Question

I’m trying to build a form where the user can drag a label and drop it on a text box. I can find an AllowDrop in the text box, but there is no property such as “AllowDrag” in the label. Also, I created methods for all the drag & drop events for the label (DragEnter, DragLeave, etc) but none of them seem to work. I can not figure out how to drag. How do I handle it?

        private void label1_Click(object sender, EventArgs e)
    {

        // This one works
        status.Text = "Click";
    }

        private void label1_DragOver(object sender, DragEventArgs e)
    {

        // this and the others do not
        status.Text = "DragOver";
    }

    private void label1_GiveFeedback(object sender, GiveFeedbackEventArgs e)
    {
        status.Text = "GiveFeedback";
    }

    private void label1_DragDrop(object sender, DragEventArgs e)
    {
        status.Text = "DragDrop";
    }

    private void label1_DragEnter(object sender, DragEventArgs e)
    {
        status.Text = "DragEnter";
    }

    private void label1_DragLeave(object sender, EventArgs e)
    {
        status.Text = "DragLeave";
    }

    private void label1_QueryContinueDrag(object sender, QueryContinueDragEventArgs e)
    {
        status.Text = "QueryContinueDrag";
    }

Answer 1

There is no “AllowDrag” property, you actively start the D+D with the DoDragDrop() method. And the event handlers need to be on the D+D target, not the source. A sample form, it needs a label and a text box:

  public partial class Form1 : Form {
    public Form1() {
      InitializeComponent();
      label1.MouseDown += new MouseEventHandler(label1_MouseDown);
      textBox1.AllowDrop = true;
      textBox1.DragEnter += new DragEventHandler(textBox1_DragEnter);
      textBox1.DragDrop += new DragEventHandler(textBox1_DragDrop);
    }

    void label1_MouseDown(object sender, MouseEventArgs e) {
      DoDragDrop(label1.Text, DragDropEffects.Copy);
    }
    void textBox1_DragEnter(object sender, DragEventArgs e) {
      if (e.Data.GetDataPresent(DataFormats.Text)) e.Effect = DragDropEffects.Copy;
    }
    void textBox1_DragDrop(object sender, DragEventArgs e) {
      textBox1.Text = (string)e.Data.GetData(DataFormats.Text);
    }
  }