Tool: fix SelectFromList on large list

[jorisvandermeulen]

Tool: fix SelectFromList on large list

Description

On large lists (2200 items)

7seconds to 2seconds
3.5 faster / 71% faster

As described on forum
https://discourse.pyrevitlabs.io/t/faster-selectfromlist/8582

Checklist

Before submitting your pull request, ensure the following requirements are met:

• Code follows the PEP 8 style guide.
• Code has been formatted with Black using the command:

  pipenv run black {source_file_or_directory}

• Changes are tested and verified to work as expected.

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Related Issues

If applicable, link the issues resolved by this pull request:

• Related Guard stack issues in large list forms #1840 Issue #1840 #1852

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Thank you for contributing to pyRevit! 🎉

[devloai]

Automatic code review is enabled for this repository. Reviewing this PR now.

[devloai]

Great performance optimization using WPF virtualization! The changes look clean and effectively reduce rendering time for large lists by 71%. I've added one suggestion for fine-tuning the virtualization cache settings that could further improve scrolling smoothness.

@devloai optimize-virtualization - Let me know if you'd like me to implement the suggested virtualization cache settings.

[devloai]

Consider adding VirtualizingStackPanel.CacheLength and VirtualizingStackPanel.CacheLengthUnit properties to fine-tune the virtualization behavior. This can help balance between memory usage and scrolling performance. Here's the recommended configuration:

<ListView ...
          ItemsPanel="{DynamicResource ItemsPanelTemplate}"
          VirtualizingStackPanel.IsVirtualizing="True"
          VirtualizingStackPanel.VirtualizationMode="Recycling"
          VirtualizingStackPanel.CacheLength="5"
          VirtualizingStackPanel.CacheLengthUnit="Page"
          ScrollViewer.CanContentScroll="True"
          ... />

This will cache 5 pages worth of items, providing smoother scrolling while still maintaining good memory efficiency.

[jmcouffin]

@jorisvandermeulen can you check if this improves the performances?

[jorisvandermeulen]

I will check that.

I believe the default value for VirtualizingStackPanel.CacheLengthUnit is "Page" but obviously it's good to explicitly set the value.

The length default value is 1. So 1 'page' before / after is kept in memory. Increasing that value, increase the memory usage but smoother scrolling experience.

Let me get back to this.

[jorisvandermeulen]

No real time improvement. Smoother scrolling ... a little bit. Can't say I notice it right away.

Tested CacheLength 1, 2, 5 and even 10.
Json items tested: 2200
Time to load: "Function 'searchandload' executed in 0.960587 seconds." (click to popup show and manually click close as fast as possible).

So perhaps 2 is a good value.

<ListView x:Name="list_lb" Grid.Column="0" MouseDoubleClick="button_select" SelectionChanged="selected_item_changed" SelectionMode="Extended" HorizontalContentAlignment="Stretch" ScrollViewer.HorizontalScrollBarVisibility="Disabled" ItemTemplate="{DynamicResource ItemContainerTemplate}" ItemsPanel="{DynamicResource ItemsPanelTemplate}" VirtualizingStackPanel.IsVirtualizing="True" VirtualizingStackPanel.VirtualizationMode="Recycling" ScrollViewer.CanContentScroll="True" VirtualizingStackPanel.CacheLength="2" VirtualizingStackPanel.CacheLengthUnit="Page"/>

[jmcouffin]

@jorisvandermeulen ok, just say the word, then I'll merge the PR