[ADDED] [#8] View model for the layout browser activity.

Author: hossain-khan

app/src/main/java/com/hossainkhan/android/demo/browse/LayoutBrowseActivity.kt

@@ -16,37 +16,48 @@
 
 package com.hossainkhan.android.demo.browse
 
-import android.support.v7.app.AppCompatActivity
+import android.arch.lifecycle.ViewModelProviders
 import android.os.Bundle
+import android.support.v7.app.AppCompatActivity
 import android.support.v7.widget.GridLayoutManager
 import android.support.v7.widget.RecyclerView
 import com.hossainkhan.android.demo.R
-import com.hossainkhan.android.demo.data.AppDataStore
 import com.hossainkhan.android.demo.layoutpreview.LayoutPreviewBaseActivity
 import com.hossainkhan.android.demo.layoutpreview.LayoutVisibilityGoneActivity
+import com.hossainkhan.android.demo.viewmodel.LayoutPreviewViewModelFactory
 import dagger.android.AndroidInjection
 import timber.log.Timber
 import javax.inject.Inject
 
+/**
+ * A list activity that shows all the available example demo layouts.
+ */
 class LayoutBrowseActivity : AppCompatActivity() {
     @Inject
-    lateinit var appDataStore: AppDataStore
+    internal lateinit var viewModelFactory: LayoutPreviewViewModelFactory
 
     private lateinit var recyclerView: RecyclerView
     private lateinit var viewAdapter: RecyclerView.Adapter<*>
     private lateinit var viewManager: RecyclerView.LayoutManager
 
+    private lateinit var viewModel: LayoutBrowseViewModel
+
     override fun onCreate(savedInstanceState: Bundle?) {
         AndroidInjection.inject(this)
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
 
-        Timber.d("Got data: ${appDataStore.isFirstTime()}")
-        appDataStore.updateFirstTimeUser(false)
+        viewModel = ViewModelProviders.of(this, viewModelFactory)
+                .get(LayoutBrowseViewModel::class.java)
+
+        setupLayoutInfoAdapter(viewModel)
+    }
 
+    private fun setupLayoutInfoAdapter(viewModel: LayoutBrowseViewModel) {
         viewManager = GridLayoutManager(this, resources.getInteger(R.integer.grid_column_count))
         viewAdapter = LayoutBrowseAdapter(
-                data = appDataStore.layoutStore.supportedLayoutInfos,
+                viewModel = viewModel,
+                lifecycleOwner = this,
                 itemSelectedListener = this::onLayoutItemSelected)
 
         recyclerView = findViewById<RecyclerView>(R.id.recycler_view).apply {

app/src/main/java/com/hossainkhan/android/demo/browse/LayoutBrowseAdapter.kt

@@ -16,6 +16,8 @@
 
 package com.hossainkhan.android.demo.browse
 
+import android.arch.lifecycle.LifecycleOwner
+import android.arch.lifecycle.Observer
 import android.support.v7.widget.RecyclerView
 import android.view.LayoutInflater
 import android.view.View
@@ -26,9 +28,20 @@ import com.hossainkhan.android.demo.R
 import com.hossainkhan.android.demo.data.LayoutInformation
 
 class LayoutBrowseAdapter(
-        private val data: List<LayoutInformation>,
+        viewModel: LayoutBrowseViewModel,
+        lifecycleOwner: LifecycleOwner,
         private val itemSelectedListener: (Int) -> Unit) : RecyclerView.Adapter<LayoutBrowseAdapter.ViewHolder>() {
 
+    private var data: List<LayoutInformation> = emptyList()
+
+    init {
+        viewModel.layoutInfos.observe(lifecycleOwner, Observer {
+            data = it!!
+            notifyDataSetChanged()
+        })
+    }
+
+
     // Provide a reference to the views for each data item
     // Complex data items may need more than one view per item, and
     // you provide access to all the views for a data item in a view holder.

app/src/main/java/com/hossainkhan/android/demo/browse/LayoutBrowseViewModel.kt

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2018 Hossain Khan
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.hossainkhan.android.demo.browse
+
+import android.arch.lifecycle.LiveData
+import android.arch.lifecycle.MutableLiveData
+import android.arch.lifecycle.ViewModel
+import com.hossainkhan.android.demo.data.AppDataStore
+import com.hossainkhan.android.demo.data.LayoutInformation
+import timber.log.Timber
+
+class LayoutBrowseViewModel(
+        appDataStore: AppDataStore) : ViewModel() {
+
+    private val layoutInfoListLiveData = MutableLiveData<List<LayoutInformation>>()
+
+    val layoutInfos: LiveData<List<LayoutInformation>>
+        get() = layoutInfoListLiveData
+
+    init {
+        Timber.d("Got data: ${appDataStore.isFirstTime()}")
+        appDataStore.updateFirstTimeUser(false)
+
+
+        layoutInfoListLiveData.value = appDataStore.layoutStore.supportedLayoutInfos
+    }
+}

app/src/main/java/com/hossainkhan/android/demo/viewmodel/LayoutPreviewViewModelFactory.kt

@@ -18,19 +18,27 @@ package com.hossainkhan.android.demo.viewmodel
 
 import android.arch.lifecycle.ViewModel
 import android.arch.lifecycle.ViewModelProvider
+import com.hossainkhan.android.demo.browse.LayoutBrowseViewModel
 import com.hossainkhan.android.demo.data.AppDataStore
 import com.hossainkhan.android.demo.layoutpreview.LayoutInfoViewModel
 import javax.inject.Inject
 
+/**
+ * The [ViewModelProvider.Factory] that provides all the ViewModels for the activities and fragments.
+ */
 class LayoutPreviewViewModelFactory @Inject constructor(
         private val dataStore: AppDataStore
 
 ) : ViewModelProvider.Factory {
     @Suppress("UNCHECKED_CAST")
     override fun <T : ViewModel?> create(modelClass: Class<T>): T {
         return when {
-            modelClass.isAssignableFrom(LayoutInfoViewModel::class.java) ->
+            modelClass.isAssignableFrom(LayoutInfoViewModel::class.java) -> {
                 LayoutInfoViewModel(dataStore) as T
+            }
+            modelClass.isAssignableFrom(LayoutBrowseViewModel::class.java) -> {
+                LayoutBrowseViewModel(dataStore) as T
+            }
             else -> throw IllegalArgumentException("Unknown ViewModel class")
         }
     }