade.presentation.util
+
+import androidx.compose.animation.core.AnimationState
+import androidx.compose.animation.core.DecayAnimationSpec
+import androidx.compose.animation.core.animateDecay
+import androidx.compose.animation.rememberSplineBasedDecay
+import androidx.compose.foundation.gestures.FlingBehavior
+import androidx.compose.foundation.gestures.ScrollScope
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import androidx.compose.ui.MotionDurationScale
+import kotlinx.coroutines.withContext
+import kotlin.math.abs
+
+/**
+ * FlingBehavior that always uses the default motion scale.
+ *
+ * This makes the scrolling animation works like View's lists
+ * when "Remove animation" settings is on.
+ */
+@Composable
+fun flingBehaviorIgnoringMotionScale(): FlingBehavior {
+    val flingSpec = rememberSplineBasedDecay<Float>()
+    return remember(flingSpec) {
+        DefaultFlingBehavior(flingSpec)
+    }
+}
+
+private val DefaultMotionDurationScale = object : MotionDurationScale {
+    // Use default motion scale factor
+    override val scaleFactor: Float = 1f
+}
+
+private class DefaultFlingBehavior(
+    private val flingDecay: DecayAnimationSpec<Float>,
+) : FlingBehavior {
+    override suspend fun ScrollScope.performFling(initialVelocity: Float): Float {
+        // come up with the better threshold, but we need it since spline curve gives us NaNs
+        return if (abs(initialVelocity) > 1f) {
+            var velocityLeft = initialVelocity
+            var lastValue = 0f
+            withContext(DefaultMotionDurationScale) {
+                AnimationState(
+                    initialValue = 0f,
+                    initialVelocity = initialVelocity,
+                ).animateDecay(flingDecay) {
+                    val delta = value - lastValue
+                    val consumed = scrollBy(delta)
+                    lastValue = value
+                    velocityLeft = this.velocity
+                    // avoid rounding errors and stop if anything is unconsumed
+                    if (abs(delta - consumed) > 0.5f) this.cancelAnimation()
+                }
+            }
+            velocityLeft
+        } else {
+            initialVelocity
+        }
+    }
+}