Occurs just before an image starts loading as the result of a URL update.
Object.defineProperty(ImageViewer.prototype,'imageLoading',
get: function(),
set: function(value)
)
imageLoading: LeadEvent;
When ImageUrl, BackImageUrl, Url, or BackImageUrl is set, a new ImageLoader is created to handle the loading process. Just before Run is called, the ImageLoading event is fired to give callbacks a chance to modify properties of the image load through ImageLoader. Properties such as UrlMode can be changed, and if the request uses AJAX (per, for example, AjaxDataUrl), then headers can be added or changed via Headers.
This event will also be fired when AutoRemoveItemElements is true and an image must be reloaded because an ImageViewerItem comes back into view.
import { ImageViewer_Example } from "../ImageViewer";
export class ImageViewer_ImageLoadingExample {
private viewerExample;
constructor() {
this.viewerExample = new ImageViewer_Example(this.run);
}
private run = (viewer: lt.Controls.ImageViewer) => {
viewer.items.clear();
viewer.viewLayout = new lt.Controls.ImageViewerVerticalViewLayout();
const output = document.getElementById("output");
viewer.imageLoading.add((sender, e) => {
// We now have access to imageLoader and item
// We can change any settings we want
const imageLoader: lt.ImageLoader = e.imageLoader;
output.innerHTML = "Image about to load: " + imageLoader.url;
});
let item: lt.Controls.ImageViewerItem = new lt.Controls.ImageViewerItem();
// Image will not load immediately. Must be added to ImageViewer.
item.url = "https://demo.leadtools.com/images/png/pngimage.png";
item.text = "Text";
setTimeout(() => {
// We set a timeout for 4 seconds, to show that the event
// will execute right before image is loaded
viewer.items.add(item);
}, 1100);
}
}
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_FloaterExample {
viewerExample;
constructor() {
this.viewerExample = new ImageViewer_Example(this.run);
}
run = (viewer) => {
viewer.items.clear();
viewer.viewLayout = new lt.Controls.ImageViewerVerticalViewLayout();
const output = document.getElementById("output");
viewer.imageLoading.add((sender, e) => {
// We now have access to imageLoader and item
// We can change any settings we want
const imageLoader = e.imageLoader;
output.innerHTML = "Image about to load: " + imageLoader.url;
});
let item = new lt.Controls.ImageViewerItem();
// Image will not load immediately. Must be added to ImageViewer.
item.url = "https://demo.leadtools.com/images/png/pngimage.png";
item.text = "Text";
setTimeout(() => {
// We set a timeout for 4 seconds, to show that the event
// will execute right before image is loaded
viewer.items.add(item);
}, 1100);
}
}
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 | ImageLoading</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.ImageLoading();
};
</script>
</html>
Parameter | Type | Description |
---|---|---|
sender | var | The source of the event. |
e | ImageViewerImageLoadingEventArgs | The event data. |
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