From 8c6da75b171b64e8a2026fcc3caf6a2e44f37787 Mon Sep 17 00:00:00 2001 From: Dan Walmsley Date: Mon, 4 Oct 2021 17:22:03 +0100 Subject: [PATCH] Merge pull request #6656 from AvaloniaUI/fixes/3429-scroll-gesture-virtualization Improve scroll gesture with virtualization. --- .../Presenters/ScrollContentPresenter.cs | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/src/Avalonia.Controls/Presenters/ScrollContentPresenter.cs b/src/Avalonia.Controls/Presenters/ScrollContentPresenter.cs index b0b52812b9..a62ba306ab 100644 --- a/src/Avalonia.Controls/Presenters/ScrollContentPresenter.cs +++ b/src/Avalonia.Controls/Presenters/ScrollContentPresenter.cs @@ -60,9 +60,6 @@ namespace Avalonia.Controls.Presenters o => o.Viewport, (o, v) => o.Viewport = v); - // Arbitrary chosen value, probably need to ask ILogicalScrollable - private const int LogicalScrollItemSize = 50; - private bool _canHorizontallyScroll; private bool _canVerticallyScroll; private bool _arranging; @@ -351,7 +348,8 @@ namespace Avalonia.Controls.Presenters if (Extent.Height > Viewport.Height || Extent.Width > Viewport.Width) { var scrollable = Child as ILogicalScrollable; - bool isLogical = scrollable?.IsLogicalScrollEnabled == true; + var isLogical = scrollable?.IsLogicalScrollEnabled == true; + var logicalScrollItemSize = new Vector(1, 1); double x = Offset.X; double y = Offset.Y; @@ -361,13 +359,18 @@ namespace Avalonia.Controls.Presenters _activeLogicalGestureScrolls?.TryGetValue(e.Id, out delta); delta += e.Delta; + if (isLogical && scrollable is object) + { + logicalScrollItemSize = Bounds.Size / scrollable.Viewport; + } + if (Extent.Height > Viewport.Height) { double dy; if (isLogical) { - var logicalUnits = delta.Y / LogicalScrollItemSize; - delta = delta.WithY(delta.Y - logicalUnits * LogicalScrollItemSize); + var logicalUnits = delta.Y / logicalScrollItemSize.Y; + delta = delta.WithY(delta.Y - logicalUnits * logicalScrollItemSize.Y); dy = logicalUnits * scrollable!.ScrollSize.Height; } else @@ -384,8 +387,8 @@ namespace Avalonia.Controls.Presenters double dx; if (isLogical) { - var logicalUnits = delta.X / LogicalScrollItemSize; - delta = delta.WithX(delta.X - logicalUnits * LogicalScrollItemSize); + var logicalUnits = delta.X / logicalScrollItemSize.X; + delta = delta.WithX(delta.X - logicalUnits * logicalScrollItemSize.X); dx = logicalUnits * scrollable!.ScrollSize.Width; } else