Add support for variable page sizes. (Resolves #59)

example/android/app/build.gradle

@@ -1,3 +1,9 @@
+plugins {
+    id "com.android.application"
+    id "kotlin-android"
+    id "dev.flutter.flutter-gradle-plugin"
+}
+
 def localProperties = new Properties()
 def localPropertiesFile = rootProject.file('local.properties')
 if (localPropertiesFile.exists()) {
@@ -6,11 +12,6 @@ if (localPropertiesFile.exists()) {
     }
 }
 
-def flutterRoot = localProperties.getProperty('flutter.sdk')
-if (flutterRoot == null) {
-    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
-}
-
 def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
 if (flutterVersionCode == null) {
     flutterVersionCode = '1'
@@ -21,13 +22,11 @@ if (flutterVersionName == null) {
     flutterVersionName = '1.0'
 }
 
-apply plugin: 'com.android.application'
-apply plugin: 'kotlin-android'
-apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
 android {
     compileSdkVersion flutter.compileSdkVersion
     ndkVersion flutter.ndkVersion
+    namespace "com.example.example"
 
     compileOptions {
         sourceCompatibility JavaVersion.VERSION_1_8
@@ -65,7 +64,3 @@ android {
 flutter {
     source '../..'
 }
-
-dependencies {
-    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
-}

example/android/build.gradle

@@ -1,16 +1,3 @@
-buildscript {
-    ext.kotlin_version = '1.7.10'
-    repositories {
-        google()
-        mavenCentral()
-    }
-
-    dependencies {
-        classpath 'com.android.tools.build:gradle:7.2.0'
-        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
-    }
-}
-
 allprojects {
     repositories {
         google()

example/android/gradle/wrapper/gradle-wrapper.properties

@@ -2,4 +2,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.5-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.4-all.zip

example/android/settings.gradle

@@ -1,11 +1,25 @@
-include ':app'
+pluginManagement {
+    def flutterSdkPath = {
+        def properties = new Properties()
+        file("local.properties").withInputStream { properties.load(it) }
+        def flutterSdkPath = properties.getProperty("flutter.sdk")
+        assert flutterSdkPath != null, "flutter.sdk not set in local.properties"
+        return flutterSdkPath
+    }()
 
-def localPropertiesFile = new File(rootProject.projectDir, "local.properties")
-def properties = new Properties()
+    includeBuild("$flutterSdkPath/packages/flutter_tools/gradle")
 
-assert localPropertiesFile.exists()
-localPropertiesFile.withReader("UTF-8") { reader -> properties.load(reader) }
+    repositories {
+        google()
+        mavenCentral()
+        gradlePluginPortal()
+    }
+}
 
-def flutterSdkPath = properties.getProperty("flutter.sdk")
-assert flutterSdkPath != null, "flutter.sdk not set in local.properties"
-apply from: "$flutterSdkPath/packages/flutter_tools/gradle/app_plugin_loader.gradle"
+plugins {
+    id "dev.flutter.flutter-plugin-loader" version "1.0.0" // apply true
+    id "com.android.application" version "8.3.0" apply false
+    id "org.jetbrains.kotlin.android" version "1.8.10" apply false
+}
+
+include ":app"

