using System;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media.Animation;
using System.Windows;
using System.Windows.Media;

namespace PanAndZoom
{
    public class PanAndZoomViewer : ContentControl
    {
        public double DefaultZoomFactor { get; set; }
        private FrameworkElement source;
        private Point ScreenStartPoint = new Point(0, 0);
        private TranslateTransform translateTransform;
        private ScaleTransform zoomTransform;
        private TransformGroup transformGroup;
        private Point startOffset;

        public PanAndZoomViewer()
        {
            this.DefaultZoomFactor = 1.4;
        }

        public override void OnApplyTemplate()
        {
            base.OnApplyTemplate();
            Setup(this);
        }

        void Setup(FrameworkElement control)
        {
            this.source = VisualTreeHelper.GetChild(this, 0) as FrameworkElement;

            this.translateTransform = new TranslateTransform();
            this.zoomTransform = new ScaleTransform();
            this.transformGroup = new TransformGroup();
            this.transformGroup.Children.Add(this.zoomTransform);
            this.transformGroup.Children.Add(this.translateTransform);
            this.source.RenderTransform = this.transformGroup;
            this.Focusable = true;
            this.KeyDown += new KeyEventHandler(source_KeyDown);
            this.MouseMove += new MouseEventHandler(control_MouseMove);
            this.MouseDown += new MouseButtonEventHandler(source_MouseDown);
            this.MouseUp += new MouseButtonEventHandler(source_MouseUp);
            this.MouseWheel += new MouseWheelEventHandler(source_MouseWheel);
        }

        void source_KeyDown(object sender, KeyEventArgs e)
        {
            // hit escape to reset everything
            if (e.Key == Key.Escape) Reset();
        }

        void source_MouseWheel(object sender, MouseWheelEventArgs e)
        {
            // zoom into the content.  Calculate the zoom factor based on the direction of the mouse wheel.
            double zoomFactor = this.DefaultZoomFactor;
            if (e.Delta <= 0) zoomFactor = 1.0 / this.DefaultZoomFactor;
            // DoZoom requires both the logical and physical location of the mouse pointer
            var physicalPoint = e.GetPosition(this);
            DoZoom(zoomFactor, this.transformGroup.Inverse.Transform(physicalPoint), physicalPoint);

        }

        void source_MouseUp(object sender, MouseButtonEventArgs e)
        {
            if (this.IsMouseCaptured)
            {
                // we‘re done.  reset the cursor and release the mouse pointer
                this.Cursor = Cursors.Arrow;
                this.ReleaseMouseCapture();
            }
        }

        void source_MouseDown(object sender, MouseButtonEventArgs e)
        {
            // Save starting point, used later when determining how much to scroll.
            this.ScreenStartPoint = e.GetPosition(this);
            this.startOffset = new Point(this.translateTransform.X, this.translateTransform.Y);
            this.CaptureMouse();
            this.Cursor = Cursors.ScrollAll;
        }


        void control_MouseMove(object sender, MouseEventArgs e)
        {
            if (this.IsMouseCaptured)
            {
                // if the mouse is captured then move the content by changing the translate transform.  
                // use the Pan Animation to animate to the new location based on the delta between the 
                // starting point of the mouse and the current point.
                var physicalPoint = e.GetPosition(this);
                this.translateTransform.BeginAnimation(TranslateTransform.XProperty, CreatePanAnimation(physicalPoint.X - this.ScreenStartPoint.X + this.startOffset.X), HandoffBehavior.Compose);
                this.translateTransform.BeginAnimation(TranslateTransform.YProperty, CreatePanAnimation(physicalPoint.Y - this.ScreenStartPoint.Y + this.startOffset.Y), HandoffBehavior.Compose);
            }
        }


        /// <summary>Helper to create the panning animation for x,y coordinates.</summary>
        /// <param name="toValue">New value of the coordinate.</param>
        /// <returns>Double animation</returns>
        private DoubleAnimation CreatePanAnimation(double toValue)
        {
            var da = new DoubleAnimation(toValue, new Duration(TimeSpan.FromMilliseconds(300)));
            da.AccelerationRatio = 0.1;
            da.DecelerationRatio = 0.9;
            da.FillBehavior = FillBehavior.HoldEnd;
            da.Freeze();
            return da;
        }


        /// <summary>Helper to create the zoom double animation for scaling.</summary>
        /// <param name="toValue">Value to animate to.</param>
        /// <returns>Double animation.</returns>
        private DoubleAnimation CreateZoomAnimation(double toValue)
        {
            var da = new DoubleAnimation(toValue, new Duration(TimeSpan.FromMilliseconds(500)));
            da.AccelerationRatio = 0.1;
            da.DecelerationRatio = 0.9;
            da.FillBehavior = FillBehavior.HoldEnd;
            da.Freeze();
            return da;
        }

