rebuild performance review

lib/widgets/collection/collection_page.dart

@@ -31,26 +31,26 @@ class _CollectionPageState extends State<CollectionPage> {
   @override
   Widget build(BuildContext context) {
     return MediaQueryDataProvider(
-      child: ChangeNotifierProvider<CollectionLens>.value(
+      child: Scaffold(
-        value: collection,
+        body: WillPopScope(
-        child: Scaffold(
+          onWillPop: () {
-          body: WillPopScope(
+            if (collection.isSelecting) {
-            onWillPop: () {
+              collection.browse();
-              if (collection.isSelecting) {
+              return SynchronousFuture(false);
-                collection.browse();
+            }
-                return SynchronousFuture(false);
+            return SynchronousFuture(true);
-              }
+          },
-              return SynchronousFuture(true);
+          child: DoubleBackPopScope(
-            },
+            child: GestureAreaProtectorStack(
-            child: DoubleBackPopScope(
+              child: ChangeNotifierProvider<CollectionLens>.value(
-              child: GestureAreaProtectorStack(
+                value: collection,
                 child: ThumbnailCollection(),
               ),
             ),
           ),
-          drawer: AppDrawer(),
-          resizeToAvoidBottomInset: false,
         ),
+        drawer: AppDrawer(),
+        resizeToAvoidBottomInset: false,
       ),
     );
   }

lib/widgets/collection/thumbnail_collection.dart

@@ -32,21 +32,26 @@ import 'package:flutter/rendering.dart';
 import 'package:flutter_staggered_animations/flutter_staggered_animations.dart';
 import 'package:provider/provider.dart';
 
-class ThumbnailCollection extends StatelessWidget {
+class ThumbnailCollection extends StatefulWidget {
-  final ValueNotifier<double> _tileExtentNotifier = ValueNotifier(0);
+  @override
+  _ThumbnailCollectionState createState() => _ThumbnailCollectionState();
+}
+
+class _ThumbnailCollectionState extends State<ThumbnailCollection> {
+  TileExtentController _tileExtentController;
 
   @override
   Widget build(BuildContext context) {
+    _tileExtentController ??= TileExtentController(
+      settingsRouteKey: context.currentRouteName,
+      columnCountDefault: 4,
+      extentMin: 46,
+      spacing: 0,
+    );
     return SafeArea(
       bottom: false,
       child: TileExtentControllerProvider(
-        controller: TileExtentController(
+        controller: _tileExtentController,
-          settingsRouteKey: context.currentRouteName,
-          extentNotifier: _tileExtentNotifier,
-          columnCountDefault: 4,
-          extentMin: 46,
-          spacing: 0,
-        ),
         child: _ThumbnailCollectionContent(),
       ),
     );

lib/widgets/common/providers/tile_extent_controller_provider.dart

@@ -15,16 +15,11 @@ class TileExtentControllerProvider extends StatelessWidget {
   Widget build(BuildContext context) {
     return LayoutBuilder(
       builder: (context, constraints) {
-        return MultiProvider(
+        return LayoutBuilder(
-          providers: [
+          builder: (context, constraints) => ProxyProvider0<TileExtentController>(
-            ProxyProvider0(
+            update: (_, __) => controller..setViewportSize(constraints.biggest),
-              update: (_, __) => constraints.biggest,
+            child: child,
-            ),
+          ),
-            ProxyProvider<Size, TileExtentController>(
-              update: (_, viewportSize, __) => controller..applyTileExtent(viewportSize: viewportSize),
-            ),
-          ],
-          child: child,
         );
       },
     );

lib/widgets/common/scaling.dart

@@ -102,9 +102,7 @@ class _GridScaleGestureDetectorState<T> extends State<GridScaleGestureDetector<T
         final tileExtentController = context.read<TileExtentController>();
         final oldExtent = tileExtentController.extentNotifier.value;
         // sanitize and update grid layout if necessary
-        final newExtent = tileExtentController.applyTileExtent(
+        final newExtent = tileExtentController.setUserPreferredExtent(_scaledExtentNotifier.value);
-          userPreferredExtent: _scaledExtentNotifier.value,
-        );
         _scaledExtentNotifier = null;
         if (newExtent == oldExtent) {
           _applyingScale = false;

lib/widgets/common/tile_extent_controller.dart

@@ -7,7 +7,7 @@ class TileExtentController {
   final String settingsRouteKey;
   final int columnCountMin, columnCountDefault;
   final double spacing, extentMin, extentMax;
-  final ValueNotifier<double> extentNotifier;
+  final ValueNotifier<double> extentNotifier = ValueNotifier(0);
 
   Size _viewportSize;
 
@@ -15,7 +15,6 @@ class TileExtentController {
 
   TileExtentController({
     @required this.settingsRouteKey,
-    @required this.extentNotifier,
     this.columnCountMin = 2,
     @required this.columnCountDefault,
     @required this.extentMin,
@@ -23,16 +22,21 @@ class TileExtentController {
     @required this.spacing,
   });
 
-  double applyTileExtent({
+  void setViewportSize(Size viewportSize) {
-    Size viewportSize,
+    // sanitize screen size (useful when reloading while screen is off, reporting a 0,0 size)
-    double userPreferredExtent = 0,
+    final viewportSizeMin = Size.square(extentMin * columnCountMin);
-  }) {
+    // dimensions are rounded to prevent updates on minor changes
-    if (viewportSize != null) {
+    // e.g. available space on S10e is `Size(360.0, 721.0)` when status bar is visible, `Size(360.0, 721.3)` when it is not
-      // sanitize screen size (useful when reloading while screen is off, reporting a 0,0 size)
+    final newViewportSize = Size(max(viewportSize.width, viewportSizeMin.width).roundToDouble(), max(viewportSize.height, viewportSizeMin.height).roundToDouble());
-      final viewportSizeMin = Size.square(extentMin * columnCountMin);
+    if (_viewportSize != newViewportSize) {
-      _viewportSize = Size(max(viewportSize.width, viewportSizeMin.width), max(viewportSize.height, viewportSizeMin.height));
+      _viewportSize = newViewportSize;
+      _update();
     }
+  }
 
+  double setUserPreferredExtent(double userPreferredExtent) => _update(userPreferredExtent: userPreferredExtent);
+
+  double _update({double userPreferredExtent = 0}) {
     final oldUserPreferredExtent = settings.getTileExtent(settingsRouteKey);
     final currentExtent = extentNotifier.value;
     final targetExtent = userPreferredExtent > 0

lib/widgets/filter_grids/common/filter_grid_page.dart

@@ -40,9 +40,7 @@ class FilterGridPage<T extends CollectionFilter> extends StatelessWidget {
   final FilterCallback onTap;
   final OffsetFilterCallback onLongPress;
 
-  final ValueNotifier<double> _tileExtentNotifier = ValueNotifier(0);
+  const FilterGridPage({
-
-  FilterGridPage({
     Key key,
     @required this.appBar,
     @required this.filterSections,
@@ -69,7 +67,6 @@ class FilterGridPage<T extends CollectionFilter> extends StatelessWidget {
               child: TileExtentControllerProvider(
                 controller: TileExtentController(
                   settingsRouteKey: settingsRouteKey ?? context.currentRouteName,
-                  extentNotifier: _tileExtentNotifier,
                   columnCountDefault: 2,
                   extentMin: 60,
                   spacing: 8,