C# - Make a borderless form movable?

Question

Is there a way to make a form that has no border (FormBorderStyle is set to "none") movable when the mouse is clicked down on the form just as if there was a border? Thanks.

Answer 1

There's no property you can flip to make this just happen magically. Look at the events for the form and it becomes fairly trivial to implement this by setting this.Top and this.Left. Specifically you'll want to look at MouseDown, MouseUp and MouseMove.

Answer 2

This article on CodeProject details a technique. Is basically boils down to:

public const int WM_NCLBUTTONDOWN = 0xA1;
public const int HT_CAPTION = 0x2;

[DllImportAttribute("user32.dll")]
public static extern int SendMessage(IntPtr hWnd, int Msg, int wParam, int lParam);
[DllImportAttribute("user32.dll")]
public static extern bool ReleaseCapture();

private void Form1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
{     
    if (e.Button == MouseButtons.Left)
    {
        ReleaseCapture();
        SendMessage(Handle, WM_NCLBUTTONDOWN, HT_CAPTION, 0);
    }
}

This essentially does exactly the same as grabbing the title bar of a window, from the window manager's point of view.

Answer 3

don't have the exact code to hand, but in a recent project I think I used MouseDown event and simply put this:

frmBorderless.DragMove();

Window.DragMove Method (MSDN)

Answer 4

use MouseDown, MouseMove and MouseUp. You can set a variable flag for that. I have a sample, but I think you need to revise.

I am coding the mouse action to a panel. Once you click the panel, your form will move with it.

//Global variables;
Private bool Dragging = false;
Private Point offset;

private void panel1_MouseDown(object sender, MouseEventArgs e)
{
   Dragging = true;  // Dragging is your variable flag
}

private void panel1_MouseUp(object sender, MouseEventArgs e)
{
   Dragging = false; 
}

private void panel1_MouseMove(object sender, MouseEventArgs e)
{
  if(Dragging)
  {
     Point currentPos = PointToScreen(e.Location);
     Location = new Point(currentPos.X - offset.X, currentPos.Y - offset.Y);
  }
}