example/lib/main_variable_page_size.dart

@@ -0,0 +1,172 @@
+import 'package:flutter/material.dart';
+import 'package:logging/logging.dart';
+import 'package:page_list_viewport/page_list_viewport.dart';
+
+void main() {
+  PageListViewportLogs.initLoggers(Level.ALL, {});
+
+  runApp(const MyApp());
+}
+
+class MyApp extends StatelessWidget {
+  const MyApp({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return const MaterialApp(
+      title: 'Page List Viewport Variable Size Demo',
+      home: MyHomePage(),
+    );
+  }
+}
+
+class MyHomePage extends StatefulWidget {
+  const MyHomePage({
+    super.key,
+  });
+
+  @override
+  State<MyHomePage> createState() => _MyHomePageState();
+}
+
+class _MyHomePageState extends State<MyHomePage> with TickerProviderStateMixin {
+  static const _pageCount = 200;
+
+  static const _pageSizes = [
+    Size(8.5, 11), // Letter
+    Size(11, 8.5), // Letter (inverse)
+  ];
+
+  late final PageListViewportWithVariableSizeController _controller;
+
+  @override
+  void initState() {
+    super.initState();
+    _controller = PageListViewportWithVariableSizeController.startAtPage(pageIndex: 5, vsync: this);
+  }
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      body: Row(
+        crossAxisAlignment: CrossAxisAlignment.stretch,
+        children: [
+          SizedBox(
+            width: 125,
+            child: _buildThumbnailList(),
+          ),
+          Expanded(
+            child: Center(
+              child: SizedBox(
+                height: _pageSizes[0].height * 72 * MediaQuery.of(context).devicePixelRatio,
+                width: _pageSizes[0].width * 72 * MediaQuery.of(context).devicePixelRatio,
+                child: _buildViewport(),
+              ),
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+
+  Widget _buildViewport() {
+    return Stack(
+      children: [
+        PageListViewportGestures(
+          controller: _controller,
+          lockPanAxis: true,
+          child: PageListViewport.variedPageSized(
+            controller: _controller,
+            pageCount: _pageCount,
+            onGetNaturalPageSize: (pageIndex) =>
+                _pageSizes[pageIndex % _pageSizes.length] * 72 * MediaQuery.of(context).devicePixelRatio,
+            pageLayoutCacheCount: 3,
+            pagePaintCacheCount: 3,
+            builder: (BuildContext context, int pageIndex) {
+              return Stack(
+                children: [
+                  Positioned.fill(
+                    child: GestureDetector(
+                      onTap: () => print('tapped at pageIndex: $pageIndex'),
+                      child: _buildPage(pageIndex),
+                    ),
+                  ),
+                ],
+              );
+            },
+          ),
+        ),
+      ],
+    );
+  }
+
+  Widget _buildThumbnailList() {
+    return RepaintBoundary(
+      child: ColoredBox(
+        color: Colors.grey.shade800,
+        child: ListView.builder(
+          padding: const EdgeInsets.all(16),
+          itemCount: _pageCount,
+          itemBuilder: (context, index) {
+            return Padding(
+              padding: const EdgeInsets.symmetric(vertical: 8),
+              child: GestureDetector(
+                onTap: () {
+                  _controller.animateToPage(index, const Duration(milliseconds: 250));
+                },
+                child: AspectRatio(
+                  aspectRatio: _pageSizes[index % _pageSizes.length].aspectRatio,
+                  child: _buildPage(index),
+                ),
+              ),
+            );
+          },
+        ),
+      ),
+    );
+  }
+
+  Widget _buildPage(int pageIndex) {
+    final pageSize = Size(
+      _pageSizes[pageIndex % _pageSizes.length].width * 72,
+      _pageSizes[pageIndex % _pageSizes.length].height * 72,
+    );
+
+    return Container(
+      color: Colors.white,
+      child: Container(
+        color: Colors.primaries[pageIndex % Colors.primaries.length],
+        width: pageSize.width,
+        height: pageSize.height,
+        child: Center(
+          child: LayoutBuilder(builder: (context, constraints) {
+            return Container(
+              width: 300 * (constraints.maxWidth / pageSize.width),
+              height: 300 * (constraints.maxHeight / pageSize.height),
+              decoration: const BoxDecoration(
+                color: Colors.white,
+                shape: BoxShape.circle,
+              ),
+              alignment: Alignment.center,
+              child: Padding(
+                padding: const EdgeInsets.all(4.0),
+                child: FittedBox(
+                  child: Text(
+                    'Page $pageIndex',
+                    style: const TextStyle(fontSize: 24),
+                  ),
+                ),
+              ),
+            );
+          }),
+        ),
+      ),
+    );
+  }
+}

lib/page_list_viewport.dart

@@ -1,6 +1,7 @@
 library page_list_viewport;
 
 export 'src/page_list_viewport.dart';
+export 'src/page_list_viewport_variable_size.dart';
 export 'src/page_list_performance_optimizer.dart';
 export 'src/logging.dart';