Question

I am supposed to load an image from a file and this image should cover 80% of pictureBox and then draw something on it… With loading there is no problem, but trying to draw anything on it drops an error that has an unproper parameter (g.FillRectangle…).

I found on stack advice to refresh pictureBox, but it changes nothing…
And i have no idea how to solve this…

private void button1_Click_1(object sender, EventArgs e)
{
    pictureBox1.Width = (int)(Width * 0.80);
    pictureBox1.Height = (int)(Height * 0.80);

    // open file dialog 
    OpenFileDialog open = new OpenFileDialog();
    // image filters
    open.Filter = "Image Files(*.jpg; *.jpeg; *.gif; *.bmp)|*.jpg; *.jpeg; *.gif; *.bmp";
    if (open.ShowDialog() == DialogResult.OK)
    {
        // display image in picture box
        pictureBox1.Image = new Bitmap(open.FileName);
        // image file path
        //  textBox1.Text = open.FileName;
        g.FillRectangle(Brushes.Red, 0, 0, 20, 50);
        pictureBox1.Refresh();
    }
}

Answer 1

Use Graphics.FromImage or Control.CreateGraphics methods for draw on your image:

var img = new Bitmap(open.FileName);
using (Graphics g = Graphics.FromImage(img))
{
    g.FillRectangle(Brushes.Red, 0, 0, 20, 50);  
}
pictureBox1.Image = img;

or draw directly on PictureBox by Paint event (for example by using Anonymous Methods):

pictureBox1.Paint += (s, e) => e.Graphics.FillRectangle(Brushes.Red, 0, 0, 20, 50);