[Epic] Wasm/Skia ListView improvements

[jeromelaban]

I'm submitting a...

• Feature request

Current behavior

Current ListView implementation for WebAssembly/Skia/macOS is not at feature parity with iOS/Android/UWP:

• Custom Panels
• Basic Virtualization
• Header and Footer
• ItemsWrapGrid (GridView) - Support for ItemsWrapGrid #468
• Grouping
• Sticky Headers
• ScrollIntoView()
• Insert/delete/replace items with animation
• Snap points
• Incremental loading support ([wasm/skia.gtk/macOS] ISupportIncrementalLoading support #5763)

More to be added in this list.

Expected behavior

Support more features.

Affected platform(s):

• WebAssembly

[dr1rrb]

Note: Items not always appearing when scrolling seems to be fixed with this commit.

Scrolling offsets was parsed as int while we usually get double. This was causing the managed ScrollViewer to think that it was at the top, while the native was actually much lower.

The fix is in the 'iosTouches' feature branch, I'll merge it in master soon.

[ritt-app]

Hi there! Is there any approximate timeline for the implementation of virtualization for Gridview (i.e. support for ItemsWrapGrid) for Skia? I tried to create a simple grid of a few thousand items, and it nearly crashed my machine due to the lack of virtualization. For me, this is the final roadblock preventing me from adopting Uno!

[jeromelaban]

@ritt-app you may want to try the ItemsRepeater instead, it also supports virtualization.

[ritt-app]

@jeromelaban Thanks for the prompt reply. While it is possible, I would have to recreate UI features like selection and grouping with ItemsRepeater, while not benefitting from customization since I just need a standard GridView experience.

Anyway, I just wanted to thank you and Uno team for creating such an amazing product!

[jeromelaban]

Thanks for your kind words!

Grouping would have to be done manually, we offer an ItemsRepeater selection behavior in the uno toolkit, which may help. For grouping, indeed it's not there by default. It could be that community members have implemented parts of it.

[HakanL]

@ritt-app I was in a similar situation, I needed grouping and I was using the ListView. I ended up using the ItemsRepeater, yes it was some work to refactor the UI code, but in the end it works really well and I was able to implement the header (grouping) I needed as well.

[ritt-app]

@jeromelaban @HakanL Thanks for the advice! I will look more into ItemsRepeater and uno toolkit.