ImageViewerSpyGlassInteractiveMode Object

Summary

Draws and pans a spy glass on the viewer.

Syntax
TypeScript
JavaScript
function lt.Controls.ImageViewerSpyGlassInteractiveMode 
	extends lt.Controls.ImageViewerInteractiveMode 
class lt.Controls.ImageViewerSpyGlassInteractiveMode() 
	extends ImageViewerInteractiveMode 
Remarks

The ImageViewerSpyGlassInteractiveMode derives from the ImageViewerInteractiveMode and subscribes to the following events of the InteractiveService:

The ImageViewerSpyGlassInteractiveMode interactive mode does not perform any action on the viewer (besides drawing the spy glass). It is up to the user to implement any custom operation required. For example, to implement a magnify glass, ImageViewerMagnifyGlassInteractiveMode derives from the ImageViewerSpyGlassInteractiveMode and overrides the OnDrawImage method to draw a magnified version of the area under the spy glass.

The ImageViewerSpyGlassInteractiveMode works as follows:

  1. When a dragStarted event is received, the InteractiveEventArgs.IsHandled property is set to true and a temporary HTML5 Canvas Element is created on top of the viewer for drawing the spy glass. Note that if you set your own canvas into the InteractiveModeCanvas property, then this object will not create a canvas (nor use the above properties). Instead, your canvas will be used as the surface for the spy glass.

  2. When a dragDelta event is received, the InteractiveEventArgs.isHandled property is set to true and the temporary canvas is moved to the current position. The ImageViewerSpyGlassInteractiveMode.DrawImage event is fired at this time to allow implementers and listeners to perform any custom operation on the spy glass surface.

  3. When a dragCompleted event is received, the InteractiveEventArgs.isHandled property is set to true and the temporary canvas is removed.

The ImageViewerSpyGlassInteractiveMode also supports redirecting the output to an external canvas instead of the viewer surface. For an example, refer to RedirectCanvas. Neither ImageViewerSpyGlassInteractiveMode nor ImageViewerMagnifyGlassInteractiveMode work when the image viewer is in Elements Mode, since the viewer does not paint the items.

For more information, refer to Image Viewer Interactive Modes.

Example

This example will use the ImageViewerSpyGlassInteractiveMode to show a flipped version of the image under the mouse.

SpyGlassInteractiveMode.ts
ImageViewer.ts
SpyGlassInteractiveMode.js
ImageViewer.js
SpyGlassInteractiveMode.html
import { ImageViewer_Example } from "../ImageViewer"; 
 
export class SpyGlassInteractiveMode_Example { 
   private viewerExample; 
   constructor() { 
      this.viewerExample = new ImageViewer_Example(this.run); 
   } 
 
   private run = (viewer: lt.Controls.ImageViewer) => { 
      viewer.interactiveModes.clearItems(); 
      viewer.interactiveModes.beginUpdate(); 
 
      // Create the spyglass 
      const spyGlass: lt.Controls.ImageViewerSpyGlassInteractiveMode = new lt.Controls.ImageViewerSpyGlassInteractiveMode(); 
      spyGlass.backgroundColor = "rgba(255, 255, 0, 0.5)"; 
      spyGlass.autoItemMode = lt.Controls.ImageViewerAutoItemMode.autoSet; 
 
      // On draw, draw the viewer flipped 
      spyGlass.drawImage.add((sender, e) => { 
         const rect: lt.LeadRectD = e.destinationRectangle; 
         const ctx: CanvasRenderingContext2D = e.context; 
         // Width and height of the canvas 
         const controlSize: lt.LeadSizeD = viewer.controlSize; 
 
         ctx.save(); 
         // Undo offset of the spyglass 
         ctx.translate(-rect.x, -rect.y); 
 
         // Flip the context 
         ctx.scale(1, -1); 
         ctx.translate(0, -controlSize.height); 
 
         // Draw the view 
         viewer.renderRedirect(ctx, new lt.Controls.ImageViewerRenderRedirectOptions(), lt.LeadRectD.empty); 
 
         ctx.restore(); 
      }); 
 
      viewer.interactiveModes.add(spyGlass); 
      viewer.interactiveModes.endUpdate(); 
   } 
} 
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 SpyGlassInteractiveMode_Example { 
   viewerExample; 
   constructor() { 
      this.viewerExample = new ImageViewer_Example(this.run); 
   } 
 
   run = (viewer) => { 
      viewer.interactiveModes.clearItems(); 
      viewer.interactiveModes.beginUpdate(); 
 
      // Create the spyglass 
      const spyGlass = new lt.Controls.ImageViewerSpyGlassInteractiveMode(); 
      spyGlass.backgroundColor = "rgba(255, 255, 0, 0.5)"; 
      spyGlass.autoItemMode = lt.Controls.ImageViewerAutoItemMode.autoSet; 
 
      // On draw, draw the viewer flipped 
      spyGlass.drawImage.add((sender, e) => { 
         const rect = e.destinationRectangle; 
         const ctx = e.context; 
         // Width and height of the canvas 
         const controlSize = viewer.controlSize; 
 
         ctx.save(); 
         // Undo offset of the spyglass 
         ctx.translate(-rect.x, -rect.y); 
 
         // Flip the context 
         ctx.scale(1, -1); 
         ctx.translate(0, -controlSize.height); 
 
         // Draw the view 
         viewer.renderRedirect(ctx, new lt.Controls.ImageViewerRenderRedirectOptions(), lt.LeadRectD.empty); 
 
         ctx.restore(); 
      }); 
 
      viewer.interactiveModes.add(spyGlass); 
      viewer.interactiveModes.endUpdate(); 
   } 
} 
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 | SpyGlassInteractiveMode</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.Spyglass.SpyGlassInteractiveMode(); 
 
   }; 
</script> 
</html> 
Requirements

Target Platforms

Help Version 22.0.2021.9.24
Products | Support | Contact Us | Intellectual Property Notices
© 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.