removing dynamically created controls C#

Question

I have a program that adds a series of "blips" to a graph. How do I have a button clear all of the "blips" that have been created with this code?

                        PictureBox blip = new PictureBox();
                        blip.Location = new Point(blipHours, blipAltitude);
                        blip.Size = new Size(6, 6);
                        blip.BackColor = System.Drawing.Color.Lime;
                        blip.Text = "";
                        blip.Name = callsign;
                        this.Controls.Add(blip);
                        this.Controls.SetChildIndex(blip, 0);

The other part of my question: See that I have named each blip with "callsign." Is there a way to change a blip's background color when it's name is equal to a certain callsign ? Each blip is associated with a selection in a listbox, and I would like have it change the blips color when that user selects it.

Answer 1

this.Controls.Clear();

Answer 2

You might want to add the blip to a List and then when the user clicks the "Clear" button, just iterate over the list, remove the blip from the Controls collection, then clear the list.

In terms of changing the background color, why don't you just use an if statement?

blip.BackColor = callsign == "SpecialSign"? System.Drawing.Color.Red : System.Drawing.Color.Lime

Answer 3

This will remove all of the PictureBox controls from the particular container (i assume a graph in your case).

 for (int i = this.Controls.Count - 1; i >= 0; i--)
            {
                PictureBox control = this.Controls[i] as PictureBox;
                if (control == null)
                    continue;

                control.Dispose();
            }

Answer 4

Everybody is forgetting a very important detail: you have to Dispose() the control or it will leak forever:

for (int ix = this.Controls.Count - 1; ix >= 0; ix--)
  if (this.Controls[ix] is PictureBox) this.Controls[ix].Dispose();