How to draw a rounded rectangle

The trick here is to use a GraphicsPath object to assemble a collection of  lines and arcs that make up the rounded rectangle shape.

Arcs are used to round off the corners, so you have to position the lines 1 radius, whatever that may be, from the actual corner.

The routine to accomplish this is shown here in C# and VB.NET.

public void DrawRoundRect(Graphics g, Pen p, float X, float Y, float width, float height, float radius)

    gp.AddLine(X + radius, Y, X + width - (radius*2), Y);

    gp.AddArc(X + width - (radius*2), Y, radius*2, radius*2, 270, 90);

    gp.AddLine(X + width, Y + radius, X + width, Y + height - (radius*2));

    gp.AddArc(X + width - (radius*2), Y + height - (radius*2), radius*2, radius*2,0,90);

    gp.AddLine(X + width - (radius*2), Y + height, X + radius, Y + height);

    gp.AddArc(X, Y + height - (radius*2), radius*2, radius*2, 90, 90);

    gp.AddLine(X, Y + height - (radius*2), X, Y + radius);

    gp.AddArc(X, Y, radius*2, radius*2, 180, 90);

    gp.CloseFigure();

    g.DrawPath(p, gp);
    gp.Dispose();
}