private void OnItemMoved(object sender, ItemMovedEventArgs e)
{
BeginUpdate();
var stateTracker = new ListBoxStateTracker(this);
stateTracker.ApplyChange(ref e);
stateTracker.Restore(this);
EndUpdate();
// UNDONE: Do some ScrollWindowEx and ValidateRect optimizations here to avoid redrawing
// the whole tree. Make sure the TopIndex doesn't change and that there aren't pending redraws
// in optimized regions. This should be done along with the OnToggleExpansion optimizations
}
// Apply the index change to the selection array and other fields.
internal void ApplyChange(ref ItemMovedEventArgs e)
{
if (e.UpdateTrailingColumns ? restoreColumn < e.Column : restoreColumn != e.Column)
{
// Nothing to do
return;
}
// The required changes are broken into two adjacent ranges. One range shifts by +/-e.ItemCount,
// and the other shifts by e.ToRow-e.FromRow. For an item moving up, the first range is
// on top with a positive shift. For an item moving down, the first range is on the bottom
// with a negative shift.
int rangeTop; // The first item in the top range
int rangeMiddle; // The first item in the bottom range
int rangeBottom; // The first item not in either range
int topShift; // The shift for the top range
int bottomShift; // The shift for the bottom range
var fromRow = e.FromRow;
var toRow = e.ToRow;
var itemCount = e.ItemCount;
if (fromRow > toRow)
{
// Item is moving up
rangeTop = toRow;
rangeMiddle = fromRow;
rangeBottom = fromRow + itemCount;
topShift = itemCount;
bottomShift = toRow - fromRow;
}
else
{
// Item is moving down
rangeTop = fromRow;
rangeMiddle = fromRow + itemCount;
rangeBottom = toRow + 1;
topShift = toRow - fromRow;
bottomShift = -itemCount;
}
if (restoreSelection != null)
{
var upper = restoreSelection.GetUpperBound(0) + 1;
int testIndex;
for (var i = 0; i < upper; ++i)
{
testIndex = restoreSelection[i];
if (testIndex >= rangeTop)
{
if (testIndex < rangeMiddle)
{
restoreSelection[i] = testIndex + topShift;
}
else if (testIndex < rangeBottom)
{
restoreSelection[i] = testIndex + bottomShift;
}
}
}
}
if (restoreTop >= rangeTop)
{
if (restoreTop < rangeMiddle)
{
restoreTop += topShift;
}
else if (restoreTop < rangeBottom)
{
restoreTop += bottomShift;
}
}
if (restoreCaret >= rangeTop)
{
if (restoreCaret < rangeMiddle)
{
restoreCaret += topShift;
}
else if (restoreCaret < rangeBottom)
{
restoreCaret += bottomShift;
}
}
if (restoreAnchorIndex >= rangeTop)
{
if (restoreAnchorIndex < rangeMiddle)
{
restoreAnchorIndex += topShift;
}
else if (restoreAnchorIndex < rangeBottom)
{
restoreAnchorIndex += bottomShift;
}
}
}