        /// <summary>Zoom into or out of the content.</summary>
        /// <param name="deltaZoom">Factor to mutliply the zoom level by. </param>
        /// <param name="mousePosition">Logical mouse position relative to the original content.</param>
        /// <param name="physicalPosition">Actual mouse position on the screen (relative to the parent window)</param>
        public void DoZoom(double deltaZoom, Point mousePosition, Point physicalPosition)
        {
            double currentZoom = this.zoomTransform.ScaleX;
            currentZoom *= deltaZoom;
            this.translateTransform.BeginAnimation(TranslateTransform.XProperty, CreateZoomAnimation(-1 * (mousePosition.X * currentZoom - physicalPosition.X)));
            this.translateTransform.BeginAnimation(TranslateTransform.YProperty, CreateZoomAnimation(-1 * (mousePosition.Y * currentZoom - physicalPosition.Y)));
            this.zoomTransform.BeginAnimation(ScaleTransform.ScaleXProperty, CreateZoomAnimation(currentZoom));
            this.zoomTransform.BeginAnimation(ScaleTransform.ScaleYProperty, CreateZoomAnimation(currentZoom));
        }

        /// <summary>Reset to default zoom level and centered content.</summary>
        public void Reset()
        {
            this.translateTransform.BeginAnimation(TranslateTransform.XProperty, CreateZoomAnimation(0));
            this.translateTransform.BeginAnimation(TranslateTransform.YProperty, CreateZoomAnimation(0));
            this.zoomTransform.BeginAnimation(ScaleTransform.ScaleXProperty, CreateZoomAnimation(1));
            this.zoomTransform.BeginAnimation(ScaleTransform.ScaleYProperty, CreateZoomAnimation(1));
        }
    }
}

            <WrapPanel Grid.Row="2" Grid.Column="0">
                <Label Name="lab长度" Content="长度：" Margin="3" />
                <Slider Name="sl长度" MinWidth="50" Margin="3" VerticalAlignment="Center" Maximum="400" Value="http://www.mamicode.com/{Binding ElementName=img图片, Path=Width, Mode=TwoWay}" />

                <Label Name="lab宽度" Content="宽度：" Margin="3" />
                <Slider Name="sl宽度" MinWidth="50" Margin="3" VerticalAlignment="Center" Maximum="400" Value="http://www.mamicode.com/{Binding ElementName=img图片, Path=Height, Mode=TwoWay}" />

                <Label Name="lab透明度" Content="透明度：" Margin="3" />
                <Slider Name="sl透明度" MinWidth="50" Margin="3" VerticalAlignment="Center" Maximum="1" Value="http://www.mamicode.com/{Binding ElementName=img图片, Path=Opacity, Mode=TwoWay}" />

                <Label Name="lab拉伸方式" Content="拉伸方式：" Margin="3" />
                <ComboBox Name="txt拉伸方式" Margin="3" MinWidth="85">
                    <ComboBoxItem Content="Fill" />
                    <ComboBoxItem Content="None" IsSelected="True" />
                    <ComboBoxItem Content="Uniform" />
                    <ComboBoxItem Content="UniformToFill" />
                </ComboBox>
            </WrapPanel>

            <local:PanAndZoomViewer Grid.Row="3" Grid.Column="0" Height="300" Margin="3">
                <Image Name="img图片" Stretch="{Binding ElementName=txt拉伸方式, Path=Text, Mode=TwoWay}" />
            </local:PanAndZoomViewer>

        private void fnStartDownload(string v_strImgPath, string v_strOutputDir, out string v_strTmpPath)
        {
            int n = v_strImgPath.LastIndexOf(‘/‘);
            string URLAddress = v_strImgPath.Substring(0, n);
            string fileName = v_strImgPath.Substring(n + 1, v_strImgPath.Length - n - 1);
            this.__OutputFileName = v_strOutputDir + "\\" + fileName.Substring(0, fileName.LastIndexOf("."));

            if (!Directory.Exists(System.Configuration.ConfigurationManager.AppSettings["tmpPath"]))
            {
                Directory.CreateDirectory(System.Configuration.ConfigurationManager.AppSettings["tmpPath"]);
            }

            string Dir = System.Configuration.ConfigurationManager.AppSettings["tmpPath"];
            v_strTmpPath = Dir + "\\" + fileName;

            WebRequest myre = WebRequest.Create(URLAddress);
            client.DownloadFile(v_strImgPath, v_strTmpPath);


            //Stream str = client.OpenRead(v_strImgPath);
            //StreamReader reader = new StreamReader(str);
            //byte[] mbyte = new byte[Int32.Parse(System.Configuration.ConfigurationManager.AppSettings["MaxDownloadImgLength"])];
            //int allmybyte = (int)mbyte.Length;
            //int startmbyte = 0;
            //while (allmybyte > 0)
            //{
            //    int m = str.Read(mbyte, startmbyte, allmybyte);
            //    if (m == 0)
            //    {
            //        break;
            //    }

            //    startmbyte += m;
            //    allmybyte -= m;
            //}

            //FileStream fstr = new FileStream(v_strTmpPath, FileMode.Create, FileAccess.Write);
            //fstr.Write(mbyte, 0, startmbyte);
            //str.Close();
            //fstr.Close();
        }

        private void fnOCR(string v_strTesseractPath, string v_strSourceImgPath, string v_strOutputPath, string v_strLangPath)
        {
            using (Process process = new System.Diagnostics.Process())
            {
                process.StartInfo.FileName = v_strTesseractPath;
                process.StartInfo.Arguments = v_strSourceImgPath + " " + v_strOutputPath + " -l " + v_strLangPath;
                process.StartInfo.UseShellExecute = false;
                process.StartInfo.CreateNoWindow = true;
                process.StartInfo.RedirectStandardOutput = true;
                process.Start();
                process.WaitForExit();
            }
        }