c# - 使用鼠标滚轮缩放图像。

Question

在下面的代码中，我试图通过鼠标滚轮缩放图像。但是代码不能正常工作，它只是刷新面板但没有调整它的大小。实际上，我正在从另一个名为 decrypt 的类创建的内存流中获取图像。完整图像显示正确，但我无法使用鼠标滚轮事件执行图像缩放。请帮助我。

private void Form2_Load(object sender, EventArgs e)
{
    this.Width = Screen.PrimaryScreen.WorkingArea.Width;
    this.Height = Screen.PrimaryScreen.WorkingArea.Height;
    this.CenterToScreen();
    PicturePanel= new PictureBox();

    PicturePanel.Dock = DockStyle.Fill;
    //PicturePanel.SizeMode = PictureBoxSizeMode.AutoSize;

    //PicturePanel.SizeMode = PictureBoxSizeMode.CenterImage;
    PicturePanel.Focus();
    //PicturePanel.MouseWheel += new System.Windows.Forms.MouseEventHandler(this.OnMouseWheel);
    this.Controls.Add(PicturePanel);


    View_codee v = new View_codee();

    try
    {
        PicturePanel.Image = Image.FromStream(Decrypt.ms1);
    }
    catch (Exception ee)
    {
        MessageBox.Show(ee.Message);
    }
    this.Name = "";
} 



protected override void OnMouseWheel(MouseEventArgs mea)
{
    // Override OnMouseWheel event, for zooming in/out with the scroll wheel
    if (PicturePanel.Image != null)
    {
        // If the mouse wheel is moved forward (Zoom in)
        if (mea.Delta > 0)
        {
            // Check if the pictureBox dimensions are in range (15 is the minimum and maximum zoom level)
            if ((PicturePanel.Width < (15 * this.Width)) && (PicturePanel.Height < (15 * this.Height)))
            {
                // Change the size of the picturebox, multiply it by the ZOOMFACTOR
                PicturePanel.Width = (int)(PicturePanel.Width * 1.25);
                PicturePanel.Height = (int)(PicturePanel.Height * 1.25);

                // Formula to move the picturebox, to zoom in the point selected by the mouse cursor
                PicturePanel.Top = (int)(mea.Y - 1.25 * (mea.Y - PicturePanel.Top));
                PicturePanel.Left = (int)(mea.X - 1.25 * (mea.X - PicturePanel.Left));
            }
        }
        else
        {
            // Check if the pictureBox dimensions are in range (15 is the minimum and maximum zoom level)
            if ((PicturePanel.Width > (this.Width / 15)) && (PicturePanel.Height > (this.Height / 15)))
            {
                // Change the size of the picturebox, divide it by the ZOOMFACTOR
                PicturePanel.Width = (int)(PicturePanel.Width / 1.25);
                PicturePanel.Height = (int)(PicturePanel.Height / 1.25);

                // Formula to move the picturebox, to zoom in the point selected by the mouse cursor
                PicturePanel.Top = (int)(mea.Y - 0.80 * (mea.Y - PicturePanel.Top));
                PicturePanel.Left = (int)(mea.X - 0.80 * (mea.X - PicturePanel.Left));
            }
        }
    }
}      

Answer 1

Source

通过添加新的 ImageProperty 更新了代码，因此您可以直接设置 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();
                }
            }
        }

        /// <summary>
        /// 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.
        /// </summary>
        /// <value>Complete filename of the picture, including path information</value>
        /// <remarks>Supported fileformat: *.gif, *.tif, *.jpg, *.bmp</remarks>
        /// 

        [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();
                    }
                }
            }
        }

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

        #endregion

        #region Other Methods

        /// <summary>
        /// Special settings for the picturebox ctrl
        /// </summary>
        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);
        }

        /// <summary>
        /// Create a simple red cross as a bitmap and display it in the picturebox
        /// </summary>
        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

        /// <summary>
        /// Make the PictureBox dimensions larger to effect the Zoom.
        /// </summary>
        /// <remarks>Maximum 5 times bigger</remarks>
        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;
            }
        }

        /// <summary>
        /// Make the PictureBox dimensions smaller to effect the Zoom.
        /// </summary>
        /// <remarks>Minimum 5 times smaller</remarks>
        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

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

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

        #endregion

        #region Disposing

        /// <summary>
        /// Die verwendeten Ressourcen bereinigen.
        /// </summary>
        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);
 }