ARTICLE

Imlememnting Drag and Drop in ListView Controls

Posted by Shripad Kulkarni Articles | Windows Forms C# July 08, 2002
Drag and Drop operations in Windows can be achieved using 3 simple events - DragEnter, DragLeave, and DragDrop.
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Drag and Drop operations in Windows can be achieved using 3 simple events - DragEnter, DragLeave, and DragDrop. The example provided in this articles shows you how to drag and drop items from one ListView control to another.

Important: If you plan to cut and paste the source code from this article , please make sure to set the AllowDrop option to True in the properties for the listView control.

Drag Data

Begin the Drag operation using

listView2.DoDragDrop(str, DragDropEffects.Copy | DragDropEffects.Move );

in this case the the drag is set to either copy or move. The example works by dragging a text object.

However any type of object can be used for dragging.

Drop Data

Use the DragEnter function to perform the type of drop operation.

private void listView1_DragEnter(object sender,System.Windows.Forms.DragEventArgs e)
{
if(e.Data.GetDataPresent(DataFormats.Text))
e.Effect = DragDropEffects.Copy;
else
e.Effect = DragDropEffects.None;
}
private void listView1_DragEnter(object sender,System.Windows.Forms.DragEventArgs e)
{
if (e.Data.GetDataPresent(DataFormats.Text))
e.Effect = DragDropEffects.Copy;
else
e.Effect = DragDropEffects.None;
}

In this case the effects are either copy or none.

Here is the complete listing of the DragDrop Class

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
namespace ODLV
{
///
/// Summary description for Form1.
///
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.ListView listView1;
private System.Windows.Forms.Splitter splitter1;
private System.Windows.Forms.ListView listView2;
private System.Windows.Forms.ColumnHeader columnHeader1;
private System.Windows.Forms.ColumnHeader columnHeader2;
///
/// Required designer variable.
///
private System.ComponentModel.Container components = null;
bool lv1_mdown = false ;
private System.Windows.Forms.ColumnHeader columnHeader3;
private System.Windows.Forms.ColumnHeader columnHeader5;
bool lv2_mdown = false;
public Form1()
{
//
// Required for Windows Form Designer support
//
InitializeComponent();
//
// TODO: Add any constructor code after InitializeComponent call
//
}
///
/// Clean up any resources being used.
///
protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}
#region Windows Form Designer generated code
///
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
///
private void InitializeComponent()
{
this.listView1 = new System.Windows.Forms.ListView();
this.columnHeader1 = new System.Windows.Forms.ColumnHeader();
this.columnHeader3 = new System.Windows.Forms.ColumnHeader();
this.splitter1 = new System.Windows.Forms.Splitter();
this.listView2 = new System.Windows.Forms.ListView();
this.columnHeader2 = new System.Windows.Forms.ColumnHeader();
this.columnHeader5 = new System.Windows.Forms.ColumnHeader();
this.SuspendLayout();
//
// listView1
//
this.listView1.AllowDrop = true;
this.listView1.Columns.AddRange(new System.Windows.Forms.ColumnHeader[] {
this.columnHeader1,this.columnHeader3});
this.listView1.Dock = System.Windows.Forms.DockStyle.Top;
this.listView1.FullRowSelect = true;
this.listView1.MultiSelect = false;
this.listView1.Name = "listView1";
this.listView1.Size = new System.Drawing.Size(232, 176);
this.listView1.TabIndex = 0;
this.listView1.View = System.Windows.Forms.View.Details;
this.listView1.MouseDown += new System.Windows.Forms.MouseEventHandler(this.listView1_MouseDown);
this.listView1.DragDrop += new System.Windows.Forms.DragEventHandler(this.listView1_DragDrop);
this.listView1.DragEnter += new System.Windows.Forms.DragEventHandler(this.listView1_DragEnter);
this.listView1.MouseMove += new System.Windows.Forms.MouseEventHandler(this.listView1_MouseMove);
//
// columnHeader1
//
this.columnHeader1.Text = "COL1";
this.columnHeader1.Width = 100;
//
// columnHeader3
//
this.columnHeader3.Text = "COL2";
this.columnHeader3.Width = 100;
//
// splitter1
//
this.splitter1.Dock = System.Windows.Forms.DockStyle.Top;
this.splitter1.Location = new System.Drawing.Point(0, 176);
this.splitter1.Name = "splitter1";
this.splitter1.Size = new System.Drawing.Size(232, 3);
this.splitter1.TabIndex = 1;
this.splitter1.TabStop = false;
//
// listView2
//
this.listView2.AllowDrop = true;
this.listView2.Columns.AddRange(new System.Windows.Forms.ColumnHeader[]
{
this.columnHeader2,this.columnHeader5});
this.listView2.Cursor = System.Windows.Forms.Cursors.Arrow;
this.listView2.Dock = System.Windows.Forms.DockStyle.Fill;
this.listView2.FullRowSelect = true;
this.listView2.Location = new System.Drawing.Point(0, 179);
this.listView2.MultiSelect = false;
this.listView2.Name = "listView2";
this.listView2.Size = new System.Drawing.Size(232, 226);
this.listView2.TabIndex = 2;
this.listView2.View = System.Windows.Forms.View.Details;
this.listView2.MouseDown += new System.Windows.Forms.MouseEventHandler(this.listView2_MouseDown);
this.listView2.DragDrop += new System.Windows.Forms.DragEventHandler(this.listView2_DragDrop);
this.listView2.DragEnter = new System.Windows.Forms.DragEventHandler(this.listView2_DragEnter);
this.listView2.MouseMove += new System.Windows.Forms.MouseEventHandler(this.listView2_MouseMove);
//
// columnHeader2
//
this.columnHeader2.Text = "COL1";
this.columnHeader2.Width = 100;
//
// columnHeader5
//
this.columnHeader5.Text = "COL2";
this.columnHeader5.Width = 100;
//
// Form1
//
this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
this.ClientSize = new System.Drawing.Size(232, 405);
this.Controls.AddRange(new System.Windows.Forms.Control[] {this.listView2,this.splitter1,this.listView1});
this.Name = "Form1";
this.Text = "Form1";
this.Load += new System.EventHandler(this.Form1_Load);
this.ResumeLayout(false);
}

