Actually the loadMoreAssets method didn't called multiple times.

I/flutter (25101): Loading more assets with page 1: 2021-05-11 11:59:40.085985
I/flutter (25101): Loading more assets with page 2: 2021-05-11 11:59:42.464812
I/flutter (25101): Loading more assets with page 3: 2021-05-11 11:59:44.597433
I/flutter (25101): Loading more assets with page 4: 2021-05-11 11:59:47.431908
I/flutter (25101): Loading more assets with page 5: 2021-05-11 11:59:49.276166
I/flutter (25101): Loading more assets with page 6: 2021-05-11 11:59:52.039088

Testing

Looks good.
In term of performance, it is better to use SliverGrid instead of GridView.builder.
The reason for that is that when the grid has to repaint itself, you can "teach" the SliverGrid how to find the elements from the previously painted grid using findChildIndexCallback. That cannot be done in the case of GridView.builder (which is specific implementation of SliverGrid).

See:
https://stackoverflow.com/a/58991316/6535274

https://medium.com/flutter/slivers-demystified-6ff68ab0296f

Picker is broken now:

══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
The following assertion was thrown building Selector<DefaultAssetPickerProvider, bool>(dirty,
dependencies: [_InheritedProviderScope], state:
_Selector0State#ce087(value: true)):
Tried to use context.select outside of the build method of a widget.

Any usage other than inside the build method of a widget are not supported.
'package:provider/src/inherited_provider.dart':
Failed assertion: line 246 pos 12: 'widget is LayoutBuilder || debugDoingBuild'

The relevant error-causing widget was:
Selector<DefaultAssetPickerProvider, bool>
file:https:///C:/dev/12Tech12/git/pull-requests/12Tech12/flutter_wechat_assets_picker/lib/src/delegates/asset_picker_builder_delegate.dart:520:13

When the exception was thrown, this was the stack:
#2      SelectContext.select (package:provider/src/inherited_provider.dart:246:12)
#3      DefaultAssetPickerBuilderDelegate.pathEntityListWidget (package:wechat_assets_picker/src/delegates/asset_picker_builder_delegate.dart:917:17)
#4      DefaultAssetPickerBuilderDelegate.androidLayout.<anonymous closure> (package:wechat_assets_picker/src/delegates/asset_picker_builder_delegate.dart:542:23)
#5      _Selector0State.buildWithChild (package:provider/src/selector.dart:85:29)
#6      SingleChildState.build (package:nested/nested.dart:317:41)
#7      StatefulElement.build (package:flutter/src/widgets/framework.dart:4612:27)
#8      SingleChildStatefulElement.build (package:nested/nested.dart:339:18)
#9      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4495:15)
#10     StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4667:11)
#11     Element.rebuild (package:flutter/src/widgets/framework.dart:4189:5)
#12     BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2694:33)
#13     WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:873:21)
#14     RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:319:5)
#15     SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1144:15)
#16     SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1082:9)
#17     SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:998:5)
#21     _invoke (dart:ui/hooks.dart:161:10)
#22     PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:253:5)
#23     _drawFrame (dart:ui/hooks.dart:120:31)
(elided 5 frames from class _AssertionError and dart:async)

Take another look.

I am constantly checking :-)

While performance is better scrolling down (due to findChildIndexCallback), there is now an issue when scrolling up (that did NOT exist with GridView.builder).
Scrolling up shows black grid items for a moment.

I am constantly checking :-)

While performance is better scrolling down (due to findChildIndexCallback), there is now an issue when scrolling up (that did NOT exist with GridView.builder).
Scrolling up shows black grid items for a moment.

It should be, otherwise items are still keepalive which makes Flutter unable to release memory cost for those images.

It should be, otherwise items are still keepalive which makes Flutter unable to release memory cost for those images.

But addAutomaticKeepAlives default to true, shouldn't that do the trick?

In any case I think this is worse in term of user experience, previous experience was better.

Maybe there an option to extend the preloading of items?

previous experience was better.

"Previous" only indicates the commit in this PR. Originally it does act like that too. The automatic keepalives flag isn't the same thing as a Widget does itself.

Correct, that is what I meant. Previous = after the split.

Going deeper, it's some GC trick that came from extended_image. So for now I would not recommend to commit that behavior.

I agree, better go back to GridView.builder.

Sorry for that...

I mean we keep this since we can ensure that it won't cost more memory consumption.

The tradeoff of optimize memory save optimize speed will always be there.
Is there some way to preload the assets in the SliverGrid case so that it will be less visible to the user?

Have you registered with Discord? You can add me Alex Li (AlexV525)#3670 then we can discuss about this.

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