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Fade animation when temporarily hiding the floating header 

Change-Id: I29cae2ef7b8d537205f413b68bebe9cd0ecebd8b
This commit is contained in:
SpiritCroc 2022-05-14 16:14:10 +02:00
parent 8c414b48d9
commit 9879659df7
2 changed files with 115 additions and 13 deletions
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118
vector/src/main/java/de/spiritcroc/recyclerview/StickyHeaderItemDecoration.kt
View File

@ -7,16 +7,23 @@ package de.spiritcroc.recyclerview
* - not require EpoxyRecyclerView
* - work with reverse layouts
* - hide the currently overlaid header for a smoother animation without duplicate headers
* - ...
*/
import android.graphics.Canvas
import android.view.View
import android.view.ViewGroup
import android.view.ViewPropertyAnimator
import androidx.core.view.isVisible
import androidx.recyclerview.widget.RecyclerView
import com.airbnb.epoxy.EpoxyController
import com.airbnb.epoxy.EpoxyModel
import com.airbnb.epoxy.EpoxyViewHolder
import org.matrix.android.sdk.api.extensions.orFalse
import org.matrix.android.sdk.api.extensions.orTrue
import kotlin.math.abs
const val FADE_DURATION = 200
abstract class StickyHeaderItemDecoration(
private val epoxyController: EpoxyController,
@ -25,6 +32,17 @@ abstract class StickyHeaderItemDecoration(
private var mStickyHeaderHeight: Int = 0
private var lastHeaderPos: Int? = null
private var lastFadeState: FadeState? = null
data class FadeState(
val headerPos: Int,
val headerView: View,
val animatedView: View,
var shouldBeVisible: Boolean = true,
var animation: ViewPropertyAnimator? = null
)
// An extra header view we still draw while it's fading out
private var oldFadingView: View? = null
override fun onDrawOver(c: Canvas, parent: RecyclerView, state: RecyclerView.State) {
super.onDrawOver(c, parent, state)
@ -45,7 +63,15 @@ abstract class StickyHeaderItemDecoration(
val headerPos = getHeaderPositionForItem(topChildPosition)
if (headerPos != RecyclerView.NO_POSITION) {
val currentHeader = getHeaderViewForItem(headerPos, parent)
val oldFadeState = lastFadeState
val newFadeState: FadeState = if (headerPos == oldFadeState?.headerPos) {
oldFadeState.copy()
} else {
val currentHeaderHolder = getHeaderViewHolderForItem(headerPos, parent)
oldFadeState?.let { onDeleteFadeState(it) }
FadeState(headerPos, currentHeaderHolder.itemView, getViewForFadeAnimation(currentHeaderHolder))
}
val currentHeader = newFadeState.headerView
fixLayoutSize(parent, currentHeader)
val contactPoint = currentHeader.bottom
@ -54,23 +80,27 @@ abstract class StickyHeaderItemDecoration(
val childInContactModel = childInContact?.let { epoxyController.adapter.getModelAtPosition(parent.getChildAdapterPosition(childInContact)) }
val childBelowModel = childBelow?.let { epoxyController.adapter.getModelAtPosition(parent.getChildAdapterPosition(childBelow)) }
if (childInContact != null) {
val shouldBeVisible = if (childInContact != null) {
if (isHeader(childInContactModel)) {
updateOverlaidHeaders(parent, headerPos)
updateFadeAnimation(newFadeState)
moveHeader(c, currentHeader, childInContact)
return
}
if (preventOverlay(childInContactModel) || preventOverlay(childBelowModel)) {
// Hide header temporarily
return
}
!(preventOverlay(childInContactModel) || preventOverlay(childBelowModel))
} else {
// Header unhide
true
}
newFadeState.shouldBeVisible = shouldBeVisible
val overlaidHeaderPos: Int? = if (!shouldBeVisible ||
// Un-hide views early, so we don't get flashing headers while scrolling
val overlaidHeaderPos: Int? = if (childBelow != childInContact &&
(childBelow != childInContact &&
childBelow != null &&
isHeader(childBelowModel) &&
contactPoint - childBelow.bottom < (childBelow.bottom - childBelow.top)/8
contactPoint - childBelow.bottom < (childBelow.bottom - childBelow.top)/8)
