Change SelectedItems to HashSet, add SelectMany method #50
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rdieske
suggested changes
Jan 23, 2025
| var newSelections = virtualListView?.SelectedItems ?? Array.Empty<ItemPosition>(); | ||
| ISet<ItemPosition> newSelections = virtualListView?.SelectedItems ?? new HashSet<ItemPosition>(); | ||
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| if (virtualListView.SelectionMode == SelectionMode.None) |
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I have a small refactoring suggestion, as i wonder if this needs to be checked for null as well? I Mean when virtualListView is null, it throws a NullReferenceException.
So in the current state when we have a virtualListView of null we have a new HashSet on Line 107 but cannot continue, as it should throw an exception on Line 109/111
Suggested change
| if (virtualListView.SelectionMode == SelectionMode.None) | |
| if (virtualListView?.SelectionMode == SelectionMode.None) |
| if (virtualListView.SelectionMode == SelectionMode.None) | ||
| newSelections = Array.Empty<ItemPosition>(); | ||
| newSelections = new HashSet<ItemPosition>(); | ||
| else if (virtualListView.SelectionMode == SelectionMode.Single && newSelections.Count > 1) |
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I see the same problem here
Suggested change
| else if (virtualListView.SelectionMode == SelectionMode.Single && newSelections.Count > 1) | |
| else if (virtualListView?.SelectionMode == SelectionMode.Single && newSelections.Count > 1) |
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I was noticing very poor performance when trying to implement a "Select All" button for lists of ~5000 elements. Refactoring SelectedItems to use a HashSet provides major performance improvements. Also added a SelectMany method that only updates the property once.