detail: continue scrolling even after toolbar collapses
This commit is contained in:
Alexander Capehart
parent
6c9f170afc
commit
1ee5645780
7 changed files with 121 additions and 169 deletions
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@ -0,0 +1,116 @@
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/*
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* Copyright (c) 2022 Auxio Project
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* ContinuousAppBarLayoutBehavior.kt is part of Auxio.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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package org.oxycblt.auxio.detail
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import android.content.Context
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import android.util.AttributeSet
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import android.view.MotionEvent
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import android.view.VelocityTracker
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import android.view.ViewGroup
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import androidx.coordinatorlayout.widget.CoordinatorLayout
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import androidx.recyclerview.widget.RecyclerView
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import com.google.android.material.appbar.AppBarLayout
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class ContinuousAppBarLayoutBehavior
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@JvmOverloads
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constructor(context: Context? = null, attrs: AttributeSet? = null) :
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AppBarLayout.Behavior(context, attrs) {
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private var recycler: RecyclerView? = null
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private var pointerId = -1
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private var velocityTracker: VelocityTracker? = null
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override fun onInterceptTouchEvent(
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parent: CoordinatorLayout,
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child: AppBarLayout,
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ev: MotionEvent
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): Boolean {
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val consumed = super.onInterceptTouchEvent(parent, child, ev)
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when (ev.actionMasked) {
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MotionEvent.ACTION_DOWN -> {
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ensureVelocityTracker()
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findRecyclerView(child).stopScroll()
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pointerId = ev.getPointerId(0)
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}
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MotionEvent.ACTION_CANCEL -> {
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velocityTracker?.recycle()
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velocityTracker = null
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pointerId = -1
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}
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else -> {}
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}
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return consumed
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}
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override fun onTouchEvent(
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parent: CoordinatorLayout,
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child: AppBarLayout,
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ev: MotionEvent
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): Boolean {
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val consumed = super.onTouchEvent(parent, child, ev)
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when (ev.actionMasked) {
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MotionEvent.ACTION_DOWN -> {
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ensureVelocityTracker()
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pointerId = ev.getPointerId(0)
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}
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MotionEvent.ACTION_UP -> {
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findRecyclerView(child).fling(0, getYVelocity(ev))
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}
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MotionEvent.ACTION_CANCEL -> {
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velocityTracker?.recycle()
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velocityTracker = null
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pointerId = -1
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}
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else -> {}
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}
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velocityTracker?.addMovement(ev)
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return consumed
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}
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private fun ensureVelocityTracker() {
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if (velocityTracker == null) {
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velocityTracker = VelocityTracker.obtain()
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}
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}
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private fun getYVelocity(event: MotionEvent): Int {
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velocityTracker?.let {
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it.addMovement(event)
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it.computeCurrentVelocity(FLING_UNITS)
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return -it.getYVelocity(pointerId).toInt()
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}
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return 0
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}
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private fun findRecyclerView(child: AppBarLayout): RecyclerView {
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val recycler = recycler
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if (recycler != null) {
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return recycler
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}
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// Use the scrolling view in order to find a RecyclerView to use.
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val newRecycler =
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(child.parent as ViewGroup).findViewById<RecyclerView>(child.liftOnScrollTargetViewId)
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this.recycler = newRecycler
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return newRecycler
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}
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companion object {
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private const val FLING_UNITS = 1000 // copied from base class
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}
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}
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@ -1,169 +0,0 @@
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/*
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* Copyright (c) 2022 Auxio Project
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* DetailAppBarLayout.kt is part of Auxio.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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package org.oxycblt.auxio.detail
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import android.animation.ValueAnimator
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import android.content.Context
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import android.util.AttributeSet
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import android.view.View
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import android.view.ViewGroup
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import android.widget.TextView
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import androidx.annotation.AttrRes
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import androidx.appcompat.widget.Toolbar
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import androidx.coordinatorlayout.widget.CoordinatorLayout
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import androidx.recyclerview.widget.LinearLayoutManager
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import androidx.recyclerview.widget.RecyclerView
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import com.google.android.material.appbar.AppBarLayout
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import java.lang.reflect.Field
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import org.oxycblt.auxio.R
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import org.oxycblt.auxio.ui.CoordinatorAppBarLayout
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import org.oxycblt.auxio.util.getInteger
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import org.oxycblt.auxio.util.lazyReflectedField
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import org.oxycblt.auxio.util.logD
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/**
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* An [CoordinatorAppBarLayout] that displays the title of a hidden [Toolbar] when the scrolling
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* view goes beyond it's first item.
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*
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* This is intended for the detail views, in which the first item is the album/artist/genre header,
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* and thus scrolling past them should make the toolbar show the name in order to give context on
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* where the user currently is.
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*
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* @author Alexander Capehart (OxygenCobalt)
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*/
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class DetailAppBarLayout
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@JvmOverloads
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constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr: Int = 0) :
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CoordinatorAppBarLayout(context, attrs, defStyleAttr) {
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private var titleView: TextView? = null
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private var recycler: RecyclerView? = null
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private var titleShown: Boolean? = null
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private var titleAnimator: ValueAnimator? = null
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override fun onAttachedToWindow() {
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super.onAttachedToWindow()
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if (!isInEditMode) {
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(layoutParams as CoordinatorLayout.LayoutParams).behavior = Behavior(context)
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}
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}
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private fun findTitleView(): TextView {
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val titleView = titleView
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if (titleView != null) {
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return titleView
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}
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// Assume that we have a Toolbar with a detail_toolbar ID, as this view is only
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// used within the detail layouts.
