diff options
| -rw-r--r-- | wear/compose/compose-material/src/commonMain/kotlin/androidx/wear/compose/material/ScalingLazyColumnSnapFlingBehavior.kt | 59 |
1 files changed, 34 insertions, 25 deletions
diff --git a/wear/compose/compose-material/src/commonMain/kotlin/androidx/wear/compose/material/ScalingLazyColumnSnapFlingBehavior.kt b/wear/compose/compose-material/src/commonMain/kotlin/androidx/wear/compose/material/ScalingLazyColumnSnapFlingBehavior.kt index 1b9b9572587..a1fdfa3699f 100644 --- a/wear/compose/compose-material/src/commonMain/kotlin/androidx/wear/compose/material/ScalingLazyColumnSnapFlingBehavior.kt +++ b/wear/compose/compose-material/src/commonMain/kotlin/androidx/wear/compose/material/ScalingLazyColumnSnapFlingBehavior.kt @@ -90,31 +90,40 @@ internal class ScalingLazyColumnSnapFlingBehavior( // We can also control the inertia of these speeds, i.e. how much it will accelerate/ // decelerate at the beginning and end. val distance = finalTarget - animationState.value - val initialSpeed = animationState.velocity - - // Inertia of the initial speed. - val initialInertia = 0.5f - - // Compute how much time we want to spend on the final snap, depending on the speed - val finalSnapDuration = lerp(FINAL_SNAP_DURATION_MIN, FINAL_SNAP_DURATION_MAX, - abs(initialSpeed) / SNAP_SPEED_THRESHOLD) - - // Initial control point. Has slope (velocity) adjustedSpeed and magnitude (inertia) - // initialInertia - val adjustedSpeed = initialSpeed * finalSnapDuration / distance - val easingX0 = initialInertia / sqrt(1f + adjustedSpeed * adjustedSpeed) - val easingY0 = easingX0 * adjustedSpeed - - // Final control point. Has slope 0, unless that will make us accelerate then decelerate, - // in that case we set the slope to 1. - val easingX1 = 0.8f - val easingY1 = if (easingX0 > easingY0) 0.8f else 1f - - animationState.animateTo(finalTarget, tween((finalSnapDuration * 1000).roundToInt(), - easing = CubicBezierEasing(easingX0, easingY0, easingX1, easingY1) - )) { - scrollBy(value - lastValue) - lastValue = value + + // If the distance to fling is zero, nothing to do (and must avoid divide-by-zero below). + if (distance != 0.0f) { + val initialSpeed = animationState.velocity + + // Inertia of the initial speed. + val initialInertia = 0.5f + + // Compute how much time we want to spend on the final snap, depending on the speed + val finalSnapDuration = lerp( + FINAL_SNAP_DURATION_MIN, FINAL_SNAP_DURATION_MAX, + abs(initialSpeed) / SNAP_SPEED_THRESHOLD + ) + + // Initial control point. Has slope (velocity) adjustedSpeed and magnitude (inertia) + // initialInertia + val adjustedSpeed = initialSpeed * finalSnapDuration / distance + val easingX0 = initialInertia / sqrt(1f + adjustedSpeed * adjustedSpeed) + val easingY0 = easingX0 * adjustedSpeed + + // Final control point. Has slope 0, unless that will make us accelerate then decelerate, + // in that case we set the slope to 1. + val easingX1 = 0.8f + val easingY1 = if (easingX0 > easingY0) 0.8f else 1f + + animationState.animateTo( + finalTarget, tween( + (finalSnapDuration * 1000).roundToInt(), + easing = CubicBezierEasing(easingX0, easingY0, easingX1, easingY1) + ) + ) { + scrollBy(value - lastValue) + lastValue = value + } } return animationState.velocity |