VB.NET optimizing drag & drop code - vb.net

Question

I'm currently struggling with drag & drop code. I have 3 images that are at the top, and I want to add them in a random order in a flow-layout-panel.
I have this code for adding the square image into the flow-layout-panel, but I have got the feeling that this is not 100% correct. Is it possible to add these with 1 sub instead of 3?
And how do you write a sub that detects what object in being dragged? Now my sub just adds a square with each dragdrop event. But I need it to drop a Square only when a Square is being dragged and drop a Trapezium or round when it's being dragged.
Public Class Form2
Private Sub PictureBox1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseMove
' Initiate dragging.
PictureBox1.DoDragDrop(PictureBox1, DragDropEffects.Copy)
End Sub
Private Sub PictureBox2_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox2.MouseMove
' Initiate dragging.
PictureBox2.DoDragDrop(PictureBox2, DragDropEffects.Copy)
End Sub
Private Sub PictureBox3_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox3.MouseMove
' Initiate dragging.
PictureBox3.DoDragDrop(PictureBox2, DragDropEffects.Copy)
End Sub
Private Sub FlowLayoutPanel1_DragEnter(ByVal sender As Object, ByVal e As _
System.Windows.Forms.DragEventArgs) Handles FlowLayoutPanel1.DragEnter
' Check the format of the data being dropped.
If (e.Data.GetDataPresent(GetType(PictureBox))) Then
' Display the copy cursor.
e.Effect = DragDropEffects.Copy
Else
' Display the no-drop cursor.
e.Effect = DragDropEffects.None
End If
End Sub
Private Sub FlowLayoutPanel1_DragDrop(ByVal sender As Object, ByVal e As _
System.Windows.Forms.DragEventArgs) Handles FlowLayoutPanel1.DragDrop
Dim oPB As New PictureBox()
oPB.Image = Image.FromFile("C:\Users\Jef\Desktop\square.jpg")
oPB.Visible = True
oPB.Width = 100
oPB.Height = 100
oPB.SizeMode = PictureBoxSizeMode.CenterImage
FlowLayoutPanel1.Controls.Add(oPB)
End Sub

Answer 1

You already got the answer in your previous question:
Private Sub FlowLayoutPanel1_DragDrop(ByVal sender As Object, ByVal e As _
System.Windows.Forms.DragEventArgs) Handles FlowLayoutPanel1.DragDrop
Dim oPB As New PictureBox()
Dim pb = CType(e.Data.GetData(GetType(PictureBox)))
oPB.Image = pb.Image
pb.Image = Nothing '' Optional
'' etc...
End Sub
You do have a bug, the probable reason why you did not use the answer:
Private Sub PictureBox3_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox3.MouseMove
' Initiate dragging.
PictureBox3.DoDragDrop(PictureBox2, DragDropEffects.Copy)
End Sub
Note how it drags the wrong control, PictureBox2 instead of PictureBox3. You avoid bugs like this by writing DRY code, Do not Repeat Yourself. The sender argument of a MouseMove event already gives you a reference to the control. So you just need one event handler for all three controls:
Private Sub PictureBox_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseMove, PictureBox2.MouseMove, PictureBox3.MouseMove
' Initiate dragging.
Me.DoDragDrop(sender, DragDropEffects.Copy)
End Sub
With the detail that we now let the Form support DoDragDrop(). Which only matters if you implement the GiveFeedback or QueryContinueDrag events.