PowerWEB Zoom for ASP.NET

An AJAX-powered Image Component



PowerWEB Zoom for ASP.NET

An AJAX-powered Image Component


By Mike Riley


The component market is so overpopulated with chart, grid, and basic UI controls that it s truly refreshing when something new like PowerWEB Zoom for ASP.NET comes along. While on the surface it may appear as if it s a fancy image control, it s really a unique, powerful viewer that provides end users with the ability to take a closer look at high-resolution digital imagery in a user-directed way.


I can recall back in the heyday of the dot-com boom, several companies touted the same functionality that PowerWEB Zoom supplies. Besides being prohibitively expensive, those solutions executed exclusively on the Windows platform because of their reliance on a custom ActiveX control or plug-in. They were also processor-hungry on the server side, substantially impacting application performance scalability. What a difference a couple of years can make modern browsers support asynchronous JavaScript calls using XML, and today s servers make those heavy systems from the dot-com days look like toy calculators. As such, a company like Dart Communications can deliver a less expensive, cross-browser solution compared to such early image manipulation attempts.


Figure 1: The PowerWEB Zoom for ASP.NET component ships with three demonstration applications. This screenshot illustrates an online catalog.


Feature-wise, PowerWEB Zoom is nearly complete considering the problem it was designed to solve. It s easy to install, instantiate, and manipulate; there s really not a lot to learn about the control. It only has a handful of properties, methods, and events. In fact, straight from the control s online documentation, here s all the code necessary to read image data from a byte array in a database and display the image in the control for further end-user scrolling and zooming:


// Copy the image into the working TileDirectory folder.

Zoom1.LoadImage(myImageBytes, "myfile.jpg");

// Set the image as the current image to display.

Zoom1.SourceImage = "myfile.jpg";


From there, the end user manipulates the image and the control handles all the dynamic AJAX data marshalling. UI elements for the control consist of the up-down-left-right compass arrows, the zoom in-out, and thumbnail icons. Clicking any of these transmits events back to the server and manipulates the image in real-time, la Google Maps. Unfortunately, the zoom in/out events are not as dynamic, as there is a brief pause between zoom requests while the server recalculates and transmits higher or lower resolution image data. While not a major distraction, it s a noticeable visual shortcoming that Dart should work on addressing in the next major release of the product. Nevertheless, if other AJAX-enabled controls were destined to be as simple to implement and use as PowerWEB Zoom, many more intranet and Internet ASP.NET applications would be laden with AJAX functionality.


While it s easy to use the control, I quickly exhausted the scenarios in which it could be applied. The obvious uses include online catalogs, medical imaging, law enforcement, real estate, and, perhaps, some insurance application scenarios. A few more, such as an online photo album, are listed in Dart s marketing literature. I demoed a photo album using the control with a few friends and family; although initially they thought it was cool, they preferred a full static image versus the scroll/zoom view window replacement that PowerWEB Zoom supplied. Perhaps if it could be controlled via voice, la the photo analysis scene in the movie Blade Runner, they might have warmed more to the effect.


Figure 2: The component works flawlessly in both Firefox and Internet Explorer.


A free version of the component is available for non-commercial use, and is similar to the full version in that it provides the on-demand image segment delivery and rendering and on-screen pan/zoom controls. Missing from the free version is the ability to customize those on-screen controls, set the auto-update image functionality, the ability to only render JPG format images, and, finally, each delivered image update has a PowerWEB Zoom watermark embedded into it. This is a good marketing approach to getting potential customers interested in applying the control in their own scenarios, but in my opinion, the commercial counterpart is still overpriced by two hundred dollars. Combined with the fact that Dart s licensing scheme requires online activation and license lock-down to the machine on which it was activated (making such justified license adherence and transfer a pain in a dynamic development and testing environment), it s difficult to validate the current selling price. Nevertheless, the component will still find a market, albeit a smaller and more specialized one than the major segment that predominantly caters to the corporate-oriented ASP.NET developer.


Mike Riley is an advanced computing professional specializing in emerging technologies and new development trends. He also is a contributing editor for asp.netPRO. Readers may contact Mike at mailto:[email protected].



Web Site: http://www.dart.com/powerweb/zoom.asp

Price: US$499; US$649 with maintenance subscription




Cool AJAX-enabled image manipulation.


Excellent cross-browser support.

Scalability may be a concern for high-traffic-volume sites.

Easy to use, quick to implement.

Heavy-handed license management.



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