Stephens' C# Programming with Visual Studio® 2010 24-Hour Trainer

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LESSON 33 Providing drag and droP

In DragSource, allow Copy and Move operations. Check the result of

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DoDragDrop and if the

operation was a Move, remove the text from the source

Label control.

1. Pass the DoDragDrop function the parameter DragDropEffects.Copy |

DragDropEffects.Move

for the allowed operations.

2. Check the result returned by DoDragDrop. If the result is DragDropEffects.Move,

clear the

Label control.

3. The code should look something like this:

// Start a drag.

private void dragLabel_MouseDown(object sender, MouseEventArgs e)

{

// If it’s not the right mouse button, do nothing.

if (e.Button != MouseButtons.Right) return;

// Make the data object.

DataObject data = new DataObject(DataFormats.Text, dragLabel.Text);

// Start the drag allowing copy and move.

if (dragLabel.DoDragDrop(data,

DragDropEffects.Copy | DragDropEffects.Move)

== DragDropEffects.Move)

{

// This is a Move. Remove the data from this application.

dragLabel.Text = “”;

}

}

In DropTarget, make the

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DragEnter event handler allow Copy and Move operations.

1. In the DragEnter event handler, if text data is available set e.Effect =

DragDropEffects.Copy | DragDropEffects.Move

to allow both Copy and Move

operations. The code should look something like this:

// A drag entered. List available formats.

private void Form1_DragEnter(object sender, DragEventArgs e)

{

// Allow text data.

if (e.Data.GetDataPresent(DataFormats.Text)) ...