Zooming of an image using mousewheel.

Question

In the code below I am trying to zoom the image via a mouse wheel. But the code is not working properly, it is just refreshing the panel but it does not resize it. Actually

Answer 1

Source

Updated code by adding a new ImageProperty so you can set directly the Image;

public class PictureBox : System.Windows.Forms.UserControl
    {
        #region Members

        private System.Windows.Forms.PictureBox PicBox;
        private Panel OuterPanel;
        private Container components = null;
        private string m_sPicName = "";

        #endregion

        #region Constants

        private double ZOOMFACTOR = 1.25;   // = 25% smaller or larger
        private int MINMAX = 5;             // 5 times bigger or smaller than the ctrl

        #endregion

        #region Designer generated code

        private void InitializeComponent()
        {
            this.PicBox = new System.Windows.Forms.PictureBox();
            this.OuterPanel = new System.Windows.Forms.Panel();
            this.OuterPanel.SuspendLayout();
            this.SuspendLayout();
            // 
            // PicBox
            // 
            this.PicBox.Location = new System.Drawing.Point(0, 0);
            this.PicBox.Name = "PicBox";
            this.PicBox.Size = new System.Drawing.Size(150, 140);
            this.PicBox.TabIndex = 3;
            this.PicBox.TabStop = false;
            // 
            // OuterPanel
            // 
            this.OuterPanel.AutoScroll = true;
            this.OuterPanel.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
            this.OuterPanel.Controls.Add(this.PicBox);
            this.OuterPanel.Dock = System.Windows.Forms.DockStyle.Fill;
            this.OuterPanel.Location = new System.Drawing.Point(0, 0);
            this.OuterPanel.Name = "OuterPanel";
            this.OuterPanel.Size = new System.Drawing.Size(210, 190);
            this.OuterPanel.TabIndex = 4;
            // 
            // PictureBox
            // 
            this.Controls.Add(this.OuterPanel);
            this.Name = "PictureBox";
            this.Size = new System.Drawing.Size(210, 190);
            this.OuterPanel.ResumeLayout(false);
            this.ResumeLayout(false);

        }
        #endregion

        #region Constructors

        public PictureBox()
        {
            InitializeComponent();
            InitCtrl(); // my special settings for the ctrl
        }

        #endregion

        #region Properties

        private Image _pictureImage;
        public Image PictureImage
        {
            get { return _pictureImage; }
            set
            {
                if (null != value)
                {
                    try
                    {
                        PicBox.Image = value;
                        _pictureImage = value;
                    }
                    catch (OutOfMemoryException ex)
                    {
                        RedCross();
                    }
                }
                else
                {
                    RedCross();
                }
            }
        }

        /// 

        /// Property to select the picture which is displayed in the picturebox. If the 
        /// file doesn´t exist or we receive an exception, the picturebox displays 
        /// a red cross.
        /// 
        /// Complete filename of the picture, including path information
        /// Supported fileformat: *.gif, *.tif, *.jpg, *.bmp
        /// 

        [Browsable(false)]
        public string Picture
        {
            get { return m_sPicName; }
            set
            {
                if (null != value)
                {
                    if (System.IO.File.Exists(value))
                    {
                        try
                        {
                            PicBox.Image = Image.FromFile(value);
                            m_sPicName = value;
                        }
                        catch (OutOfMemoryException ex)
                        {
                            RedCross();
                        }
                    }
                    else
                    {
                        RedCross();
                    }
                }
            }
        }

        /// 

        /// Set the frametype of the picturbox
        /// 
        [Browsable(false)]
        public BorderStyle Border
        {
            get { return OuterPanel.BorderStyle; }
            set { OuterPanel.BorderStyle = value; }
        }

        #endregion

        #region Other Methods

        /// 

        /// Special settings for the picturebox ctrl
        /// 
        private void InitCtrl()
        {
            PicBox.SizeMode = PictureBoxSizeMode.StretchImage;
            PicBox.Location = new Point(0, 0);
            OuterPanel.Dock = DockStyle.Fill;
            OuterPanel.Cursor = System.Windows.Forms.Cursors.NoMove2D;
            OuterPanel.AutoScroll = true;
            OuterPanel.MouseEnter += new EventHandler(PicBox_MouseEnter);
            PicBox.MouseEnter += new EventHandler(PicBox_MouseEnter);
            OuterPanel.MouseWheel += new MouseEventHandler(PicBox_MouseWheel);
        }

        /// 

        /// Create a simple red cross as a bitmap and display it in the picturebox
        /// 
        private void RedCross()
        {
            Bitmap bmp = new Bitmap(OuterPanel.Width, OuterPanel.Height, System.Drawing.Imaging.PixelFormat.Format16bppRgb555);
            Graphics gr;
            gr = Graphics.FromImage(bmp);
            Pen pencil = new Pen(Color.Red, 5);
            gr.DrawLine(pencil, 0, 0, OuterPanel.Width, OuterPanel.Height);
            gr.DrawLine(pencil, 0, OuterPanel.Height, OuterPanel.Width, 0);
            PicBox.Image = bmp;
            gr.Dispose();
        }

        #endregion

        #region Zooming Methods

        /// 

        /// Make the PictureBox dimensions larger to effect the Zoom.
        /// 
        /// Maximum 5 times bigger
        private void ZoomIn()
        {
            if ((PicBox.Width < (MINMAX * OuterPanel.Width)) &&
                (PicBox.Height < (MINMAX * OuterPanel.Height)))
            {
                PicBox.Width = Convert.ToInt32(PicBox.Width * ZOOMFACTOR);
                PicBox.Height = Convert.ToInt32(PicBox.Height * ZOOMFACTOR);
                PicBox.SizeMode = PictureBoxSizeMode.StretchImage;
            }
        }

        /// 

        /// Make the PictureBox dimensions smaller to effect the Zoom.
        /// 
        /// Minimum 5 times smaller
        private void ZoomOut()
        {
            if ((PicBox.Width > (OuterPanel.Width / MINMAX)) &&
                (PicBox.Height > (OuterPanel.Height / MINMAX)))
            {
                PicBox.SizeMode = PictureBoxSizeMode.StretchImage;
                PicBox.Width = Convert.ToInt32(PicBox.Width / ZOOMFACTOR);
                PicBox.Height = Convert.ToInt32(PicBox.Height / ZOOMFACTOR);
            }
        }

        #endregion

        #region Mouse events

        /// 

        /// We use the mousewheel to zoom the picture in or out
        /// 
        /// 
        /// 
        private void PicBox_MouseWheel(object sender, MouseEventArgs e)
        {
            if (e.Delta < 0)
            {
                ZoomIn();
            }
            else
            {
                ZoomOut();
            }
        }

        /// 

        /// Make sure that the PicBox have the focus, otherwise it doesn´t receive 
        /// mousewheel events !.
        /// 
        /// 
        /// 
        private void PicBox_MouseEnter(object sender, EventArgs e)
        {
            if (PicBox.Focused == false)
            {
                PicBox.Focus();
            }
        }

        #endregion

        #region Disposing

        /// 

        /// Die verwendeten Ressourcen bereinigen.
        /// 
        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                if (components != null)
                    components.Dispose();
            }
            base.Dispose(disposing);
        }

        #endregion
    }


 private void Form2_Load(object sender, EventArgs e)
 {
      pictureBox1.PictureImage = Image.FromStream(Decrypt.ms1);
 }