Drag and Drop Files with C#
By Dave Ceddia

Download DragDropFiles.zip

This tutorial will explain how to handle drag and drop events sent to one of the windows in your program by the Windows shell. In other words, this tutorial will teach you how to allow users to drag and drop files onto your form so you can do stuff with them. This was bugging me for a little while, because it was so simple in VB and for some reason it took me a while to figure it out in C#...anyway, on to the tutorial! This is the first tutorial I've ever written, so bear with me :)

To start, create a new C# Windows Application project called DragDropFiles. Put a ListBox control somewhere on the form. Set its AllowDrop property to "true". Click the Events lightning bolt to get to the events of the ListBox.

Now, to be able to handle files being dropped, at least two events need to be dealt with. The first is DragEnter, where basically all you have to do is allow the drag operation to continue. If you don't allow the operation to continue, say, because the user is dragging text into the control, the mouse cursor will stay a "NO" symbol instead of becoming the "Copy Here" symbol (the pointer with a "+" next to it).

The second event that must be handled (assuming they get past the DragEnter event) is DragDrop. This is where you actually read the files in the list and, in this application, add them to a ListBox.

So, scroll down in the events list (make sure you have the ListBox selected, not your form) until you find DragEnter and doubleclick it. Enter the following code in the listBox1_DragEnter method:

// make sure they're actually dropping files (not text or anything else)
if( e.Data.GetDataPresent(DataFormats.FileDrop, false) == true )
// allow them to continue
// (without this, the cursor stays a "NO" symbol
e.Effect = DragDropEffects.All;

// transfer the filenames to a string array
// (yes, everything to the left of the "=" can be put in the 
// foreach loop in place of "files", but this is easier to understand.)
string[] files = (string[])e.Data.GetData(DataFormats.FileDrop);

// loop through the string array, adding each filename to the ListBox
foreach( string file in files )
{
listBox1.Items.Add(file);
}