Zoom Method

using Leadtools; 
using Leadtools.Controls; 
using Leadtools.Codecs; 
using Leadtools.Drawing; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
 
 
public void ImageViewerZoom_Example() 
{ 
   // Create the form that holds the ImageViewer 
   new MyForm2().ShowDialog(); 
} 
 
class MyForm2 : Form 
{ 
   public MyForm2() 
   { 
      this.Size = new Size(800, 800); 
   } 
 
   // LEADTOOLS ImageViewer to be used with this example 
   private ImageViewer _imageViewer; 
   // Ratio to use when the user zooms in or out. Change this if another value is needed, 
   // for example, 2.0 will zoom the viewer in by 200% and out by 50% each time 
   private const double _zoomRatio = 1.2; 
 
   protected override void OnLoad(EventArgs e) 
   { 
      // Create a panel to the top 
      var panel = new Panel(); 
      panel.Dock = DockStyle.Top; 
      panel.BorderStyle = BorderStyle.FixedSingle; 
      this.Controls.Add(panel); 
 
      // Add a combo box for the zoom values 
      var zoomComboBox = new ComboBox(); 
      zoomComboBox.Name = "zoomComboBox"; 
      zoomComboBox.Location = new Point(8, 8); 
      zoomComboBox.DropDownStyle = ComboBoxStyle.DropDown; 
 
      // Add default zoom values 
      zoomComboBox.Items.AddRange(new string[] 
      { 
         "10%", "25%", "50%", "75%", "100%", "125%", "200%", "400%", "800%", 
         "1600%", "2400%", "3200%", "6400%", "Actual Size", "Fit Page", "Fit Width", "Fit Height" 
      }); 
      panel.Controls.Add(zoomComboBox); 
 
      // Add zoom in and out buttons 
      var zoomInButton = new Button(); 
      zoomInButton.Text = "+"; 
      zoomInButton.Location = new Point(zoomComboBox.Right + 8, zoomComboBox.Top - 1); 
      panel.Controls.Add(zoomInButton); 
      var zoomOutButton = new Button(); 
      zoomOutButton.Text = "-"; 
      zoomOutButton.Location = new Point(zoomInButton.Right + 2, zoomComboBox.Top - 1); 
      panel.Controls.Add(zoomOutButton); 
 
      // Create the image viewer taking the rest of the form 
      _imageViewer = new ImageViewer(); 
      _imageViewer.Dock = DockStyle.Fill; 
      _imageViewer.ViewBorderThickness = 1; 
      this.Controls.Add(_imageViewer); 
      _imageViewer.BringToFront(); 
 
      // Set UseDpi to true to view the image at its original resolution 
      _imageViewer.UseDpi = true; 
 
      // Add Pan/Zoom interactive mode 
      // Click and drag to pan, CTRL-Click and drag to zoom in and out 
      _imageViewer.DefaultInteractiveMode = new ImageViewerPanZoomInteractiveMode(); 
 
      // Initialize the zoom system 
      InitZoom(zoomComboBox, zoomInButton, zoomOutButton); 
 
      // Load an image 
      using (var codecs = new RasterCodecs()) 
         _imageViewer.Image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif")); 
 
      base.OnLoad(e); 
   } 
 
   private void UpdateZoomValueFromView() 
   { 
      // Get the current scale factor from the viewer and set it in the zoom combo box 
      var percentage = _imageViewer.ScaleFactor * 100.0; 
      var zoomComboBox = this.Controls.Find("zoomComboBox", true)[0] as ComboBox; 
      zoomComboBox.Text = percentage.ToString("F1") + "%"; 
   } 
 
   private void InitZoom(ComboBox zoomComboBox, Button zoomInButton, Button zoomOutButton) 
   { 
      // Add support for user typing the zoom value in the combo box directly 
      zoomComboBox.LostFocus += (sender, e) => 
      { 
         // When the user moves away from the combo box, make sure it has a valid value 
         UpdateZoomValueFromView(); 
      }; 
 
      zoomComboBox.KeyPress += (sender, e) => 
      { 
         // Check if the finished editing by pressing Enter 
         if (e.KeyChar == (char)Keys.Return) 
         { 
            // Yes, get the new value 
            var value = zoomComboBox.Text.Trim(); 
            if (!string.IsNullOrEmpty(value)) 
            { 
               // Remove the % sign if present 
               if (value.EndsWith("%")) 
                  value = value.Remove(value.Length - 1, 1).Trim(); 
 
               // Try to parse the new zoom value 
               double percentage; 
               if (double.TryParse(value, out percentage)) 
               { 
                  // Valid value, zoom the viewer 
                  _imageViewer.Zoom(ControlSizeMode.None, percentage / 100.0, _imageViewer.DefaultZoomOrigin); 
               } 
 
               // And update the combo box from this value (in case we set a value not in the min/max range) 
               UpdateZoomValueFromView(); 
            } 
         } 
      }; 
 
      zoomComboBox.SelectedIndexChanged += (sender, e) => 
      { 
         // Get the value from the combo box 
         var value = zoomComboBox.Text.Trim(); 
         switch (value) 
         { 
            case "Actual Size": 
               _imageViewer.Zoom(ControlSizeMode.ActualSize, 1, _imageViewer.DefaultZoomOrigin); 
               break; 
 
            case "Fit Page": 
               _imageViewer.Zoom(ControlSizeMode.FitAlways, 1, _imageViewer.DefaultZoomOrigin); 
               break; 
 
            case "Fit Width": 
               _imageViewer.Zoom(ControlSizeMode.FitWidth, 1, _imageViewer.DefaultZoomOrigin); 
               break; 
 
            case "Fit Height": 
               _imageViewer.Zoom(ControlSizeMode.FitHeight, 1, _imageViewer.DefaultZoomOrigin); 
               break; 
 
            default: 
               if (!string.IsNullOrEmpty(value)) 
               { 
                  // A percentage, use it 
                  var percentage = double.Parse(value.Substring(0, value.Length - 1)); 
                  _imageViewer.Zoom(ControlSizeMode.None, percentage / 100.0, _imageViewer.DefaultZoomOrigin); 
               } 
               break; 
         } 
      }; 
 
      // For zoom in button, use current ScaleFactor multiplied by the ratio 
      zoomInButton.Click += (sender, e) => 
      { 
         _imageViewer.Zoom(ControlSizeMode.None, _imageViewer.ScaleFactor * _zoomRatio, _imageViewer.DefaultZoomOrigin); 
      }; 
 
      // For zoom out button, use current ScaleFactor divided by the ratio 
      zoomOutButton.Click += (sender, e) => 
      { 
         _imageViewer.Zoom(ControlSizeMode.None, _imageViewer.ScaleFactor / _zoomRatio, _imageViewer.DefaultZoomOrigin); 
      }; 
 
      // Also update the value from the viewer when the transform changed, this happens if the user selects a fit mode, 
      // such as fit width or fit page. The viewer will change the scale factor accordingly and we need to update it 
      // in our combo box 
      // This also takes care of Pan/Zoom interactive mode updating the scale fatcor 
      _imageViewer.TransformChanged += (sender, e) => 
      { 
         UpdateZoomValueFromView(); 
      }; 
 
      // Get the value from the viewer into the combo box 
      UpdateZoomValueFromView(); 
   } 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images"; 
}