Question

I have a TableLayoutPanel which holds a dynamic number of controls inside a SplitterPanel. A user may want to resize the panel to fit these Controls to avoid use of a scroll bar. This creates jitter on the container resize as well as the controls within the container. Sometimes the parent container lags significantly behind movement of the mouse during resize (up to a 3 second lag).

Is there any way to prevent redrawing of Controls during a parent container resize, such as hiding all elements during resize or halting a resize event which occuring during a mousedrag, firing only on an onMouseUp event?

Answer 1

As Hans commented, SuspendLayout and ResumeLayout work well in this situation, along with Suspending the drawing of the control for the container:

public static class Win32 {

  public const int WM_SETREDRAW = 0x0b;

  [DllImport("user32.dll")]
  public static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam);

  public static void SuspendPainting(IntPtr hWnd) {
    SendMessage(hWnd, WM_SETREDRAW, (IntPtr)0, IntPtr.Zero);
  }

  public static void ResumePainting(IntPtr hWnd) {
    SendMessage(hWnd, WM_SETREDRAW, (IntPtr)1, IntPtr.Zero);
  }
}

Then from you resize events:

private void Form1_ResizeBegin(object sender, EventArgs e) {
  tableLayoutPanel1.SuspendLayout();
}

private void Form1_ResizeEnd(object sender, EventArgs e) {
  Win32.SuspendPainting(tableLayoutPanel1.Handle);
  tableLayoutPanel1.ResumeLayout();
  Win32.ResumePainting(tableLayoutPanel1.Handle);
  this.Refresh();
}