I use a ListView in a virtual mode. When the number of columns increases (>500) - drawing becomes too slow. To scroll hangs. Please tell me how to get rid of this problem and increase the performance of ListView?
Simple test project:
public partial class Form1 : Form
{
private const int maxLines = 1000000;//rows
private const int columns = 1024;
ListViewItem lvi = new ListViewItem();
public Form1()
{
InitializeComponent();
//ListView Properties
this.listView1.FullRowSelect = true;
this.listView1.GridLines = true;
this.listView1.MultiSelect = false;
this.listView1.Name = "listView1";
this.listView1.UseCompatibleStateImageBehavior = false;
this.listView1.View = System.Windows.Forms.View.Details;
this.listView1.RetrieveVirtualItem += new System.Windows.Forms.RetrieveVirtualItemEventHandler(this.listView1_RetrieveVirtualItem);
}
private void Form1_Load(object sender, EventArgs e)
{
listView1.VirtualMode = true;
listView1.VirtualListSize = maxLines;
PropertyInfo aProp = typeof(ListView).GetProperty("DoubleBuffered", BindingFlags.NonPublic | BindingFlags.Instance);
aProp.SetValue(listView1, true, null);
//create columns
for (int i = 0; i < columns; i++)
listView1.Columns.Add(i.ToString(), 40);
//create test data
for (int i = 0; i < columns; i++)
{
ListViewItem.ListViewSubItem lvsi = new ListViewItem.ListViewSubItem();
lvsi.Text = i.ToString();
lvi.SubItems.Add(lvsi);
}
}
//get item in virtual mode
private void listView1_RetrieveVirtualItem(object sender, RetrieveVirtualItemEventArgs e)
{
e.Item = lvi;
}
}
You need to use ownerdraw or customdraw to only draw visible columns. You can use HitTest to check what column is at the top left corner and start from there...