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Fix #5151 same as Microsoft

pull/5203/head
Mike Ward 5 years ago
parent
c85fa2b997
commit
eeb2745db5
1 changed files with 43 additions and 44 deletions
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  1. 87
      src/Avalonia.Layout/ElementManager.cs

87
src/Avalonia.Layout/ElementManager.cs
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@ -129,7 +129,7 @@ namespace Avalonia.Layout
{
for (int i = 0; i < count; i++)
{
// Clear from the edges so that ItemsRepeater can optimize on maintaining
// Clear from the edges so that ItemsRepeater can optimize on maintaining
// realized indices without walking through all the children every time.
int index = realizedIndex == 0 ? realizedIndex + i : (realizedIndex + count - 1) - i;
var elementRef = _realizedElements[index];
@ -212,7 +212,7 @@ namespace Avalonia.Layout
public ILayoutable GetRealizedElement(int dataIndex)
{
return IsVirtualizingContext ?
GetAt(GetRealizedRangeIndexFromDataIndex(dataIndex)) :
GetAt(GetRealizedRangeIndexFromDataIndex(dataIndex)) :
_context.GetOrCreateElementAt(
dataIndex,
ElementRealizationOptions.ForceCreate | ElementRealizationOptions.SuppressAutoRecycle);
@ -252,7 +252,6 @@ namespace Avalonia.Layout
(orientation == ScrollOrientation.Vertical ? ScrollOrientation.Horizontal : ScrollOrientation.Vertical) :
orientation;
var windowStart = effectiveOrientation == ScrollOrientation.Vertical ? window.Y : window.X;
var windowEnd = effectiveOrientation == ScrollOrientation.Vertical ? window.Y + window.Height : window.X + window.Width;
var firstElementStart = effectiveOrientation == ScrollOrientation.Vertical ? firstElementBounds.Y : firstElementBounds.X;
@ -273,53 +272,53 @@ namespace Avalonia.Layout
switch (args.Action)
{
case NotifyCollectionChangedAction.Add:
{
OnItemsAdded(args.NewStartingIndex, args.NewItems.Count);
}
break;
{
OnItemsAdded(args.NewStartingIndex, args.NewItems.Count);
}
break;
case NotifyCollectionChangedAction.Replace:
{
int oldSize = args.OldItems.Count;
int newSize = args.NewItems.Count;
int oldStartIndex = args.OldStartingIndex;
int newStartIndex = args.NewStartingIndex;
if (oldSize == newSize &&
oldStartIndex == newStartIndex &&
IsDataIndexRealized(oldStartIndex) &&
IsDataIndexRealized(oldStartIndex + oldSize -1))
{
// Straight up replace of n items within the realization window.
// Removing and adding might causes us to lose the anchor causing us
// to throw away all containers and start from scratch.
// Instead, we can just clear those items and set the element to
// null (sentinel) and let the next measure get new containers for them.
var startRealizedIndex = GetRealizedRangeIndexFromDataIndex(oldStartIndex);
for (int realizedIndex = startRealizedIndex; realizedIndex < startRealizedIndex + oldSize; realizedIndex++)
int oldSize = args.OldItems.Count;
int newSize = args.NewItems.Count;
int oldStartIndex = args.OldStartingIndex;
int newStartIndex = args.NewStartingIndex;
if (oldSize == newSize &&
oldStartIndex == newStartIndex &&
IsDataIndexRealized(oldStartIndex) &&
IsDataIndexRealized(oldStartIndex + oldSize - 1))
{
var elementRef = _realizedElements[realizedIndex];
if (elementRef != null)
// Straight up replace of n items within the realization window.
// Removing and adding might causes us to lose the anchor causing us
// to throw away all containers and start from scratch.
// Instead, we can just clear those items and set the element to
// null (sentinel) and let the next measure get new containers for them.
var startRealizedIndex = GetRealizedRangeIndexFromDataIndex(oldStartIndex);
for (int realizedIndex = startRealizedIndex; realizedIndex < startRealizedIndex + oldSize; realizedIndex++)
{
_context.RecycleElement(elementRef);
_realizedElements[realizedIndex] = null;
var elementRef = _realizedElements[realizedIndex];
if (elementRef != null)
{
_context.RecycleElement(elementRef);
_realizedElements[realizedIndex] = null;
}
}
}
else
{
OnItemsRemoved(oldStartIndex, oldSize);
OnItemsAdded(newStartIndex, newSize);
}
}
else
{
OnItemsRemoved(oldStartIndex, oldSize);
OnItemsAdded(newStartIndex, newSize);
}
}
break;
break;
case NotifyCollectionChangedAction.Remove:
{
OnItemsRemoved(args.OldStartingIndex, args.OldItems.Count);
}
break;
{
OnItemsRemoved(args.OldStartingIndex, args.OldItems.Count);
}
break;
case NotifyCollectionChangedAction.Reset:
ClearRealizedRange();
@ -376,7 +375,7 @@ namespace Avalonia.Layout
int backCutoffIndex = realizedRangeSize;
for (int i = 0;
i<realizedRangeSize &&
i < realizedRangeSize &&
!Intersects(window, _realizedElementLayoutBounds[i], orientation);
++i)
{
@ -391,7 +390,7 @@ namespace Avalonia.Layout
--backCutoffIndex;
}
if (backCutoffIndex<realizedRangeSize - 1)
if (backCutoffIndex < realizedRangeSize - 1)
{
ClearRealizedRange(backCutoffIndex + 1, realizedRangeSize - backCutoffIndex - 1);
}
@ -419,14 +418,14 @@ namespace Avalonia.Layout
// to insert items.
int lastRealizedDataIndex = _firstRealizedDataIndex + GetRealizedElementCount() - 1;
int newStartingIndex = index;
if (newStartingIndex > _firstRealizedDataIndex &&
if (newStartingIndex >= _firstRealizedDataIndex &&
newStartingIndex <= lastRealizedDataIndex)
{
// Inserted within the realized range
int insertRangeStartIndex = newStartingIndex - _firstRealizedDataIndex;
for (int i = 0; i < count; i++)
{
// Insert null (sentinel) here instead of an element, that way we dont
// Insert null (sentinel) here instead of an element, that way we dont
// end up creating a lot of elements only to be thrown out in the next layout.
int insertRangeIndex = insertRangeStartIndex + i;
int dataIndex = newStartingIndex + i;

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