Question

I am writing a control in vb.net that will allow a user to resize something. So far, resizing works, but I can’t get moving to work properly, instead of moving where the mouse moves, it seems to flicker between two positions, but I can’t figure out where these positions are coming from. It follows the mouse sort of. I know the explanation isn’t very good so here is some code so you can see for your self: pastebin.

Apologies for this bad quality (please point out the bad stuff so I can correct), but this is really giving me a nightmare and I couldn’t figure out a clean way to write this.

If anyone has any answers as to why it wont move to the correct position, I would be very grateful!

Edit: To clear the code up a little, the moving takes place where the selected handle is “m”. Which is this part:

If SelectedHandle.Contains("m") Then
    If e.Button = MouseButtons.None Then
        SelectedHandle = ""
    Else
        Me.Location = e.Location
    End If
End If

Changing it to this works, but it jumps to the middle of the control whereas I would like it to move relative to where the user clicked the mouse on the control

If SelectedHandle.Contains("m") Then
    If e.Button = MouseButtons.None Then
        SelectedHandle = ""
    Else
        Dim newloc = Me.Location
        newloc.Offset(e.X, e.Y)
        newloc.Offset(-0.5 * Width, -0.5 * Height)
        Me.Location = newloc
    End If
End If

Answer 1

Looks like y_difference and x_difference are calculated using the X and Y coordinates which can be relative to the context where the move (or click) happens. Check the article here.

For example, when the Control.MouseMove event is handled, the mouse coordinate values are relative to the coordinates of the control that raised the event

Always using e.Location should give the correct numbers.