Extract photo item list

lib/widget/home_photos.dart

@@ -94,16 +94,6 @@ class _HomePhotosState extends State<HomePhotos>
 
   Widget _buildContent(BuildContext context, ScanDirBlocState state) {
     return LayoutBuilder(builder: (context, constraints) {
-      if (_prevListWidth == null) {
-        _prevListWidth = constraints.maxWidth;
-      }
-      if (constraints.maxWidth != _prevListWidth) {
-        _log.info(
-            "[_buildContent] updateListHeight: list viewport width changed");
-        WidgetsBinding.instance.addPostFrameCallback((_) => updateListHeight());
-        _prevListWidth = constraints.maxWidth;
-      }
-
       final scrollExtent = _getScrollViewExtent(constraints);
       return Stack(
         children: [
@@ -583,7 +573,6 @@ class _HomePhotosState extends State<HomePhotos>
 
   final ScrollController _scrollController = ScrollController();
 
-  double _prevListWidth;
   double _appBarExtent;
 
   static final _log = Logger("widget.home_photos._HomePhotosState");

lib/widget/measurable_item_list.dart

@@ -0,0 +1,134 @@
+import 'package:flutter/widgets.dart';
+import 'package:flutter_staggered_grid_view/flutter_staggered_grid_view.dart';
+import 'package:logging/logging.dart';
+import 'package:nc_photos/widget/measureable_sliver_staggered_grid.dart';
+import 'package:uuid/uuid.dart';
+
+abstract class MeasurableItemListState {
+  void updateListHeight();
+}
+
+class MeasurableItemList extends StatefulWidget {
+  MeasurableItemList({
+    Key key,
+    @required this.maxCrossAxisExtent,
+    @required this.itemCount,
+    @required this.itemBuilder,
+    @required this.staggeredTileBuilder,
+    this.onMaxExtentChanged,
+  }) : super(key: key);
+
+  @override
+  createState() => _MeasurableItemListState();
+
+  final double maxCrossAxisExtent;
+  final int itemCount;
+  final IndexedWidgetBuilder itemBuilder;
+  final IndexedStaggeredTileBuilder staggeredTileBuilder;
+  final ValueChanged<double> onMaxExtentChanged;
+}
+
+class _MeasurableItemListState extends State<MeasurableItemList>
+    with WidgetsBindingObserver
+    implements MeasurableItemListState {
+  @override
+  initState() {
+    super.initState();
+
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      _prevOrientation = MediaQuery.of(context).orientation;
+      WidgetsBinding.instance.addObserver(this);
+    });
+  }
+
+  @override
+  dispose() {
+    WidgetsBinding.instance.removeObserver(this);
+    super.dispose();
+  }
+
+  @override
+  didChangeMetrics() {
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      final orientation = MediaQuery.of(context).orientation;
+      if (orientation != _prevOrientation) {
+        _log.info(
+            "[didChangeMetrics] updateListHeight: orientation changed: $orientation");
+        _prevOrientation = orientation;
+        updateListHeight();
+      }
+    });
+  }
+
+  @override
+  build(BuildContext context) {
+    return SliverLayoutBuilder(builder: (context, constraints) {
+      if (_prevListWidth == null) {
+        _prevListWidth = constraints.crossAxisExtent;
+      }
+      if (constraints.crossAxisExtent != _prevListWidth) {
+        _log.info("[build] updateListHeight: list viewport width changed");
+        WidgetsBinding.instance.addPostFrameCallback((_) => updateListHeight());
+        _prevListWidth = constraints.crossAxisExtent;
+      }
+
+      // need to rebuild grid after cell size changed
+      final cellSize = widget.maxCrossAxisExtent;
+      if (cellSize != _prevCellSize) {
+        _log.info("[build] updateListHeight: cell size changed");
+        WidgetsBinding.instance.addPostFrameCallback((_) => updateListHeight());
+        _prevCellSize = cellSize;
+      }
+      _gridKey = _GridKey("$_uniqueToken $cellSize");
+      return MeasurableSliverStaggeredGrid.extentBuilder(
+        key: _gridKey,
+        maxCrossAxisExtent: widget.maxCrossAxisExtent,
+        itemCount: widget.itemCount,
+        itemBuilder: widget.itemBuilder,
+        staggeredTileBuilder: widget.staggeredTileBuilder,
+      );
+    });
+  }
+
+  @override
+  updateListHeight() {
+    double newMaxExtent;
+    try {
+      final renderObj = _gridKey.currentContext.findRenderObject()
+          as RenderMeasurableSliverStaggeredGrid;
+      final maxExtent = renderObj.calculateExtent();
+      _log.info("[updateListHeight] Max extent: $maxExtent");
+      if (maxExtent == 0) {
+        // ?
+        newMaxExtent = null;
+      } else {
+        newMaxExtent = maxExtent;
+      }
+    } catch (e, stacktrace) {
+      _log.shout("[updateListHeight] Failed while calculateMaxScrollExtent", e,
+          stacktrace);
+      newMaxExtent = null;
+    }
+
+    if (newMaxExtent != _maxExtent) {
+      _maxExtent = newMaxExtent;
+      widget.onMaxExtentChanged?.call(newMaxExtent);
+    }
+  }
+
+  double _prevListWidth;
+  double _prevCellSize;
+  double _maxExtent;
+  Orientation _prevOrientation;
+
+  // this unique token is there to keep the global key unique
+  final _uniqueToken = Uuid().v4();
+  GlobalObjectKey _gridKey;
+
+  static final _log =
+      Logger("widget.measurable_item_list._MeasurableItemListState");
+}
+
+class _GridKey extends GlobalObjectKey {
+  const _GridKey(Object value) : super(value);
+}

lib/widget/selectable_item_stream_list_mixin.dart

@@ -12,8 +12,7 @@ import 'package:nc_photos/platform/k.dart' as platform_k;
 import 'package:nc_photos/session_storage.dart';
 import 'package:nc_photos/snack_bar_manager.dart';
 import 'package:nc_photos/theme.dart';
-import 'package:nc_photos/widget/measureable_sliver_staggered_grid.dart';
-import 'package:uuid/uuid.dart';
+import 'package:nc_photos/widget/measurable_item_list.dart';
 
 abstract class SelectableItemStreamListItem {
   const SelectableItemStreamListItem({
@@ -29,36 +28,11 @@ abstract class SelectableItemStreamListItem {
   final StaggeredTile staggeredTile;
 }
 
