我想觀察 onFling 函式來檢測 Velocityx 和 Velocity Means Swaping force/Velocity。在android中，我們將它附加到android視圖。但是沒有找到一種方法如何在Jetpack compose中呼叫它或在jetpack compose中為此呼叫替代函式......？
uj5u.com熱心網友回復：
請參加Animation-in-Compose代碼實驗室以更好地理解，但現在，您可以通過以下方式實作類似的東西
private fun Modifier.swipeToDismiss(
onDismissed: () -> Unit
): Modifier = composed {
// This `Animatable` stores the horizontal offset for the element.
val offsetX = remember { Animatable(0f) }
pointerInput(Unit) {
// Used to calculate a settling position of a fling animation.
val decay = splineBasedDecay<Float>(this)
// Wrap in a coroutine scope to use suspend functions for touch events and animation.
coroutineScope {
while (true) {
// Wait for a touch down event.
val pointerId = awaitPointerEventScope { awaitFirstDown().id }
// Interrupt any ongoing animation.
offsetX.stop()
// Prepare for drag events and record velocity of a fling.
val velocityTracker = VelocityTracker()
// Wait for drag events.
awaitPointerEventScope {
horizontalDrag(pointerId) { change ->
// Record the position after offset
val horizontalDragOffset = offsetX.value change.positionChange().x
launch {
// Overwrite the `Animatable` value while the element is dragged.
offsetX.snapTo(horizontalDragOffset)
}
// Record the velocity of the drag.
velocityTracker.addPosition(change.uptimeMillis, change.position)
// Consume the gesture event, not passed to external
change.consumePositionChange()
}
}
// Dragging finished. Calculate the velocity of the fling.
val velocity = velocityTracker.calculateVelocity().x
// Calculate where the element eventually settles after the fling animation.
val targetOffsetX = decay.calculateTargetValue(offsetX.value, velocity)
// The animation should end as soon as it reaches these bounds.
offsetX.updateBounds(
lowerBound = -size.width.toFloat(),
upperBound = size.width.toFloat()
)
launch {
if (targetOffsetX.absoluteValue <= size.width) {
// Not enough velocity; Slide back to the default position.
offsetX.animateTo(targetValue = 0f, initialVelocity = velocity)
} else {
// Enough velocity to slide away the element to the edge.
offsetX.animateDecay(velocity, decay)
// The element was swiped away.
onDismissed()
}
}
}
}
}
// Apply the horizontal offset to the element.
.offset { IntOffset(offsetX.value.roundToInt(), 0) }
}
我不建議您嘗試僅從這里理解此代碼，您可能應該參考手頭的檔案，同時學習 codelab。這在 compose-sample 應用程式中的簡單串列項上實作了滑動關閉功能，您將在 codelab 的開頭找到鏈接到的代碼。以下是為撰寫發布的所有示例應用程式，供您參考。
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