Added one-click scroll to the bottom

app/src/main/java/com/topjohnwu/magisk/ui/log/LogViewModel.kt

@@ -43,6 +43,8 @@ class LogViewModel(
     private val logItem get() = items[0] as LogRvItem
     private val magiskLogItem get() = items[1] as MagiskLogRvItem
 
+    val scrollPosition = KObservableField(0)
+
     init {
         currentPage.addOnPropertyChangedCallback {
             it ?: return@addOnPropertyChangedCallback
@@ -59,6 +61,10 @@ class LogViewModel(
         else -> ""
     }
 
+    fun scrollDownPressed() {
+        scrollPosition.value = magiskLogItem.items.size - 1
+    }
+
     fun refresh() {
         fetchLogs().subscribeK { logItem.update(it) }
         fetchMagiskLog().subscribeK { magiskLogItem.update(it) }

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

@@ -11,8 +11,10 @@ import androidx.databinding.InverseBindingAdapter
 import androidx.databinding.InverseBindingListener
 import androidx.drawerlayout.widget.DrawerLayout
 import androidx.interpolator.view.animation.FastOutSlowInInterpolator
+import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
 import androidx.viewpager.widget.ViewPager
+import com.google.android.material.floatingactionbutton.FloatingActionButton
 import com.google.android.material.navigation.NavigationView
 import com.skoumal.teanity.extensions.subscribeK
 import com.topjohnwu.magisk.R
@@ -176,4 +178,32 @@ fun setScrollToLast(view: RecyclerView, shouldScrollToLast: Boolean) {
     } else {
         view.adapter?.removeListener()
     }
-}
+}
+
+@BindingAdapter("hide")
+fun setHidden(view: FloatingActionButton, hide: Boolean) {
+    if (hide) view.hide() else view.show()
+}
+
+@BindingAdapter("scrollPosition", "scrollPositionSmooth", requireAll = false)
+fun setScrollPosition(view: RecyclerView, position: Int, smoothScroll: Boolean) = when {
+    smoothScroll -> view.smoothScrollToPosition(position)
+    else -> view.scrollToPosition(position)
+}
+
+@BindingAdapter("recyclerScrollEvent")
+fun setScrollListener(view: RecyclerView, listener: InverseBindingListener) {
+    view.addOnScrollListener(object : RecyclerView.OnScrollListener() {
+        override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
+            // don't change this or the recycler will stop at every line, effectively disabling smooth scroll
+            if (newState == RecyclerView.SCROLL_STATE_IDLE) {
+                listener.onChange()
+            }
+        }
+    })
+}
+
+@InverseBindingAdapter(attribute = "scrollPosition", event = "recyclerScrollEvent")
+fun getScrollPosition(view: RecyclerView) = (view.layoutManager as? LinearLayoutManager)
+    ?.findLastCompletelyVisibleItemPosition()
+    ?: -1

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

@@ -0,0 +1,10 @@
+<?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="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="#000"
+        android:pathData="M16.59,5.59L18,7L12,13L6,7L7.41,5.59L12,10.17L16.59,5.59M16.59,11.59L18,13L12,19L6,13L7.41,11.59L12,16.17L16.59,11.59Z" />
+</vector>

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

@@ -15,20 +15,39 @@
 
     </data>
 
-    <HorizontalScrollView
+    <FrameLayout
         android:layout_width="match_parent"
         android:layout_height="match_parent">
 
-        <androidx.recyclerview.widget.RecyclerView
+        <HorizontalScrollView
-            adapter="@{viewModel.itemsAdapter}"
+            android:layout_width="match_parent"
-            itemBinding="@{viewModel.itemBinding}"
+            android:layout_height="match_parent">
-            items="@{item.items}"
+
-            android:layout_width="wrap_content"
+            <androidx.recyclerview.widget.RecyclerView
-            android:layout_height="match_parent"
+                adapter="@{viewModel.itemsAdapter}"
-            android:orientation="vertical"
+                itemBinding="@{viewModel.itemBinding}"
-            app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
+                items="@{item.items}"
-            tools:listitem="@layout/item_console" />
+                scrollPosition="@={viewModel.scrollPosition}"
+                scrollPositionSmooth="@{true}"
+                android:layout_width="wrap_content"
+                android:layout_height="match_parent"
+                android:orientation="vertical"
+                app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
+                tools:listitem="@layout/item_console" />
+
+        </HorizontalScrollView>
+
+        <com.google.android.material.floatingactionbutton.FloatingActionButton
+            hide="@{viewModel.scrollPosition == item.items.size - 1}"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="bottom|end"
+            android:layout_margin="@dimen/margin_generic"
+            android:onClick="@{() -> viewModel.scrollDownPressed()}"
+            app:srcCompat="@drawable/ic_arrow_down"
+            app:tint="@color/colorTextInverse" />
+
+    </FrameLayout>
 
-    </HorizontalScrollView>
 
 </layout>