recycler: redesign fast scroller

- Use new "bump" design
- Base off fundamental RV primitives over custom item
calculations
- Make possible to use by non-home views

app/src/main/java/org/oxycblt/auxio/home/fastscroll/FastScrollPopupView.kt

@@ -1,185 +0,0 @@
-/*
- * Copyright (c) 2022 Auxio Project
- * FastScrollPopupView.kt is part of Auxio.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
- 
-package org.oxycblt.auxio.home.fastscroll
-
-import android.content.Context
-import android.graphics.Canvas
-import android.graphics.ColorFilter
-import android.graphics.Matrix
-import android.graphics.Outline
-import android.graphics.Paint
-import android.graphics.Path
-import android.graphics.PixelFormat
-import android.graphics.Rect
-import android.graphics.drawable.Drawable
-import android.os.Build
-import android.text.TextUtils
-import android.util.AttributeSet
-import android.view.Gravity
-import androidx.core.widget.TextViewCompat
-import com.google.android.material.R as MR
-import com.google.android.material.textview.MaterialTextView
-import org.oxycblt.auxio.R
-import org.oxycblt.auxio.util.getAttrColorCompat
-import org.oxycblt.auxio.util.getDimenPixels
-import org.oxycblt.auxio.util.isRtl
-
-/**
- * A [MaterialTextView] that displays the popup indicator used in FastScrollRecyclerView
- *
- * @author Alexander Capehart (OxygenCobalt), Hai Zhang
- */
-class FastScrollPopupView
-@JvmOverloads
-constructor(context: Context, attrs: AttributeSet? = null, defStyleRes: Int = 0) :
-    MaterialTextView(context, attrs, defStyleRes) {
-    init {
-        minimumWidth = context.getDimenPixels(R.dimen.size_touchable_mid_huge)
-        minimumHeight = context.getDimenPixels(R.dimen.size_touchable_large)
-
-        TextViewCompat.setTextAppearance(this, R.style.TextAppearance_Auxio_HeadlineLarge)
-        setTextColor(context.getAttrColorCompat(MR.attr.colorOnSecondary))
-        ellipsize = TextUtils.TruncateAt.MIDDLE
-        gravity = Gravity.CENTER
-        includeFontPadding = false
-
-        alpha = 0f
-        elevation = context.getDimenPixels(MR.dimen.m3_sys_elevation_level2).toFloat()
-        background = FastScrollPopupDrawable(context)
-    }
-
-    private class FastScrollPopupDrawable(context: Context) : Drawable() {
-        private val paint: Paint =
-            Paint().apply {
-                isAntiAlias = true
-                color =
-                    context
-                        .getAttrColorCompat(com.google.android.material.R.attr.colorSecondary)
-                        .defaultColor
-                style = Paint.Style.FILL
-            }
-
-        private val path = Path()
-        private val matrix = Matrix()
-
-        private val paddingStart = context.getDimenPixels(R.dimen.spacing_medium)
-        private val paddingEnd = context.getDimenPixels(R.dimen.spacing_mid_huge)
-
-        override fun draw(canvas: Canvas) {
-            canvas.drawPath(path, paint)
-        }
-
-        override fun onBoundsChange(bounds: Rect) {
-            updatePath()
-        }
-
-        override fun onLayoutDirectionChanged(layoutDirection: Int): Boolean {
-            updatePath()
-            return true
-        }
-
-        @Suppress("DEPRECATION")
-        override fun getOutline(outline: Outline) {
-            when {
-                Build.VERSION.SDK_INT >= Build.VERSION_CODES.R -> outline.setPath(path)
-
-                // Paths don't need to be convex on android Q, but the API was mislabeled and so
-                // we still have to use this method.
-                Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q -> outline.setConvexPath(path)
-                else ->
-                    if (!path.isConvex) {
-                        // The outline path must be convex before Q, but we may run into floating
-                        // point errors caused by calculations involving sqrt(2) or OEM differences,
-                        // so in this case we just omit the shadow instead of crashing.
-                        super.getOutline(outline)
-                    }
-            }
-        }
-
-        override fun getPadding(padding: Rect): Boolean {
-            if (isRtl) {
-                padding[paddingEnd, 0, paddingStart] = 0
-            } else {
-                padding[paddingStart, 0, paddingEnd] = 0
-            }
-
-            return true
-        }
-
-        override fun isAutoMirrored(): Boolean = true
-
-        override fun setAlpha(alpha: Int) {}
-
-        override fun setColorFilter(colorFilter: ColorFilter?) {}
-
-        override fun getOpacity(): Int = PixelFormat.TRANSLUCENT
-
-        private fun updatePath() {
-            val r = bounds.height().toFloat() / 2
-            val w = (r + SQRT2 * r).coerceAtLeast(bounds.width().toFloat())
-
-            path.apply {
-                reset()
-
-                // Draw the left pill shape
-                val o1X = w - SQRT2 * r
-                arcToSafe(r, r, r, 90f, 180f)
-                arcToSafe(o1X, r, r, -90f, 45f)
-
-                // Draw the right arrow shape
-                val point = r / 5
-                val o2X = w - SQRT2 * point
-                arcToSafe(o2X, r, point, -45f, 90f)
-                arcToSafe(o1X, r, r, 45f, 45f)
-
-                close()
-            }
-
-            matrix.apply {
-                reset()
-                if (isRtl) setScale(-1f, 1f, w / 2, 0f)
-                postTranslate(bounds.left.toFloat(), bounds.top.toFloat())
-            }
-
-            path.transform(matrix)
-        }
-
-        private fun Path.arcToSafe(
-            centerX: Float,
-            centerY: Float,
-            radius: Float,
-            startAngle: Float,
-            sweepAngle: Float
-        ) {
-            arcTo(
-                centerX - radius,
-                centerY - radius,
-                centerX + radius,
-                centerY + radius,
-                startAngle,
-                sweepAngle,
-                false)
-        }
-    }
-
-    private companion object {
-        // Pre-calculate sqrt(2)
-        const val SQRT2 = 1.4142135f
-    }
-}

