Legacy Controls NOTICE

This article references our legacy Web Forms Web Viewing controls (WebImageViewer, WebAnnotationViewer, WebThumbnailViewer). It is preserved for archival purposes, but support strongly recommends using our modern HTML5 web controls: WebDocumentViewer, WebDocumentThumbnailer instead)

INFO: WebDocumentViewer Whitepaper - Getting Started With Web Viewing

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Sometimes, it is necessary to abort/cancel the user/interactive creation of an annotation on our WebAnnotationViewer after it has begun.

For example: a user starts creating a highlight annotation, but drags the mouse off the control and clicks on a different page in the WebThumbnailViewer; technically, annotation creation is still occurring back on the previous page/layer.

Adding a handler for WebThumbnailViewer1.SelectedIndexChanged that will call WebAnnotationViewer1.CancelCreateAnnotation(); will stop the creation of the initial annotation without leaving a partial annotation on the existed page.

WebThumbnailViewer1.SelectedIndexChanged = CancelCreation;

function CancelCreation() {
WebAnnotationViewer1.CancelCreateAnnotation();
}

This is also useful when you wish to give the user the option to manually cancel interactive creation. You can make a simple button with a call to this will cancel the current creation:

(note the use of return false; to keep the button from posting back - this is important to the proper functioning of our WebAnnotationViewer/WebThumbnailViewer controls.

NOTE: This article is specifically about our ASP.NET web control: WebAnnotationViewer. For cancelation of interactive annotation creation in a WinForms solution using our AnnotateViewer control, please see Q10112 - HOWTO: How can I cancel a call to CreateAnnotation in WinForms apps using AnnotateViewer?

Original Article:
Q10387 - HOWTO: Cancel Creation of Annotations in WebAnnotationViewer control (Legacy Web Controls)