Breaking up Step 5 of animations (#2260)

This is a fast follow PR finishing the work of
#2258

## Pre-launch Checklist

- [x] I read the [Effective Dart: Style] _recently_, and have followed
its advice.
- [x] I signed the [CLA].
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-devrel
channel on [Discord].

<!-- Links -->
[Effective Dart: Style]:
https://dart.dev/guides/language/effective-dart/style
[CLA]: https://cla.developers.google.com/
[Discord]:
https://github.com/flutter/flutter/blob/master/docs/contributing/Chat.md

Author: domesticmouse

animations/codelab_rebuild.yaml

@@ -1002,8 +1002,8 @@ steps:
       - name: Use PageRouteBuilder
         path: quiz/lib/home_screen.dart
         patch-u: |
-          --- a/animations/step_05/lib/home_screen.dart
-          +++ b/animations/step_05/lib/home_screen.dart
+          --- b/animations/step_05_a/lib/home_screen.dart
+          +++ a/animations/step_05_a/lib/home_screen.dart
           @@ -26,14 +26,19 @@ class HomeScreen extends StatelessWidget {
                            // Show the question screen to start the game
                            Navigator.push(
@@ -1015,9 +1015,9 @@ steps:
           -                  ),
           +                  PageRouteBuilder(
           +                      pageBuilder: (context, animation, secondaryAnimation) {
-          +                        return const QuestionScreen();
-          +                      }, transitionsBuilder:
-          +                      (context, animation, secondaryAnimation, child) {
+          +                    return const QuestionScreen();
+          +                  }, transitionsBuilder:
+          +                          (context, animation, secondaryAnimation, child) {
           +                    return FadeTransition(
           +                      opacity: animation,
           +                      child: child,
@@ -1030,20 +1030,26 @@ steps:
                        ),
                      ],
                    ),
+      - name: Remove step_05_a
+        rmdir: step_05_a
+      - name: Copy step_05_a
+        copydir:
+          from: quiz
+          to: step_05_a
       - name: Use package:animations FadeThroughTransition
         path: quiz/lib/home_screen.dart
         patch-u: |
-          --- a/animations/step_05/lib/home_screen.dart
-          +++ b/animations/step_05/lib/home_screen.dart
+          --- b/animations/step_05_b/lib/home_screen.dart
+          +++ a/animations/step_05_b/lib/home_screen.dart
           @@ -1,3 +1,4 @@
           +import 'package:animations/animations.dart';
            import 'package:flutter/material.dart';
            import 'question_screen.dart';
            
           @@ -31,8 +32,9 @@ class HomeScreen extends StatelessWidget {
-                                   return const QuestionScreen();
-                                 }, transitionsBuilder:
-                                 (context, animation, secondaryAnimation, child) {
+                               return const QuestionScreen();
+                             }, transitionsBuilder:
+                                     (context, animation, secondaryAnimation, child) {
           -                    return FadeTransition(
           -                      opacity: animation,
           +                    return FadeThroughTransition(
@@ -1078,11 +1084,17 @@ steps:
                  ),
                  home: HomeScreen(),
                );
+      - name: Remove step_05_b
+        rmdir: step_05_b
+      - name: Copy step_05_b
+        copydir:
+          from: quiz
+          to: step_05_b
       - name: Change back to MaterialPageRoute
         path: quiz/lib/home_screen.dart
         patch-u: |
-          --- a/animations/step_05/lib/home_screen.dart
-          +++ b/animations/step_05/lib/home_screen.dart
+          --- b/animations/step_05_c/lib/home_screen.dart
+          +++ a/animations/step_05_c/lib/home_screen.dart
           @@ -1,4 +1,3 @@
           -import 'package:animations/animations.dart';
            import 'package:flutter/material.dart';
@@ -1094,16 +1106,15 @@ steps:
                              context,
           -                  PageRouteBuilder(
           -                      pageBuilder: (context, animation, secondaryAnimation) {
-          -                        return const QuestionScreen();
-          -                      }, transitionsBuilder:
-          -                      (context, animation, secondaryAnimation, child) {
+          +                  MaterialPageRoute(builder: (context) {
+                               return const QuestionScreen();
+          -                  }, transitionsBuilder:
+          -                          (context, animation, secondaryAnimation, child) {
           -                    return FadeThroughTransition(
           -                      animation: animation,
           -                      secondaryAnimation: secondaryAnimation,
           -                      child: child,
           -                    );
-          +                  MaterialPageRoute(builder: (context) {
-          +                    return const QuestionScreen();
                              }),
                            );
                          },
@@ -1156,6 +1167,12 @@ steps:
                  child: Card(
                    key: ValueKey(question),
                    elevation: 4,
+      - name: Remove step_05_c
+        rmdir: step_05_c
+      - name: Copy step_05_c
+        copydir:
+          from: quiz
+          to: step_05_c
       - name: Use OpenContainer
         path: quiz/lib/question_screen.dart
         patch-u: | 
@@ -1330,6 +1347,12 @@ steps:
                  ),
                );
              }
+      - name: Remove step_05_d
+        rmdir: step_05_d
+      - name: Copy step_05_d
+        copydir:
+          from: quiz
+          to: step_05_d
       - name: dart analyze
         path: quiz
         dart: analyze --fatal-infos

animations/step_05_a/.gitignore

@@ -0,0 +1,43 @@
+# Miscellaneous
+*.class
+*.log
+*.pyc
+*.swp
+.DS_Store
+.atom/
+.buildlog/
+.history
+.svn/
+migrate_working_dir/
+
+# IntelliJ related
+*.iml
+*.ipr
+*.iws
+.idea/
+
+# The .vscode folder contains launch configuration and tasks you configure in
+# VS Code which you may wish to be included in version control, so this line
+# is commented out by default.
+#.vscode/
+
+# Flutter/Dart/Pub related
+**/doc/api/
+**/ios/Flutter/.last_build_id
+.dart_tool/
+.flutter-plugins
+.flutter-plugins-dependencies
+.pub-cache/
+.pub/
+/build/
+
+# Symbolication related
+app.*.symbols
+
+# Obfuscation related
+app.*.map.json
+
+# Android Studio will place build artifacts here
+/android/app/debug
+/android/app/profile
+/android/app/release

