Question

I have a text box and it is in square form now I want to convert that square into oval shape
i am using win forms application

can any one tell any idea about this

Answer 1

You can use the SetWindowRgn API Function to change the shape of a window.
This function – as you can see here – gets three arguments:

1. Window Handle: That can be your TextBox Handle and you can get it by Handle Property.
2. A Window RGN: That you can create it by calling CreateRoundRectRgn (or another RGN creator functions that you can find them here)
3. A Boolean to determine Redraw: That it is better to be true.

You can subclass from TextBox and create a Oval shaped TextBox by using this functions in OnHandleCreated Method. The class can be something like this:

class OvalTextBox : TextBox
{
    [DllImport("user32.dll")]
    static extern int SetWindowRgn(IntPtr hWnd, IntPtr hRgn, bool bRedraw);

    [DllImport("gdi32.dll")]
    static extern IntPtr CreateRoundRectRgn(int x1, int y1, int x2, int y2, int cx, int cy);

    public OvalTextBox()
    {
        base.BorderStyle = System.Windows.Forms.BorderStyle.None;
    }

    protected override void OnHandleCreated(EventArgs e)
    {
        base.OnHandleCreated(e);
        SetWindowRgn(this.Handle, CreateRoundRectRgn(0, 0, this.Width, this.Height, 20, 20), true);
    }
}