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val toolbar = findViewById<Toolbar>(R.id.detail_normal_toolbar)
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// The Toolbar's title view is actually hidden. To avoid having to create our own
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// title view, we just reflect into Toolbar and grab the hidden field.
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val newTitleView =
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(TOOLBAR_TITLE_TEXT_FIELD.get(toolbar) as TextView).apply {
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// We can never properly initialize the title view's state before draw time,
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// so we just set it's alpha to 0f to produce a less jarring initialization
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// animation.
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alpha = 0f
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}
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this.titleView = newTitleView
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return newTitleView
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}
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private fun findRecyclerView(): RecyclerView {
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val recycler = recycler
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if (recycler != null) {
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return recycler
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}
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// Use the scrolling view in order to find a RecyclerView to use.
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val newRecycler = (parent as ViewGroup).findViewById<RecyclerView>(liftOnScrollTargetViewId)
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this.recycler = newRecycler
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return newRecycler
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}
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private fun setTitleVisibility(visible: Boolean) {
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if (titleShown == visible) return
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titleShown = visible
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// Emulate the AppBarLayout lift animation (Linear, alpha 0f -> 1f), but now with
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// the title view's alpha instead of the AppBarLayout's elevation.
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val titleView = findTitleView()
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val from: Float
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val to: Float
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if (visible) {
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from = 0f
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to = 1f
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} else {
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from = 1f
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to = 0f
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}
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if (titleView.alpha == to) {
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// Nothing to do
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return
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}
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logD("Changing title visibility [from: $from to: $to]")
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titleAnimator?.cancel()
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titleAnimator =
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ValueAnimator.ofFloat(from, to).apply {
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addUpdateListener { titleView.alpha = it.animatedValue as Float }
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duration =
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if (titleShown == true) {
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context.getInteger(R.integer.anim_fade_enter_duration).toLong()
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} else {
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context.getInteger(R.integer.anim_fade_exit_duration).toLong()
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}
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start()
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}
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}
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class Behavior
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@JvmOverloads
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constructor(context: Context? = null, attrs: AttributeSet? = null) :
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AppBarLayout.Behavior(context, attrs) {
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override fun onNestedPreScroll(
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coordinatorLayout: CoordinatorLayout,
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child: AppBarLayout,
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target: View,
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dx: Int,
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dy: Int,
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consumed: IntArray,
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type: Int
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) {
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super.onNestedPreScroll(coordinatorLayout, child, target, dx, dy, consumed, type)
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val appBarLayout = child as DetailAppBarLayout
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val recycler = appBarLayout.findRecyclerView()
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// Title should be visible if we are no longer showing the top item
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// (i.e the header)
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appBarLayout.setTitleVisibility(
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(recycler.layoutManager as LinearLayoutManager).findFirstVisibleItemPosition() > 0)
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}
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}
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private companion object {
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val TOOLBAR_TITLE_TEXT_FIELD: Field by lazyReflectedField(Toolbar::class, "mTitleTextView")
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}
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}
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@ -11,6 +11,7 @@
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<org.oxycblt.auxio.ui.CoordinatorAppBarLayout
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android:id="@+id/detail_appbar"
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style="@style/Widget.Auxio.AppBarLayout"
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app:layout_behavior="org.oxycblt.auxio.detail.ContinuousAppBarLayoutBehavior"
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app:liftOnScroll="true"
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app:liftOnScrollTargetViewId="@id/detail_recycler">
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@ -11,6 +11,7 @@
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<org.oxycblt.auxio.ui.CoordinatorAppBarLayout
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android:id="@+id/detail_appbar"
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style="@style/Widget.Auxio.AppBarLayout"
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app:layout_behavior="org.oxycblt.auxio.detail.ContinuousAppBarLayoutBehavior"
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app:liftOnScroll="true"
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app:liftOnScrollTargetViewId="@id/detail_recycler">
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@ -11,6 +11,7 @@
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<org.oxycblt.auxio.ui.CoordinatorAppBarLayout
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android:id="@+id/detail_appbar"
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style="@style/Widget.Auxio.AppBarLayout"
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app:layout_behavior="org.oxycblt.auxio.detail.ContinuousAppBarLayoutBehavior"
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app:liftOnScroll="true"
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app:liftOnScrollTargetViewId="@id/detail_recycler">
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@ -11,6 +11,7 @@
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<org.oxycblt.auxio.ui.CoordinatorAppBarLayout
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android:id="@+id/detail_appbar"
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style="@style/Widget.Auxio.AppBarLayout"
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app:layout_behavior="org.oxycblt.auxio.detail.ContinuousAppBarLayoutBehavior"
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app:liftOnScroll="true"
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app:liftOnScrollTargetViewId="@id/detail_recycler">
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@ -12,6 +12,7 @@
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android:id="@+id/detail_appbar"
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style="@style/Widget.Auxio.AppBarLayout"
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app:liftOnScroll="true"
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app:layout_behavior="org.oxycblt.auxio.detail.ContinuousAppBarLayoutBehavior"
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app:liftOnScrollTargetViewId="@id/detail_recycler">
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<com.google.android.material.appbar.CollapsingToolbarLayout
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