app/src/main/java/org/oxycblt/auxio/home/list/AlbumListFragment.kt

@@ -29,12 +29,12 @@ import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.FragmentHomeListBinding
 import org.oxycblt.auxio.detail.DetailViewModel
 import org.oxycblt.auxio.home.HomeViewModel
-import org.oxycblt.auxio.home.fastscroll.FastScrollRecyclerView
 import org.oxycblt.auxio.list.ListFragment
 import org.oxycblt.auxio.list.ListViewModel
 import org.oxycblt.auxio.list.SelectableListListener
 import org.oxycblt.auxio.list.adapter.SelectionIndicatorAdapter
 import org.oxycblt.auxio.list.recycler.AlbumViewHolder
+import org.oxycblt.auxio.list.recycler.FastScrollRecyclerView
 import org.oxycblt.auxio.list.sort.Sort
 import org.oxycblt.auxio.music.Album
 import org.oxycblt.auxio.music.Music

app/src/main/java/org/oxycblt/auxio/home/list/ArtistListFragment.kt

@@ -27,12 +27,12 @@ import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.FragmentHomeListBinding
 import org.oxycblt.auxio.detail.DetailViewModel
 import org.oxycblt.auxio.home.HomeViewModel
-import org.oxycblt.auxio.home.fastscroll.FastScrollRecyclerView
 import org.oxycblt.auxio.list.ListFragment
 import org.oxycblt.auxio.list.ListViewModel
 import org.oxycblt.auxio.list.SelectableListListener
 import org.oxycblt.auxio.list.adapter.SelectionIndicatorAdapter
 import org.oxycblt.auxio.list.recycler.ArtistViewHolder
+import org.oxycblt.auxio.list.recycler.FastScrollRecyclerView
 import org.oxycblt.auxio.list.sort.Sort
 import org.oxycblt.auxio.music.Artist
 import org.oxycblt.auxio.music.Music

app/src/main/java/org/oxycblt/auxio/home/list/GenreListFragment.kt

@@ -27,11 +27,11 @@ import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.FragmentHomeListBinding
 import org.oxycblt.auxio.detail.DetailViewModel
 import org.oxycblt.auxio.home.HomeViewModel
-import org.oxycblt.auxio.home.fastscroll.FastScrollRecyclerView
 import org.oxycblt.auxio.list.ListFragment
 import org.oxycblt.auxio.list.ListViewModel
 import org.oxycblt.auxio.list.SelectableListListener
 import org.oxycblt.auxio.list.adapter.SelectionIndicatorAdapter
+import org.oxycblt.auxio.list.recycler.FastScrollRecyclerView
 import org.oxycblt.auxio.list.recycler.GenreViewHolder
 import org.oxycblt.auxio.list.sort.Sort
 import org.oxycblt.auxio.music.Genre

