use SliverList instead of multiple SliverGrid + SliverStickyHeader

lib/widgets/album/collection_list_sliver.dart

@@ -0,0 +1,105 @@
+import 'dart:math';
+
+import 'package:aves/model/collection_lens.dart';
+import 'package:aves/widgets/album/collection_section.dart';
+import 'package:flutter/material.dart';
+
+// use a `SliverList` instead of multiple `SliverGrid` because having one `SliverGrid` per section does not scale up
+// with the multiple `SliverGrid` solution, thumbnails at the beginning of each sections are built even though they are offscreen
+// because of `RenderSliverMultiBoxAdaptor.addInitialChild` called by `RenderSliverGrid.performLayout` (line 547), as of Flutter v1.17.0
+class CollectionListSliver extends StatelessWidget {
+  final CollectionLens collection;
+  final bool showHeader;
+  final int columnCount;
+  final double tileExtent;
+
+  const CollectionListSliver({
+    Key key,
+    @required this.collection,
+    @required this.showHeader,
+    @required this.columnCount,
+    @required this.tileExtent,
+  }) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    final sectionLayouts = <_SectionLayout>[];
+    final sectionKeys = collection.sections.keys.toList();
+    var firstIndex = 0;
+    sectionKeys.forEach((sectionKey) {
+      final sectionEntryCount = collection.sections[sectionKey].length;
+      final rowCount = (sectionEntryCount / columnCount).ceil();
+      final widgetCount = rowCount + (showHeader ? 1 : 0);
+      // closure of `firstIndex` on `sectionFirstIndex`
+      final sectionFirstIndex = firstIndex;
+      sectionLayouts.add(
+        _SectionLayout(
+          sectionKey: sectionKey,
+          widgetCount: widgetCount,
+          firstIndex: sectionFirstIndex,
+          builder: (context, listIndex) {
+            listIndex -= sectionFirstIndex;
+            if (showHeader) {
+              if (listIndex == 0) {
+                return SectionHeader(
+                  collection: collection,
+                  sections: collection.sections,
+                  sectionKey: sectionKey,
+                );
+              }
+              listIndex--;
+            }
+
+            final section = collection.sections[sectionKey];
+            final minEntryIndex = listIndex * columnCount;
+            final maxEntryIndex = min(sectionEntryCount, minEntryIndex + columnCount);
+            final children = <Widget>[];
+            for (var i = minEntryIndex; i < maxEntryIndex; i++) {
+              children.add(GridThumbnail(
+                collection: collection,
+                index: i,
+                entry: section[i],
+                tileExtent: tileExtent,
+              ));
+            }
+            return Row(
+              mainAxisSize: MainAxisSize.min,
+              children: children,
+            );
+          },
+        ),
+      );
+      firstIndex += widgetCount;
+    });
+    final childCount = firstIndex;
+
+    return SliverList(
+      delegate: SliverChildBuilderDelegate(
+        (context, index) {
+          if (index >= childCount) return null;
+          final sectionLayout = sectionLayouts.firstWhere((section) => section.hasChild(index));
+          return sectionLayout.builder(context, index);
+        },
+        childCount: childCount,
+        addAutomaticKeepAlives: false,
+      ),
+    );
+  }
+}
+
+class _SectionLayout {
+  final dynamic sectionKey;
+  final int widgetCount;
+  final int firstIndex;
+  final int lastIndex;
+  final IndexedWidgetBuilder builder;
+
+  const _SectionLayout({
+    @required this.sectionKey,
+    @required this.widgetCount,
+    @required this.firstIndex,
+    @required this.builder,
+  }) : lastIndex = firstIndex + widgetCount - 1;
+
+  bool hasChild(int index) => firstIndex <= index && index <= lastIndex;
+}

