Chat scroll indicator added as first simple implementation.

app/src/main/java/com/xabber/android/ui/ChatViewer.java

@@ -27,6 +27,7 @@ import android.view.MenuItem;
 import android.view.View;
 import android.view.inputmethod.InputMethodManager;
 import android.widget.ImageView;
+import android.widget.LinearLayout;
 
 import com.xabber.android.data.ActivityManager;
 import com.xabber.android.data.Application;
@@ -50,6 +51,7 @@ import com.xabber.android.data.notification.NotificationManager;
 import com.xabber.android.data.roster.AbstractContact;
 import com.xabber.android.data.roster.OnContactChangedListener;
 import com.xabber.android.data.roster.RosterManager;
+import com.xabber.android.ui.adapter.ChatScrollIndicatorAdapter;
 import com.xabber.android.ui.adapter.ChatViewerAdapter;
 import com.xabber.android.ui.dialog.ChatExportDialogFragment;
 import com.xabber.android.ui.helper.ContactTitleActionBarInflater;
@@ -85,6 +87,7 @@ public class ChatViewer extends ManagedActivity implements OnChatChangedListener
 
     private String extraText = null;
 
+    ChatScrollIndicatorAdapter chatScrollIndicatorAdapter;
     ChatViewerAdapter chatViewerAdapter;
 
     ViewPager viewPager;
@@ -144,6 +147,10 @@ public class ChatViewer extends ManagedActivity implements OnChatChangedListener
             isChatSelected = false;
         }
 
+        chatScrollIndicatorAdapter = new ChatScrollIndicatorAdapter(this,
+                (LinearLayout)findViewById(R.id.chat_scroll_indicator));
+        chatScrollIndicatorAdapter.update(chatViewerAdapter.getRealCount());
+
         viewPager = (ViewPager) findViewById(R.id.pager);
         viewPager.setAdapter(chatViewerAdapter);
         viewPager.setOnPageChangeListener(this);
@@ -284,6 +291,7 @@ public class ChatViewer extends ManagedActivity implements OnChatChangedListener
             return;
 
         chatViewerAdapter.updateChats();
+        chatScrollIndicatorAdapter.update(chatViewerAdapter.getRealCount());
 
         String account = getAccount(intent);
         String user = getUser(intent);
@@ -292,6 +300,7 @@ public class ChatViewer extends ManagedActivity implements OnChatChangedListener
         }
 
         selectPage(account, user, false);
+
     }
 
     @Override
@@ -539,6 +548,8 @@ public class ChatViewer extends ManagedActivity implements OnChatChangedListener
 
         if (chatViewerAdapter.updateChats()) {
             selectPage(currentAccount, currentUser, false);
+            chatScrollIndicatorAdapter.update(chatViewerAdapter.getRealCount());
+
         } else {
             updateRegisteredChats();
             updateRegisteredRecentChatsFragments();
@@ -605,6 +616,7 @@ public class ChatViewer extends ManagedActivity implements OnChatChangedListener
         hideKeyboard(this);
 
         AbstractChat selectedChat = chatViewerAdapter.getChatByPageNumber(position);
+        chatScrollIndicatorAdapter.select(chatViewerAdapter.getRealPagePosition(position));
 
         isChatSelected = selectedChat != null;
 

app/src/main/java/com/xabber/android/ui/adapter/ChatScrollIndicatorAdapter.java

+package com.xabber.android.ui.adapter;
+
+import android.app.Activity;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.widget.LinearLayout;
+
+import com.xabber.androiddev.R;
+
+public class ChatScrollIndicatorAdapter {
+
+    private final Activity activity;
+    private final LinearLayout linearLayout;
+
+    public ChatScrollIndicatorAdapter(Activity activity, LinearLayout linearLayout) {
+        this.activity = activity;
+        this.linearLayout = linearLayout;
+    }
+
+    public void select(int selectedPosition) {
+        for (int index = 0; index < linearLayout.getChildCount(); index++) {
+            final View view = linearLayout.getChildAt(index);
+            final AccountViewHolder accountViewHolder = (AccountViewHolder) view.getTag();
+
+            accountViewHolder.selection.setVisibility(index == selectedPosition ? View.VISIBLE : View.GONE);
+            accountViewHolder.body.setVisibility(index == selectedPosition ? View.GONE : View.VISIBLE);
+        }
+    }
+
+    public void update(int size) {
+
+        final LayoutInflater inflater
+                = (LayoutInflater) activity.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
+
+        while (linearLayout.getChildCount() < size) {
+            final View view = inflater.inflate(R.layout.chat_scroll_indicator_item, linearLayout, false);
+            linearLayout.addView(view);
+            final AccountViewHolder accountViewHolder = new AccountViewHolder(view);
+
+            accountViewHolder.body.getBackground().setAlpha(127);
+            accountViewHolder.selection.getBackground().setAlpha(127);
+            view.setTag(accountViewHolder);
+        }
+
+        while (linearLayout.getChildCount() > size) {
+            linearLayout.removeViewAt(size);
+        }
+    }
+
+    private static class AccountViewHolder {
+        final View body;
+        final View selection;
+
+        public AccountViewHolder(View view) {
+            body = view.findViewById(R.id.indicator_item_body);
+            selection = view.findViewById(R.id.indicator_item_selection);
+        }
+    }
+}

app/src/main/java/com/xabber/android/ui/adapter/ChatViewerAdapter.java

@@ -144,7 +144,7 @@ public class ChatViewerAdapter extends FragmentStatePagerAdapter {
     }
 
 
-    private int getRealPagePosition(int virtualPosition) {
+    public int getRealPagePosition(int virtualPosition) {
         int realCount = getRealCount();
 
         int pageNumber = abs(virtualPosition - OFFSET) % realCount;
@@ -194,4 +194,5 @@ public class ChatViewerAdapter extends FragmentStatePagerAdapter {
     public Fragment getCurrentFragment() {
         return currentFragment;
     }
+
 }
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app/src/main/res/layout/activity_chat_viewer.xml

 <?xml version="1.0" encoding="utf-8"?>
-<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
+
+<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+<android.support.v4.view.ViewPager
     android:id="@+id/pager"
     android:layout_width="match_parent"
     android:layout_height="match_parent"/>
+
+
+<LinearLayout
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
+    android:orientation="horizontal"
+    android:layout_centerHorizontal="true"
+    android:layout_marginTop="16dp"
+    android:id="@+id/chat_scroll_indicator"
+
+    >
+    </LinearLayout>
+
+</RelativeLayout>
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app/src/main/res/layout/chat_scroll_indicator_item.xml

+<?xml version="1.0" encoding="utf-8"?>
+<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:orientation="vertical" android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
+    android:layout_marginEnd="3dp"
+    android:layout_marginRight="3dp"
+    android:layout_marginLeft="3dp"
+    android:layout_marginStart="3dp"
+    >
+
+    <ImageView
+        android:id="@+id/indicator_item_body"
+        android:layout_width="8dp"
+        android:layout_height="8dp"
+        android:layout_margin="3dp"
+        android:background="@color/grey_500"
+        />
+
+    <View
+        android:id="@+id/indicator_item_selection"
+        android:layout_width="14dp"
+        android:layout_height="14dp"
+        android:background="@color/grey_500"
+        android:visibility="gone"
+        />
+
+</RelativeLayout>
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