animations/step_05_a/analysis_options.yaml

@@ -0,0 +1,13 @@
+include: package:flutter_lints/flutter.yaml
+
+analyzer:
+  errors:
+    unused_field: ignore
+
+linter:
+  rules:
+    annotate_overrides: false
+    prefer_const_constructors: false
+    prefer_const_constructors_in_immutables: false
+    prefer_const_declarations: false
+    prefer_const_literals_to_create_immutables: false

animations/step_05_a/android/.gitignore

@@ -0,0 +1,13 @@
+gradle-wrapper.jar
+/.gradle
+/captures/
+/gradlew
+/gradlew.bat
+/local.properties
+GeneratedPluginRegistrant.java
+
+# Remember to never publicly share your keystore.
+# See https://flutter.dev/to/reference-keystore
+key.properties
+**/*.keystore
+**/*.jks

animations/step_05_a/android/app/build.gradle

@@ -0,0 +1,44 @@
+plugins {
+    id "com.android.application"
+    id "kotlin-android"
+    // The Flutter Gradle Plugin must be applied after the Android and Kotlin Gradle plugins.
+    id "dev.flutter.flutter-gradle-plugin"
+}
+
+android {
+    namespace = "com.example.quiz"
+    compileSdk = flutter.compileSdkVersion
+    ndkVersion = flutter.ndkVersion
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_1_8
+        targetCompatibility = JavaVersion.VERSION_1_8
+    }
+
+    kotlinOptions {
+        jvmTarget = JavaVersion.VERSION_1_8
+    }
+
+    defaultConfig {
+        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
+        applicationId = "com.example.quiz"
+        // You can update the following values to match your application needs.
+        // For more information, see: https://flutter.dev/to/review-gradle-config.
+        minSdk = flutter.minSdkVersion
+        targetSdk = flutter.targetSdkVersion
+        versionCode = flutter.versionCode
+        versionName = flutter.versionName
+    }
+
+    buildTypes {
+        release {
+            // TODO: Add your own signing config for the release build.
+            // Signing with the debug keys for now, so `flutter run --release` works.
+            signingConfig = signingConfigs.debug
+        }
+    }
+}
+
+flutter {
+    source = "../.."
+}

animations/step_05_a/android/app/src/debug/AndroidManifest.xml

@@ -0,0 +1,7 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <!-- The INTERNET permission is required for development. Specifically,
+         the Flutter tool needs it to communicate with the running application
+         to allow setting breakpoints, to provide hot reload, etc.
+    -->
+    <uses-permission android:name="android.permission.INTERNET"/>
+</manifest>

animations/step_05_a/android/app/src/main/AndroidManifest.xml

@@ -0,0 +1,45 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <application
+        android:label="quiz"
+        android:name="${applicationName}"
+        android:icon="@mipmap/ic_launcher">
+        <activity
+            android:name=".MainActivity"
+            android:exported="true"
+            android:launchMode="singleTop"
+            android:taskAffinity=""
+            android:theme="@style/LaunchTheme"
+            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
+            android:hardwareAccelerated="true"
+            android:windowSoftInputMode="adjustResize">
+            <!-- Specifies an Android theme to apply to this Activity as soon as
+                 the Android process has started. This theme is visible to the user
+                 while the Flutter UI initializes. After that, this theme continues
+                 to determine the Window background behind the Flutter UI. -->
+            <meta-data
+              android:name="io.flutter.embedding.android.NormalTheme"
+              android:resource="@style/NormalTheme"
+              />
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN"/>
+                <category android:name="android.intent.category.LAUNCHER"/>
+            </intent-filter>
+        </activity>
+        <!-- Don't delete the meta-data below.
+             This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
+        <meta-data
+            android:name="flutterEmbedding"
+            android:value="2" />
+    </application>
+    <!-- Required to query activities that can process text, see:
+         https://developer.android.com/training/package-visibility and
+         https://developer.android.com/reference/android/content/Intent#ACTION_PROCESS_TEXT.
+
+         In particular, this is used by the Flutter engine in io.flutter.plugin.text.ProcessTextPlugin. -->
+    <queries>
+        <intent>
+            <action android:name="android.intent.action.PROCESS_TEXT"/>
+            <data android:mimeType="text/plain"/>
+        </intent>
+    </queries>
+</manifest>

animations/step_05_a/android/app/src/main/kotlin/com/example/quiz/MainActivity.kt

@@ -0,0 +1,5 @@
+package com.example.quiz
+
+import io.flutter.embedding.android.FlutterActivity
+
+class MainActivity: FlutterActivity()

animations/step_05_a/android/app/src/main/res/drawable-v21/launch_background.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Modify this file to customize your launch splash screen -->
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:drawable="?android:colorBackground" />
+
+    <!-- You can insert your own image assets here -->
+    <!-- <item>
+        <bitmap
+            android:gravity="center"
+            android:src="@mipmap/launch_image" />
+    </item> -->
+</layer-list>

animations/step_05_a/android/app/src/main/res/drawable/launch_background.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Modify this file to customize your launch splash screen -->
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:drawable="@android:color/white" />
+
+    <!-- You can insert your own image assets here -->
+    <!-- <item>
+        <bitmap
+            android:gravity="center"
+            android:src="@mipmap/launch_image" />
+    </item> -->
+</layer-list>