Prevent redrawing of controls on resize for Windows Forms

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 scrol

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();
}

Answer 2

For me it worked well with making the TableLayoutPanel double-buffered, then I didn't even need to suspend the layout. I found the solution on this thread: How to avoid flickering in TableLayoutPanel in c#.net using the double-buffered TableLayoutPanel class from this website: https://www.richard-banks.org/2007/09/how-to-create-flicker-free.html

After that all I needed to do was, after rebuilding the project and restarting Visual Studio a couple of times (to get the InitializeComponent()s working), go inside the .Designer.cs file and change the System.Windows.Forms.TableLayoutPanel class to the new DBLayoutPanel class. To go inside the Designer file and change the class there helped me save time because I already had a lot of controls inside the TableLayoutPanel.

Answer 3

You could hook up the resize event of your parent container and set the e.Handled or e.Cancel property to true and then do a manual redraw on onMouseUp.