private void Form1_Load(object sender, EventArgs e)
{
listView.View = View.Details;
listView.VirtualMode = true;
listView.VirtualListSize = NorthwindDB.GetOrdersCount();
// Suspending automatic refreshes as items are added/removed.
listView.BeginUpdate();
listView.SmallImageList = imagesSmall;
listView.LargeImageList = imagesLarge;
// Add column headers for Details view.
listView.Columns.Add("ID", 100, HorizontalAlignment.Left);
listView.Columns.Add("ShippedDate", 100, HorizontalAlignment.Left);
// Re-enable the display.
listView.EndUpdate();
}
private void listView_RetrieveVirtualItem(object sender, RetrieveVirtualItemEventArgs e)
{
// Check if the item is in the local cache.
DataRow match = null;
if (dtCachedItems != null)
{
match = dtCachedItems.Rows.Find(e.ItemIndex + 1);
}
if (match == null)
{
// The item isn't in memory.
// Get a new range of 100 records.
int from, to;
if (e.ItemIndex < 50)
{
from = 0;
}
else
{
from = (e.ItemIndex - 50);
}
to = from + 100;
dtCachedItems = NorthwindDB.GetOrders(from, to);
// Don't use the MessageBox to show this information.
// Hiding any part of the ListView can retrigger this event.
lblStatus.Text = String.Format(
"Fetched rows from {0} to {1}.",
from.ToString(), to.ToString());
match = dtCachedItems.Rows.Find(e.ItemIndex + 1);
}
// Create the ListViewItem for the matching record.
e.Item = new ListViewItem(match["OrderID"].ToString());
e.Item.SubItems.Add(match["ShippedDate"].ToString());
}
