Ever since we announced the Project Freewheel technology preview, our email boxes have been filled with messages from excited customers. Many have asked: How does it work? DWF Technical Evangelist and Software Engineer, Ben Cochran, has provided a high level overview:
Using just his browser, a user sends an URL (Uniform Resource Locator) to the Project Freewheel server. The URL identifies the location of a DWF file publicly available on the internet. Alternatively, the user can specify the path to a DWF file on a local or network hard drive.
The Project Freewheel server uses the internet to retrieve a copy of the DWF file onto the local hard drive of the server. Password protected DWF files or files in a location where a user name and password are required will not work (at this time).
To create Project Freewheel, we took the core rendering engine from the Autodesk DWF Viewer and AutoCAD, tuned it for a web server, and repackaged it. Project Freewheel uses this rendering engine to convert the DWF file to a PNG (Portable Network Graphics) or JPEG (Joint Photographic Experts Group) image file.
The Project Freewheel server returns the image to the user's browser. Since image files can be viewed natively by browsers, no additional software is required. Nothing has to be installed on the user's machine. A low resolution image is returned for immediate viewing while a higher resolution image is generated and then returned.
As the user zooms, pans, or orbits, JavaScript on the user's computer makes requests to the Project Freewheel server for new image files. This is also possible without installing additional software since browsers support JavaScript. The Project Freewheel server applies the pan, zoom, or orbit to the DWF file, creates a new image file using the rendering engine, and returns the image file to the user's browser.
The ability to pan, zoom, and orbit DWF files free from installing software and independent of a particular platform help DWF go beyond what can be done with traditional paper.
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