Improved message view

- fixed scroll behaviour
- use Paging’s BoundaryCallback for loadMore detection

app/build.gradle.kts

@@ -106,9 +106,9 @@ dependencies {
   implementation(appArch("lifecycle", "reactivestreams"))
   kapt(appArch("lifecycle", "compiler"))
 
-  implementation(appArch("persistence.room", "runtime", "1.0.0"))
-  implementation(appArch("persistence.room", "rxjava2", "1.0.0"))
-  kapt(appArch("persistence.room", "compiler", "1.0.0"))
+  implementation(appArch("persistence.room", "runtime", "1.1.0-alpha2"))
+  implementation(appArch("persistence.room", "rxjava2", "1.1.0-alpha2"))
+  kapt(appArch("persistence.room", "compiler", "1.1.0-alpha2"))
 
   implementation(appArch("paging", "runtime", version = "1.0.0-alpha5")) {
     exclude(group = "junit", module = "junit")

app/src/main/java/de/kuschku/quasseldroid_ng/persistence/AccountDatabase.kt

 package de.kuschku.quasseldroid_ng.persistence
 
-import android.arch.paging.LivePagedListProvider
+import android.arch.paging.DataSource
 import android.arch.persistence.room.*
 import android.content.Context
 
@@ -32,7 +32,7 @@ abstract class AccountDatabase : RoomDatabase() {
     fun findById(id: Long): AccountDatabase.Account?
 
     @Query("SELECT * FROM account ORDER BY lastUsed DESC")
-    fun all(): LivePagedListProvider<Int, Account>
+    fun all(): DataSource.Factory<Int, Account>
 
     @Delete
     fun delete(account: AccountDatabase.Account)

app/src/main/java/de/kuschku/quasseldroid_ng/persistence/QuasselDatabase.kt

 package de.kuschku.quasseldroid_ng.persistence
 
-import android.arch.paging.LivePagedListProvider
+import android.arch.paging.DataSource
 import android.arch.persistence.room.*
 import android.content.Context
 import android.support.annotation.IntRange
@@ -60,8 +60,8 @@ abstract class QuasselDatabase : RoomDatabase() {
     @Query("SELECT * FROM message WHERE bufferId = :bufferId ORDER BY messageId ASC")
     fun findByBufferId(bufferId: Int): List<DatabaseMessage>
 
-    @Query("SELECT * FROM message WHERE bufferId = :bufferId ORDER BY messageId ASC")
-    fun findByBufferIdPaged(bufferId: Int): LivePagedListProvider<Int, DatabaseMessage>
+    @Query("SELECT * FROM message WHERE bufferId = :bufferId ORDER BY messageId DESC")
+    fun findByBufferIdPaged(bufferId: Int): DataSource.Factory<Int, DatabaseMessage>
 
     @Query("SELECT * FROM message WHERE bufferId = :bufferId ORDER BY messageId DESC LIMIT 1")
     fun findLastByBufferId(bufferId: Int): DatabaseMessage?

app/src/main/java/de/kuschku/quasseldroid_ng/ui/chat/MessageAdapter.kt

@@ -21,10 +21,6 @@ class MessageAdapter(context: Context) :
 
   private val messageCache = LruCache<Int, FormattedMessage>(512)
 
-  init {
-    setHasStableIds(true)
-  }
-
   override fun onBindViewHolder(holder: QuasselMessageViewHolder, position: Int) {
     getItem(position)?.let {
       messageRenderer.bind(

app/src/main/java/de/kuschku/quasseldroid_ng/ui/chat/MessageListFragment.kt

@@ -3,6 +3,7 @@ package de.kuschku.quasseldroid_ng.ui.chat
 import android.arch.lifecycle.LiveData
 import android.arch.lifecycle.MutableLiveData
 import android.arch.lifecycle.Observer
+import android.arch.paging.LivePagedListBuilder
 import android.arch.paging.PagedList
 import android.os.Bundle
 import android.support.design.widget.FloatingActionButton
@@ -14,13 +15,10 @@ import android.view.ViewGroup
 import butterknife.BindView
 import butterknife.ButterKnife
 import de.kuschku.libquassel.protocol.BufferId
-import de.kuschku.libquassel.session.Backend
-import de.kuschku.libquassel.session.SessionManager
 import de.kuschku.quasseldroid_ng.R
 import de.kuschku.quasseldroid_ng.persistence.QuasselDatabase
 import de.kuschku.quasseldroid_ng.util.AndroidHandlerThread
 import de.kuschku.quasseldroid_ng.util.helper.invoke
-import de.kuschku.quasseldroid_ng.util.helper.map
 import de.kuschku.quasseldroid_ng.util.helper.switchMap
 import de.kuschku.quasseldroid_ng.util.helper.toggle
 import de.kuschku.quasseldroid_ng.util.service.ServiceBoundFragment
@@ -39,37 +37,70 @@ class MessageListFragment : ServiceBoundFragment() {
   @BindView(R.id.scrollDown)
   lateinit var scrollDown: FloatingActionButton
 
-  private val sessionManager: LiveData<SessionManager?> = backend.map(Backend::sessionManager)
-
   override fun onCreate(savedInstanceState: Bundle?) {
     handler.onCreate()
     super.onCreate(savedInstanceState)
     setHasOptionsMenu(true)
   }
 
