items Property

Summary

The collection of items in this ImageViewer.

Syntax
TypeScript
JavaScript
Object.defineProperty(ImageViewer.prototype, 'items', 
	get: function() 
) 
items: ImageViewerItems; // read-only 

Property Value

The collection of items in this ImageViewer.

Remarks

Items is of type ImageViewerItems which supports standard collection operations such as adding, removing, and enumerating the items.

The viewer listens to the events of ImageViewerItems (using LeadCollection.CollectionChanged) and automatically re-calculates the view layout and updates the transformations used when an item is added, removed, or changed by the view and items by calling UpdateTransform.

Use BeginUpdate and EndUpdate to optimize this behavior when adding or removing multiple items at once.

The viewer will automatically keep the ActiveItem property set to an item inside this collection. Usually, it is the first item added if the user did not change the value. When an item is removed, the viewer will set ActiveItem to the new item that takes its index in the collection. Finally, when no items are left in the collection, ActiveItem will be set to null.

For more information, refer to Image Viewer Items.

Example

This example will show how to add, remove, and enumerate items in the viewer.

Items.ts
ImageViewer.ts
Items.js
ImageViewer.js
Items.html
import { ImageViewer_Example } from "../ImageViewer"; 
 
export class ImageViewer_ItemsExample { 
   private viewerExample; 
   constructor() { 
      this.viewerExample = new ImageViewer_Example(this.run); 
   } 
 
   private run = (viewer: lt.Controls.ImageViewer) => { 
      // Clear all the images already the viewer 
      viewer.items.clear(); 
 
      // Use vertical view layout to show multiple items 
      viewer.viewLayout = new lt.Controls.ImageViewerVerticalViewLayout(); 
      viewer.imageBorderThickness = 1; 
 
      // Add 4 items to the viewer 
      for (let page = 1; page <= 4; page++) { 
         const item: lt.Controls.ImageViewerItem = new lt.Controls.ImageViewerItem(); 
         const imageUrl: string = "https://demo.leadtools.com/images/png/ocr" + page.toString() + ".png"; 
         item.text = "Page " + page; 
         item.url = imageUrl; 
         viewer.items.add(item); 
      } 
 
      let panZoom: lt.Controls.ImageViewerPanZoomInteractiveMode = viewer.interactiveModes.findById(lt.Controls.ImageViewerInteractiveMode.panZoomModeId) as lt.Controls.ImageViewerPanZoomInteractiveMode; 
      panZoom.minimumScaleFactor = 0.01; 
      viewer.zoom(lt.Controls.ControlSizeMode.fitHeight, .25, viewer.defaultZoomOrigin); 
 
      // Show the count 
      alert("The count should be 4: " + viewer.items.count); 
 
      // Not required, just used for the example 
      setTimeout(() => { 
 
         // Remove the item at index 1 (page 2) 
         viewer.items.removeAt(1); 
         alert("After removing an item, the count should be 3: " + viewer.items.count); 
 
         // Not required, just used for the example 
         setTimeout(() => { 
 
            // Loop through each item and show the text. Since we removed page 2, it must say 1, 3, 4 
            let lines: string[] = []; 
            for (let i = 0; i < viewer.items.count; i++) { 
               const item: lt.Controls.ImageViewerItem = viewer.items.item(i); 
               lines.push("Item " + i + " has text '" + item.text + "'"); 
            } 
            alert(lines.join("\r\n")); 
 
         }, 1000); 
      }, 1000); 
   } 
} 
export class ImageViewer_Example { 
   // LEADTOOLS ImageViewer to be used with this example 
   protected imageViewer: lt.Controls.ImageViewer = null; 
   // Generic state value used by the examples 
   public timesClicked: number = 0; 
 
   constructor(callback?: (viewer: lt.Controls.ImageViewer) => void) { 
      // Set the LEADTOOLS license. Replace this with your actual license file 
      lt.RasterSupport.setLicenseUri("https://demo.leadtools.com/licenses/js/LEADTOOLSEVAL.txt", "EVAL", null); 
 
      // Create an image viewer inside the imageViewerDiv element 
      const imageViewerDiv = document.getElementById("imageViewerDiv"); 
      const createOptions: lt.Controls.ImageViewerCreateOptions = new lt.Controls.ImageViewerCreateOptions(imageViewerDiv); 
      this.imageViewer = new lt.Controls.ImageViewer(createOptions); 
      this.imageViewer.viewVerticalAlignment = lt.Controls.ControlAlignment.center; 
      this.imageViewer.viewHorizontalAlignment = lt.Controls.ControlAlignment.center; 
      this.imageViewer.autoCreateCanvas = true; 
 
      // Add Pan/Zoom interactive mode 
      // Click and drag to pan, CTRL-Click and drag to zoom in and out 
      this.imageViewer.interactiveModes.add(new lt.Controls.ImageViewerPanZoomInteractiveMode()); 
 
      // Load an image 
      this.imageViewer.imageUrl = "https://demo.leadtools.com/images/jpeg/cannon.jpg"; 
 
      this.imageViewer.zoom(lt.Controls.ControlSizeMode.fit, .9, this.imageViewer.defaultZoomOrigin); 
 
      const exampleButton = document.getElementById("exampleButton"); 
      exampleButton.addEventListener("click", () => { 
         this.timesClicked++; 
         // Run the example 
         if (callback) 
            callback(this.imageViewer); 
      }); 
   } 
} 
import { ImageViewer_Example } from "../ImageViewer"; 
 
export class ImageViewer_ItemsExample { 
   viewerExample; 
   constructor() { 
      this.viewerExample = new ImageViewer_Example(this.run); 
   } 
 
   run = (viewer) => { 
      // Clear all the images already the viewer 
      viewer.items.clear(); 
 
      // Use vertical view layout to show multiple items 
      viewer.viewLayout = new lt.Controls.ImageViewerVerticalViewLayout(); 
      viewer.imageBorderThickness = 1; 
 
      // Add 4 items to the viewer 
      for (let page = 1; page <= 4; page++) { 
         const item = new lt.Controls.ImageViewerItem(); 
         const imageUrl = "https://demo.leadtools.com/images/png/ocr" + page.toString() + ".png"; 
         item.text = "Page " + page; 
         item.url = imageUrl; 
         viewer.items.add(item); 
      } 
 
      let panZoom = viewer.interactiveModes.findById(lt.Controls.ImageViewerInteractiveMode.panZoomModeId); 
      panZoom.minimumScaleFactor = 0.01; 
      viewer.zoom(lt.Controls.ControlSizeMode.fitHeight, .25, viewer.defaultZoomOrigin); 
 
      // Show the count 
      alert("The count should be 4: " + viewer.items.count); 
 
      // Not required, just used for the example 
      setTimeout(() => { 
 
         // Remove the item at index 1 (page 2) 
         viewer.items.removeAt(1); 
         alert("After removing an item, the count should be 3: " + viewer.items.count); 
 
         // Not required, just used for the example 
         setTimeout(() => { 
 
            // Loop through each item and show the text. Since we removed page 2, it must say 1, 3, 4 
            let lines = []; 
            for (let i = 0; i < viewer.items.count; i++) { 
               const item = viewer.items.item(i); 
               lines.push("Item " + i + " has text '" + item.text + "'"); 
            } 
            alert(lines.join("\r\n")); 
 
         }, 1000); 
      }, 1000); 
   } 
} 
export class ImageViewer_Example { 
   // LEADTOOLS ImageViewer to be used with this example 
   imageViewer = null; 
   // Generic state value used by the examples 
   timesClicked = 0; 
 
   constructor(callback) { 
      // Set the LEADTOOLS license. Replace this with your actual license file 
      lt.RasterSupport.setLicenseUri("https://demo.leadtools.com/licenses/js/LEADTOOLSEVAL.txt", "EVAL", null); 
 
      // Create an image viewer inside the imageViewerDiv element 
      const imageViewerDiv = document.getElementById("imageViewerDiv"); 
      const createOptions = new lt.Controls.ImageViewerCreateOptions(imageViewerDiv); 
      this.imageViewer = new lt.Controls.ImageViewer(createOptions); 
      this.imageViewer.viewVerticalAlignment = lt.Controls.ControlAlignment.center; 
      this.imageViewer.viewHorizontalAlignment = lt.Controls.ControlAlignment.center; 
      this.imageViewer.autoCreateCanvas = true; 
 
      // Add Pan/Zoom interactive mode 
      // Click and drag to pan, CTRL-Click and drag to zoom in and out 
      this.imageViewer.interactiveModes.add(new lt.Controls.ImageViewerPanZoomInteractiveMode()); 
 
      // Load an image 
      this.imageViewer.imageUrl = "https://demo.leadtools.com/images/jpeg/cannon.jpg"; 
 
      this.imageViewer.zoom(lt.Controls.ControlSizeMode.fit, .9, this.imageViewer.defaultZoomOrigin); 
 
      const exampleButton = document.getElementById("exampleButton"); 
      exampleButton.addEventListener("click", () => { 
         this.timesClicked++; 
         // Run the example 
         if (callback) 
            callback(this.imageViewer); 
      }); 
   } 
} 
<!doctype html> 
<html lang="en"> 
<title>Controls Example | Items</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> 
   <style> 
      body { 
         font-family: 'Segoe UI', sans-serif; 
      } 
 
      #imageViewerDiv { 
         border: 1px solid #888; 
         width: 500px; 
         height: 500px; 
         background-color: #eee; 
      } 
   </style> 
 
   <!-- All demo files are bundled and appended to the window --> 
   <script src="../../bundle.js" type="text/javascript"></script> 
</head> 
 
<body> 
   <p>Press and drag on the image to pan.</p> 
   <p>Hold down the control key and press and drag on the image or pinch with two fingers to zoom in and out.</p> 
   <div> 
      <button type="button" id="exampleButton">Run Example</button> 
   </div> 
   <div id="imageViewerDiv"></div> 
   <div id="output"></div> 
</body> 
 
<script> 
   window.onload = () => { 
      const example = new window.examples.ImageViewer.Items(); 
 
   }; 
</script> 
</html> 
Requirements

Target Platforms

Help Version 22.0.2021.9.24
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© 1991-2021 LEAD Technologies, Inc. All Rights Reserved.

Leadtools.Controls Assembly
Products | Support | Contact Us | Intellectual Property Notices
© 1991-2021 LEAD Technologies, Inc. All Rights Reserved.