zoom Method

ImageViewer.prototype.zoom = function(sizeMode, zoomValue, origin) 

var myImageViewer = this._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 
var _zoomRatio = 1.2; 
 
var updateZoomValueFromView = function () { 
   // Get the current scale factor from the viewer and set it in the zoom combo box 
   var percentage = myImageViewer.scaleFactor * 100.0; 
   var zoomComboBox = document.getElementById("zoomComboBox"); 
   zoomComboBox.selectedItem = percentage + "%"; 
}; 
 
var initZoom = function (zoomComboBox, zoomInButton, zoomOutButton) { 
   // Add support for user typing the zoom value in the combo box directly 
   zoomComboBox.onfocusout = function () { 
      // When the user moves away from the combo box, make sure it has a valid value 
      updateZoomValueFromView(); 
   }; 
 
   zoomComboBox.onkeydown = function (e) { 
      // Check if the finished editing by pressing Enter 
      if (e.keyCode == 13) { 
         // Yes, get the new value 
         var value = zoomComboBox.textContent.trim(); 
         if (value != null && value.length > 0) { 
            // Remove the % sign if present 
            if (value.endsWith("%")) 
               value = value.remove(value.length - 1, 1).Trim(); 
 
            // Try to parse the new zoom value 
            var percentage = value; 
            //if (double.TryParse(value, out percentage)) { 
            if (percentage != undefined) 
               // Valid value, zoom the viewer 
               myImageViewer.zoom(lt.Controls.ControlSizeMode.none, percentage / 100.0, myImageViewer.defaultZoomOrigin); 
         } 
 
         // And update the combo box from this value (in case we set a value not in the min/max range) 
         updateZoomValueFromView(); 
      } 
   }; 
 
   zoomComboBox.addEventListener("change", function () { 
      // Get the value from the combo box 
      var value = zoomComboBox.value.trim(); 
      switch (value) { 
         case "Actual Size": 
            myImageViewer.zoom(lt.Controls.ControlSizeMode.actualSize, 1, myImageViewer.defaultZoomOrigin); 
            break; 
 
         case "Fit Page": 
            myImageViewer.zoom(lt.Controls.ControlSizeMode.fitAlways, 1, myImageViewer.defaultZoomOrigin); 
            break; 
 
         case "Fit Width": 
            myImageViewer.zoom(lt.Controls.ControlSizeMode.fitWidth, 1, myImageViewer.defaultZoomOrigin); 
            break; 
 
         case "Fit Height": 
            myImageViewer.zoom(lt.Controls.ControlSizeMode.fitHeight, 1, myImageViewer.defaultZoomOrigin); 
            break; 
 
         default: 
            if (value != null && value.length > 0) { 
               // A percentage, use it 
               var percentage = value.substring(0, value.length - 1); 
               myImageViewer.zoom(lt.Controls.ControlSizeMode.none, percentage / 100.0, myImageViewer.defaultZoomOrigin); 
            } 
            break; 
      } 
   }); 
 
   // For zoom in button, use current ScaleFactor multiplied by the ratio 
   zoomInButton.addEventListener("click", function () { 
      myImageViewer.zoom(lt.Controls.ControlSizeMode.none, myImageViewer.scaleFactor * _zoomRatio, myImageViewer.defaultZoomOrigin); 
   }); 
 
   // For zoom out button, use current ScaleFactor divided by the ratio 
   zoomOutButton.addEventListener("click", function () { 
      myImageViewer.zoom(lt.Controls.ControlSizeMode.none, myImageViewer.scaleFactor / _zoomRatio, myImageViewer.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 
   myImageViewer.transformChanged.add(function (sender, e) { 
      updateZoomValueFromView(); 
   }); 
 
   // Get the value from the viewer into the combo box 
   updateZoomValueFromView(); 
} 
 
// Create a panel to the top 
var panel = document.createElement("div"); 
panel.style.width = "800"; 
panel.style.height = "800"; 
document.body.appendChild(panel); 
 
// Add a combo box for the zoom values 
var zoomComboBox = document.createElement("select"); 
zoomComboBox.id = "zoomComboBox"; 
zoomComboBox.offsetTop = 8; 
zoomComboBox.offsetLeft = 8; 
 
var itemsArray = ["10%", "25%", "50%", "75%", "100%", "125%", "200%", "400%", "800%", 
   "1600%", "2400%", "3200%", "6400%", "Actual Size", "Fit Page", "Fit Width", "Fit Height"]; 
 
// Add default zoom values 
for (var i = 0; i < itemsArray.length; i++) { 
   var option = document.createElement("option"); 
   option.textContent = itemsArray[i]; 
   zoomComboBox.appendChild(option); 
} 
 
panel.appendChild(zoomComboBox); 
 
// Add zoom in and out buttons 
var zoomInButton = document.createElement("button"); 
zoomInButton.textContent = "+"; 
zoomInButton.offsetTop = zoomComboBox.offsetTop - 1; 
zoomInButton.offsetLeft = zoomComboBox.offsetWidth + 8; 
panel.appendChild(zoomInButton); 
 
var zoomOutButton = document.createElement("button"); 
zoomOutButton.textContent = "-"; 
zoomOutButton.offsetTop = zoomComboBox.offsetTop - 1; 
zoomOutButton.offsetLeft = zoomComboBox.offsetWidth + 2; 
panel.appendChild(zoomOutButton); 
 
// Set UseDpi to true to view the image at its original resolution 
this._imageViewer.useDpi = true; 
 
// Add Pan/Zoom interactive mode 
// Click and drag to pan, CTRL-Click and drag to zoom in and out 
this._imageViewer.defaultInteractiveMode = new lt.Controls.ImageViewerPanZoomInteractiveMode(); 
 
// Initialize the zoom system 
initZoom(zoomComboBox, zoomInButton, zoomOutButton);