C# drop and drop problems

Question

0.00/5 (No votes)

See more:

VS2010

Hi everyone, i've a question.

I'm trying to do one code that the user use the drop and drag, but my problem is when i pressing two times on listBox. If the listBox is null then nothing happen, but if have some text then he stop and go to this part of code:

C#

string s = ltbCamposLinhas.Items[ltbCamposLinhas.IndexFromPoint(e.X, e.Y)].ToString();

C#

private void ltbCamposLinhas_MouseDown(object sender, MouseEventArgs e)
        {
            if (ltbCamposLinhas.Items.Count == 0) return;
            string s = ltbCamposLinhas.Items[ltbCamposLinhas.IndexFromPoint(e.X, e.Y)].ToString();
            DragDropEffects dde1 = DoDragDrop(s, DragDropEffects.All);

            if (dde1 == DragDropEffects.All)
            {
                ltbCamposLinhas.Items.RemoveAt(ltbCamposLinhas.IndexFromPoint(e.X, e.Y));
            }
        }

If you guys could help would be awesome.

Well, first i want to drag items from listBox1 to listBox2.

Second i want to drag items from listBox2 to out and then they will delete.

But my problem is none of them, because, if i press 2 times with mouse in listBox1 with items(text) he show one error:

InvalidArgument=Value '-1

Posted 13-Nov-12 0:50am

Breno Oliveira

Updated 13-Nov-12 1:41am

v2

Add a Solution

Comments

Alan N 13-Nov-12 7:20am

Are you trying to rearrange listbox items OR drag items out of the listbox and drop them on a different control.
Edit your question using the "Improve Question" button to clarify what you want to do.

2 solutions

Solution 3

I think your code in the original question and your solution is far too simple.

You should use separate events to select an object (MouseDown) and to initiate the drag drop operation (MouseMove).

In my code example DragDropEffects is set to 'Move' if the item was dropped onto listbox2. In that case it's ok to delete the item from listbox1.

In the other situation where the item has been dragged and the mouse button released when not over listbox2 the effect will be 'None'. Now we delete only if the cursor is outside the bounds of the form.

C#

private Object itemToDrag;

private void listBox1_MouseDown(object sender, MouseEventArgs e) {
  itemToDrag = null;
  if (e.Button == MouseButtons.Left) {
    Int32 idx = listBox1.IndexFromPoint(e.Location);
    if (idx != ListBox.NoMatches) {  // NoMatches = -1
      itemToDrag = listBox1.Items[idx];
      Debug.Print("Item selected for drag: {0}", itemToDrag);
    }
  }
}

private void listBox1_MouseMove(object sender, MouseEventArgs e) {
  if (e.Button == MouseButtons.Left && itemToDrag != null) {
    Debug.Print("DragDrop starting");
    DragDropEffects effect = listBox1.DoDragDrop(itemToDrag, DragDropEffects.Move);
    Debug.Print("DragDrop ended : Effect {0}", effect);
    if (effect == DragDropEffects.Move) {
      Debug.Print("Item moved");
      listBox1.Items.Remove(itemToDrag);
    } else if (effect == DragDropEffects.None) {
      // Is mouse currently outside the form
      if (!this.DesktopBounds.Contains(Cursor.Position)) {
        Debug.Print("Item deleted");
        listBox1.Items.Remove(itemToDrag);
      }
    }
    itemToDrag = null;
  }
}

private void listBox2_DragDrop(object sender, DragEventArgs e) {
  String droppedItem = (String)e.Data.GetData(DataFormats.StringFormat);
  Debug.Print("listbox2 DragDrop  {0}", droppedItem);
  listBox2.Items.Add(droppedItem);
}

private void listBox2_DragEnter(object sender, DragEventArgs e) {
  e.Effect = DragDropEffects.Move;
  Debug.Print("DragEnter listbox2");
}

Alan.

Posted 13-Nov-12 3:24am

Alan N

Updated 13-Nov-12 3:26am

v2

Comments

werfog 13-Nov-12 11:01am

I voted your answer 4 because your code looked more classical then author's one.
Just 4 because you seem to be a professional in programing.
Best wishes.

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Breno Oliveira · Accepted Answer · 2012-11-13T02:51:00

<lang>I've fixed the problem.

C#

private void ltbCamposLinhas_MouseDown(object sender, MouseEventArgs e)
        {
            int indice = ltbCamposLinhas.IndexFromPoint(e.X, e.Y);
            if (ltbCamposLinhas.Items.Count == 0 || indice < 0) return;
            string s = ltbCamposLinhas.Items[indice].ToString();
            DragDropEffects dde1 = DoDragDrop(s, DragDropEffects.All);

            if (dde1 == DragDropEffects.All)
            {
      ltbCamposLinhas.Items.RemoveAt(ltbCamposLinhas.IndexFromPoint(e.X, e.Y));
            }
        }

Ty all.