First Impressions of Firefox 1.5 BETA1

As of today, there is light at the end of the tunnel: the beta of Mozilla Firefox 1.5 not only has SVG support, said SVG support is switched on, and even works a bit.

I am afraid this note mainly concentrates on the bad news (things that don’t work). I plan to write more when I have had a chance to try out some of the new possibilities and adapt my existing SVG projects to exploit them.


These are listed on the Mozilla SVG status page.

Declarative animation is not supported (bug 216462): you can see this in the Flickr badge on my home page. Viewed via Adobe SVG Viewer, you will see the last few images of mine from Flickr fade in and out. In Firefox, you just see a black background with my icon in the top corner, and a couple of spurious scrollbars.

Second, SVG fonts are not supported (bug 119490). I used those in the Alleged Tarot to render the titles of the cards. For example, in The Lovers, at the bottom-left corner we should see the title of the card in a unicase font peculiar to this series. On Windows this is replaced with Helvetica, which does not look as bad as all that. On Mac OS X, I seem to be missing the text altogether: even the text that does not use special fonts.

Tweaks required

There is a peculiar hack used by Adobe to make SVG files look less bulky: if it detects that the file contains a Zip archive, it unpacks the archive and uses the contained file. Mozilla supports a more approach: it displays a yellow box complaining of an XML parsing error. The solution is described on the Mozilla SVG Wiki: program your web server to corretly label .svg files as having Content-Encoding:gzip and they work. I had to add to my site’s .htaccess file, but now SVG files do display.

Layout Trouble

There are a couple of layout problems in Firefox with regard to SVG files embedded with an embed tag. The first is that the presence of embed throws their paragraph-layout system in to some sort of fit: witness these two screen grabs:

The page in question uses HTML code as follows:

<embed src="../2004/firefox-logo.svgz" 
    width="120" height="120" alt="(logo)" 
    align="left" />
The FireFox logo to the left of this paragraph is ...

The Safari capture uses the Adobe SVG Viewer plug-in. The graphic is shown floated left within the paragraph as expected. There is some space around the embed because of a CSS rule:

p embed[align='left'] {
    margin: 0.25em 0.5em 0.25em 0;

All in all, it behaves pretty much as an image would, which is more or less what I expect. The Firefox paragraph goes very weird. The left margin is lost (notice how the T of The is to the left of the d of displayed, and exactly matches the right edge of the column with the # in it), and once it is past the embedded image it slurps all the way over to the left edge of the viewport. The margin between this paragraph and the next one is also gone.

A Whole New Viewport Problem

Another weird thing I see is that the graphic has scrollbars. My embed tag specifies width 120 and height 120 whereas the SVG file gives its natural dimensions as width 132·72, height 127·219. Firefox shows the image at its natural size and adds scrollbars. I had expected the image to be displayed with the standard SVG viewport rules, under which the image would have been scaled until it fit in to the 120-pixel-by-120-pixel box I specified.

To see this effect even more strongly, visit the Alleged Tarot front page. The left picture should show a card scaled down to thumbnail size, but instead shows only its top-left corner, plus scrollbars.

I assume the reason for this is that embed is being treated as an iframe containing another browser document, as opposed to being part of this page. (Update: this is Mozilla Bug 288276.)

Another consequence of this is that, when I click on a a tag in the SVG document, the page I linked to replaces the SVG file, not the whole page! To see this, click on the Flickr badge; in Safari this replaces the whole page, in Firefox the Flickr page gets embedded where the SVG was.

Moving On

I don’t want to give the impression that all is gloom, however. Getting SVG integrated in the Mozilla is an impressive pice of work, especially given how few developers have actually been working on it, and considering that they are attempting to do SVG the hard way, by integrating it in to Mozilla's existing HTML + MathML layout engine, rather than write a standalone plug-in that goes its own way. The result is that it has taken a long time, but the combination of SVG with Mozilla’s existing XML-based features (like XUL and XBL) could make for some powerful synergy in the future.