Crop image using a fixed-size draggable picturebox

Question

I\'m working on a winforms project that involves cropping an image. My goal is to do this by using a fixed-size draggable picturebox control, allowing the user to select the are

Answer 1

Try This Code for Cropping the Image in picturebox

    public static Image Fit2PictureBox(this Image image, PictureBox picBox)
    {
        Bitmap bmp = null;
        Graphics g;

        // Scale:
        double scaleY = (double)image.Width / picBox.Width;
        double scaleX = (double)image.Height / picBox.Height;
        double scale = scaleY < scaleX ? scaleX : scaleY;

        // Create new bitmap:
        bmp = new Bitmap(
            (int)((double)image.Width / scale),
            (int)((double)image.Height / scale));

        // Set resolution of the new image:
        bmp.SetResolution(
            image.HorizontalResolution,
            image.VerticalResolution);

        // Create graphics:
        g = Graphics.FromImage(bmp);

        // Set interpolation mode:
        g.InterpolationMode = InterpolationMode.HighQualityBicubic;

        // Draw the new image:
        g.DrawImage(
            image,
            new Rectangle(          // Ziel
                0, 0,
                bmp.Width, bmp.Height),
            new Rectangle(          // Quelle
                0, 0,
                image.Width, image.Height),
            GraphicsUnit.Pixel);

        // Release the resources of the graphics:
        g.Dispose();

        // Release the resources of the origin image:
        image.Dispose();

        return bmp;
    }       

    public static Image Crop(this Image image, Rectangle selection)
    {
        Bitmap bmp = image as Bitmap;

        // Check if it is a bitmap:
        if (bmp == null)
            throw new ArgumentException("Kein gültiges Bild (Bitmap)");

        // Crop the image:
        Bitmap cropBmp = bmp.Clone(selection, bmp.PixelFormat);

        // Release the resources:
        image.Dispose();

        return cropBmp;
    }

Write The Following Code For Mouse Event on PictureBox

        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                _selecting = true;
                _selection = new Rectangle(new Point(e.X, e.Y), new Size());
            }
        }

        private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left && _selecting)
            {
                // Create cropped image:
                try
                {
                    Image img = pictureBox1.Image.Crop(_selection);


                    // Fit image to the picturebox:
                    pictureBox1.Image = img.Fit2PictureBox(pictureBox1);
                }
                catch { }
                _selecting = false;
            }
        }

        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            // Update the actual size of the selection:
            if (_selecting)
            {
                _selection.Width = e.X - _selection.X;
                _selection.Height = e.Y - _selection.Y;

                // Redraw the picturebox:
                pictureBox1.Refresh();
            }
        }

        private void pictureBox1_Paint(object sender, PaintEventArgs e)
        {
            if (_selecting)
            {
                // Draw a rectangle displaying the current selection
                Pen pen = Pens.LightSkyBlue;
                e.Graphics.DrawRectangle(pen, _selection);
            }
        }

Output Screen

1. Before Cropping

2. After Cropping