Liaison Statement from IDPF AHL WG
to W3C SVG WG
Source: IDPF Advanced/Hybrid Layouts WG
Date: 2013-05-26
IDPF is an international trade and standardization organization for digital publications. IDPF develops and maintains EPUB, which is a standard for digital books. EPUB is based on web technologies including SVG. The IDPF Advanced/Hybrid Layouts (AHL) WG is a new working group for extending EPUB for better support of image-based publications such as comics and magazines.
Major deliverables of AHL are rendition selection, inter-rendition navigation, and intra-rendition navigation. Rendition selection allows automatic and interactive selection from multiple renditions (e.g., a rasterized rendition and an XHTML rendition) in a given EPUB publication. Inter-rendition navigation allows navigation from a rendition to another, while intra-rendition navigation allows navigation within a single rendition. Both types of navigation are based on regions in image-based renditions. Rectangular regions are often sufficient for magazines, but non-rectangular regions are strongly needed for panels and balloons in comics.
AHL plans to use two mechanisms for representing regions. One is W3C media fragments, and the other is SVG elements.
We plan to specify media fragments as part of our markup vocabulary for specifying inter- and intra-navigation sequences.
We are aware that W3C media fragments allow rectangular regions only, but we are considering whether they can be extended for non-rectangular regions.
SVG (or SVG in HTML) can be used as wrappers for images. We intend to use SVG for representing regions and then reference such representations from our markup vocabulary for specifying inter- and intra-navigation sequences.
We understand that SVG provides rectangular views as fragments and view elements. But again we are wondering how we can capture non-rectangular regions using SVG. One possibility is to have invisible polygons, path, and rect elements in rendition trees and reference such regions by fragment identifiers (e.g, bare names).
AHL thanks SVG WG for spending one session in the upcoming SVG F2F meeting in Tokyo for EPUB related issues. Some members of AHL including a co-chair are happy to attend this meeting. We hope to explain further details of our work and are eager to hear comments from the SVG WG.