PUMA
Istituto di Informatica e Telematica     
Tesconi M., Marchetti A. POWERXML UN'ALTERNATIVA OPEN A POWERPOINT. Technical report, 2005.
 
 
Abstract
(English)
Building a presentation entails organizing our thoughts into a logical sequence in order to present them in an easly understandable way. What does this involve? Psychologists, communication and cognitive experts and man-machine interface researchers are still debating the best practice, but for millions of people the answer is exactly PowerPoint (Ppt). 1)Ppt is easy to use: it's possible rapidly to create attractive slides full of very pleasant multimedia effects to impress the audience. 2)The tool is widely available since it is part of very popular MS Office. 3)Ppt format is a de facto standard. It is often required as the official format for presenting.However there are also several reasons to seek an alternative solution •Ppt format is not based on XML, but is a proprietary format. In order to export a Ppt presentation is necessary to convert it into html, losing many multimedia features. In other words, a Ppt presentation depends on the application. •Ppt presentations are flat sequences of slides and points; thus data can not be easily processed. •Ms Office is a proprietary solution, that is, it is not free. •If we want to web publish a Ppt presentation, respecting the accessibility guidelines, we must convert it into html and process it with a tool. For these and other reasons a plethora of alternative tools for creating and displaying presentations were created. To overcome the difficulties to deploy new software these new tools use other products such as PDF readers and web browsers. These first products were basic, with few multimedia effects, which can liven up the most boring presentations interesting. The publication of Scalable Vector Graphics (SVG) 1.0 Specification, on September 4th 2001, renewed the hopes of realizing competitive presentation tools. Several SVG based products appeared (SVG Slidemaker, Jack SVG …). One of the main limits of these solutions is the positioning and distribution of the text in the slide. To overcome a set of drawbacks of these new proposals and with the aim of developing a more powerful open-source solution we started the project PowerXML totally based on XML technologies and open-source components.In PowerXML every presentation is stored in a single XML source file. We defined a language to express these XML source files, called, of course, PowerXmlML. In this language every presentation is organized into chapters, sections and slides. Every slide is divided into items. It is possible to assign each item a predefined semantic value that clarifies the meaning of the item itself. For example an item can be classified as a definition, a warning statement, or a potential target and so on. These semantic values are interpreted by the application and rendered by associating an icon, a sound or an animation or a combination of these. This list of semantic values with relative multimedia renderings can be easily personalized. It is possible to assign an id to each element of the presentation (chapter, section, slide, and item) in order to refer to it. This mechanism can be extended to presentation level. In this way, it is possible to include a presentation or a part of it in another presentation, or it is possible to create links between presentations. In the XML source file containing the presentation there is no reference to rendering information. Therefore these presentations are independent from any rendering format. It has been defined an XML document, called Mixed Style Sheet, containing any rendering information useful for the presentation. We called it Mixed because it is a mix of CSS and SVG proprieties, expressed into xml syntax. The organization of a MSS file is similar to a CSS document where for each object displayed are defined a set of associated properties as the position in the slide, the background, the animation, the associated icon, the sound and so on. PowerXML is a web application, based on Cocoon. It generates the slides through the Cocoon pipelines of XSLT transformations, serializing as SVG, PDF, or XHTML page, according to the browser's capabilities. SVG is the main output format; PDF is used prevalently for print output while XHTML has been thought for the browsers without SVG capabilities. Of course the best results are obtained with SVG; in particular in this format the generated slides are full of multimedia effects like animations, sounds, images and icons. For improving the text layout some new features, introduced with SVG 1.2 version as text flow, are heavily used. The SVG format, that we used, respects the accessibility guidelines. Every slide is generated directly from the XML source and MSS style sheet, this means that the presentation is always coherent with the source and that is always possible to change the style during the presentation. It is also possible to generate immediately all the SVG presentation off-line as a sequence of SVG files, compressed into a zip file. In this way the presentation can be used without Cocoon. Of course, in this case, the presentation is static, can not be modified on fly. Among the future plans we are going to deploying a PowerXmlML editor and a MSS Editor always based on Cocoon functionalities.
Subject SVG
XML
XSLT
Animation
Presentation
Accessibility
Cocoon
Powerpoint
K3 [Computers and Education] Collaborative Learning, Distance Learning


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