) {
null
} else {
@ -78,11 +108,75 @@ abstract class StickyHeaderItemDecoration(
}
updateOverlaidHeaders(parent, overlaidHeaderPos)
updateFadeAnimation(newFadeState)
drawHeader(c, currentHeader)
} else {
// Show hidden header again
updateOverlaidHeaders(parent, null)
}
// Fade out an old header view
oldFadingView?.let {
if (it.alpha == 0.0f) {
oldFadingView = null
} else {
drawHeader(c, it)
}
}
// Keep invalidating while we are animating, so we can draw animation updates
if (oldFadingView != null || !lastFadeState?.hasTargetAlpha().orTrue()) {
parent.invalidate()
}
}
private fun onDeleteFadeState(oldState: FadeState) {
oldState.animation?.cancel()
oldState.animatedView.alpha = 1.0f
}
private fun updateFadeAnimation(newState: FadeState) {
val oldState = lastFadeState
if (oldState == null) {
newState.applyAlphaImmediate()
} else if (oldState.headerPos == newState.headerPos) {
if (oldState.shouldBeVisible != newState.shouldBeVisible) {
newState.startAlphaAnimation()
}
} else {
if (!oldState.shouldBeVisible && oldState.animatedView.alpha != 1.0f) {
// Keep drawing for soft fade out
oldFadingView = oldState.animatedView
}
newState.applyAlphaImmediate()
}
lastFadeState = newState
}
private fun FadeState.targetAlpha(): Float {
return if (shouldBeVisible) 1.0f else 0.0f
}
private fun FadeState.hasTargetAlpha(): Boolean {
return animatedView.alpha == targetAlpha()
}
private fun FadeState.applyAlphaImmediate() {
animation?.cancel()
animation = null
animatedView.alpha = targetAlpha()
}
private fun FadeState.startAlphaAnimation() {
animation?.cancel()
val targetAlpha = targetAlpha()
val currentAlpha = animatedView.alpha
val remainingAlpha = abs(targetAlpha - currentAlpha)
// Shorter duration if we just aborted a different fade animation, thus leaving us with less necessary alpha changes
val duration = (remainingAlpha * FADE_DURATION).toLong()
animation = animatedView.animate().alpha(targetAlpha()).setDuration(duration).apply {
start()
}
}
private fun updateOverlaidHeaders(parent: RecyclerView, headerPos: Int?) {
@ -113,13 +207,17 @@ abstract class StickyHeaderItemDecoration(
return false
}
open fun getHeaderViewForItem(headerPosition: Int, parent: RecyclerView): View {
open fun getHeaderViewHolderForItem(headerPosition: Int, parent: RecyclerView): EpoxyViewHolder {
val viewHolder = epoxyController.adapter.onCreateViewHolder(
parent,
epoxyController.adapter.getItemViewType(headerPosition)
)
epoxyController.adapter.onBindViewHolder(viewHolder, headerPosition)
return viewHolder.itemView
return viewHolder
}
open fun getViewForFadeAnimation(holder: EpoxyViewHolder): View {
return holder.itemView
}
private fun drawHeader(c: Canvas, header: View) {

8
vector/src/main/java/im/vector/app/features/home/room/detail/TimelineFragment.kt
View File

@ -1507,7 +1507,7 @@ class TimelineFragment @Inject constructor(
return model is TimelineReadMarkerItem
}
override fun getHeaderViewForItem(headerPosition: Int, parent: RecyclerView): View {
override fun getHeaderViewHolderForItem(headerPosition: Int, parent: RecyclerView): EpoxyViewHolder {
// Same as super
val viewHolder = timelineEventController.adapter.onCreateViewHolder(
parent,
@ -1519,7 +1519,7 @@ class TimelineFragment @Inject constructor(
// We want to hide the separator line for floating dates
(viewHolder.holder as? DaySeparatorItem.Holder)?.let { DaySeparatorItem.asFloatingDate(it) }
return viewHolder.itemView
return viewHolder
}
// While the header has a sticky overlay, only hide its text, not the separator lines
@ -1532,6 +1532,10 @@ class TimelineFragment @Inject constructor(
}
return false
}
override fun getViewForFadeAnimation(holder: EpoxyViewHolder): View {
return (holder.holder as? DaySeparatorItem.Holder)?.dayTextView ?: super.getViewForFadeAnimation(holder)
}
}
)
}