app/src/main/java/org/oxycblt/auxio/home/list/PlaylistListFragment.kt

@@ -26,11 +26,11 @@ import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.FragmentHomeListBinding
 import org.oxycblt.auxio.detail.DetailViewModel
 import org.oxycblt.auxio.home.HomeViewModel
-import org.oxycblt.auxio.home.fastscroll.FastScrollRecyclerView
 import org.oxycblt.auxio.list.ListFragment
 import org.oxycblt.auxio.list.ListViewModel
 import org.oxycblt.auxio.list.SelectableListListener
 import org.oxycblt.auxio.list.adapter.SelectionIndicatorAdapter
+import org.oxycblt.auxio.list.recycler.FastScrollRecyclerView
 import org.oxycblt.auxio.list.recycler.PlaylistViewHolder
 import org.oxycblt.auxio.list.sort.Sort
 import org.oxycblt.auxio.music.Music

app/src/main/java/org/oxycblt/auxio/home/list/SongListFragment.kt

@@ -28,11 +28,11 @@ import java.util.Formatter
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.databinding.FragmentHomeListBinding
 import org.oxycblt.auxio.home.HomeViewModel
-import org.oxycblt.auxio.home.fastscroll.FastScrollRecyclerView
 import org.oxycblt.auxio.list.ListFragment
 import org.oxycblt.auxio.list.ListViewModel
 import org.oxycblt.auxio.list.SelectableListListener
 import org.oxycblt.auxio.list.adapter.SelectionIndicatorAdapter
+import org.oxycblt.auxio.list.recycler.FastScrollRecyclerView
 import org.oxycblt.auxio.list.recycler.SongViewHolder
 import org.oxycblt.auxio.list.sort.Sort
 import org.oxycblt.auxio.music.Music

app/src/main/java/org/oxycblt/auxio/list/recycler/FastScrollRecyclerView.kt

@@ -16,31 +16,25 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
  
-package org.oxycblt.auxio.home.fastscroll
+package org.oxycblt.auxio.list.recycler
 
 import android.animation.Animator
 import android.content.Context
 import android.graphics.Canvas
 import android.graphics.Rect
 import android.util.AttributeSet
-import android.view.Gravity
 import android.view.MotionEvent
-import android.view.View
 import android.view.ViewConfiguration
-import android.view.ViewGroup
 import android.view.WindowInsets
-import android.widget.FrameLayout
 import androidx.annotation.AttrRes
-import androidx.core.view.isInvisible
-import androidx.recyclerview.widget.GridLayoutManager
-import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
 import kotlin.math.abs
+import kotlin.math.max
+import kotlin.math.roundToInt
 import org.oxycblt.auxio.R
-import org.oxycblt.auxio.list.recycler.AuxioRecyclerView
+import org.oxycblt.auxio.ui.MaterialSlider
-import org.oxycblt.auxio.ui.MaterialFader
 import org.oxycblt.auxio.util.getDimenPixels
-import org.oxycblt.auxio.util.getDrawableCompat
+import org.oxycblt.auxio.util.inflater
 import org.oxycblt.auxio.util.isRtl
 import org.oxycblt.auxio.util.isUnder
 import org.oxycblt.auxio.util.systemBarInsetsCompat
@@ -67,6 +61,7 @@ import org.oxycblt.auxio.util.systemBarInsetsCompat
  * - Variable names are no longer prefixed with m
  * - Added drag listener
  * - Added documentation
+ * - Completely new design
  *
  * @author Hai Zhang, Alexander Capehart (OxygenCobalt)
  *
@@ -78,14 +73,12 @@ class FastScrollRecyclerView
 constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr: Int = 0) :
     AuxioRecyclerView(context, attrs, defStyleAttr) {
     // Thumb
-    private val thumbView =
+    private val thumbSize = context.getDimenPixels(R.dimen.size_touchable_small)
-        View(context).apply {
+    private val slider = MaterialSlider(context, thumbSize)
-            scaleX = 0f
+    private var thumbAnimator: Animator? = null
-            background = context.getDrawableCompat(R.drawable.ui_scroll_thumb)
-        }
 
