Show a placeholder when no items are available

app/src/main/kotlin/com/simplemobiletools/applauncher/activities/MainActivity.kt

@@ -33,6 +33,8 @@ class MainActivity : SimpleActivity(), RefreshRecyclerViewListener {
     private var mStoredPrimaryColor = 0
     private var mStoredTextColor = 0
 
+    private val emptyViews by lazy { arrayOf(add_icons_placeholder, no_items_placeholder) }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
@@ -43,13 +45,9 @@ class MainActivity : SimpleActivity(), RefreshRecyclerViewListener {
         setupGridLayoutManager()
 
         fab.setOnClickListener {
-            if (allLaunchers != null) {
-                val shownLaunchers = (launchers_grid.adapter as LaunchersAdapter).launchers
-                AddLaunchersDialog(this, allLaunchers!!, shownLaunchers) {
-                    setupLaunchers()
-                }
-            }
+            fabClicked()
         }
+        setupEmptyView()
     }
 
     override fun onResume() {
@@ -58,7 +56,8 @@ class MainActivity : SimpleActivity(), RefreshRecyclerViewListener {
             getGridAdapter()?.updateTextColor(getProperTextColor())
         }
 
-        if (mStoredPrimaryColor != getProperPrimaryColor()) {
+        val properPrimaryColor = getProperPrimaryColor()
+        if (mStoredPrimaryColor != properPrimaryColor) {
             getGridAdapter()?.apply {
                 updatePrimaryColor()
                 notifyDataSetChanged()
@@ -66,7 +65,8 @@ class MainActivity : SimpleActivity(), RefreshRecyclerViewListener {
         }
 
         updateTextColors(coordinator_layout)
-        launchers_fastscroller.updateColors(getProperPrimaryColor())
+        add_icons_placeholder.setTextColor(properPrimaryColor)
+        launchers_fastscroller.updateColors(properPrimaryColor)
     }
 
     override fun onPause() {
@@ -126,13 +126,20 @@ class MainActivity : SimpleActivity(), RefreshRecyclerViewListener {
         checkInvalidApps()
         initZoomListener()
         setupAdapter(displayedLaunchers)
+        maybeShowEmptyView(displayedLaunchers)
     }
 
     private fun setupAdapter(launchers: ArrayList<AppLauncher>) {
         AppLauncher.sorting = config.sorting
         launchers.sort()
 
-        LaunchersAdapter(this, launchers, this, launchers_grid) {
+        LaunchersAdapter(
+            activity = this,
+            launchers = launchers,
+            listener = this,
+            recyclerView = launchers_grid,
+            onItemsRemoved = ::onItemsRemoved,
+        ) {
             hideKeyboard()
             val launchIntent = packageManager.getLaunchIntentForPackage((it as AppLauncher).packageName)
             if (launchIntent != null) {
@@ -256,4 +263,36 @@ class MainActivity : SimpleActivity(), RefreshRecyclerViewListener {
             checkWhatsNew(this, BuildConfig.VERSION_CODE)
         }
     }
+
+    private fun fabClicked() {
+        if (allLaunchers != null) {
+            val shownLaunchers = (launchers_grid.adapter as LaunchersAdapter).launchers
+            AddLaunchersDialog(this, allLaunchers!!, shownLaunchers) {
+                setupLaunchers()
+            }
+        }
+    }
+
+    private fun setupEmptyView() {
+        val properPrimaryColor = getProperPrimaryColor()
+        add_icons_placeholder.underlineText()
+        add_icons_placeholder.setTextColor(properPrimaryColor)
+        add_icons_placeholder.setOnClickListener {
+            fabClicked()
+        }
+    }
+
+    private fun onItemsRemoved() {
+        maybeShowEmptyView()
+    }
+
+    private fun maybeShowEmptyView(displayedLaunchers: ArrayList<AppLauncher> = dbHelper.getLaunchers()) {
+        if (displayedLaunchers.isEmpty()) {
+            launchers_fastscroller.fadeOut()
+            emptyViews.forEach { it.fadeIn() }
+        } else {
+            emptyViews.forEach { it.fadeOut() }
+            launchers_fastscroller.fadeIn()
+        }
+    }
 }

app/src/main/kotlin/com/simplemobiletools/applauncher/adapters/LaunchersAdapter.kt

@@ -27,8 +27,12 @@ import kotlinx.android.synthetic.main.item_launcher_label.view.*
 import java.util.*
 
 class LaunchersAdapter(
-    activity: SimpleActivity, val launchers: ArrayList<AppLauncher>, val listener: RefreshRecyclerViewListener?,
-    recyclerView: MyRecyclerView, itemClick: (Any) -> Unit
+    activity: SimpleActivity,
+    val launchers: ArrayList<AppLauncher>,
+    val listener: RefreshRecyclerViewListener?,
+    recyclerView: MyRecyclerView,
+    var onItemsRemoved: (() -> Unit)? = null,
+    itemClick: (Any) -> Unit
 ) : MyRecyclerViewAdapter(activity, recyclerView, itemClick), ItemTouchHelperContract, RecyclerViewFastScroller.OnPopupTextUpdate {
 
     private var isChangingOrder = false
@@ -171,10 +175,11 @@ class LaunchersAdapter(
             }
         }
 
-        launchers.removeAll(removeLaunchers)
+        launchers.removeAll(removeLaunchers.toSet())
         activity.dbHelper.deleteLaunchers(removeIds)
         positions.sortDescending()
         removeSelectedItems(positions)
+        onItemsRemoved?.invoke()
     }
 
     private fun setupView(view: View, launcher: AppLauncher, holder: ViewHolder) {

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

@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
     android:id="@+id/coordinator_layout"
     android:layout_width="match_parent"
     android:layout_height="match_parent">
@@ -10,6 +11,36 @@
         android:layout_width="match_parent"
         android:layout_height="wrap_content">
 
+        <com.simplemobiletools.commons.views.MyTextView
+            android:id="@+id/no_items_placeholder"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_centerHorizontal="true"
+            android:alpha="0.8"
+            android:gravity="center"
+            android:paddingStart="@dimen/activity_margin"
+            android:paddingTop="@dimen/activity_margin"
+            android:paddingEnd="@dimen/activity_margin"
+            android:text="@string/no_items_found"
+            android:textSize="@dimen/bigger_text_size"
+            android:textStyle="italic"
+            android:visibility="gone"
+            tools:visibility="visible" />
+
+        <com.simplemobiletools.commons.views.MyTextView
+            android:id="@+id/add_icons_placeholder"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_below="@+id/no_items_placeholder"
+            android:layout_centerHorizontal="true"
+            android:background="?attr/selectableItemBackground"
+            android:gravity="center"
+            android:padding="@dimen/activity_margin"
+            android:text="@string/manage_visible_app_icons"
+            android:textSize="@dimen/bigger_text_size"
+            android:visibility="gone"
+            tools:visibility="visible" />
+
         <com.qtalk.recyclerviewfastscroller.RecyclerViewFastScroller
             android:id="@+id/launchers_fastscroller"
             android:layout_width="match_parent"