The HTML5 Canvas Element associated with this item.
Object.defineProperty(ImageViewerItem.prototype, 'canvas',get: function(),set: function(value))
canvas: HTMLCanvasElement;
The canvas associated with this item. The default value is null.
The item can have a value in only one of Image, Element, or Canvas. Setting one value will automatically delete the values of the others. Element accepts any element, but may still be null after the set operation. An HTML Image Element set to Element will actually be set to Image, and an HTML5 Canvas Element set to Element will actually be set to Canvas.
Changing the value of this property will fire the ItemChanged event with ImageViewerItemChangedReason.Image. The value of Resolution will not be automatically updated with the DPI of the new image. The user must set this value manually.
Canvas property of ImageViewer will update this member if this is the active item when the viewer is used in single item mode.
For more information, refer to Image Viewer Items.
This example creates a canvas and draws to it before adding it to an item in the viewer.
import { ImageViewer_Example } from "../ImageViewer";export class ImageViewerItem_CanvasExample {private viewerExample;constructor() {this.viewerExample = new ImageViewer_Example(this.run);}private run = (viewer: lt.Controls.ImageViewer) => {viewer.itemBorderThickness = 5;const canvas = document.createElement("canvas") as HTMLCanvasElement;canvas.width = 150;canvas.height = 150;const context: CanvasRenderingContext2D = canvas.getContext("2d");context.fillStyle = "green";context.fillRect(0, 0, 150, 150);context.fillStyle = "blue";context.fillRect(25, 25, 100, 100);const item: lt.Controls.ImageViewerItem = new lt.Controls.ImageViewerItem();item.canvas = canvas;viewer.items.clear();viewer.items.add(item);}}
export class ImageViewer_Example {// LEADTOOLS ImageViewer to be used with this exampleprotected imageViewer: lt.Controls.ImageViewer = null;// Generic state value used by the examplespublic timesClicked: number = 0;constructor(callback?: (viewer: lt.Controls.ImageViewer) => void) {// Set the LEADTOOLS license. Replace this with your actual license filelt.RasterSupport.setLicenseUri("https://demo.leadtools.com/licenses/js/LEADTOOLSEVAL.txt", "EVAL", null);// Create an image viewer inside the imageViewerDiv elementconst 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 outthis.imageViewer.interactiveModes.add(new lt.Controls.ImageViewerPanZoomInteractiveMode());// Load an imagethis.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 exampleif (callback)callback(this.imageViewer);});}}
import { ImageViewer_Example } from "../ImageViewer";export class ImageViewerItem_CanvasExample {viewerExample;constructor() {this.viewerExample = new ImageViewer_Example(this.run);}run = (viewer) => {viewer.itemBorderThickness = 5;const canvas = document.createElement("canvas");canvas.width = 150;canvas.height = 150;const context = canvas.getContext("2d");context.fillStyle = "green";context.fillRect(0, 0, 150, 150);context.fillStyle = "blue";context.fillRect(25, 25, 100, 100);const item = new lt.Controls.ImageViewerItem();item.canvas = canvas;viewer.items.clear();viewer.items.add(item);}}
export class ImageViewer_Example {// LEADTOOLS ImageViewer to be used with this exampleimageViewer = null;// Generic state value used by the examplestimesClicked = 0;constructor(callback) {// Set the LEADTOOLS license. Replace this with your actual license filelt.RasterSupport.setLicenseUri("https://demo.leadtools.com/licenses/js/LEADTOOLSEVAL.txt", "EVAL", null);// Create an image viewer inside the imageViewerDiv elementconst 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 outthis.imageViewer.interactiveModes.add(new lt.Controls.ImageViewerPanZoomInteractiveMode());// Load an imagethis.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 exampleif (callback)callback(this.imageViewer);});}}
<!doctype html><html lang="en"><title>Controls Example | Canvas</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.ImageViewerItem.Canvas();};</script></html>
Help Collections
Raster .NET | C API | C++ Class Library | HTML5 JavaScript
Document .NET | C API | C++ Class Library | HTML5 JavaScript
Medical .NET | C API | C++ Class Library | HTML5 JavaScript
Medical Web Viewer .NET
Multimedia
Direct Show .NET | C API | Filters
Media Foundation .NET | C API | Transforms
Supported Platforms
.NET, Java, Android, and iOS/macOS Assemblies
Imaging, Medical, and Document
C API/C++ Class Libraries
Imaging, Medical, and Document
HTML5 JavaScript Libraries
Imaging, Medical, and Document