-mixin SelectableItemStreamListMixin<T extends StatefulWidget>
-    on State<T>, WidgetsBindingObserver {
+mixin SelectableItemStreamListMixin<T extends StatefulWidget> on State<T> {
   @override
   initState() {
     super.initState();
     _keyboardFocus.requestFocus();
-
-    WidgetsBinding.instance.addPostFrameCallback((_) {
-      _prevOrientation = MediaQuery.of(context).orientation;
-      WidgetsBinding.instance.addObserver(this);
-    });
-  }
-
-  @override
-  dispose() {
-    WidgetsBinding.instance.removeObserver(this);
-    super.dispose();
-  }
-
-  @override
-  didChangeMetrics() {
-    WidgetsBinding.instance.addPostFrameCallback((_) {
-      final orientation = MediaQuery.of(context).orientation;
-      if (orientation != _prevOrientation) {
-        _log.info(
-            "[didChangeMetrics] updateListHeight: orientation changed: $orientation");
-        _prevOrientation = orientation;
-        updateListHeight();
-      }
-    });
   }
 
   @protected
@@ -82,20 +56,16 @@ mixin SelectableItemStreamListMixin<T extends StatefulWidget>
 
   @protected
   Widget buildItemStreamList(BuildContext context) {
-    // need to rebuild grid after cell size changed
-    final cellSize = itemStreamListCellSize;
-    if (cellSize != _prevItemStreamListCellSize) {
-      _log.info("[buildItemStreamList] updateListHeight: cell size changed");
-      WidgetsBinding.instance.addPostFrameCallback((_) => updateListHeight());
-      _prevItemStreamListCellSize = cellSize;
-    }
-    _gridKey = _GridKey("$_uniqueToken $cellSize");
-    return MeasurableSliverStaggeredGrid.extentBuilder(
-      key: _gridKey,
+    return MeasurableItemList(
+      key: _listKey,
       maxCrossAxisExtent: itemStreamListCellSize.toDouble(),
       itemCount: _items.length,
       itemBuilder: _buildItem,
       staggeredTileBuilder: (index) => _items[index].staggeredTile,
+      onMaxExtentChanged: (newExtent) {
+        _calculatedMaxExtent = newExtent;
+        onMaxExtentChanged(newExtent);
+      },
     );
   }
 
@@ -107,27 +77,6 @@ mixin SelectableItemStreamListMixin<T extends StatefulWidget>
     _selectedItems.clear();
   }
 
-  @protected
-  void updateListHeight() {
-    try {
-      final renderObj = _gridKey.currentContext.findRenderObject()
-          as RenderMeasurableSliverStaggeredGrid;
-      final maxExtent = renderObj.calculateExtent();
-      _log.info("[updateListHeight] Max extent: $maxExtent");
-      if (maxExtent == 0) {
-        // ?
-        _calculatedMaxExtent = null;
-      } else {
-        _calculatedMaxExtent = maxExtent;
-        onMaxExtentChanged(maxExtent);
-      }
-    } catch (e, stacktrace) {
-      _log.shout("[updateListHeight] Failed while calculateMaxScrollExtent", e,
-          stacktrace);
-      _calculatedMaxExtent = null;
-    }
-  }
-
   @protected
   bool get isSelectionMode => _selectedItems.isNotEmpty;
 
@@ -160,7 +109,8 @@ mixin SelectableItemStreamListMixin<T extends StatefulWidget>
     _lastSelectPosition = newLastSelectPosition;
 
     _log.info("[itemStreamListItems] updateListHeight: list item changed");
-    WidgetsBinding.instance.addPostFrameCallback((_) => updateListHeight());
+    WidgetsBinding.instance.addPostFrameCallback((_) =>
+        (_listKey.currentState as MeasurableItemListState)?.updateListHeight());
   }
 
   @protected
@@ -281,16 +231,12 @@ mixin SelectableItemStreamListMixin<T extends StatefulWidget>
 
   int _lastSelectPosition;
   bool _isRangeSelectionMode = false;
-  int _prevItemStreamListCellSize;
-  double _calculatedMaxExtent;
-  Orientation _prevOrientation;
 
   final _items = <SelectableItemStreamListItem>[];
   final _selectedItems = <SelectableItemStreamListItem>{};
 
-  // this unique token is there to keep the global key unique
-  final _uniqueToken = Uuid().v4();
-  GlobalObjectKey _gridKey;
+  final _listKey = GlobalKey();
+  double _calculatedMaxExtent;
 
   /// used to gain focus on web for keyboard support
   final _keyboardFocus = FocusNode();
@@ -299,10 +245,6 @@ mixin SelectableItemStreamListMixin<T extends StatefulWidget>
       "widget.selectable_item_stream_list_mixin.SelectableItemStreamListMixin");
 }
 
-class _GridKey extends GlobalObjectKey {
-  const _GridKey(Object value) : super(value);
-}
-
 class _SelectableItemWidget extends StatelessWidget {
   _SelectableItemWidget({
     Key key,