lib/widgets/album/collection_scaling.dart

@@ -8,7 +8,6 @@ import 'package:aves/widgets/album/tile_extent_manager.dart';
 import 'package:aves/widgets/common/data_providers/media_query_data_provider.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
-import 'package:flutter_sticky_header/flutter_sticky_header.dart';
 
 class GridScaleGestureDetector extends StatefulWidget {
   final GlobalKey scrollableKey;
@@ -53,7 +52,7 @@ class _GridScaleGestureDetectorState extends State<GridScaleGestureDetector> {
         final renderMetaData = firstOf<RenderMetaData>(result);
         // abort if we cannot find an image to show on overlay
         if (renderMetaData == null) return;
-        _renderSliver = firstOf<RenderSliverStickyHeader>(result) ?? firstOf<RenderSliverGrid>(result);
+        _renderSliver = firstOf<RenderSliverList>(result);
         _renderViewport = firstOf<RenderViewport>(result);
         _metadata = renderMetaData.metaData;
         _startExtent = tileExtentNotifier.value;

lib/widgets/album/collection_section.dart

@@ -7,62 +7,6 @@ import 'package:aves/widgets/album/transparent_material_page_route.dart';
 import 'package:aves/widgets/common/icons.dart';
 import 'package:aves/widgets/fullscreen/fullscreen_page.dart';
 import 'package:flutter/material.dart';
-import 'package:flutter_sticky_header/flutter_sticky_header.dart';
-
-class SectionSliver extends StatelessWidget {
-  final CollectionLens collection;
-  final dynamic sectionKey;
-  final double tileExtent;
-  final bool showHeader;
-
-  const SectionSliver({
-    Key key,
-    @required this.collection,
-    @required this.sectionKey,
-    @required this.tileExtent,
-    @required this.showHeader,
-  }) : super(key: key);
-
-  @override
-  Widget build(BuildContext context) {
-    final sections = collection.sections;
-    final sectionEntries = sections[sectionKey];
-    final childCount = sectionEntries.length;
-
-    final sliver = SliverGrid(
-      delegate: SliverChildBuilderDelegate(
-        // TODO TLAD thumbnails at the beginning of each sections are built even though they are offscreen
-        // because of `RenderSliverMultiBoxAdaptor.addInitialChild`
-        // called by `RenderSliverGrid.performLayout` (line 547)
-        (context, index) => index < childCount
-            ? GridThumbnail(
-                collection: collection,
-                index: index,
-                entry: sectionEntries[index],
-                tileExtent: tileExtent,
-              )
-            : null,
-        childCount: childCount,
-        addAutomaticKeepAlives: false,
-      ),
-      gridDelegate: SliverGridDelegateWithMaxCrossAxisExtent(
-        maxCrossAxisExtent: tileExtent,
-      ),
-    );
-
-    return showHeader
-        ? SliverStickyHeader(
-            header: SectionHeader(
-              collection: collection,
-              sections: sections,
-              sectionKey: sectionKey,
-            ),
-            sliver: sliver,
-            overlapsContent: false,
-          )
-        : sliver;
-  }
-}
 
 class GridThumbnail extends StatelessWidget {
   final CollectionLens collection;

pubspec.lock

@@ -136,15 +136,6 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.0.6"
-  flutter_sticky_header:
-    dependency: "direct main"
-    description:
-      path: "."
-      ref: HEAD
-      resolved-ref: "14be154f50f5d14e88cc05b93b12377012b8905a"
-      url: "git://github.com/deckerst/flutter_sticky_header.git"
-    source: git
-    version: "0.4.2"
   flutter_svg:
     dependency: "direct main"
     description:

pubspec.yaml

@@ -30,9 +30,6 @@ dependencies:
       url: https://github.com/AndreHaueisen/flushbar.git
       ref: 13c55a8
   flutter_native_timezone:
-  flutter_sticky_header:
-    git:
-      url: git://github.com/deckerst/flutter_sticky_header.git
   flutter_svg:
   geocoder:
   google_maps_flutter: