currentPageNumber Property

Summary

Gets the current page number.

Syntax
TypeScript
JavaScript
Object.defineProperty(DocumentViewer.prototype, 'currentPageNumber', 
	get: function() 
) 
currentPageNumber: number; // read-only 

Property Value

The 1-based number of the current page.

Remarks

The CurrentPageNumber is the page with the largest area currently visible in the View.

This is obtained by calling View.ImageViewer.GetLargestVisibleItemIndex.

The value changes when the user scrolls the view, or zooms in or out. It should not be saved. Instead, use CurrentPageNumber every time the "largest visible page" is needed. For example, the application can have a "Find text in this page" or "Find text in the whole document" operation. When the user runs the "Find text in this page", they are referring to the largest page in the viewer, and the application should call CurrentPageNumber to get this value when the action is invoked.

currentPageNumber is used in end-user applications as well as internally with many commands. The currentPageNumber value updates automatically as the user scrolls and interacts with the view. The currentPageNumber algorithm is "smart" and will generally show one of the following states:

To tie currentPageNumber with the current view's ImageViewer.activeItem and not update when the user scrolls the view, set the value of smartCurrentPageNumber to false.

Users can listen for changes to currentPageNumber (and cancel incoming changes) by listening for the DocumentViewerOperation.currentPageNumberChanged operation. CurrentPageNumberChangeData and CurrentPageNumberChangedCause will be available to inspect the changing page number and its cause.

Example

In this example, clicking the example button will add a callback to show the updated current page number when the user clicks a link or thumbnail.

CurrentPageNumber.ts
ViewerInitializer.ts
CurrentPageNumber.js
ViewerInitializer.js
CurrentPageNumber.html
examples.css
import { ViewerInitializer } from "../utilities/ViewerInitializer"; 
 
export class CurrentPageNumberTSExample { 
   public run = () => { 
      new ViewerInitializer(this.addOperationEvent); 
   } 
 
   addOperationEvent = (documentViewer: lt.Document.Viewer.DocumentViewer) => { 
      const outputElement = document.getElementById('output'); 
      // Add a callback for when the user clicks a link (bookmark on the page, for example) 
      documentViewer.operation.add((sender:any, e:lt.Document.Viewer.DocumentViewerOperationEventArgs)=>{ 
         // If the user went to a new page (e.g. after clicking a link or thumbnail)... 
         if (e.operation === lt.Document.Viewer.DocumentViewerOperation.gotoPage && e.isPostOperation) { 
             // ...update the page number 
             outputElement.innerHTML = 'The current page number is now ' + documentViewer.currentPageNumber; 
         } 
     }); 
   } 
} 
export class ViewerInitializer { 
   private callback: (viewer: lt.Document.Viewer.DocumentViewer) => void = null; 
 
   constructor(callback?: (viewer: lt.Document.Viewer.DocumentViewer) => void) { 
      this.callback = callback; 
      this.init(); 
   } 
 
   public static showServiceError = (jqXHR, statusText, errorThrown) => { 
      alert('Error returned from service. See the console for details.') 
      const serviceError = lt.Document.ServiceError.parseError(jqXHR, statusText, errorThrown); 
      console.error(serviceError); 
   } 
 
   private init = () => { 
      this.initFactory(); 
      this.testConnection(); 
   } 
 
   private initFactory = () => { 
      lt.RasterSupport.setLicenseUri('https://demo.leadtools.com/licenses/v200/LEADTOOLSEVAL.txt', 'EVAL', null); 
 
      // To communicate with the DocumentsService, it must be running! 
      // Change these parameters to match the path to the service. 
      lt.Document.DocumentFactory.serviceHost = 'http://localhost:40000'; 
      lt.Document.DocumentFactory.servicePath = ''; 
      lt.Document.DocumentFactory.serviceApiPath = 'api'; 
   } 
 
   private testConnection = () => { 
      const serviceStatus = document.getElementById('serviceStatus'); 
      serviceStatus.innerHTML = 'Connecting to service: ' + lt.Document.DocumentFactory.serviceUri; 
 
      lt.Document.DocumentFactory.verifyService() 
         .done((serviceData) => { 
            serviceStatus.innerHTML = 'Service connection verified!'; 
            this.createDocumentViewer(); 
         }) 
         .fail((jqXHR, statusText, errorThrown) => { 
            serviceStatus.innerHTML = 'Service connection unavailable.'; 
            ViewerInitializer.showServiceError(jqXHR, statusText, errorThrown); 
         }); 
   } 
 
   private createDocumentViewer = () => { 
      // Initialize the user interface 
      const interactiveSelect = document.getElementById('interactiveSelect'); 
 
      const panZoomOption = document.createElement('option'); 
      panZoomOption.innerHTML = 'Pan / Zoom'; 
      panZoomOption.value = lt.Document.Viewer.DocumentViewerCommands.interactivePanZoom; 
      interactiveSelect.appendChild(panZoomOption); 
 
      const textOption = document.createElement('option'); 
      textOption.value = lt.Document.Viewer.DocumentViewerCommands.interactiveSelectText; 
      textOption.innerHTML = 'Select Text'; 
      interactiveSelect.appendChild(textOption); 
 
      let documentViewer: lt.Document.Viewer.DocumentViewer = null; 
      interactiveSelect.onchange = (e) => documentViewer.commands.run((e.target as HTMLSelectElement).value, null); 
 
      const annotationsSelect = document.getElementById('annotationsSelect'); 
 
      const annSelectOption = document.createElement('option'); 
      annSelectOption.innerHTML = 'Select Annotation'; 
      annSelectOption.value = lt.Annotations.Engine.AnnObject.selectObjectId.toString(); 
      annotationsSelect.appendChild(annSelectOption); 
 
      const annLineOption = document.createElement('option'); 
      annLineOption.innerHTML = 'Line Object'; 
      annLineOption.value = lt.Annotations.Engine.AnnObject.lineObjectId.toString(); 
      annotationsSelect.appendChild(annLineOption); 
 
      const annRectOption = document.createElement('option'); 
      annRectOption.innerHTML = 'Rectangle Object'; 
      annRectOption.value = lt.Annotations.Engine.AnnObject.rectangleObjectId.toString(); 
      annotationsSelect.appendChild(annRectOption); 
      annotationsSelect.onchange = (e) => { 
         const value = +(e.currentTarget as HTMLSelectElement).value; 
         documentViewer.annotations.automationManager.currentObjectId = value; 
      } 
 
      // Init the document viewer, pass along the panels 
      const createOptions = new lt.Document.Viewer.DocumentViewerCreateOptions(); 
      // We are not going to use elements mode in this example 
      createOptions.viewCreateOptions.useElements = false; 
      createOptions.thumbnailsCreateOptions.useElements = false; 
 
      // The middle panel for the view 
      createOptions.viewContainer = document.getElementById('viewer'); 
      // The left panel for the thumbnails 
      createOptions.thumbnailsContainer = document.getElementById('thumbnails'); 
      // The right panel is for bookmarks 
      createOptions.bookmarksContainer = document.getElementById('bookmarks'); 
      createOptions.useAnnotations = true; 
 
      // Create the document viewer 
      documentViewer = lt.Document.Viewer.DocumentViewerFactory.createDocumentViewer(createOptions); 
 
      // We prefer SVG viewing 
      documentViewer.view.preferredItemType = lt.Document.Viewer.DocumentViewerItemType.svg; 
 
      // Create html5 rendering engine 
      documentViewer.annotations.automationManager.renderingEngine = new lt.Annotations.Rendering.AnnHtml5RenderingEngine(); 
      // Initialize documentViewer annotations 
      documentViewer.annotations.initialize(); 
 
      documentViewer.annotations.automationManager.currentObjectIdChanged.add(function (sender, e) { 
         // When done drawing, the manager will return to the select object; so we need force the annotationsSelect element to return to the select object option 
         (annotationsSelect as HTMLSelectElement).value = sender.currentObjectId; 
      }); 
 
      this.loadDefaultDoc(documentViewer, interactiveSelect as HTMLSelectElement) 
   } 
 
   private loadDefaultDoc = (viewer: lt.Document.Viewer.DocumentViewer, interactiveSelect: HTMLSelectElement) => { 
      // Load a PDF document 
      const url = 'https://demo.leadtools.com/images/pdf/leadtools.pdf'; 
      lt.Document.DocumentFactory.loadFromUri(url, null) 
         .done((doc: lt.Document.LEADDocument) => { 
            const ready = () => { 
               viewer.setDocument(doc); 
               const panZoom = lt.Document.Viewer.DocumentViewerCommands.interactivePanZoom; 
               interactiveSelect.value = panZoom; 
               viewer.commands.run(panZoom, null); 
               if(this.callback) 
                  this.callback(viewer); 
            } 
 
            if (doc.isStructureSupported && !doc.structure.isParsed) 
               doc.structure.parse() 
                  .done(ready) 
                  .fail(ViewerInitializer.showServiceError); 
            else 
               ready(); 
         }) 
         .fail(ViewerInitializer.showServiceError); 
   } 
} 
import { ViewerInitializer } from "../utilities/ViewerInitializer"; 
 
export class CurrentPageNumberJSExample { 
   run = () => { 
      new ViewerInitializer(this.addOperationEvent); 
   } 
 
   addOperationEvent = (documentViewer) => { 
      const outputElement = document.getElementById("output"); 
      // Add a callback for when the user clicks a link (bookmark on the page, for example) 
      documentViewer.operation.add((sender, e)=>{ 
         // If the user went to a new page (e.g. after clicking a link or thumbnail)... 
         if (e.operation === lt.Document.Viewer.DocumentViewerOperation.gotoPage && e.isPostOperation) { 
             // ...update the page number 
             outputElement.innerHTML = "The current page number is now " + documentViewer.currentPageNumber; 
         } 
     }); 
   } 
} 
export class ViewerInitializer { 
   constructor(callback) { 
      this.callback = callback; 
      this.init(); 
   } 
 
   static showServiceError = (jqXHR, statusText, errorThrown) => { 
      alert("Error returned from service. See the console for details.") 
      const serviceError = lt.Document.ServiceError.parseError(jqXHR, statusText, errorThrown); 
      console.error(serviceError); 
   } 
 
   init = () => { 
      this.initFactory(); 
      this.testConnection(); 
   } 
 
   initFactory = () => { 
      lt.RasterSupport.setLicenseUri("https://demo.leadtools.com/licenses/v200/LEADTOOLSEVAL.txt", "EVAL", null); 
 
      // To communicate with the DocumentsService, it must be running! 
      // Change these parameters to match the path to the service. 
      lt.Document.DocumentFactory.serviceHost = "http://localhost:40000"; 
      lt.Document.DocumentFactory.servicePath = ""; 
      lt.Document.DocumentFactory.serviceApiPath = "api"; 
   } 
 
   testConnection = () => { 
      const serviceStatus = document.getElementById("serviceStatus"); 
      serviceStatus.innerHTML = "Connecting to service: " + lt.Document.DocumentFactory.serviceUri; 
 
      lt.Document.DocumentFactory.verifyService() 
         .done((serviceData) => { 
            serviceStatus.innerHTML = "Service connection verified!"; 
            this.createDocumentViewer(); 
         }) 
         .fail((jqXHR, statusText, errorThrown) => { 
            serviceStatus.innerHTML = "Service connection unavailable."; 
            ViewerInitializer.showServiceError(jqXHR, statusText, errorThrown); 
         }); 
   } 
 
   createDocumentViewer = () => { 
      // Initialize the user interface 
      const interactiveSelect = document.getElementById("interactiveSelect"); 
 
      const panZoomOption = document.createElement("option"); 
      panZoomOption.innerHTML = "Pan / Zoom"; 
      panZoomOption.value = lt.Document.Viewer.DocumentViewerCommands.interactivePanZoom; 
      interactiveSelect.appendChild(panZoomOption); 
 
      const textOption = document.createElement("option"); 
      textOption.value = lt.Document.Viewer.DocumentViewerCommands.interactiveSelectText; 
      textOption.innerHTML = "Select Text"; 
      interactiveSelect.appendChild(textOption); 
 
      let documentViewer = null; 
      interactiveSelect.onchange = (e) => documentViewer.commands.run(e.target.value, null); 
 
      const annotationsSelect = document.getElementById("annotationsSelect"); 
 
      const annSelectOption = document.createElement("option"); 
      annSelectOption.innerHTML = "Select Annotation"; 
      annSelectOption.value = lt.Annotations.Engine.AnnObject.selectObjectId.toString(); 
      annotationsSelect.appendChild(annSelectOption); 
 
      const annLineOption = document.createElement("option"); 
      annLineOption.innerHTML = "Line Object"; 
      annLineOption.value = lt.Annotations.Engine.AnnObject.lineObjectId.toString(); 
      annotationsSelect.appendChild(annLineOption); 
 
      const annRectOption = document.createElement("option"); 
      annRectOption.innerHTML = "Rectangle Object"; 
      annRectOption.value = lt.Annotations.Engine.AnnObject.rectangleObjectId.toString(); 
      annotationsSelect.appendChild(annRectOption); 
      annotationsSelect.onchange = (e) => { 
         const value = +e.currentTarget.value; 
         documentViewer.annotations.automationManager.currentObjectId = value; 
      } 
 
      // Init the document viewer, pass along the panels 
      const createOptions = new lt.Document.Viewer.DocumentViewerCreateOptions(); 
      // We are not going to use elements mode in this example 
      createOptions.viewCreateOptions.useElements = false; 
      createOptions.thumbnailsCreateOptions.useElements = false; 
 
      // The middle panel for the view 
      createOptions.viewContainer = document.getElementById("viewer"); 
      // The left panel for the thumbnails 
      createOptions.thumbnailsContainer = document.getElementById("thumbnails"); 
      // The right panel is for bookmarks 
      createOptions.bookmarksContainer = document.getElementById("bookmarks"); 
      createOptions.useAnnotations = true; 
 
      // Create the document viewer 
      documentViewer = lt.Document.Viewer.DocumentViewerFactory.createDocumentViewer(createOptions); 
 
      // We prefer SVG viewing 
      documentViewer.view.preferredItemType = lt.Document.Viewer.DocumentViewerItemType.svg; 
 
      // Create html5 rendering engine 
      documentViewer.annotations.automationManager.renderingEngine = new lt.Annotations.Rendering.AnnHtml5RenderingEngine(); 
      // Initialize documentViewer annotations 
      documentViewer.annotations.initialize(); 
 
      documentViewer.annotations.automationManager.currentObjectIdChanged.add(function (sender, e) { 
         // When done drawing, the manager will return to the select object; so we need force the annotationsSelect element to return to the select object option 
         annotationsSelect.value = sender.currentObjectId; 
      }); 
 
      this.loadDefaultDoc(documentViewer, interactiveSelect) 
   } 
 
   loadDefaultDoc = (viewer, interactiveSelect) => { 
      // Load a PDF document 
      const url = "https://demo.leadtools.com/images/pdf/leadtools.pdf"; 
      lt.Document.DocumentFactory.loadFromUri(url, null) 
         .done((doc) => { 
            const ready = () => { 
               viewer.setDocument(doc); 
               const panZoom = lt.Document.Viewer.DocumentViewerCommands.interactivePanZoom; 
               interactiveSelect.value = panZoom; 
               viewer.commands.run(panZoom, null); 
               if(this.callback) 
                  this.callback(viewer); 
            } 
 
            if (doc.isStructureSupported && !doc.structure.isParsed) 
               doc.structure.parse() 
                  .done(ready) 
                  .fail(ViewerInitializer.showServiceError); 
            else 
               ready(); 
         }) 
         .fail(ViewerInitializer.showServiceError); 
   } 
} 
<!doctype html> 
<html lang="en"> 
<title>DocViewer Example | DocumentViewer</title> 
 
<head> 
   <script src="https://code.jquery.com/jquery-2.2.4.min.js" 
      integrity="sha256-BbhdlvQf/xTY9gja0Dq3HiwQF8LaCRTXxZKRutelT44=" crossorigin="anonymous"></script> 
 
   <script src="../LT/Leadtools.js"></script> 
   <script src="../LT/Leadtools.Controls.js"></script> 
   <script src="../LT/Leadtools.Annotations.Engine.js"></script> 
   <script src="../LT/Leadtools.Annotations.Designers.js"></script> 
   <script src="../LT/Leadtools.Annotations.Rendering.Javascript.js"></script> 
   <script src="../LT/Leadtools.Annotations.Automation.js"></script> 
   <script src="../LT/Leadtools.ImageProcessing.Main.js"></script> 
   <script src="../LT/Leadtools.ImageProcessing.Color.js"></script> 
   <script src="../LT/Leadtools.ImageProcessing.Core.js"></script> 
   <script src="../LT/Leadtools.ImageProcessing.Effects.js"></script> 
   <script src="../LT/Leadtools.Document.js"></script> 
   <script src="../LT/Leadtools.Document.Viewer.js"></script> 
   <link rel="stylesheet" type="text/css" href="../css/examples.css"> 
 
   <!-- All demo files are bundled and appended to the window --> 
   <script src="../bundle.js" type="text/javascript"></script> 
</head> 
 
 
<body> 
   <div class="container"> 
      <div class="toolbar"> 
         <div class="vcenter push-right"> 
            <button type="button" id="exampleButton">Run Example</button> 
         </div> 
         <div class="vcenter push-right"> 
            <label for="interactiveSelect">Interactive mode:</label> 
            <select id="interactiveSelect"></select> 
         </div> 
         <div class="vcenter push-right"> 
            <label for="annotationsSelect">Annotations objects:</label> 
            <select id="annotationsSelect"></select> 
         </div> 
         <div id="output" class="vcenter push-right"></div> 
         <div id="serviceStatus" class="vcenter push-right"></div> 
      </div> 
      <div class="docContainer"> 
         <div class="sidepanel" id="thumbnails"></div> 
         <div class="centerpanel" id="viewer"></div> 
         <div class="sidepanel" id="bookmarks"></div> 
      </div> 
   </div> 
</body> 
<script> 
   window.onload = () => { 
      const button = document.getElementById('exampleButton'); 
      button.onclick = () => { 
         const example = new window.examples.CurrentPageNumberExample(); 
         example.run(); 
      } 
   }; 
</script> 
 
</html> 
 /* 
   Remove default body styling. 
   Set the body to flex as a column; 
*/ 
body { 
   margin: 0; 
   display: flex; 
   flex-direction: column; 
} 
 
.container { 
   margin: 10px; 
   width: calc(100% - 20px); 
   height: calc(100vh - 20px); 
} 
 
.toolbar { 
   height: 5%; 
   width: 100%; 
   border-bottom: 2px solid #333; 
   flex-direction: row; 
   display: flex; 
} 
#bookmarks{ 
   overflow: hidden; 
} 
 
.vcenter { 
   margin-top: auto; 
   margin-bottom: auto; 
} 
 
.hcenter{ 
   margin-left: auto; 
   margin-right: auto; 
} 
 
.push-right{ 
   margin-left: 10px; 
} 
 
.docContainer{ 
   height: 95%; 
   width: 100%; 
   display: flex; 
   flex-direction: row; 
} 
 
.sidepanel{ 
   width: 15%; 
   height: 100%; 
} 
 
.centerpanel{ 
   width:100%; 
   height:100%; 
} 
 
 /* Styles for Elements Mode. */ 
 .lt-item, .lt-image-border { 
   /* Box Shadow (view, item, image border) */ 
   box-shadow: #333 2px 2px 5px 1px; 
 } 
 .lt-view,.lt-thumb-item { 
   /* View */ 
   margin: 5px; 
   padding: 5px; 
 } 
 .lt-item { 
   /* Item */ 
   border: 2px solid #6ecaab; 
   background-color: #b2decf; 
   padding: 10px; 
 } 
 .lt-image-border { 
   /* Image Border */ 
   border: 3px solid #444; 
   background-color: white; 
 } 
 .lt-thumb-item { 
   /* Thumbnail Item */ 
   border: 2px solid #6ecaab; 
   background-color: #b2decf; 
 } 
 .lt-thumb-item.lt-thumb-item-selected { 
   /* Selected Thumbnail Item */ 
   border: 2px solid #59b2ba; 
   background-color: #8ce1e1; 
 } 
 .lt-thumb-item-hovered { 
   /* Hovered Thumbnail Item */ 
   border: 2px solid #52b996; 
   background-color: #87c7b1; 
 } 
 .small-modal { 
   max-width: 200px; 
   width: 200px; 
 } 

Requirements

Target Platforms

Help Version 20.0.2019.10.14
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Leadtools.Document.Viewer Assembly