Problem about pictureBox in Visual Studio C Sharp.NET ?

Question

Hi I am designing a paint brush type program…..for drawing area where I can draw something then I used pictureBox…..like as Pen p = new Pen ( Color .Red 5); g = pictureBox2.CreateGraphics(); g.DrawEllipse(p e.X e.Y 5 7); in this program I can draw anything but when I want to save this drawing by the help of this command: pictureBox2.Image.Save(saveFileDialog1.FileName); then an error occur : “NullReferenceExpection was unhandled !” “Object reference not set to an instance of an object.” I need your help………can anybody solve my problem Thanks

zeeShan Ansari · Answer

Hi follwing code solve just half problem................means save only last ellipse but i want whole drawing -------------------------------------------------------------- private void pictureBox2_MouseDown(object sender MouseEventArgs e) { if (e.Button == MouseButtons.Left) { Bitmap bmp = new Bitmap(pictureBox2.Width pictureBox2.Height); Graphics g = Graphics.FromImage(bmp); Pen p = new Pen(Color.Red 5); g.DrawEllipse(p e.X e.Y 5 7); } --------------------------------------------------------------- and then ......... ... . if (saveFileDialog1.ShowDialog() == DialogResult.OK) { pictureBox2.Image = bmp; pictureBox2.Image.Save(saveFileDialog1.FileName); } ----------------------------------------------------------------- i think there is something missing in Graphics g = Graphics.FromImage(bmp); or pictureBox2.Image = bmp; (like: pictureBox2.Image += bmp; but illegal ) ----------------------------------------------------------------- bmp or pictureBox does not update with previous condition it always losing the previous ellipse and save the last drawn ellipse

zeeShan Ansari · Answer

thanks.............you are right

Alan · Answer

See if this will work: Bitmap bmp = new Bitmap(pictureBox2.Width pictureBox2.Height); Graphics g = Graphics.FromImage(bmp); Pen p = new Pen(Color.Red 5); g.DrawEllipse(p e.X e.Y 5 7); pictureBox2.Image = bmp;