Add readme

Change-Id: Ia37ef8fb111498e4a335c22868044cfe6a8b1733

Author: Nagesh Susarla

README.md

@@ -0,0 +1,49 @@
+Constraint Layout Samples
+=========================
+This repository contains a list of layouts that showcases the various features and usage of
+[ConstraintLayout](https://developer.android.com/reference/android/support/constraint/ConstraintLayout.html)
+
+Pre-requisites
+--------------
+- Android Studio 2.3 Beta 4
+- Constaint Layout library 1.0.0-beta5
+
+Getting Started
+---------------
+Import the project using Android Studio. Navigate to the app>res>layout> and open one of the layouts
+in the layout editor. This sample is best understood by seeing the constraints in the Design mode
+of the layout editor.
+
+Screenshots
+------------
+
+![Constraint Set Example](screenshots/constraint_set_example.png "Constraint Set Example")
+![Advanced Chains Example](screenshots/advanced_chains.png "Advanced usage of Chains")
+
+Support
+-------
+If you've found an error in this sample, please file an issue.
+To learn more about ConstraintLayout checkout the
+[Constraint Layout Training Guide](https://developer.android.com/training/constraint-layout/index.html)
+Patches are encouraged, and may be submitted by forking this project and
+submitting a pull request through GitHub. Please see CONTRIBUTING.md for more details.
+
+License
+-------
+
+Copyright 2017 The Android Open Source Project, Inc.
+
+Licensed to the Apache Software Foundation (ASF) under one or more contributor
+license agreements.  See the NOTICE file distributed with this work for
+additional information regarding copyright ownership.  The ASF licenses this
+file to you 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.

app/src/main/res/layout/constraint_example_1.xml

@@ -72,7 +72,8 @@
         tools:layout_constraintBottom_creator="1"
         app:layout_constraintBottom_toBottomOf="@+id/button31"
         tools:layout_constraintLeft_creator="1"
-        app:layout_constraintTop_toTopOf="@+id/button3" />
+        app:layout_constraintTop_toTopOf="@+id/button3"
+        app:layout_constraintHorizontal_bias="0.0" />
 
     <Button
         android:id="@+id/button33"
@@ -84,7 +85,8 @@
         app:layout_constraintBottom_toTopOf="@+id/button32"
         app:layout_constraintTop_toTopOf="@+id/button32"
         tools:layout_constraintTop_creator="1"
-        tools:layout_constraintBottom_creator="1" />
+        tools:layout_constraintBottom_creator="1"
+        app:layout_constraintHorizontal_bias="0.5" />
 
     <Button
         android:id="@+id/button34"
@@ -99,6 +101,7 @@
         tools:layout_constraintTop_creator="1"
         tools:layout_constraintBottom_creator="1"
         app:layout_constraintBottom_toBottomOf="@+id/button32"
-        app:layout_constraintTop_toTopOf="@+id/button3" />
+        app:layout_constraintTop_toTopOf="@+id/button3"
+        app:layout_constraintHorizontal_bias="0.52" />
 
 </android.support.constraint.ConstraintLayout>

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

@@ -58,6 +58,8 @@
         app:layout_constraintBottom_toBottomOf="parent"
         android:layout_marginBottom="16dp"
         tools:layout_constraintTop_creator="1"
-        tools:layout_constraintBottom_creator="1" />
+        tools:layout_constraintBottom_creator="1"
+        app:layout_constraintHorizontal_bias="0.0"
+        app:layout_constraintVertical_bias="0.0" />
 
 </android.support.constraint.ConstraintLayout>

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

@@ -32,7 +32,8 @@
         app:layout_constraintTop_toTopOf="@+id/textView9"
         tools:layout_constraintBottom_creator="1"
         tools:layout_constraintTop_creator="1"
-        android:contentDescription="@string/lake_tahoe_image" />
+        android:contentDescription="@string/lake_tahoe_image"
+        app:layout_constraintVertical_bias="0.0" />
 
     <TextView
         android:id="@+id/textView9"