Split from #6827.

Migrating Widgets and Example Apps

Will start with the following widgets (in order of priority):

• Scrollables (e.g. ListView, PageView, etc), PR: Make Scrollables restorable #63131
  • ListWheelScrollView
  • NestedScrollView
  • PageView
  • ScrollView
  • CustomScrollView
  • BoxScrollView
  • ListView
  • GridView
  • Scrollable
  • SingleChildScrollView
• Textfields, PR: Make textfields restorable #63401
  • CupertinoTextField
  • TextField
  • EditableText (uses a Scrollable)
• Navigator, PR: Make Navigator restorable (inkl. WidgetsApp, MaterialApp, CupertinoApp) #65658
• Root-level app widgets, PR: Make Navigator restorable (inkl. WidgetsApp, MaterialApp, CupertinoApp) #65658
  • WidgetsApp
  • CupertinoApp
  • MaterialApp
• Migrate Veggie Seasons App (required for State Restoration support for Veggie Seasons app samples#433)
  • CupertinoTabView, PR: Make CupertinoTabView restorable #67169
  • CupertinoTabScaffold, PR: Make CupertinoTabScaffold restorable #67770
• Widgets for the Flutter Gallery app to make the app restorable
  • [Reply] State restorable pages, PR: [State Restoration] [Reply] Partially State Restorable Pages gallery#368, OpenContainer not supported
  • Gallery Demo Pages, PR: [State Restoration] Restorable Material Code Samples - Part 1/3 gallery#378, [State Restoration] Restorable Material Code Samples - Part 2/3 gallery#379, [State Restoration] Restorable Material Code Samples - Part 3/3 gallery#382, [State Restoration] Material Dialogs, Cupertino Dialogs, CupertinoTabScaffold/TabView, CupertinoTextFields gallery#409, [State Restoration] Cupertino Widgets gallery#408
    • RestorableBoolN for Checkbox: PR - [State Restoration] RestorableBoolN #71653, [State Restoration] Use RestorableBoolN for checkbox tristate gallery#388
    • TextFormField/Form: [State Restoration] DatePicker, DateRangePicker, TextFormField gallery#476
    • Dialog/Pickers: [State Restoration] showDialog/showGeneralDialog not state restorable #70918, [State Restoration] DatePicker, DateRangePicker, TextFormField gallery#476
    • DataTable (selected row count data): [State Restoration] DataTable selected index/counts #70916
    • Drawer/endDrawer: [State Restoration] Drawer not restorable #70925
  • Other mini apps:
    • Shrine: [State Restoration] Shrine gallery#389
    • Fortnightly: [State Restoration] Fortnightly app gallery#390
    • Rally: [State Restoration] Rally gallery#394, OpenContainer not supported
    • Crane: [State Restoration] Crane app gallery#392, StaggeredGridView not state restorable yet
      • StaggeredGridView: Add support for state restoration letsar/flutter_staggered_grid_view#148, [State Restoration] Upgrade to use restorable StaggeredGridView gallery#396
    • Starter: [State Restoration] Starter app gallery#391, Drawer is not state restorable yet

Could be simpler:

• FloatingActionButton contains constants for different configurations, but it's not an enum so it's not easily accessible for state restoration unless a List/Map of some sort from String/int index-to-location is created.

Documentation

• Hot reload/restart doesn't work with state restoration

Integration with other platforms

• enable state restoration for iOS (Enable State Restoration in iOS embedder #62915)

Punted:

• integrate state restoration with Nav 2.0 for the web (see also Navigator 2.0 Remaining Work #65776)
  • may require [web] implement PluginUtilities for flutter web #33615
• PageStorage (used by some Scrollables to retain page state): [State Restoration] PageStorage #70520
• Support state restoration for OpenContainer in animations package: [animations] OpenContainer does not support state restoration #69924
• BottomSheet: [State Restoration] Bottom Sheet #70915
• Time Picker: [State Restoration] Material Time Picker #80564