scrollOffset Property

Summary

Scroll offset value.

Syntax
TypeScript
JavaScript
Object.defineProperty(ImageViewer.prototype, 'scrollOffset', 
	get: function(), 
	set: function(value) 
) 
scrollOffset: LeadPointD; 

Property Value

The current scroll offset value. The default value is 0,0.

Remarks

Changing the value of this property will fire the PropertyChanged, ScrollOffsetChanged and TransformChanged events.

When the value of ScrollMode is ControlScrollMode.Auto, then the value of ScrollOffset contains the current scrollbars offset. When the user clicks and drags on the scrollbars, the value of ScrollOffset (and the scrollbars thumbs) changes accordingly. The minimum value allowed is 0,0 (top-left) and the maximum value allowed is stored in MaximumScrollSize (setting ScrollOffset to MaximumScrollSize will cause the viewer to scroll the view to the bottom-right corner. You can manually pan the image by setting a value in ScrollOffset or calling ScrollBy.

When the value of ScrollMode is ControlScrollMode.Hidden, then the value of ScrollOffset contains the virtual scroll (pan) offset, you can pan the image by changing the value of ScrollOffset or calling ScrollBy. If the value of RestrictScroll is true, then the minimum and maximum scroll values are the same as the case above. If the value of RestrictScroll is false, then there is no minimum and maximum scroll ranges, you are allowed to set ScrollOffset to any value. 0,0 and MaximumScrollSize will still be the values to use if you want to either scroll the image to top-left or right-bottom.

When the value of ScrollMode is ControlScrollMode.Disabled, then trying to change the value of ScrollOffset or calling ScrollBy will be ignored.

For more information, refer to Image Viewer Scrolling.

Example
ScrollMode.ts
ImageViewer.ts
ScrollMode.js
ImageViewer.js
ScrollMode.html
import { ImageViewer_Example } from "../ImageViewer"; 
 
export class ImageViewer_ScrollModeExample { 
   private viewerExample; 
   constructor() { 
      this.viewerExample = new ImageViewer_Example(this.run); 
   } 
 
   private run = (viewer: lt.Controls.ImageViewer) => { 
      // Zoom in so we can see scroll bars for the example 
      viewer.zoom(1.5, lt.Controls.ControlSizeMode.fit, viewer.defaultZoomOrigin); 
 
      const scrollModes = ["Auto", "Hidden", "Disabled"]; 
      const output = document.getElementById("output"); 
      const textOutput = document.createElement("p"); 
      output.appendChild(textOutput); 
 
      const updateOutput = () => { 
         textOutput.innerHTML = "ScrollMode: " + scrollModes[viewer.scrollMode]; 
      } 
      updateOutput(); 
 
      // Add a button to update the scroll mode 
      const button = document.createElement("button"); 
      button.innerHTML = "Change Scroll Mode"; 
      button.onclick = () => { 
         // Flip through the options 
         viewer.scrollMode = (viewer.scrollMode + 1) % scrollModes.length; 
 
         // Allow movement all over the view while we're at it when hidden 
         if (viewer.scrollMode === lt.Controls.ControlScrollMode.hidden) 
            viewer.restrictScroll = false; 
         else 
            viewer.restrictScroll = true; 
 
         updateOutput(); 
      }; 
      output.appendChild(button); 
   } 
} 
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_ScrollModeExample { 
   viewerExample; 
   constructor() { 
      this.viewerExample = new ImageViewer_Example(this.run); 
   } 
 
   run = (viewer) => { 
      // Zoom in so we can see scroll bars for the example 
      viewer.zoom(1.5, lt.Controls.ControlSizeMode.fit, viewer.defaultZoomOrigin); 
 
      const scrollModes = ["Auto", "Hidden", "Disabled"]; 
      const output = document.getElementById("output"); 
      const textOutput = document.createElement("p"); 
      output.appendChild(textOutput); 
 
      const updateOutput = () => { 
         textOutput.innerHTML = "ScrollMode: " + scrollModes[viewer.scrollMode]; 
      } 
      updateOutput(); 
 
      // Add a button to update the scroll mode 
      const button = document.createElement("button"); 
      button.innerHTML = "Change Scroll Mode"; 
      button.onclick = () => { 
         // Flip through the options 
         viewer.scrollMode = (viewer.scrollMode + 1) % scrollModes.length; 
 
         // Allow movement all over the view while we're at it when hidden 
         if (viewer.scrollMode === lt.Controls.ControlScrollMode.hidden) 
            viewer.restrictScroll = false; 
         else 
            viewer.restrictScroll = true; 
 
         updateOutput(); 
      }; 
      output.appendChild(button); 
   } 
} 
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 | ScrollMode</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.ScrollMode(); 
 
   }; 
</script> 
</html> 
Requirements

Target Platforms

Help Version 23.0.2024.2.29
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Leadtools.Controls Assembly
Products | Support | Contact Us | Intellectual Property Notices
© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.