// Called when an item is added to the items collection
void OnItemAdded(object item, int index)
{
if (_itemMap == null)
{
// reentrant call (from RemoveAllInternal) shouldn't happen,
// but if it does, don't crash
Debug.Assert(false, "unexpected reentrant call to OnItemAdded");
return;
}
ValidateAndCorrectIndex(item, ref index);
GeneratorPosition position = new GeneratorPosition(-1,0);
// find the block containing the new item
ItemBlock block = _itemMap.Next;
int offset = index;
while (block != _itemMap && offset >= block.ItemCount)
{
offset -= block.ItemCount;
position.Index += block.ContainerCount;
block = block.Next;
}
position.Offset = offset + 1;
// if it's an unrealized block, add the item by bumping the count
UnrealizedItemBlock uib = block as UnrealizedItemBlock;
if (uib != null)
{
MoveItems(uib, offset, 1, uib, offset+1, 0);
++ uib.ItemCount;
}
// if the item can be added to a previous unrealized block, do so
else if ((offset == 0 || block == _itemMap) &&
((uib = block.Prev as UnrealizedItemBlock) != null))
{
++ uib.ItemCount;
}
// otherwise, create a new unrealized block
else
{
uib = new UnrealizedItemBlock();
uib.ItemCount = 1;
// split the current realized block, if necessary
RealizedItemBlock rib;
if (offset > 0 && (rib = block as RealizedItemBlock) != null)
{
RealizedItemBlock newBlock = new RealizedItemBlock();
MoveItems(rib, offset, rib.ItemCount - offset, newBlock, 0, offset);
newBlock.InsertAfter(rib);
position.Index += block.ContainerCount;
position.Offset = 1;
block = newBlock;
}
uib.InsertBefore(block);
}
// tell generators what happened
if (MapChanged != null)
{
MapChanged(null, index, +1, uib, 0, 0);
}
// tell layout what happened
if (ItemsChanged != null)
{
ItemsChanged(this, new ItemsChangedEventArgs(NotifyCollectionChangedAction.Add, position, 1, 0));
}
}
void OnItemMoved(object item, int oldIndex, int newIndex)
{
if (_itemMap == null)
{
// reentrant call (from RemoveAllInternal) shouldn't happen,
// but if it does, don't crash
Debug.Assert(false, "unexpected reentrant call to OnItemMoved");
return;
}
DependencyObject container = null; // the corresponding container
int containerCount = 0;
UnrealizedItemBlock uib;
// search for the moved item
GeneratorPosition position;
ItemBlock block;
int offsetFromBlockStart;
int correctIndex;
GetBlockAndPosition(item, oldIndex, true, out position, out block, out offsetFromBlockStart, out correctIndex);
GeneratorPosition oldPosition = position;
RealizedItemBlock rib = block as RealizedItemBlock;
if (rib != null)
{
containerCount = 1;
container = rib.ContainerAt(offsetFromBlockStart);
}
// remove the item, and remove the block if it's now empty
MoveItems(block, offsetFromBlockStart + 1, block.ItemCount - offsetFromBlockStart - 1, block, offsetFromBlockStart, 0);
--block.ItemCount;
RemoveAndCoalesceBlocksIfNeeded(block);
//
// now insert into the new spot.
