Gallery qualification: DataGridShowCase declares 65 DataGrid instances and 210 column declarations. Column reordering is available on the column header presenters, and the optimized path applies to drag and drop-location indicators clipped by frozen column regions during standard and grouped header reordering.
Operation frequency: column reordering indicator arrange/clip updates can run during pointer move, auto-scroll, horizontal scrolling, resizing, and grid relayout while a column is being dragged. Previously each clipped indicator update allocated a new RectangleGeometry.
Avalonia source basis: Visual.Clip is a styled property registered with AffectsRender, and InvalidateVisual marks the visual dirty (.referenceprojects/Avalonia/src/Avalonia.Base/Visual.cs:52-53,141-149,418-421,446-500). RectangleGeometry.Rect participates in geometry invalidation (.referenceprojects/Avalonia/src/Avalonia.Base/Media/RectangleGeometry.cs:25-33; .referenceprojects/Avalonia/src/Avalonia.Base/Media/Geometry.cs:146-172).
Benefit: repeated clipped column reordering indicator updates now reuse cached RectangleGeometry instances after first use, reducing repeated clip geometry allocation from 1/clipped indicator update to 0 after first while preserving Clip clearing when clipping is no longer needed or an indicator is replaced.
Verification: dotnet build -c Release -f net10.0 tools/performances/AtomUI.Performance/AtomUI.Performance.csproj; dotnet run -c Release -f net10.0 --no-build --project tools/performances/AtomUI.Performance/AtomUI.Performance.csproj -- --verify-datagrid-states; dotnet run -c Release -f net10.0 --no-build --project tools/performances/AtomUI.Performance/AtomUI.Performance.csproj -- --suite datagrid --count 100; git diff --check.
Gallery qualification: DataGridShowCase declares 65 DataGrid instances and 210 column declarations. Grouped header scenarios include DataGridColumnGroupItem leaves, and frozen-column examples use LeftFrozenColumnCount and RightFrozenColumnCount. The optimized path applies to grouped leaf DataGridHeaderViewItem instances that require clipping under frozen columns.
Operation frequency: group column header presenter arrange runs during initial layout, horizontal scrolling, resizing, column width changes, and grid relayout. Previously each clipped grouped leaf header arrange allocated a new RectangleGeometry.
Avalonia source basis: Visual.Clip is a styled property registered with AffectsRender, and InvalidateVisual marks the visual dirty (.referenceprojects/Avalonia/src/Avalonia.Base/Visual.cs:52-53,141-149,418-421,446-500). RectangleGeometry.Rect participates in geometry invalidation (.referenceprojects/Avalonia/src/Avalonia.Base/Media/RectangleGeometry.cs:25-33; .referenceprojects/Avalonia/src/Avalonia.Base/Media/Geometry.cs:146-172).
Benefit: repeated clipped group column header view item arrange now reuses one RectangleGeometry after first use, reducing repeated clip geometry allocation from 1/clipped grouped leaf header arrange to 0 after first while preserving Clip clearing when clipping is no longer needed.
Verification: dotnet build -c Release -f net10.0 tools/performances/AtomUI.Performance/AtomUI.Performance.csproj; dotnet run -c Release -f net10.0 --no-build --project tools/performances/AtomUI.Performance/AtomUI.Performance.csproj -- --verify-datagrid-states; dotnet run -c Release -f net10.0 --no-build --project tools/performances/AtomUI.Performance/AtomUI.Performance.csproj -- --suite datagrid --count 100; git diff --check.
Gallery qualification: DataGridShowCase declares 65 DataGrid instances and 210 column declarations, including multiple frozen-column examples with LeftFrozenColumnCount and RightFrozenColumnCount. The optimized path applies to realized DataGridColumnHeader instances that require clipping under frozen columns or header viewport constraints.
Operation frequency: column header presenter arrange runs during initial layout, horizontal scrolling, resizing, column width changes, and grid relayout. Previously each clipped header arrange allocated a new RectangleGeometry.
Avalonia source basis: Visual.Clip is a styled property registered with AffectsRender, and InvalidateVisual marks the visual dirty (.referenceprojects/Avalonia/src/Avalonia.Base/Visual.cs:52-53,141-149,418-421,446-500). RectangleGeometry.Rect participates in geometry invalidation (.referenceprojects/Avalonia/src/Avalonia.Base/Media/RectangleGeometry.cs:25-33; .referenceprojects/Avalonia/src/Avalonia.Base/Media/Geometry.cs:146-172).
Benefit: repeated clipped column header arrange now reuses one RectangleGeometry after first use, reducing repeated clip geometry allocation from 1/clipped header arrange to 0 after first while preserving Clip clearing when clipping is no longer needed.
Verification: dotnet build -c Release -f net10.0 tools/performances/AtomUI.Performance/AtomUI.Performance.csproj; dotnet run -c Release -f net10.0 --no-build --project tools/performances/AtomUI.Performance/AtomUI.Performance.csproj -- --verify-datagrid-states; dotnet run -c Release -f net10.0 --no-build --project tools/performances/AtomUI.Performance/AtomUI.Performance.csproj -- --suite datagrid --count 100; git diff --check.
Gallery qualification: DataGridShowCase declares 65 DataGrid instances, including multiple frozen-column examples with LeftFrozenColumnCount and RightFrozenColumnCount. The optimized path applies to realized DataGridCell instances that require clipping under frozen columns or horizontal virtualization.
Operation frequency: cells presenter arrange runs during initial layout, horizontal scrolling, resizing, column width changes, grid relayout, and row virtualization reuse. Previously each clipped cell arrange allocated a new RectangleGeometry.
