How to move and resize a form without a border?

Question

Does anyone know how I can resize a winform when it has no border. I don't want the default border that Windows has, so I changed the property "FormBorderStyle" to "None". This removed the border, although now it can't be resized. I've figured out how to move the form around, I just need to know how to resize it.

Answer 1

Some sample code that allow moving and resizing the form:

  public partial class Form1 : Form {     public Form1() {       InitializeComponent();       this.FormBorderStyle = FormBorderStyle.None;       this.DoubleBuffered = true;       this.SetStyle(ControlStyles.ResizeRedraw, true);     }     private const int cGrip = 16;      // Grip size     private const int cCaption = 32;   // Caption bar height;      protected override void OnPaint(PaintEventArgs e) {       Rectangle rc = new Rectangle(this.ClientSize.Width - cGrip, this.ClientSize.Height - cGrip, cGrip, cGrip);       ControlPaint.DrawSizeGrip(e.Graphics, this.BackColor, rc);       rc = new Rectangle(0, 0, this.ClientSize.Width, cCaption);       e.Graphics.FillRectangle(Brushes.DarkBlue, rc);     }      protected override void WndProc(ref Message m) {       if (m.Msg == 0x84) {  // Trap WM_NCHITTEST         Point pos = new Point(m.LParam.ToInt32());         pos = this.PointToClient(pos);         if (pos.Y < cCaption) {           m.Result = (IntPtr)2;  // HTCAPTION           return;         }         if (pos.X >= this.ClientSize.Width - cGrip && pos.Y >= this.ClientSize.Height - cGrip) {           m.Result = (IntPtr)17; // HTBOTTOMRIGHT           return;         }       }       base.WndProc(ref m);     }   } 

Answer 2

Here's a complete example of a customized form with all 8 points of resizing:

public partial class Form1 : Form { public Form1() {   InitializeComponent();   this.FormBorderStyle = FormBorderStyle.None; // no borders   this.DoubleBuffered = true;   this.SetStyle(ControlStyles.ResizeRedraw, true); // this is to avoid visual artifacts }  protected override void OnPaint(PaintEventArgs e) // you can safely omit this method if you want {     e.Graphics.FillRectangle(Brushes.Green, Top);     e.Graphics.FillRectangle(Brushes.Green, Left);     e.Graphics.FillRectangle(Brushes.Green, Right);     e.Graphics.FillRectangle(Brushes.Green, Bottom); }  private const int     HTLEFT = 10,     HTRIGHT = 11,     HTTOP = 12,     HTTOPLEFT = 13,     HTTOPRIGHT = 14,     HTBOTTOM = 15,     HTBOTTOMLEFT = 16,     HTBOTTOMRIGHT = 17;  const int _ = 10; // you can rename this variable if you like  Rectangle Top { get { return new Rectangle(0, 0, this.ClientSize.Width, _); } } Rectangle Left { get { return new Rectangle(0, 0, _, this.ClientSize.Height); } } Rectangle Bottom { get { return new Rectangle(0, this.ClientSize.Height - _, this.ClientSize.Width, _); } } Rectangle Right { get { return new Rectangle(this.ClientSize.Width - _, 0, _, this.ClientSize.Height); } }  Rectangle TopLeft { get { return new Rectangle(0, 0, _, _); } } Rectangle TopRight { get { return new Rectangle(this.ClientSize.Width - _, 0, _, _); } } Rectangle BottomLeft { get { return new Rectangle(0, this.ClientSize.Height - _, _, _); } } Rectangle BottomRight { get { return new Rectangle(this.ClientSize.Width - _, this.ClientSize.Height - _, _, _); } }   protected override void WndProc(ref Message message) {     base.WndProc(ref message);      if (message.Msg == 0x84) // WM_NCHITTEST     {         var cursor = this.PointToClient(Cursor.Position);          if (TopLeft.Contains(cursor)) message.Result = (IntPtr)HTTOPLEFT;    else if (TopRight.Contains(cursor)) message.Result = (IntPtr)HTTOPRIGHT;    else if (BottomLeft.Contains(cursor)) message.Result = (IntPtr)HTBOTTOMLEFT;    else if (BottomRight.Contains(cursor)) message.Result = (IntPtr)HTBOTTOMRIGHT;     else if (Top.Contains(cursor)) message.Result = (IntPtr)HTTOP;    else if (Left.Contains(cursor)) message.Result = (IntPtr)HTLEFT;    else if (Right.Contains(cursor)) message.Result = (IntPtr)HTRIGHT;    else if (Bottom.Contains(cursor)) message.Result = (IntPtr)HTBOTTOM;     } }}