createTransform Method

Summary

Helper method to create the transformation matrix used to redirect the rendering of the ImageViewer.

Syntax
TypeScript
JavaScript
ImageViewerRenderRedirectOptions.prototype.createTransform = function( 
   imageViewer, 
   destinationRect, 
   sourceRect, 
   sizeMode, 
   horizontalAlignment, 
   verticalAlignment 
) 

Parameters

imageViewer

The image viewer instance that will be used as the source of RenderRedirect. This value

cannot be null.

destinationRect

Destination rectangle to use. For example, the client area of the external control.

sourceRect

The source rectangle into the current view of imageViewer. Pass Empty to render

the whole view.

sizeMode

Controls how the source rectangle is positioned and scaled inside the destination rectangle.

horizontalAlignment

Controls how the source rectangle is aligned horizontally inside the destination rectangle.

verticalAlignment

Controls how the source rectangle is aligned vertically inside the destination rectangle.

Remarks

This method will set the transformation matrix into Transform.

Use this method CreateTransform can be used to easily create a transformation matrix for common scenarios such as rendering a thumbnail of the content of the viewer.

For more information, refer to Image Viewer Rendering.

Example
RenderRedirect.ts
ImageViewer.ts
RenderRedirect.js
ImageViewer.js
RenderRedirect.html
import { ImageViewer_Example } from "../ImageViewer"; 
 
export class ImageViewer_RenderRedirectExample { 
   private viewerExample; 
   constructor() { 
      this.viewerExample = new ImageViewer_Example(this.run); 
   } 
 
   private run = (viewer: lt.Controls.ImageViewer) => { 
      viewer.itemBorderThickness = 5; 
 
      // Create the canvas we will render to 
      const redirectCanvas = document.createElement("canvas"); 
      redirectCanvas.style.border = "2px solid black"; 
      const redirectWidth: number = 300; 
      const redirectHeight: number = 300; 
      redirectCanvas.width = redirectWidth; 
      redirectCanvas.height = redirectHeight; 
 
      // Add it to the page 
      const output = document.getElementById("output"); 
      output.appendChild(redirectCanvas); 
 
      // Add a 20px margin around the redirect render area 
      const delta: number = 20; 
      const destRect: lt.LeadRectD = lt.LeadRectD.create(0, 0, redirectWidth, redirectHeight); 
      destRect.inflate(-delta, -delta); 
 
      const options: lt.Controls.ImageViewerRenderRedirectOptions = new lt.Controls.ImageViewerRenderRedirectOptions(); 
 
      viewer.rotateAngle = 35; 
      // Use "null" to draw the whole imageViewer 
      //let item = null; 
      const item: lt.Controls.ImageViewerItem = viewer.activeItem; 
 
      if (item) { 
         // Don't worry about rendering the below 
         options.renderBackgrounds = false; 
         options.renderBorders = false; 
         options.renderItemStates = false; 
         options.renderShadows = false; 
         options.renderText = false; 
      } 
 
      // On imageViewer render... 
      viewer.redirectRender.add(() => { 
         let sourceRect: lt.LeadRectD; 
         let sourceRectClipped: lt.LeadRectD; 
         if (!item) { 
            // Draw the whole imageViewer 
            sourceRect = viewer.getViewBounds(true, false); 
            sourceRectClipped = viewer.getViewBounds(true, true); 
         } 
         else { 
            // Only draw the rect for the active item 
            sourceRect = viewer.getItemViewBounds(item, lt.Controls.ImageViewerItemPart.image, false); 
            sourceRectClipped = viewer.getItemViewBounds(item, lt.Controls.ImageViewerItemPart.image, true); 
         } 
 
         const ctx: CanvasRenderingContext2D = redirectCanvas.getContext("2d"); 
         ctx.clearRect(0, 0, redirectWidth, redirectHeight); 
 
         // Draw a rect around the maximum render area 
         ctx.strokeStyle = "green"; 
         ctx.strokeRect(destRect.x, destRect.y, destRect.width, destRect.height); 
 
         // Create the transformation for this rect 
         options.createTransform(viewer, destRect, sourceRect, lt.Controls.ControlSizeMode.fit, lt.Controls.ControlAlignment.center, lt.Controls.ControlAlignment.center); 
 
         // Draw a rect around the actual render area 
         const clipRect: lt.LeadRectD = options.transform.transformRect(sourceRect); 
         ctx.strokeStyle = "orange"; 
         ctx.strokeRect(clipRect.x, clipRect.y, clipRect.width, clipRect.height); 
 
         // Do the redirect render 
         viewer.renderRedirect(ctx, options, lt.LeadRectD.empty); 
 