Avalonia source basis: Visual.Clip is a styled property registered with AffectsRender, and InvalidateVisual marks the visual dirty (.referenceprojects/Avalonia/src/Avalonia.Base/Visual.cs:52-53,141-149,418-421,446-500). RectangleGeometry.Rect participates in geometry invalidation (.referenceprojects/Avalonia/src/Avalonia.Base/Media/RectangleGeometry.cs:25-33; .referenceprojects/Avalonia/src/Avalonia.Base/Media/Geometry.cs:146-172).
Benefit: repeated clipped cell arrange now reuses one RectangleGeometry after first use, reducing repeated clip geometry allocation from 1/clipped cell arrange to 0 after first while preserving Clip clearing when clipping is no longer needed.
Verification: dotnet build -c Release -f net10.0 tools/performances/AtomUI.Performance/AtomUI.Performance.csproj; dotnet run -c Release -f net10.0 --no-build --project tools/performances/AtomUI.Performance/AtomUI.Performance.csproj -- --verify-datagrid-states; dotnet run -c Release -f net10.0 --no-build --project tools/performances/AtomUI.Performance/AtomUI.Performance.csproj -- --suite datagrid --count 100; git diff --check.
Gallery qualification: DataGridShowCase declares 65 DataGrid instances; each realized DataGrid creates multiple DataGridRow instances, and every templated row owns one PART_BottomGridLine.
Operation frequency: DataGridRow.ArrangeOverride runs during page navigation layout, resizing, horizontal scrolling, row recycling, and grid relayout; the previous code allocated one RectangleGeometry for the bottom gridline on each realized row arrange.
Avalonia basis: Visual.Clip is a StyledProperty registered with AffectsRender and InvalidateVisual queues the visual for repaint (.referenceprojects/Avalonia/src/Avalonia.Base/Visual.cs:52-53,141-149,418-421). RectangleGeometry.RectProperty is registered with AffectsGeometry, so the reused geometry updates its platform geometry while this change explicitly invalidates the bottom gridline when Rect changes (.referenceprojects/Avalonia/src/Avalonia.Base/Media/RectangleGeometry.cs:25-33; .referenceprojects/Avalonia/src/Avalonia.Base/Media/Geometry.cs:146-172).
Verification: dotnet build -c Release -f net10.0 tools/performances/AtomUI.Performance/AtomUI.Performance.csproj; dotnet run -c Release -f net10.0 --no-build --project tools/performances/AtomUI.Performance/AtomUI.Performance.csproj -- --verify-datagrid-states; dotnet run -c Release -f net10.0 --no-build --project tools/performances/AtomUI.Performance/AtomUI.Performance.csproj -- --suite datagrid --count 100.
Gallery qualification: DataGridShowCase declares 65 DataGrid instances, and each realized DataGrid template owns one DataGridRowsPresenter.
Operation frequency: DataGridRowsPresenter.ArrangeOverride runs during page navigation layout, resizing, and scroll-triggered layout passes; the previous code allocated one RectangleGeometry per arrange.
Avalonia basis: Visual.Clip is a StyledProperty registered with AffectsRender and InvalidateVisual queues the visual for repaint (.referenceprojects/Avalonia/src/Avalonia.Base/Visual.cs:52-53,141-149,418-421). RectangleGeometry.RectProperty is registered with AffectsGeometry, so the reused geometry updates its platform geometry while this change explicitly invalidates the presenter when Rect changes (.referenceprojects/Avalonia/src/Avalonia.Base/Media/RectangleGeometry.cs:25-33; .referenceprojects/Avalonia/src/Avalonia.Base/Media/Geometry.cs:146-172).
Verification: dotnet build -c Release -f net10.0 tools/performances/AtomUI.Performance/AtomUI.Performance.csproj; dotnet run -c Release -f net10.0 --no-build --project tools/performances/AtomUI.Performance/AtomUI.Performance.csproj -- --verify-datagrid-states; dotnet run -c Release -f net10.0 --no-build --project tools/performances/AtomUI.Performance/AtomUI.Performance.csproj -- --suite datagrid --count 100.
Gallery qualification: DataGridShowCase declares 65 DataGrid instances, and each template creates one DataGridRowsPresenter. This removes one constructor-time local ScrollGesture routed subscription per rows presenter. Setup happens whenever a DataGrid template is realized; ScrollGesture runs when users scroll DataGrid rows with touchpad or gesture input.
Behavior: DataGridRowsPresenter now handles ScrollGesture through a class handler and still calls the existing OwningGrid.UpdateScroll(-e.Delta) path. State verification confirms no local ScrollGesture handler remains, the gesture is still marked handled when scrolling occurs, and VerticalOffset still changes.
Documentation: updates the DataGrid performance notes and roadmap, and adds the performance-skill rule that every optimization completion must proactively report benefit in a table with baseline, optimized, formula, improvement, and conclusion.
Avalonia basis: ScrollGestureEvent is a bubble routed event. Event adders call AddHandler and store local routed subscriptions in Interactive._eventHandlers, while AddClassHandler subscribes once through RoutedEvent.Raised and filters by route/type.
Sources: .referenceprojects/Avalonia/src/Avalonia.Base/Input/InputElement.Gestures.cs:65-69; .referenceprojects/Avalonia/src/Avalonia.Base/Input/InputElement.Gestures.cs:197-200; .referenceprojects/Avalonia/src/Avalonia.Base/Interactivity/Interactive.cs:30-64; .referenceprojects/Avalonia/src/Avalonia.Base/Interactivity/Interactive.cs:176-190; .referenceprojects/Avalonia/src/Avalonia.Base/Interactivity/RoutedEvent.cs:78-99.
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