-    private val thumbWidth = thumbView.background.intrinsicWidth
+    private val thumbView =
-    private val thumbHeight = thumbView.background.intrinsicHeight
+        context.inflater.inflate(R.layout.view_scroll_thumb, null).apply { slider.jumpOut(this) }
     private val thumbPadding = Rect(0, 0, 0, 0)
     private var thumbOffset = 0
 
@@ -96,27 +89,6 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
         }
     }
 
-    // Popup
-    private val popupView =
-        FastScrollPopupView(context).apply {
-            scaleX = 0f
-            scaleY = 0f
-            alpha = 0f
-            layoutParams =
-                FrameLayout.LayoutParams(
-                        ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT)
-                    .apply {
-                        gravity = Gravity.CENTER_HORIZONTAL or Gravity.TOP
-                        marginEnd = context.getDimenPixels(R.dimen.spacing_small)
-                    }
-        }
-
-    private val fader = MaterialFader.quickLopsided(context)
-    private var thumbAnimator: Animator? = null
-    private var popupAnimator: Animator? = null
-
-    private var showingPopup = false
-
     // Touch
     private val minTouchTargetSize = context.getDimenPixels(R.dimen.size_touchable_small)
     private val touchSlop = ViewConfiguration.get(context).scaledTouchSlop
@@ -144,23 +116,18 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
             if (field) {
                 removeCallbacks(hideThumbRunnable)
                 showScrollbar()
-                showPopup()
             } else {
                 postAutoHideScrollbar()
-                hidePopup()
             }
 
             listener?.onFastScrollingChanged(field)
         }
 
-    private val tRect = Rect()
-
     var popupProvider: PopupProvider? = null
     var listener: Listener? = null
 
     init {
         overlay.add(thumbView)
-        overlay.add(popupView)
 
         addItemDecoration(
             object : ItemDecoration() {
@@ -192,85 +159,17 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
         updateScrollbarState()
 
         thumbView.layoutDirection = layoutDirection
-        popupView.layoutDirection = layoutDirection
+        thumbView.measure(
-
+            MeasureSpec.makeMeasureSpec(thumbSize, MeasureSpec.EXACTLY),
+            MeasureSpec.makeMeasureSpec(thumbSize, MeasureSpec.EXACTLY))
+        val thumbTop = thumbPadding.top + thumbOffset
         val thumbLeft =
             if (isRtl) {
                 thumbPadding.left
             } else {
-                width - thumbPadding.right - thumbWidth
+                width - thumbPadding.right - thumbSize
             }
-
+        thumbView.layout(thumbLeft, thumbTop, thumbLeft + thumbSize, thumbTop + thumbSize)
-        val thumbTop = thumbPadding.top + thumbOffset
-
-        thumbView.layout(thumbLeft, thumbTop, thumbLeft + thumbWidth, thumbTop + thumbHeight)
-
-        val child = getChildAt(0)
-        val firstAdapterPos =
-            if (child != null) {
-                layoutManager?.getPosition(child) ?: NO_POSITION
-            } else {
-                NO_POSITION
-            }
-
-        val popupText: String
-        val provider = popupProvider
-        if (firstAdapterPos != NO_POSITION && provider != null) {
-            popupView.isInvisible = false
-            // Get the popup text. If there is none, we default to "?".
-            popupText = provider.getPopup(firstAdapterPos) ?: "?"
-        } else {
-            // No valid position or provider, do not show the popup.
-            popupView.isInvisible = true
-            popupText = ""
-        }
-
-        val popupLayoutParams = popupView.layoutParams as FrameLayout.LayoutParams
-
-        if (popupView.text != popupText) {
-            popupView.text = popupText
-
-            val widthMeasureSpec =
-                ViewGroup.getChildMeasureSpec(
-                    MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY),
-                    thumbPadding.left +
-                        thumbPadding.right +
-                        thumbWidth +
-                        popupLayoutParams.leftMargin +
-                        popupLayoutParams.rightMargin,
-                    popupLayoutParams.width)
-
-            val heightMeasureSpec =
-                ViewGroup.getChildMeasureSpec(
-                    MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY),
-                    thumbPadding.top +
-                        thumbPadding.bottom +
-                        popupLayoutParams.topMargin +
-                        popupLayoutParams.bottomMargin,
-                    popupLayoutParams.height)
-
-            popupView.measure(widthMeasureSpec, heightMeasureSpec)
-        }
-
-        val popupWidth = popupView.measuredWidth
-        val popupHeight = popupView.measuredHeight
-        val popupLeft =
-            if (layoutDirection == View.LAYOUT_DIRECTION_RTL) {
-                thumbPadding.left + thumbWidth + popupLayoutParams.leftMargin
-            } else {
-                width - thumbPadding.right - thumbWidth - popupLayoutParams.rightMargin - popupWidth
-            }
-
-        val popupAnchorY = popupHeight / 2
-        val thumbAnchorY = thumbView.paddingTop
-
-        val popupTop =
-            (thumbTop + thumbAnchorY - popupAnchorY)
-                .coerceAtLeast(thumbPadding.top + popupLayoutParams.topMargin)
-                .coerceAtMost(
-                    height - thumbPadding.bottom - popupLayoutParams.bottomMargin - popupHeight)
-
-        popupView.layout(popupLeft, popupTop, popupLeft + popupWidth, popupTop + popupHeight)
     }
 
