Active item of this image viewer.
Object.defineProperty(ImageViewer.prototype, 'activeItem',
get: function(),
set: function(value)
)
activeItem: ImageViewerItem;
The active item of this image viewer. This value cannot be null.
For more information, refer to Image Viewer Items.
This example will use the viewer as a single-selection-enabled list of images and show how to track the current active item.
import { ImageViewer_Example } from "../ImageViewer";
export class ImageViewer_ActiveItemChangedExample {
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
viewer.viewLayout = new lt.Controls.ImageViewerVerticalViewLayout();
// Make sure the item size is larger than the image size (thumbnails mode)
viewer.itemBorderThickness = 3;
// Change the active item background color
viewer.activeItemBorderColor = "forestgreen";
// 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.url = imageUrl;
viewer.items.add(item);
}
const panZoom: lt.Controls.ImageViewerPanZoomInteractiveMode = viewer.interactiveModes.findById(lt.Controls.ImageViewerInteractiveMode.panZoomModeId) as lt.Controls.ImageViewerPanZoomInteractiveMode;
// Tell the mode to set the active item for us
panZoom.autoItemMode = lt.Controls.ImageViewerAutoItemMode.autoSetActive;
const output = document.getElementById("output");
// Hook to the ActiveItemChanged event and update the label
const updateActiveItem = () => {
const index = viewer.items.indexOf(viewer.activeItem);
output.innerHTML = "Active item index: " + index;
}
viewer.activeItemChanged.add(updateActiveItem);
updateActiveItem();
}
}
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_ActiveItemChangedExample {
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
viewer.viewLayout = new lt.Controls.ImageViewerVerticalViewLayout();
// Make sure the item size is larger than the image size (thumbnails mode)
viewer.itemBorderThickness = 3;
// Change the active item background color
viewer.activeItemBorderColor = "forestgreen";
// 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.url = imageUrl;
viewer.items.add(item);
}
const panZoom = viewer.interactiveModes.findById(lt.Controls.ImageViewerInteractiveMode.panZoomModeId);
// Tell the mode to set the active item for us
panZoom.autoItemMode = lt.Controls.ImageViewerAutoItemMode.autoSetActive;
const output = document.getElementById("output");
// Hook to the ActiveItemChanged event and update the label
const updateActiveItem = () => {
const index = viewer.items.indexOf(viewer.activeItem);
output.innerHTML = "Active item index: " + index;
}
viewer.activeItemChanged.add(updateActiveItem);
updateActiveItem();
}
}
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 | ActiveItemChanged</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.ActiveItemChanged();
};
</script>
</html>
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