Question

I have this simple code each time i click the button its drawing a point in the pictureBox1 at location 100,100

But i want to calculate first ( i need to learn how to do it ) the center of the pictureBox1.

Then i want to use the Random so each time i click the button it will draw a point randomaly from the pictureBox1 center location + 10

private void button5_MouseClick(object sender, MouseEventArgs e)
        {
            Random rnd = new Random();
            drawPoint(100, 100);
        }

        public void drawPoint(int x, int y)
        {
         Graphics g = Graphics.FromHwnd(pictureBox1.Handle);
         SolidBrush brush = new SolidBrush(Color.LimeGreen);
         Point dPoint = new Point(x, (pictureBox1.Height - y));
         dPoint.X = dPoint.X - 2;
         dPoint.Y = dPoint.Y - 2;
         Rectangle rect = new Rectangle(dPoint, new Size(4, 4));
         g.FillRectangle(brush, rect);
         g.Dispose();
        }

Answer 1

Try this. It will calculate random offset from the centre by +10 -10

    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            var halfX = pictureBox1.ClientRectangle.Width / 2;
            var halfY = pictureBox1.ClientRectangle.Height / 2;

            Random rnd = new Random();
            var offsetX = rnd.Next(-10, 10);
            var offsetY = rnd.Next(-10, 10);

            drawPoint(halfX + offsetX, halfY + offsetY);
        }

        public void drawPoint(int x, int y)
        {
            Graphics g = Graphics.FromHwnd(pictureBox1.Handle);
            SolidBrush brush = new SolidBrush(Color.LimeGreen);
            Point dPoint = new Point(x, (pictureBox1.Height - y));
            dPoint.X = dPoint.X - 2;
            dPoint.Y = dPoint.Y - 2;
            Rectangle rect = new Rectangle(dPoint, new Size(4, 4));
            g.FillRectangle(brush, rect);
            g.Dispose();
        }
     }