public void Clear()
{
if (owner.itemCount <= 0)
{
return;
}
owner.ApplyUpdateCachedItems();
if (owner.IsHandleCreated && !owner.ListViewHandleDestroyed)
{
// Walk the items to see which ones are selected.
// We use the LVM_GETNEXTITEM message to see what the next selected item is
// so we can avoid checking selection for each one.
int count = owner.Items.Count;
int nextSelected = (int)User32.SendMessageW(owner, (User32.WM)LVM.GETNEXTITEM, -1, (nint)LVNI.SELECTED);
for (int i = 0; i < count; i++)
{
ListViewItem item = owner.Items[i];
Debug.Assert(item is not null, $"Failed to get item at index {i}");
if (item is not null)
{
// If it's the one we're looking for, ask for the next one.
if (i == nextSelected)
{
item.StateSelected = true;
nextSelected = (int)User32.SendMessageW(owner, (User32.WM)LVM.GETNEXTITEM, nextSelected, (nint)LVNI.SELECTED);
}
else
{
// Otherwise it's false.
item.StateSelected = false;
}
item.UnHost(i, false);
}
}
Debug.Assert(owner.listItemsArray is null, "listItemsArray not null, even though handle created");
User32.SendMessageW(owner, (User32.WM)LVM.DELETEALLITEMS);
// There's a problem in the list view that if it's in small icon, it won't pick upo the small icon
// sizes until it changes from large icon, so we flip it twice here...
if (owner.View == View.SmallIcon)
{
if (Application.ComCtlSupportsVisualStyles)
{
owner.FlipViewToLargeIconAndSmallIcon = true;
}
else
{
Debug.Assert(!owner.FlipViewToLargeIconAndSmallIcon, "we only set this when comctl 6.0 is loaded");
owner.View = View.LargeIcon;
owner.View = View.SmallIcon;
}
}
}
else
{
int count = owner.Items.Count;
for (int i = 0; i < count; i++)
{
ListViewItem item = owner.Items[i];
if (item is not null)
{
item.UnHost(i, true);
}
}
Debug.Assert(owner.listItemsArray is not null, "listItemsArray is null, but the handle isn't created");
owner.listItemsArray.Clear();
}
owner.listItemsTable.Clear();
if (owner.IsHandleCreated && !owner.CheckBoxes)
{
owner.savedCheckedItems = null;
}
owner.itemCount = 0;
if (owner.ExpectingMouseUp)
{
owner.ItemCollectionChangedInMouseDown = true;
}
}