     override fun onScrolled(dx: Int, dy: Int) {
@@ -295,26 +194,15 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
     }
 
     private fun updateScrollbarState() {
-        if (scrollRange <= height || childCount == 0) {
-            return
-        }
-
-        // Combine the previous item dimensions with the current item top to find our scroll
-        // position
-        getDecoratedBoundsWithMargins(getChildAt(0), tRect)
-        val child = getChildAt(0)
-        val firstAdapterPos =
-            when (val mgr = layoutManager) {
-                is GridLayoutManager -> mgr.getPosition(child) / mgr.spanCount
-                is LinearLayoutManager -> mgr.getPosition(child)
-                else -> 0
-            }
-
-        val scrollOffset = paddingTop + (firstAdapterPos * itemHeight) - tRect.top
-
         // Then calculate the thumb position, which is just:
         // [proportion of scroll position to scroll range] * [total thumb range]
-        thumbOffset = (thumbOffsetRange.toLong() * scrollOffset / scrollOffsetRange).toInt()
+        val offsetY = computeVerticalScrollOffset()
+        if (computeVerticalScrollRange() < height || childCount == 0) {
+            return
+        }
+        val extentY = computeVerticalScrollExtent()
+        val fraction = (offsetY).toFloat() / (computeVerticalScrollRange() - extentY)
+        thumbOffset = (thumbOffsetRange * fraction).toInt()
     }
 
     private fun onItemTouch(event: MotionEvent): Boolean {
@@ -331,10 +219,11 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
 
                     if (thumbView.isUnder(eventX, eventY, minTouchTargetSize)) {
                         dragStartThumbOffset = thumbOffset
-                    } else {
+                    } else if (eventX > thumbView.right - thumbSize / 4) {
-                        dragStartThumbOffset =
+                        dragStartThumbOffset = (eventY - thumbPadding.top - thumbSize / 2f).toInt()
-                            (eventY - thumbPadding.top - thumbHeight / 2f).toInt()
                         scrollToThumbOffset(dragStartThumbOffset)
+                    } else {
+                        return false
                     }
 
                     dragging = true
@@ -349,8 +238,7 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
                         dragStartThumbOffset = thumbOffset
                     } else {
                         dragStartY = eventY
-                        dragStartThumbOffset =
+                        dragStartThumbOffset = (eventY - thumbPadding.top - thumbSize / 2f).toInt()
-                            (eventY - thumbPadding.top - thumbHeight / 2f).toInt()
                         scrollToThumbOffset(dragStartThumbOffset)
                     }
 