         // Show how to draw the item's border 
         const manuallyComputeRedirectedBorder = () => { 
            const points: lt.LeadPointD[] = [lt.LeadPointD.create(sourceRectClipped.left, sourceRectClipped.top), lt.LeadPointD.create(sourceRectClipped.right, sourceRectClipped.bottom)]; 
            options.transform.transformPoints(points); 
 
            let xmin = points[0].x; 
            let ymin = points[0].y; 
            let xmax = xmin; 
            let ymax = ymin; 
 
            for (let i = 1; i < points.length; i++) { 
               if (points[i].x < xmin) xmin = points[i].x; 
               if (points[i].x > xmax) xmax = points[i].x; 
               if (points[i].y < ymin) ymin = points[i].y; 
               if (points[i].y > ymax) ymax = points[i].y; 
            } 
 
            const bounds: lt.LeadRectD = lt.LeadRectD.fromLTRB(xmin, ymin, xmax, ymax); 
 
            ctx.strokeStyle = "blue"; 
            ctx.strokeRect(bounds.x, bounds.y, bounds.width, bounds.height); 
         }; 
         manuallyComputeRedirectedBorder(); 
      }); 
      viewer.invalidate(lt.LeadRectD.empty); 
   } 
} 
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_RenderRedirectExample { 
   viewerExample; 
   constructor() { 
      this.viewerExample = new ImageViewer_Example(this.run); 
   } 
 
   run = (viewer) => { 
      viewer.itemBorderThickness = 5; 
 
      // Create the canvas we will render to 
      const redirectCanvas = document.createElement("canvas"); 
      redirectCanvas.style.border = "2px solid black"; 
      const redirectWidth = 300; 
      const redirectHeight = 300; 
      redirectCanvas.width = redirectWidth; 
      redirectCanvas.height = redirectHeight; 
 
      // Add it to the page 
      const output = document.getElementById("output"); 
      output.appendChild(redirectCanvas); 
 
      // Add a 20px margin around the redirect render area 
      const delta = 20; 
      const destRect = lt.LeadRectD.create(0, 0, redirectWidth, redirectHeight); 
      destRect.inflate(-delta, -delta); 
 
      const options = new lt.Controls.ImageViewerRenderRedirectOptions(); 
 
      viewer.rotateAngle = 35; 
      // Use "null" to draw the whole imageViewer 
      //let item = null; 
      const item = viewer.activeItem; 
 
      if (item) { 
         // Don't worry about rendering the below 
         options.renderBackgrounds = false; 
         options.renderBorders = false; 
         options.renderItemStates = false; 
         options.renderShadows = false; 
         options.renderText = false; 
      } 
 
      // On imageViewer render... 
      viewer.redirectRender.add(() => { 
         let sourceRect; 
         let sourceRectClipped; 
         if (!item) { 
            // Draw the whole imageViewer 
            sourceRect = viewer.getViewBounds(true, false); 
            sourceRectClipped = viewer.getViewBounds(true, true); 
         } 
         else { 
            // Only draw the rect for the active item 
            sourceRect = viewer.getItemViewBounds(item, lt.Controls.ImageViewerItemPart.image, false); 
            sourceRectClipped = viewer.getItemViewBounds(item, lt.Controls.ImageViewerItemPart.image, true); 
         } 
 
         const ctx = redirectCanvas.getContext("2d"); 
         ctx.clearRect(0, 0, redirectWidth, redirectHeight); 
 
         // Draw a rect around the maximum render area 
         ctx.strokeStyle = "green"; 
         ctx.strokeRect(destRect.x, destRect.y, destRect.width, destRect.height); 
 
         // Create the transformation for this rect 
         options.createTransform(viewer, destRect, sourceRect, lt.Controls.ControlSizeMode.fit, lt.Controls.ControlAlignment.center, lt.Controls.ControlAlignment.center); 
 
         // Draw a rect around the actual render area 
         const clipRect = options.transform.transformRect(sourceRect); 
         ctx.strokeStyle = "orange"; 
         ctx.strokeRect(clipRect.x, clipRect.y, clipRect.width, clipRect.height); 
 
         // Do the redirect render 
         viewer.renderRedirect(ctx, options, lt.LeadRectD.empty); 
 
         // Show how to draw the item's border 
         const manuallyComputeRedirectedBorder = () => { 
            const points = [lt.LeadPointD.create(sourceRectClipped.left, sourceRectClipped.top), lt.LeadPointD.create(sourceRectClipped.right, sourceRectClipped.bottom)]; 
            options.transform.transformPoints(points); 
 
            let xmin = points[0].x; 
            let ymin = points[0].y; 
            let xmax = xmin; 
            let ymax = ymin; 
 
            for (let i = 1; i < points.length; i++) { 
               if (points[i].x < xmin) xmin = points[i].x; 
               if (points[i].x > xmax) xmax = points[i].x; 
               if (points[i].y < ymin) ymin = points[i].y; 
               if (points[i].y > ymax) ymax = points[i].y; 
            } 
 
            const bounds = lt.LeadRectD.fromLTRB(xmin, ymin, xmax, ymax); 
 
            ctx.strokeStyle = "blue"; 
            ctx.strokeRect(bounds.x, bounds.y, bounds.width, bounds.height); 
         }; 
         manuallyComputeRedirectedBorder(); 
      }); 
      viewer.invalidate(lt.LeadRectD.empty); 
   } 
} 
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 | RenderRedirect</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.RenderRedirect(); 
 
   }; 
</script> 
</html> 
Requirements

Target Platforms

Help Version 22.0.2023.2.4
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© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.

Leadtools.Controls Assembly

Products | Support | Contact Us | Intellectual Property Notices
© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.