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fix hang when margin is not a multiple of DPI rounding quantum (#5841) #6016

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Merged
merged 1 commit into from
Feb 7, 2022
Merged

fix hang when margin is not a multiple of DPI rounding quantum (#5841) #6016

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32 changes: 32 additions & 0 deletions src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Controls/ItemsControl.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3078,6 +3078,38 @@ internal static ElementViewportPosition GetElementViewportPosition(FrameworkElem
return ElementViewportPosition.None;
}

// this version also returns the element's layout rectangle (in viewport's coordinates).
// VirtualizingStackPanel needs this, to determine the element's scroll offset.
internal static ElementViewportPosition GetElementViewportPosition(FrameworkElement viewPort,
UIElement element,
FocusNavigationDirection axis,
bool fullyVisible,
bool ignorePerpendicularAxis,
out Rect elementRect,
out Rect layoutRect)
{
ElementViewportPosition position = GetElementViewportPosition(
viewPort,
element,
axis,
fullyVisible,
false,
out elementRect);

if (position == ElementViewportPosition.None)
{
layoutRect = Rect.Empty;
}
else
{
Visual parent = VisualTreeHelper.GetParent(element) as Visual;
Debug.Assert(element != viewPort && element.IsArrangeValid && parent != null, "GetElementViewportPosition called in unsupported situation");
layoutRect = CorrectCatastrophicCancellation(parent.TransformToAncestor(viewPort)).TransformBounds(element.PreviousArrangeRect);
}

return position;
}

// in large virtualized hierarchical lists (TreeView or grouping), the transform
// returned by element.TransformToAncestor(viewport) is vulnerable to catastrophic
// cancellation. If element is at the top of the viewport, but embedded in
Expand Down
49 changes: 31 additions & 18 deletions ...ft.DotNet.Wpf/src/PresentationFramework/System/Windows/Controls/VirtualizingStackPanel.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1189,6 +1189,7 @@ private FrameworkElement ComputeFirstContainerInViewport(
if (fe.IsVisible)
{
Rect elementRect;
Rect layoutRect;

// get the vp-position of the element, ignoring the secondary axis
// (DevDiv2 1136036, 1203626 show two different cases why we
Expand All @@ -1201,7 +1202,8 @@ private FrameworkElement ComputeFirstContainerInViewport(
direction,
false /*fullyVisible*/,
!isVSP45Compat /*ignorePerpendicularAxis*/,
out elementRect);
out elementRect,
out layoutRect);

if (elementPosition == ElementViewportPosition.PartiallyInViewport ||
elementPosition == ElementViewportPosition.CompletelyInViewport)
Expand Down Expand Up @@ -1287,20 +1289,35 @@ private FrameworkElement ComputeFirstContainerInViewport(
{
if (direction == FocusNavigationDirection.Down)
{
firstContainerOffsetFromViewport = elementRect.Y;
if (!isVSP45Compat)
{
firstContainerOffsetFromViewport -= fe.Margin.Top;
}
}
if (isVSP45Compat)
{
firstContainerOffsetFromViewport = elementRect.Y;
}
else
{
// include the leading margin in the offset. Simply subtracting
// the margin doesn't work when layout rounding is in effect, as
// we can't deduce how rounding affected the arrangement of the
// element and its margin. Instead, just use the layout rect directly.
firstContainerOffsetFromViewport = layoutRect.Top;
}
}
else // (direction == FocusNavigationDirection.Right)
{
firstContainerOffsetFromViewport = elementRect.X;
if (!isVSP45Compat)
{
firstContainerOffsetFromViewport -= fe.Margin.Left;
}
}

if (isVSP45Compat)
{
firstContainerOffsetFromViewport = elementRect.X;
}
else
{
// include the leading margin in the offset. Simply subtracting
// the margin doesn't work when layout rounding is in effect, as
// we can't deduce how rounding affected the arrangement of the
// element and its margin. Instead, just use the layout rect directly.
firstContainerOffsetFromViewport = layoutRect.Left;
}
}
}
else if (findTopContainer && isTopContainer)
{
Expand Down Expand Up @@ -1931,7 +1948,7 @@ public ScrollViewer ScrollOwner
}
set
{
if (_scrollData == null) EnsureScrollData();
EnsureScrollData();
if (value != _scrollData._scrollOwner)
{
ResetScrolling(this);
Expand Down Expand Up @@ -9510,10 +9527,6 @@ private int ItemCount
private void EnsureScrollData()
{
if (_scrollData == null) { _scrollData = new ScrollData(); }
else
{
Debug.Assert(_scrollData._scrollOwner != null, "Scrolling an unconnected VSP");
}
}

private static void ResetScrolling(VirtualizingStackPanel element)
Expand Down