Save User Drawn Bitmap Graphics in c#

Question

I have made a program that allows users to draw lines onto a picturebox image but now need to save these lines to be opened at a later date. This is my current code for drawing the lines:

 public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            pictureBox1.Image = new Bitmap(pictureBox1.Width, pictureBox1.Height);
        }
        int Drawshape;




        private Point p1, p2;
        List<Point> p1List = new List<Point>();
        List<Point> p2List = new List<Point>();

        private void Form1_MouseDown(object sender, MouseEventArgs e)
        {


        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {
            Drawshape = 5;
        }

        private void button2_Click(object sender, EventArgs e)
        {
            Drawshape = 2;
        }

        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            if (Drawshape == 5)
            {
                if (p1.X == 0)
                {
                    p1.X = e.X;
                    p1.Y = e.Y;
                }
                else
                {
                    p2.X = e.X;
                    p2.Y = e.Y;

                    p1List.Add(p1);
                    p2List.Add(p2);

                    pictureBox1.Invalidate();
                    p1.X = 0;
                }
            }
        }

        private void pictureBox1_ParentChanged(object sender, EventArgs e)
        {

        }

        private void pictureBox1_Paint(object sender, PaintEventArgs e)
        {
            Graphics G = Graphics.FromImage(pictureBox1.Image);
            if (Drawshape == 5)
            {
                using (var p = new Pen(Color.Blue, 4))
                {
                    for (int x = 0; x < p1List.Count; x++)
                    {
                        G.DrawLine(p, p1List[x], p2List[x]);
                    }
                }
            }

        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            pictureBox1.Invalidate();
        }

        private void Save_Click(object sender, EventArgs e)
        {



        } 
    }
}

I don't know how to save these lines and also open them again at a later time when the user wants to. I have put in open and save filedialogs but not sure how to make them do the job i want them to do. Please Help.

Thanks

Answer 1

If you want to save the image that is displayed in the picture box, complete with any lines that may have been drawn on top of it during run-time, you can use the Control.DrawToBitmap method.

I can't tell for sure if you're also asking how to use a SaveFileDialog to determine where the user wants to save the file or if you've already got that part figured out, but it's very simple.

Here's an example of a complete solution. First, the user is prompted by a save dialog (entitled "Save Image" and filtering to bitmap images (*.bmp) by default). If they click OK, the image displayed in the picture box is drawn to a temporary bitmap, and that temporary bitmap is saved to the location they specified. If they click Cancel, the file is not saved and the method simply exits.

private void Save_Click(object sender, EventArgs e)
{
    //Show a save dialog to allow the user to specify where to save the image file
    using (SaveFileDialog dlgSave = new SaveFileDialog())
    {
        dlgSave.Title = "Save Image";
        dlgSave.Filter = "Bitmap Images (*.bmp)|*.bmp|All Files (*.*)|*.*";
        if (dlgSave.ShowDialog(this) == DialogResult.OK)
        {
            //If user clicked OK, then save the image into the specified file
            using (Bitmap bmp = new Bitmap(pictureBox1.Width, pictureBox1.Height))
            {
                picturebox1.DrawToBitmap(bmp, new Rectangle(0, 0, bmp.Width, bmp.Height));
                bmp.Save(dlgSave.FileName);
            }
        }
    }
}

Answer 2

Have a look at

PictureBox.Image Property

and

Image.Save Method (String, ImageFormat)

and

Image.FromFile Method (String, Boolean)

Answer 3

It's not clear what you want... do you want to save the resulting image, or the list of points ?

If you want to save the image, just use pictureBox1.Image.Save(fileName).

If you want to save the list of points, you could use serialization (it should work with either binary or XML serialization)