//
position = new GeneratorPosition(-1,0);
block = _itemMap.Next;
offsetFromBlockStart = newIndex;
while (block != _itemMap && offsetFromBlockStart >= block.ItemCount)
{
offsetFromBlockStart -= block.ItemCount;
if (block.ContainerCount > 0)
{
position.Index += block.ContainerCount;
position.Offset = 0;
}
else
{
position.Offset += block.ItemCount;
}
block = block.Next;
}
position.Offset += offsetFromBlockStart + 1;
// if it's an unrealized block, add the item by bumping the count
uib = block as UnrealizedItemBlock;
if (uib != null)
{
MoveItems(uib, offsetFromBlockStart, 1, uib, offsetFromBlockStart+1, 0);
++ uib.ItemCount;
}
// if the item can be added to a previous unrealized block, do so
else if ((offsetFromBlockStart == 0 || block == _itemMap) &&
((uib = block.Prev as UnrealizedItemBlock) != null))
{
++ uib.ItemCount;
}
// otherwise, create a new unrealized block
else
{
uib = new UnrealizedItemBlock();
uib.ItemCount = 1;
// split the current realized block, if necessary
if (offsetFromBlockStart > 0 && (rib = block as RealizedItemBlock) != null)
{
RealizedItemBlock newBlock = new RealizedItemBlock();
MoveItems(rib, offsetFromBlockStart, rib.ItemCount - offsetFromBlockStart, newBlock, 0, offsetFromBlockStart);
newBlock.InsertAfter(rib);
position.Index += block.ContainerCount;
position.Offset = 1;
offsetFromBlockStart = 0;
block = newBlock;
}
uib.InsertBefore(block);
}
DependencyObject parent = VisualTreeHelper.GetParentInternal(container);
// tell layout what happened
if (ItemsChanged != null)
{
ItemsChanged(this, new ItemsChangedEventArgs(NotifyCollectionChangedAction.Move, position, oldPosition, 1, containerCount));
}
// unhook the container. Do this after layout has (presumably) removed it from
// the UI, so that it doesn't inherit DataContext falsely.
if (container != null)
{
if (parent == null || VisualTreeHelper.GetParentInternal(container) != parent)
{
UnlinkContainerFromItem(container, item);
}
else
{
// If the container has the same visual parent as before then that means that
// the container was just repositioned within the parent's VisualCollection.
// we don't need to unlink the container, but we do need to re-realize the block.
Realize(uib, offsetFromBlockStart, item, container);
}
}
// fix up the AlternationIndex on containers affected by the move
if (_alternationCount > 0)
{
// start with the smaller of the two positions, and proceed forward.
// This tends to preserve the AlternatonIndex on containers at the
// front of the list, as users expect
int index = Math.Min(oldIndex, newIndex);
GetBlockAndPosition(index, out position, out block, out offsetFromBlockStart);
SetAlternationIndex(block, offsetFromBlockStart, GeneratorDirection.Forward);
}
}
// Called when an item is added to the items collection
void OnItemAdded(object item, int index)
{
ValidateAndCorrectIndex(item, ref index);
GeneratorPosition position = new GeneratorPosition(-1,0);
// find the block containing the new item
ItemBlock block = _itemMap.Next;
int offset = index;
while (block != _itemMap && offset >= block.ItemCount)
{
offset -= block.ItemCount;
position.Index += block.ContainerCount;
block = block.Next;
}
position.Offset = offset + 1;
// if it's an unrealized block, add the item by bumping the count
UnrealizedItemBlock uib = block as UnrealizedItemBlock;
if (uib != null)
{
MoveItems(uib, offset, 1, uib, offset+1, 0);
++ uib.ItemCount;
}
// if the item can be added to a previous unrealized block, do so
else if ((offset == 0 || block == _itemMap) &&
((uib = block.Prev as UnrealizedItemBlock) != null))
{
++ uib.ItemCount;
}
// otherwise, create a new unrealized block
else
{
uib = new UnrealizedItemBlock();
uib.ItemCount = 1;
// split the current realized block, if necessary
RealizedItemBlock rib;
if (offset > 0 && (rib = block as RealizedItemBlock) != null)
{
RealizedItemBlock newBlock = new RealizedItemBlock();
MoveItems(rib, offset, rib.ItemCount - offset, newBlock, 0, offset);
newBlock.InsertAfter(rib);
position.Index += block.ContainerCount;
position.Offset = 1;
block = newBlock;
}
uib.InsertBefore(block);
}
if (_traceLog != null)
_traceLog.Add("OnItemAdded {0} index = {1}", TraceLog.IdFor(item), index);
// tell generators what happened
if (MapChanged != null)
{
MapChanged(null, index, +1, null, 0, 0);
}
// tell layout what happened
if (ItemsChanged != null)
{
ItemsChanged(this, new ItemsChangedEventArgs(NotifyCollectionChangedAction.Add, position, 1, 0));
}
}