#endregion
///
/// The main entry point for the application.
///
[STAThread]
static void Main()
{
Application.Run(new Form1());
}
private void Form1_Load(object sender, System.EventArgs e)
{
ImageList il = new ImageList();
il.Images.Add(
new System.Drawing.Icon("D:\\smk\\odlv\\tick.ico"));
listView1.SmallImageList = il ;
ImageList i2 =
new ImageList();
i2.Images.Add(
new System.Drawing.Icon("D:\\smk\\odlv\\key04.ico"));
listView2.SmallImageList = i2 ;
string[] items = new string[2];
items[0] = "LA" ; items[1] = "Los Angeles";
listView1.Items.Add(
new ListViewItem(items,0));
items[0] = "WA" ; items[1] = "Seattle";
listView1.Items.Add(
new ListViewItem(items,0));
items[0] = "IL" ; items[1] = "Chicago";
listView1.Items.Add(
new ListViewItem(items,0));
items[0] = "FR" ; items[1] = "Paris";
listView2.Items.Add(
new ListViewItem(items,0));
items[0] = "BR" ; items[1] = "London";
listView2.Items.Add(
new ListViewItem(items,0));
items[0] = "IN" ; items[1] = "Mumbai";
listView2.Items.Add(
new ListViewItem(items,0));
}
private void listView1_DragDrop(object sender,System.Windows.Forms.DragEventArgs e)
{
string textBox1 = e.Data.GetData(DataFormats.Text).ToString();
string[] items = textBox1.Split(',');
listView1.Items.Add(
new ListViewItem(items,0));
lv1_mdown =
false ;
lv2_mdown =
false ;
}
private void listView2_DragDrop(object sender,System.Windows.Forms.DragEventArgs e)
{
string textBox1 = e.Data.GetData(DataFormats.Text).ToString();
string[] items = textBox1.Split(',');
listView2.Items.Add(
new ListViewItem(items,0));
lv2_mdown =
false ;
lv1_mdown =
false ;
}
private void listView2_DragEnter(object sender,System.Windows.Forms.DragEventArgs e)
{
if (e.Data.GetDataPresent(DataFormats.Text))
e.Effect = DragDropEffects.Copy;
else
e.Effect = DragDropEffects.None;
}
private void listView1_DragEnter(object sender,System.Windows.Forms.DragEventArgs e)
{
if (e.Data.GetDataPresent(DataFormats.Text))
e.Effect = DragDropEffects.Copy;
else
e.Effect = DragDropEffects.None;
}
private void listView1_MouseMove(object sender,System.Windows.Forms.MouseEventArgs e)
{
if ( ! lv1_mdown ) return ;
if ( e.Button == MouseButtons.Right ) return ;
string str = GetItemText(listView1) ;
if ( str == "" ) return ;
listView1.DoDragDrop(str , DragDropEffects.Copy | DragDropEffects.Move ) ;
}
private void listView2_MouseMove(object sender,System.Windows.Forms.MouseEventArgs e)
{
if ( ! lv2_mdown ) return ;
if ( e.Button == MouseButtons.Right ) return ;
string str = GetItemText(listView2) ;
if ( str == "" ) return ;
listView2.DoDragDrop(str, DragDropEffects.Copy | DragDropEffects.Move ) ;
}
private void listView1_MouseDown(object sender,System.Windows.Forms.MouseEventArgs e)
{
lv1_mdown =
true ;
}
private void listView2_MouseDown(object sender,System.Windows.Forms.MouseEventArgs e)
{
lv2_mdown =
true ;
}
public string GetItemText(ListView LVIEW)
{
int nTotalSelected = LVIEW.SelectedIndices.Count;
if ( nTotalSelected <= 0 ) return "";
IEnumerator selCol = LVIEW.SelectedItems.GetEnumerator();
selCol.MoveNext() ;
ListViewItem lvi = (ListViewItem)selCol.Current;
string mDir = "";
for ( int i=0; i < lvi.SubItems.Count;i++)
mDir += lvi.SubItems[i].Text +",";
mDir = mDir.Substring(0,mDir.Length-1);
return mDir ;
}
}
}

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