@@ -371,44 +259,19 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
     }
 
     private fun scrollToThumbOffset(thumbOffset: Int) {
-        val clampedThumbOffset = thumbOffset.coerceAtLeast(0).coerceAtMost(thumbOffsetRange)
+        val rangeY = computeVerticalScrollRange() - computeVerticalScrollExtent()
-
+        val previousThumbOffset = this.thumbOffset.coerceAtLeast(0).coerceAtMost(thumbOffsetRange)
-        val scrollOffset =
+        val previousOffsetY = rangeY * (previousThumbOffset / thumbOffsetRange.toFloat())
-            (scrollOffsetRange.toLong() * clampedThumbOffset / thumbOffsetRange).toInt() -
+        val newThumbOffset = thumbOffset.coerceAtLeast(0).coerceAtMost(thumbOffsetRange)
-                paddingTop
+        val newOffsetY = rangeY * (newThumbOffset / thumbOffsetRange.toFloat())
-
+        if (newOffsetY == 0f) {
-        scrollTo(scrollOffset)
+            // Hacky workaround to drift in vertical scroll offset where we just snap
-    }
+            // to the top if the thumb offset hit zero.
-
+            scrollToPosition(0)
-    private fun scrollTo(offset: Int) {
-        if (childCount == 0) {
             return
         }
-
+        val dy = newOffsetY - previousOffsetY
-        stopScroll()
+        scrollBy(0, max(dy.roundToInt(), -computeVerticalScrollOffset()))
-
-        val trueOffset = offset - paddingTop
-        val itemHeight = itemHeight
-
-        val firstItemPosition = 0.coerceAtLeast(trueOffset / itemHeight)
-        val firstItemTop = firstItemPosition * itemHeight - trueOffset
-
-        scrollToPositionWithOffset(firstItemPosition, firstItemTop)
-    }
-
-    private fun scrollToPositionWithOffset(position: Int, offset: Int) {
-        var targetPosition = position
-        val trueOffset = offset - paddingTop
-
-        when (val mgr = layoutManager) {
-            is GridLayoutManager -> {
-                targetPosition *= mgr.spanCount
-                mgr.scrollToPositionWithOffset(targetPosition, trueOffset)
-            }
-            is LinearLayoutManager -> {
-                mgr.scrollToPositionWithOffset(targetPosition, trueOffset)
-            }
-        }
     }
 
     // --- SCROLLBAR APPEARANCE ---
@@ -425,7 +288,7 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
 
         showingThumb = true
         thumbAnimator?.cancel()
-        thumbAnimator = fader.fadeIn(thumbView).also { it.start() }
+        thumbAnimator = slider.slideIn(thumbView).also { it.start() }
     }
 
     private fun hideScrollbar() {
@@ -435,79 +298,16 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
 
         showingThumb = false
         thumbAnimator?.cancel()
-        thumbAnimator = fader.fadeOut(thumbView).also { it.start() }
+        thumbAnimator = slider.slideOut(thumbView).also { it.start() }
-    }
-
-    private fun showPopup() {
-        if (showingPopup) {
-            return
-        }
-
-        popupView.scaleX = 0f
-        popupView.scaleY = 0f
-
-        popupView.alpha = 1f
-        showingPopup = true
-        popupAnimator?.cancel()
-        popupAnimator = fader.fadeIn(popupView).also { it.start() }
-    }
-
-    private fun hidePopup() {
-        if (!showingPopup) {
-            return
-        }
-
-        showingPopup = false
-        popupAnimator?.cancel()
-        popupAnimator = fader.fadeOut(popupView).also { it.start() }
     }
 
     // --- LAYOUT STATE ---
 
     private val thumbOffsetRange: Int
         get() {
-            return height - thumbPadding.top - thumbPadding.bottom - thumbHeight
+            return height - thumbPadding.top - thumbPadding.bottom - thumbSize
         }
 
-    private val scrollRange: Int
-        get() {
-            val itemCount = itemCount
-
-            if (itemCount == 0) {
-                return 0
-            }
-
-            val itemHeight = itemHeight
-
-            return if (itemHeight != 0) {
-                paddingTop + itemCount * itemHeight + paddingBottom
-            } else {
-                0
-            }
-        }
-
-    private val scrollOffsetRange: Int
-        get() = scrollRange - height
-
-    private val itemHeight: Int
-        get() {
-            if (childCount == 0) {
-                return 0
-            }
-
-            val itemView = getChildAt(0)
-            getDecoratedBoundsWithMargins(itemView, tRect)
-            return tRect.height()
-        }
-
-    private val itemCount: Int
-        get() =
-            when (val mgr = layoutManager) {
-                is GridLayoutManager -> (mgr.itemCount - 1) / mgr.spanCount + 1
-                is LinearLayoutManager -> mgr.itemCount
-                else -> 0
-            }
-
     /** An interface to provide text to use in the popup when fast-scrolling. */
     interface PopupProvider {
         /**
@@ -531,6 +331,6 @@ constructor(context: Context, attrs: AttributeSet? = null, @AttrRes defStyleAttr
     }
 
