How do I properly select a certain part of an image inside a picture box in C# and highlight it?

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I have been trying to write a program to be able to load an image on a form and select a rectangle on it, then load it onto another picture box (pictureBox2), and I also want to be able to highlight what I have selected on the original picture, in pictureBox1 as I move my mouse, so far I have this code but it doesn't properly respond to the mouseMove event, whenever I move my mouse up, it moves to the left, whenever I move it down it moves to the right, basically it doesn't work correctly, what is the problem with this code?

public partial class Form1 : Form
{
    Bitmap original;
    bool isSelecting;
    int x0, y0, x1, y1;
    public Form1()
    {
        InitializeComponent();
        pictureBox1.MouseDown += new MouseEventHandler(picOriginal_MouseDown);
        pictureBox1.MouseMove += new MouseEventHandler(picOriginal_MouseMove);
        pictureBox1.MouseUp   += new MouseEventHandler(picOriginal_MouseUp);
    }

    #region helpder methods

    // Start selecting the rectangle.
    private void picOriginal_MouseDown(object sender, MouseEventArgs e)
    {
        if(original != null)
        {
            isSelecting = true;
            // Save the start point.
            x0 = e.X;
            y0 = e.Y;
        }
    }

    // Continue selecting.
    private void picOriginal_MouseMove(object sender, MouseEventArgs e)
    {
        if(original != null)
        {
            // Do nothing it we're not selecting an area.
            if(!isSelecting) return;

            // Save the new point.
            x1 = e.X;
            x1 = e.Y;

            // Make a Bitmap to display the selection rectangle.
            Bitmap bm = new Bitmap(original);

            // Draw the rectangle.
            using(Graphics gr = Graphics.FromImage(bm))
            {
                gr.DrawRectangle(Pens.Red,
                    Math.Min(x0, x1), Math.Min(y0, y1),
                    Math.Abs(x0 - x1), Math.Abs(y0 - y1)
                    );
            }

            // Display the temporary bitmap.
            pictureBox1.Image = new Bitmap(bm, new Size(pictureBox1.Width, pictureBox1.Height));
        }
    }

    // Finish selecting the area.
    private void picOriginal_MouseUp(object sender, MouseEventArgs e)
    {
        if(original != null)
        {
            // Do nothing it we're not selecting an area.
            if(!isSelecting) return;
            isSelecting = false;

            // Display the original image.
            pictureBox2.Image = original;

            // Copy the selected part of the image.
            int wid = Math.Abs(x0 - x1);
            int hgt = Math.Abs(y0 - y1);
            if((wid < 1) || (hgt < 1)) return;

            Bitmap area = new Bitmap(wid, hgt);
            using(Graphics gr = Graphics.FromImage(area))
            {
                Rectangle source_rectangle =
                    new Rectangle(Math.Min(x0, x1), Math.Min(y0, y1),
                        wid, hgt);
                Rectangle dest_rectangle =
                    new Rectangle(0, 0, wid, hgt);
                gr.DrawImage(original, dest_rectangle,
                    source_rectangle, GraphicsUnit.Pixel);
            }

            // Display the result.
            pictureBox2.Image = area;
        }
    }

    #endregion

    private void button1_Click(object sender, EventArgs e)
    {
        if(original != null)
        {

        }
    }

    private void button2_Click(object sender, EventArgs e)
    {
        OpenFileDialog dialog = new OpenFileDialog();
        dialog.Filter = "jpg files (*.jpg)|*.jpg|All files(*.*)|*.*";
        if(dialog.ShowDialog() == DialogResult.OK)
        {
            original = new Bitmap(dialog.FileName);
            pictureBox1.Image = new Bitmap(original, new Size(pictureBox1.Width,     pictureBox1.Height));
        }
        dialog.Dispose();
    }
   }

asked 18 secs ago

paulpaul1076

28

How do I properly select a certain part of an image inside a picture box in C# and highlight it?