ListView VirtualMode 示例

using System;
using System.ComponentModel;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Diagnostics;

namespace ListViewVirtualMode
{
    public partial class Form1 : Form
    {
        private ListViewItem[] lvi;
        private ListView listView1;

        public Form1()
        {
            InitializeComponent();
        }

        void listView_RetrieveVirtualItem(object sender, RetrieveVirtualItemEventArgs e)
        {
            e.Item = lvi[e.ItemIndex];
        }

        void listView_DrawItem(object sender, DrawListViewItemEventArgs e)
        {
            e.DrawDefault = true;
            if (!e.Item.Checked)
            {
                e.Item.Checked = true;
                e.Item.Checked = false;
            }
        }

        void listView_MouseClick(object sender, MouseEventArgs e)
        {
            ListView lv = (ListView)sender;
            ListViewItem lvi = lv.GetItemAt(e.X, e.Y);
            if (lvi != null)
            {
                if (e.X < (lvi.Bounds.Left + 16))
                {
                    lvi.Checked = !lvi.Checked;
                    lv.Invalidate(lvi.Bounds);
                }
            }
        }

        void listView_MouseDoubleClick(object sender, MouseEventArgs e)
        {
            ListView lv = (ListView)sender;
            ListViewItem lvi = lv.GetItemAt(e.X, e.Y);
            if (lvi != null)
                lv.Invalidate(lvi.Bounds);
        }


        void SetupListview(bool blnVirtual)
        {
            // Get ListView working
            this.listView1 = new ListView();
            this.listView1.Dock = DockStyle.Fill;

            // This is what we want!!
            this.listView1.View = View.List;
            this.listView1.CheckBoxes = true;

            if (blnVirtual)
            {
                // This makes it real fast!!
                this.listView1.RetrieveVirtualItem +=
                    new RetrieveVirtualItemEventHandler(
                    listView_RetrieveVirtualItem);
                this.listView1.VirtualListSize = lvi.Length;
                this.listView1.VirtualMode = true;

                // This is what you need, for drawing unchecked checkboxes
                this.listView1.OwnerDraw = true;
                this.listView1.DrawItem +=
                    new DrawListViewItemEventHandler(listView_DrawItem);

                // Redraw when checked or doubleclicked
                this.listView1.MouseClick += new MouseEventHandler(listView_MouseClick);
                this.listView1.MouseDoubleClick += new MouseEventHandler(listView_MouseDoubleClick);
            }
            else
            {
                // The other way
                this.listView1.Items.AddRange(lvi);
            }

            // Show in main form
            this.Controls.Add(this.listView1);
        }

        private void Test()
        {
            // You can switch between Virtual and Normal
            bool blnVirtual = true;

            // Get the ListViewItem cache up and running
            int NR = 100000;

            lvi = new ListViewItem[NR];
            for (int intI = 0; intI < lvi.Length; intI++)
                lvi[intI] = new ListViewItem(intI + " test");

            // Check some random items, just for testing
            lvi[3].Checked = true;
            lvi[5].Checked = true;
            lvi[12].Checked = true;
            lvi[NR-2].Checked = true;


            Stopwatch stopwatch = new Stopwatch();
            stopwatch.Reset();
            stopwatch.Start();

            SetupListview(blnVirtual);

            stopwatch.Stop();
            this.Text = "ListView VirtualMode=" + blnVirtual + 
                " : "+ lvi.Length + " items in " + 
                stopwatch.ElapsedMilliseconds + " mS";
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            Test();           
        }

        private void button1_Click(object sender, EventArgs e)
        {
            StringBuilder sb = new StringBuilder();
            foreach (ListViewItem var in lvi)
            {
                if (var.Checked)
                {
                    sb.Append(var.Text);
                    sb.Append("\r\n");
                }
            }
            MessageBox.Show(sb.ToString());
        }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Diagnostics;

namespace ListViewVirtualMode
{
    public partial class Form2 : Form
    {
        private ListViewItem[] lvi;

        public Form2()
        {
            InitializeComponent();
        }

        void listView_RetrieveVirtualItem(object sender, RetrieveVirtualItemEventArgs e)
        {
            e.Item = lvi[e.ItemIndex];
        }

        private void Test()
        {
            int NR = 10000;

            lvi = new ListViewItem[NR];
            for (int intI = 0; intI < lvi.Length; intI++)
                lvi[intI] = new ListViewItem(new string[] { intI + " test1", intI + " test2" });

            listView1.RetrieveVirtualItem += new RetrieveVirtualItemEventHandler(listView_RetrieveVirtualItem);

            listView1.VirtualListSize = lvi.Length;
            listView1.VirtualMode = true;
        }

        private void Form2_Load(object sender, EventArgs e)
        {
            Test();
        }

        //更新
        private void button1_Click(object sender, EventArgs e)
        {
            int NR = 10000;

            lvi = new ListViewItem[NR];
            for (int intI = 0; intI < lvi.Length; intI++)
                lvi[intI] = new ListViewItem(new string[] { intI + " " + DateTime.Now.ToString(), intI + " " + DateTime.Now.ToString() });

            listView1.Visible = false;
            listView1.Visible = true;
        }        
    }
}

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