+  private val boundaryCallback = object :
+    PagedList.BoundaryCallback<QuasselDatabase.DatabaseMessage>() {
+    override fun onItemAtFrontLoaded(itemAtFront: QuasselDatabase.DatabaseMessage)
+      = Unit
+
+    override fun onItemAtEndLoaded(itemAtEnd: QuasselDatabase.DatabaseMessage)
+      = loadMore()
+  }
+
   override fun onCreateView(inflater: LayoutInflater,
                             container: ViewGroup?,
                             savedInstanceState: Bundle?): View? {
     val view = inflater.inflate(R.layout.fragment_messages, container, false)
     ButterKnife.bind(this, view)
 
+    val adapter = MessageAdapter(context!!)
+
+    messageList.adapter = adapter
+    val linearLayoutManager = LinearLayoutManager(context)
+    linearLayoutManager.reverseLayout = true
+    messageList.layoutManager = linearLayoutManager
+
+    messageList.addOnScrollListener(
+      object : RecyclerView.OnScrollListener() {
+        override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
+          val canScrollDown = recyclerView.canScrollVertically(1)
+          val isScrollingDown = dy > 0
+
+          scrollDown.visibility = View.VISIBLE
+          scrollDown.toggle(canScrollDown && isScrollingDown)
+        }
+      }
+    )
+
     database = QuasselDatabase.Creator.init(context!!.applicationContext)
     val data = buffer.switchMap {
-      database.message().findByBufferIdPaged(it).create(
-        Int.MAX_VALUE,
-        PagedList.Config.Builder()
-          .setPageSize(50)
-          .setEnablePlaceholders(false)
-          .setPrefetchDistance(50)
+      LivePagedListBuilder(database.message().findByBufferIdPaged(it), 20)
+        .setBoundaryCallback(boundaryCallback)
+        .setInitialLoadKey(null)
         .build()
-      )
     }
 
-    val adapter = MessageAdapter(context!!)
-
     data.observe(
       this, Observer { list ->
+      val findFirstVisibleItemPosition = linearLayoutManager.findFirstVisibleItemPosition()
       adapter.setList(list)
+      if (findFirstVisibleItemPosition < 2) {
+        activity?.runOnUiThread {
+          messageList.smoothScrollToPosition(0)
+        }
+        handler.postDelayed(
+          {
+            activity?.runOnUiThread {
+              messageList.smoothScrollToPosition(0)
+            }
+          }, 16
+        )
+      }
     }
     )
 
@@ -77,35 +108,22 @@ class MessageListFragment : ServiceBoundFragment() {
       this, Observer {
       handler.post {
         // Try loading messages when switching to isEmpty buffer
-        if (it != null && database.message().bufferSize(it) == 0) {
+        if (it != null) {
+          if (database.message().bufferSize(it) == 0) {
             loadMore()
           }
+          activity?.runOnUiThread {
+            messageList.scrollToPosition(0)
           }
         }
-    )
-
-    var recyclerViewMeasuredHeight = 0
-    val scrollDownListener = object : RecyclerView.OnScrollListener() {
-      override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
-        if (!recyclerView.canScrollVertically(-1)) {
-          loadMore()
-        }
-        if (recyclerViewMeasuredHeight == 0)
-          recyclerViewMeasuredHeight = recyclerView.measuredHeight
-        val canScrollDown = recyclerView.canScrollVertically(1)
-        val isScrollingDown = dy > 0
-        val scrollOffsetFromBottom = recyclerView.computeVerticalScrollRange() - recyclerView.computeVerticalScrollOffset() - recyclerViewMeasuredHeight
-        val isMoreThanOneScreenFromBottom = scrollOffsetFromBottom > recyclerViewMeasuredHeight
-        val smartVisibility = scrollDown.visibility == View.VISIBLE || isMoreThanOneScreenFromBottom
-        scrollDown.toggle(canScrollDown && isScrollingDown && smartVisibility)
       }
     }
+    )
 
-    messageList.adapter = adapter
-    messageList.layoutManager = LinearLayoutManager(context)
-    messageList.addOnScrollListener(scrollDownListener)
-
-    scrollDown.setOnClickListener { messageList.scrollToPosition(adapter.itemCount) }
+    scrollDown.hide()
+    scrollDown.setOnClickListener {
+      messageList.scrollToPosition(0)
+    }
 
     return view
   }

app/src/main/java/de/kuschku/quasseldroid_ng/ui/setup/accounts/AccountViewModel.kt

@@ -3,6 +3,7 @@ package de.kuschku.quasseldroid_ng.ui.setup.accounts
 import android.app.Application
 import android.arch.lifecycle.AndroidViewModel
 import android.arch.lifecycle.LiveData
+import android.arch.paging.LivePagedListBuilder
 import android.arch.paging.PagedList
 import de.kuschku.quasseldroid_ng.persistence.AccountDatabase
 
@@ -10,11 +11,6 @@ class AccountViewModel(application: Application) : AndroidViewModel(application)
   private val database: AccountDatabase = AccountDatabase.Creator.init(
     getApplication()
   )
-  val accounts: LiveData<PagedList<AccountDatabase.Account>> = database.accounts().all().create(
-    0,
-    PagedList.Config.Builder()
-      .setPageSize(50)
-      .setPrefetchDistance(50)
-      .build()
-  )
+  val accounts: LiveData<PagedList<AccountDatabase.Account>>
+    = LivePagedListBuilder(database.accounts().all(), 20).build()
 }

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

@@ -24,6 +24,7 @@
     android:layout_marginEnd="12dp"
     android:layout_marginRight="12dp"
     android:tint="@color/colorFillDark"
+    android:visibility="gone"
     app:backgroundTint="#8A808080"
     app:elevation="0dip"
     app:fabSize="mini"