Fix aspect ratio landscape (#45)

* Add support for layout-land resources
* Adjusted constrain_example_5 to better fit land mode

Author: tomashavlicek

constraintlayout/src/main/java/com/example/android/constraintlayoutexamples/MainActivity.java

@@ -17,31 +17,36 @@
 package com.example.android.constraintlayoutexamples;
 
 import android.content.Intent;
+import android.content.res.Configuration;
 import android.os.Bundle;
 import android.support.v7.app.AppCompatActivity;
 import android.view.View;
 
 public class MainActivity extends AppCompatActivity {
-    private boolean mShowingLayout = false;
+    private String mTag = "activity_main";
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
-        setContentView(R.layout.activity_main);
+        setContentView(mTag);
+    }
+
+    @Override
+    public void onConfigurationChanged(Configuration newConfig) {
+        super.onConfigurationChanged(newConfig);
+        setContentView(mTag);
     }
 
     public void show(View v) {
-        String tag = (String) v.getTag();
-        int id = getResources().getIdentifier(tag, "layout", getPackageName());
-        setContentView(id);
-        mShowingLayout = true;
+        mTag = (String) v.getTag();
+        setContentView(mTag);
     }
 
     @Override
     public void onBackPressed() {
-        if (mShowingLayout) {
-            setContentView(R.layout.activity_main);
-            mShowingLayout = false;
+        if (!mTag.equals("activity_main")) {
+            mTag = "activity_main";
+            setContentView(mTag);
         } else {
             super.onBackPressed();
         }
@@ -50,4 +55,9 @@ public void onBackPressed() {
     public void showConstraintSetExample(View view) {
         startActivity(new Intent(this, ConstraintSetExampleActivity.class));
     }
+
+    private void setContentView(String tag) {
+        int id = getResources().getIdentifier(tag, "layout", getPackageName());
+        setContentView(id);
+    }
 }

constraintlayout/src/main/res/layout-land/constraint_example_5.xml

@@ -0,0 +1,86 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  Copyright (C) 2017 The Android Open Source Project
+  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.
+  -->
+<android.support.constraint.ConstraintLayout 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:orientation="vertical"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <TextView
+        android:id="@+id/textView3"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="16dp"
+        android:text="@string/aspect_ratio"
+        android:textSize="30sp"
+        app:layout_constraintLeft_toLeftOf="parent"
+        app:layout_constraintRight_toRightOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
+        tools:layout_constraintLeft_creator="1"
+        tools:layout_constraintRight_creator="1"
+        tools:layout_constraintTop_creator="1" />
+
+    <TextView
+        android:id="@+id/textView4"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="24dp"
+        android:text="@string/big_android_icon"
+        android:textSize="24sp"
+        app:layout_constraintLeft_toRightOf="@+id/imageButton"
+        app:layout_constraintTop_toBottomOf="@+id/imageView"
+        tools:layout_constraintTop_creator="1" />
+
+    <TextView
+        android:id="@+id/textView5"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="@string/textview"
+        android:textSize="24sp"
+        app:layout_constraintLeft_toLeftOf="@+id/textView4"
+        app:layout_constraintTop_toBottomOf="@+id/textView4"
+        tools:layout_constraintLeft_creator="1"
+        tools:layout_constraintTop_creator="1" />
+
+    <ImageView
+        android:id="@+id/imageView"
+        android:layout_width="0dp"
+        android:layout_height="0dp"
+        android:layout_marginLeft="16dp"
+        android:layout_marginTop="16dp"
+        android:layout_marginRight="16dp"
+        android:contentDescription="@string/lake_tahoe_image"
+        android:scaleType="centerCrop"
+        app:layout_constraintDimensionRatio="h,6:1"
+        app:layout_constraintLeft_toLeftOf="parent"
+        app:layout_constraintRight_toRightOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/textView3"
+        app:srcCompat="@drawable/lake"
+        tools:layout_constraintLeft_creator="1"
+        tools:layout_constraintRight_creator="1" />
+
+    <ImageButton
+        android:id="@+id/imageButton"
+        android:layout_width="0dp"
+        android:layout_height="0dp"
+        app:srcCompat="@drawable/ic_android_black_24dp"
+        tools:layout_constraintBottom_creator="1"
+        app:layout_constraintBottom_toBottomOf="@+id/textView5"
+        app:layout_constraintTop_toTopOf="@+id/textView4"
+        android:layout_marginStart="16dp"
+        app:layout_constraintLeft_toLeftOf="parent"
+        app:layout_constraintDimensionRatio="w,1:1"
+        android:contentDescription="@string/android_button" />
+</android.support.constraint.ConstraintLayout>