There are a lot of places on the web that talk about this concept and it’s clear there are a few ways to create a drag and drop TextBox in WPF.
Here is what I recommend to accomplish this task:
Given:
Your TextBox name is “TextBox1”
C#
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
// Initialize UI
InitializeComponent();
// Loaded event
this.Loaded += delegate
{
TextBox1.AllowDrop = true;
TextBox1.PreviewDragEnter += TextBox1PreviewDragEnter;
TextBox1.PreviewDragOver += TextBox1PreviewDragOver;
TextBox1.Drop += TextBox1DragDrop;
};
}
/// <summary>
/// We have to override this to allow drop functionality.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void TextBox1PreviewDragOver(object sender, DragEventArgs e)
{
e.Handled = true;
}
/// <summary>
/// Evaluates the Data and performs the DragDropEffect
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void TextBox1PreviewDragEnter(object sender, DragEventArgs e)
{
if (e.Data.GetDataPresent(DataFormats.FileDrop))
{
e.Effects = DragDropEffects.Copy;
}
else
{
e.Effects = DragDropEffects.None;
}
}
/// <summary>
/// The drop activity on the textbox.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void TextBox1DragDrop(object sender, DragEventArgs e)
{
// Get data object
var dataObject = e.Data as DataObject;
// Check for file list
if (dataObject.ContainsFileDropList())
{
// Clear values
TextBox1.Text = string.Empty;
// Process file names
StringCollection fileNames = dataObject.GetFileDropList();
StringBuilder bd = new StringBuilder();
foreach (var fileName in fileNames)
{
bd.Append(fileName + "\n");
}
// Set text
TextBox1.Text = bd.ToString();
}
}
}
Now, let’s look at each event and cover what is going on:
/// <summary>
/// We have to override this to allow drop functionality.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void TextBox1PreviewDragOver(object sender, DragEventArgs e)
{
e.Handled = true;
}
We need to add this to override the default PreviewDrag behavior. If we don’t, then the Drop Event will not fire.
/// <summary>
/// Evaluates the Data and performs the DragDropEffect
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void TextBox1PreviewDragEnter(object sender, DragEventArgs e)
{
if (e.Data.GetDataPresent(DataFormats.FileDrop))
{
e.Effects = DragDropEffects.Copy;
}
else
{
e.Effects = DragDropEffects.None;
}
}
This piece deals with the source being dragged over the textbox. The data is evaluated at this point, and the DragDropEffects are executed accordingly. Notice that the data is checked for the correct type.
MSDN breaks down the DragDropEffects here.
/// <summary>
/// The drop activity on the textbox.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void TextBox1DragDrop(object sender, DragEventArgs e)
{
// Get data object
var dataObject = e.Data as DataObject;
// Check for file list
if (dataObject.ContainsFileDropList())
{
// Clear values
TextBox1.Text = string.Empty;
// Process file names
StringCollection fileNames = dataObject.GetFileDropList();
StringBuilder bd = new StringBuilder();
foreach (var fileName in fileNames)
{
bd.Append(fileName + "\n");
}
// Set text
TextBox1.Text = bd.ToString();
}
}
In the drop event, a few things occur:
- We grab the DataObject from “e”.
- Then evaluate the DataObject to ensure it has a StringCollection using GetFileDropList.
- We grab the StringCollection.
- We enumerate through the collection and append each filename to a StringBuilder object.
- Finally, we add the StringBuilder content to the TextBox Text field.
Thank you. This is exactly what I wanted.