ypresto/recyclerview-absolutelayoutmanager

Implement RecyclerView custom layout as easy as UICollectionViewLayout.

ypresto 💻👶🧑‍🍳🌈

I'm full stack software engineer and designer with 10+ years experience, especially focused on frontend development.

• 🌏 Web Frontend: 10+ years (React, Vue 1.x)
• 📱 Android/iOS: 4+ years
• ⚙️ Backend: 7+ years
• 🎨 UX Design: 3+ years
• 🏠 Remote Work: 5+ years

Works

• 入りやすい保育園マップ (nursery school map visualizes admission difficulty) which is a finalist of OpenData Hackathon held by Tokyo Metropolitan Government. With @sagaraya.
• See pinned repo and Qiita.

Notable OSS Contributions

• Currently I'm working on TypeScript Compiler and MUI type check performance. mui/material-ui#27381
• 10x speed up on slow path in TypeScript type checker, affects MUI and emotion. microsoft/TypeScript#45195
• Reported a bug in Xamarin.Forms which caused possible data-loss in COCOA (COVID-19 Contact-Confirming Application). xamarin/Xamarin.Forms#13676
• Fix performance issue in Node.js child_process, improved 2x-4x nodejs/node#10557
• Added RuboCop rules to check unexpected return in interator rubocop/rubocop#1728
• See public pull requests.
• Notable StackOverflow answer: "JavaScript: How come map.has is so much faster than set.has and array.indexOf?" (dive into V8 code) https://stackoverflow.com/a/69338420/1474113

recyclerview-absolutelayoutmanager's Issues

Occasionally crashes on onSaveInstanceState()

Currently onSaveInstanceState() returns empty state if getItemCount() == 0.
But we face crashes caused by out-of-sync state of LayoutProvider: LayoutProvider.mState.mItemCount == 0 while getItemCount() > 0.

Fatal Exception: java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
       at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
       at java.util.ArrayList.get(ArrayList.java:308)
       at us.mitene.app.album.ui.AlbumThumbnailLayoutProvider.getLayoutAttributeForItemAtPosition(Unknown Source:144)
       at net.ypresto.recyclerview.absolutelayoutmanager.AbsoluteLayoutManager.net.ypresto.recyclerview.absolutelayoutmanager.AnchorHelper.calculateAnchorItemInRect(Unknown Source:17041)
       at us.mitene.app.album.ui.MonthlyAlbumFragment.onSaveInstanceState(Unknown Source:205)

onItemsChanged() or its family methods are lazy fired inside of dispatchLayout(). This can cause out-of-sync with following step:

1. Change adapter content and call notifyDataSetChanged() or etc.
2. Call prepareLayoutProvider() from onSaveInstanceState() but no update is performed.
3. onItemsChanged() is called from dispatchLayout() and mIsLayoutProviderDirty is set to true.
4. prepareLayoutProvider() is called from onLayoutChildren() and provider state is updated at last.

scrollToPositionWithAlignment() does not call awakenScrollBars()

So scroll bars are not shown when it is called, while they are shown when scrollToPosition() is called.
This is because awakenScrollBars() is protected and creating subclass of RecyclerView (or reflection) is required.
If you need this feature vote by reaction.

Check if current impl does handle item change

Currently relying on state.didStructureChange(), not using RecyclerView.AdapterDataObserver.
I'm not sure whether this value is true or not when item is ONLY changed, not added or removed.

Also didStructureChange() defined as "changed since last onLayoutChidlren() call", so checking it from smoothScrollToPostion() might not be good.

RecyclerView-AbsoluteLayoutManager/lib/src/main/java/net/ypresto/recyclerview/absolutelayoutmanager/AbsoluteLayoutManager.java

Line 449 in c6fe51c

prepareLayoutProvider(state);

Changing layout manager might reset scroll position

Add document for supporting auto inflate

In RecyclerView documentation:

If the LayoutManager specifies a default constructor or one with the signature (Context, AttributeSet, int, int), RecyclerView will instantiate and set the LayoutManager when being inflated.

Creating subclass of AbsoluteLayoutManager and implement LayoutProvider, then super(this) (is it possible!?) enables this.

Keep scroll position by anchoring view

This library does not keep current visible cell after layout change.
Currently it scrolls to absolute x and y position of previous layout instead.
To reproduce: change screen orientation on example app.