Toolbar and bottom nav scroll snap (#5915)

2021-09-19 03:41:23 +07:00
parent 774f818bbb
commit a2d007f2a9
3 changed files with 173 additions and 2 deletions
--- a/app/src/main/java/com/google/android/material/appbar/HideToolbarOnScrollBehavior.kt
+++ b/app/src/main/java/com/google/android/material/appbar/HideToolbarOnScrollBehavior.kt
@@ -0,0 +1,102 @@
+package com.google.android.material.appbar
+
+import android.animation.ValueAnimator
+import android.view.View
+import android.view.animation.DecelerateInterpolator
+import androidx.appcompat.widget.Toolbar
+import androidx.coordinatorlayout.widget.CoordinatorLayout
+import androidx.core.animation.doOnEnd
+import androidx.core.view.ViewCompat
+import androidx.core.view.marginTop
+import eu.kanade.tachiyomi.util.system.animatorDurationScale
+import eu.kanade.tachiyomi.util.view.findChild
+import eu.kanade.tachiyomi.widget.ElevationAppBarLayout
+import kotlin.math.roundToLong
+
+/**
+ * Hide toolbar on scroll behavior for [AppBarLayout].
+ *
+ * Inside this package to access some package-private methods.
+ */
+class HideToolbarOnScrollBehavior : AppBarLayout.Behavior() {
+
+    @ViewCompat.NestedScrollType
+    private var lastStartedType: Int = 0
+
+    private var offsetAnimator: ValueAnimator? = null
+
+    private var toolbarHeight: Int = 0
+
+    override fun onStartNestedScroll(
+        parent: CoordinatorLayout,
+        child: AppBarLayout,
+        directTargetChild: View,
+        target: View,
+        nestedScrollAxes: Int,
+        type: Int
+    ): Boolean {
+        lastStartedType = type
+        offsetAnimator?.cancel()
+        return super.onStartNestedScroll(parent, child, directTargetChild, target, nestedScrollAxes, type)
+    }
+
+    override fun onStopNestedScroll(
+        parent: CoordinatorLayout,
+        layout: AppBarLayout,
+        target: View,
+        type: Int
+    ) {
+        super.onStopNestedScroll(parent, layout, target, type)
+        if (toolbarHeight == 0) {
+            toolbarHeight = layout.findChild<Toolbar>()?.height ?: 0
+        }
+        if (lastStartedType == ViewCompat.TYPE_TOUCH || type == ViewCompat.TYPE_NON_TOUCH) {
+            animateToolbarVisibility(
+                parent,
+                layout,
+                getTopBottomOffsetForScrollingSibling(layout) > -toolbarHeight / 2
+            )
+        }
+    }
+
+    override fun onFlingFinished(parent: CoordinatorLayout, layout: AppBarLayout) {
+        super.onFlingFinished(parent, layout)
+        animateToolbarVisibility(
+            parent,
+            layout,
+            getTopBottomOffsetForScrollingSibling(layout) > -toolbarHeight / 2
+        )
+    }
+
+    private fun getTopBottomOffsetForScrollingSibling(abl: AppBarLayout): Int {
+        return topBottomOffsetForScrollingSibling - abl.marginTop
+    }
+
+    private fun animateToolbarVisibility(
+        coordinatorLayout: CoordinatorLayout,
+        child: AppBarLayout,
+        isVisible: Boolean
+    ) {
+        offsetAnimator?.cancel()
+        offsetAnimator = ValueAnimator().apply {
+            interpolator = DecelerateInterpolator()
+            duration = (150 * child.context.animatorDurationScale).roundToLong()
+            addUpdateListener {
+                setHeaderTopBottomOffset(coordinatorLayout, child, it.animatedValue as Int)
+            }
+            doOnEnd {
+                if (!isVisible &&
+                    !child.isLifted &&
+                    (child as? ElevationAppBarLayout)?.isTransparentWhenNotLifted == true
+                ) {
+                    child.isLifted = true
+                }
+            }
+        }
+        offsetAnimator?.setIntValues(
+            getTopBottomOffsetForScrollingSibling(child),
+            if (isVisible) 0 else -toolbarHeight
+        )
+        offsetAnimator?.start()
+    }
+}