Updated navigation behavior to be consistent and easily manageable

app/src/main/java/com/topjohnwu/magisk/utils/HideBottomViewOnScrollBehavior.kt

@@ -11,14 +11,17 @@ import com.google.android.material.snackbar.Snackbar
 import com.topjohnwu.magisk.R
 import kotlin.math.roundToInt
 
-class HideBottomViewOnScrollBehavior<T : View> : HideBottomViewOnScrollBehavior<T>() {
+class HideBottomViewOnScrollBehavior<V : View> : HideBottomViewOnScrollBehavior<V>(),
+    HideableBehavior<V> {
 
-    override fun layoutDependsOn(parent: CoordinatorLayout, child: T, dependency: View) =
+    private var lockState: Boolean = false
+
+    override fun layoutDependsOn(parent: CoordinatorLayout, child: V, dependency: View) =
         super.layoutDependsOn(parent, child, dependency) or (dependency is Snackbar.SnackbarLayout)
 
     override fun onDependentViewChanged(
         parent: CoordinatorLayout,
-        child: T,
+        child: V,
         dependency: View
     ) = when (dependency) {
         is Snackbar.SnackbarLayout -> onDependentViewChanged(parent, child, dependency)
@@ -27,7 +30,7 @@ class HideBottomViewOnScrollBehavior<T : View> : HideBottomViewOnScrollBehavior<
 
     override fun onDependentViewRemoved(
         parent: CoordinatorLayout,
-        child: T,
+        child: V,
         dependency: View
     ) = when (dependency) {
         is Snackbar.SnackbarLayout -> onDependentViewRemoved(parent, child, dependency)
@@ -38,7 +41,7 @@ class HideBottomViewOnScrollBehavior<T : View> : HideBottomViewOnScrollBehavior<
 
     private fun onDependentViewChanged(
         parent: CoordinatorLayout,
-        child: T,
+        child: V,
         dependency: Snackbar.SnackbarLayout
     ): Boolean {
         val viewMargin = (child.layoutParams as ViewGroup.MarginLayoutParams).bottomMargin
@@ -58,7 +61,7 @@ class HideBottomViewOnScrollBehavior<T : View> : HideBottomViewOnScrollBehavior<
 
     private fun onDependentViewRemoved(
         parent: CoordinatorLayout,
-        child: T,
+        child: V,
         dependency: Snackbar.SnackbarLayout
     ) {
         // checks whether the navigation is not hidden via scroll
@@ -69,6 +72,36 @@ class HideBottomViewOnScrollBehavior<T : View> : HideBottomViewOnScrollBehavior<
 
     //---
 
+    override fun slideUp(child: V) {
+        if (lockState) return
+        super.slideUp(child)
+    }
+
+    override fun slideDown(child: V) {
+        if (lockState) return
+        super.slideDown(child)
+    }
+
+    override fun setHidden(
+        view: V,
+        hide: Boolean,
+        lockState: Boolean
+    ) {
+        if (!lockState) {
+            this.lockState = lockState
+        }
+
+        if (hide) {
+            slideDown(view)
+        } else {
+            slideUp(view)
+        }
+
+        this.lockState = lockState
+    }
+
+    //---
+
     private fun View.translationY(destination: Float) = animate()
         .translationY(destination)
         .setInterpolator(FastOutSlowInInterpolator())

app/src/main/java/com/topjohnwu/magisk/utils/HideTopViewOnScrollBehavior.kt

@@ -10,7 +10,8 @@ import androidx.core.view.ViewCompat
 import com.google.android.material.animation.AnimationUtils
 import com.google.android.material.behavior.HideBottomViewOnScrollBehavior
 
-class HideTopViewOnScrollBehavior<V : View> : HideBottomViewOnScrollBehavior<V>() {
+class HideTopViewOnScrollBehavior<V : View> : HideBottomViewOnScrollBehavior<V>(),
+    HideableBehavior<V> {
 
     companion object {
         private const val STATE_SCROLLED_DOWN = 1
@@ -21,6 +22,7 @@ class HideTopViewOnScrollBehavior<V : View> : HideBottomViewOnScrollBehavior<V>(
     private var currentState = STATE_SCROLLED_UP
     private var additionalHiddenOffsetY = 0
     private var currentAnimator: ViewPropertyAnimator? = null
+    private var lockState: Boolean = false
 
     override fun onLayoutChild(
         parent: CoordinatorLayout,
@@ -63,10 +65,30 @@ class HideTopViewOnScrollBehavior<V : View> : HideBottomViewOnScrollBehavior<V>(
         dxUnconsumed: Int,
         dyUnconsumed: Int
     ) {
-        when {
-            dyConsumed > 0 -> slideUp(child)
-            dyConsumed < 0 -> slideDown(child)
+        // when initiating scroll while the view is at the bottom or at the top and pushing it
+        // further, the parent will report consumption of 0
+        if (dyConsumed == 0) return
+
+        setHidden(child, dyConsumed > 0, false)
+    }
+
+    @Suppress("UNCHECKED_CAST")
+    override fun setHidden(
+        view: V,
+        hide: Boolean,
+        lockState: Boolean
+    ) {
+        if (!lockState) {
+            this.lockState = lockState
         }
+
+        if (hide) {
+            slideUp(view)
+        } else {
+            slideDown(view)
+        }
+
+        this.lockState = lockState
     }
 
     /**
@@ -74,7 +96,7 @@ class HideTopViewOnScrollBehavior<V : View> : HideBottomViewOnScrollBehavior<V>(
      * screen.
      */
     override fun slideDown(child: V) {
-        if (currentState == STATE_SCROLLED_UP) {
+        if (currentState == STATE_SCROLLED_UP || lockState) {
             return
         }
 
@@ -97,7 +119,7 @@ class HideTopViewOnScrollBehavior<V : View> : HideBottomViewOnScrollBehavior<V>(
      * screen.
      */
     override fun slideUp(child: V) {
-        if (currentState == STATE_SCROLLED_DOWN) {
+        if (currentState == STATE_SCROLLED_DOWN || lockState) {
             return
         }
 

app/src/main/java/com/topjohnwu/magisk/utils/HideableBehavior.kt

@@ -0,0 +1,9 @@
+package com.topjohnwu.magisk.utils
+
+import android.view.View
+
+interface HideableBehavior<V : View> {
+
+    fun setHidden(view: V, hide: Boolean, lockState: Boolean = false)
+
+}