     private companion object {
-        const val AUTO_HIDE_SCROLLBAR_DELAY_MILLIS = 1500
+        const val AUTO_HIDE_SCROLLBAR_DELAY_MILLIS = 500
     }
 }

app/src/main/java/org/oxycblt/auxio/ui/Animations.kt

@@ -200,3 +200,25 @@ class MaterialFlipper(context: Context) {
         return AnimatorSet().apply { playTogether(outAnimator, inAnimator) }
     }
 }
+
+class MaterialSlider(context: Context, private val x: Int) {
+    private val outConfig =
+        AnimConfig.of(context, AnimConfig.EMPHASIZED_ACCELERATE, AnimConfig.SHORT3)
+    private val inConfig =
+        AnimConfig.of(context, AnimConfig.EMPHASIZED_DECELERATE, AnimConfig.MEDIUM1)
+
+    fun jumpOut(view: View) {
+        view.translationX = x.toFloat()
+    }
+
+    fun slideOut(view: View): Animator {
+        val animator =
+            outConfig.genericFloat(view.translationX, x.toFloat()) { view.translationX = it }
+        return animator
+    }
+
+    fun slideIn(view: View): Animator {
+        val animator = inConfig.genericFloat(view.translationX, 0f) { view.translationX = it }
+        return animator
+    }
+}

app/src/main/res/drawable/ic_scroll_24.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="960"
+    android:viewportHeight="960"
+    android:tint="?attr/colorControlNormal">
+  <path
+      android:fillColor="@android:color/white"
+      android:pathData="M480,840L300,660L358,602L480,724L602,602L660,660L480,840ZM358,362L300,304L480,124L660,304L602,362L480,240L358,362Z"/>
+</vector>

app/src/main/res/drawable/ui_popup.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shape="rectangle"
+    android:tint="?attr/colorSecondary">
+
+    <corners android:radius="16dp" />
+    <size
+        android:width="56dp"
+        android:height="56dp" />
+    <solid android:color="@android:color/white" />
+</shape>

app/src/main/res/drawable/ui_scroll_thumb.xml

@@ -3,14 +3,9 @@
     android:shape="rectangle"
     android:tint="?attr/colorSecondary">
 
-    <corners android:radius="8dp" />
+    <corners android:topLeftRadius="24dp" android:bottomLeftRadius="24dp" />
-    <padding
-        android:bottom="4dp"
-        android:left="2dp"
-        android:right="2dp"
-        android:top="4dp" />
     <size
-        android:width="8dp"
+        android:width="48dp"
-        android:height="52dp" />
+        android:height="48dp" />
     <solid android:color="@android:color/white" />
 </shape>

app/src/main/res/layout/fragment_home_list.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<org.oxycblt.auxio.home.fastscroll.FastScrollRecyclerView xmlns:android="http://schemas.android.com/apk/res/android"
+<org.oxycblt.auxio.list.recycler.FastScrollRecyclerView xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:id="@+id/home_recycler"
     style="@style/Widget.Auxio.RecyclerView.Grid.WithAdaptiveFab"

app/src/main/res/layout/view_scroll_thumb.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:background="@drawable/ui_scroll_thumb">
+
+    <ImageView
+        android:layout_width="@dimen/size_touchable_small"
+        android:layout_height="@dimen/size_touchable_small"
+        app:tint="?attr/colorOnSecondary"
+        android:scaleType="centerInside"
+        android:src="@drawable/ic_scroll_24" />
+
+</FrameLayout>

app/src/main/res/values/dimens.xml

@@ -25,6 +25,9 @@
     <dimen name="size_icon_large">40dp</dimen>
     <dimen name="size_icon_huge">48dp</dimen>
 
+    <dimen name="width_scroll_thumb">48dp</dimen>
+    <dimen name="height_scroll_thumb">48dp</dimen>
+
     <!-- Misc -->
     <dimen name="m3_shape_corners_large">16dp</dimen>
     <dimen name="m3_shape_corners_full">128dp</dimen>