Subject: SVG and compound images
From: F J Franklin (F.J.Franklin@sheffield.ac.uk)
Date: Fri May 04 2001 - 04:34:38 CDT
Hi, I'm currently working on WMF -> SVG translation as part of libwmf2.
Here are my thoughts on SVG generally and with regard to AbiWord.
(1) Viewing / Editing
To view SVG I can use the JAVA-based svgtoolkit, which is very slow but a
fairly rigorous implementation (I think) and comes with a selection of SVG
images - I don't know exactly what the copyright is on these.
sodipodi is coming along nicely and can be used to edit as well as create
SVG images, and has recently begun collecting clipart.
I have no experience with librsvg but it looks to be very GNOME. And I
have no experience with Adobe's SVG plugin.
WMF files can contain raster and/or vector graphics. If the metafile
describes a single raster image then WMF -> PNG would be the sensible
translation; similarly, if the image contains no raster images (i.e.,
vector graphics only) then WMF -> SVG is trivial.
The difficulty arises when (a) there are multiple raster images; and/or
(b) there is a mixture of raster and vector graphics.
In case (a) it is technically possible just to combine all images into a
single image - but I don't know how sensible that would be; and, besides,
it doesn't solve case (b).
Assuming, therefore, for the moment, that the image has multiple raster
graphics as well as vector graphics. SVG can describe all this, but the
raster images are separate and referred to by URL. Thus, the WMF would
break down as, for example:
eg.wmf -> eg.svg eg-1.png eg-2.png ...
(A compliant SVG displayer is expected to be able to handle both PNG and
As such, importing a `single' SVG image into AbiWord would entail
importing multiple secondary images (some of which, for the general
non-WMF case, may even have hyperlinks to images on the web) - I assume
that AbiWord would not want to leave these as hyperlinks (since images
there today may be gone tomorrow...).
One consequent thought: perhaps all PNG (and JPEG if that's ever an
option, and personally I think it ought to be if we want to claim to
support SVG) should be given an SVG wrapper? So that all images in AbiWord
are ostensibly SVG, even if in effect they are a single PNG image.
Francis James Franklin
Their consultation consisted chiefly in propounding and supporting, for
the thousandth time, each his favourite theories.
--- George MacDonald
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