Reinventing Fire

With SVG being integrated more and more into HTML5, both included via <object> and <img> elements, and inline in the same document, some natural questions about SVG and CSS are receiving more focus. This includes box model questions like background and border, and pointer events.

I’m interested in comments from the community on what direction SVG should take.

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Korzybski remarked that “the map is not the territory”, reminding us that we shouldn’t confuse our mental models for reality. But maps, and data visualizations of all kinds, are really powerful, conveying complex ideas easily, and even shaping (or misshaping) perceptions about facts. This is one reason why decentralization of mapping resources and services is good; no one organization should control our common maps.

SVG is a natural fit for mapping. There’s even a detailed proposal by KDDI’s Satoru Takagi-sensei for tiling, layering, and coordinate resolution that fits on top of SVG, which I’d like to see standardized.

I’ve had an idea for a small open-source project for a while, which I’ve discussed with the brilliant Andreas Neumann of Carto.net; he’s been too busy planning SVG Open every year to help out with it thus far, and I don’t have the skills to do it without a great investment in time.
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I’ve been doing a lot of website stuff this week. Here’s some highlights:
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SVG paths have a pretty good set of shape commands, enough to let you draw any 2D shape you might want in an authoring tool: horizontal, vertical, and diagonal straight lines, elliptical arc segments, and cubic and quadratic Bézier curves. Béziers are great, giving you precise control over the position and curve interpolation of each point in a concise format, using control points (“handles”), and are easily chained together to create complex shapes.

But let’s say you have a series of points, and you want to draw a smooth line between them, e.g. for stock data, an audio wave, or a mathematical graphing equation. Béziers are not as handy there, because not all the points needed to define a Bézier spline are on the curve itself. Obviously, you can decompose any set of points into a set of Béziers, but that takes math, and who wants to do that? (Put your hand down, nerd. I’m talking to the normals.)

Sometimes, you just want to lay down a set of points, and let the browser draw a smooth curve (unlike polylines, where each segment is just a straight line between the points). Like this:

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Recently, a browser implementer asked me for examples of SVG. He was having trouble finding good examples of SVG in use, particularly as parts of an HTML document. This question has come up again and again, actually, and it always vexes me. I’ve been active in the SVG community for close to a decade, and I’ve seen thousands of amazing SVG files (and many more of mediocre to average quality), but somehow they seem to have disappeared or bitrotted over the years. Some of those files only worked with the slightly-unstandard Adobe SVG Viewer, or didn’t quite work with Firefox’s incomplete support, I know, but surely not all of them. Where is all the great SVG content I remember, the games and GUIs and design and development? Where are all those files to be found?

I hear some browser implementers say that people just don’t use SVG. Intuitively, this feels false to me, based on my own experience. But could it be true?

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I’m really excited about W3C’s new public Audio Incubator Group, just launched today, and open for collaborators, innovators, and instigators. Go take a look for yourself, and see if you can contribute.

To celebrate the occasion, here’s a simple example of an experimental audio inteface, in the world’s first (and worst) audio synthesizer in SVG (you’ll need a special Minefield build to use it). Just click on the keyboard… it’s pretty rough still, but it shows some of the potential:

(standalone SVG file)

For some background, read on after this break…
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I’m working with a professional designer, Michael, on some graphics for my upcoming MIX presentation.  I’ve worked with designers before on various projects, some SVG, some traditional Web design, but this is my first time working on an SVG project with someone who never used SVG before, and it’s been an interesting experience, which I thought I’d jot down for anyone interested.

Both of us have been busy with other projects, and since we are in different places (me in Chapel Hill NC, him in Atlanta GA), we have only gotten to touch base a few times.  Michael has delivered some first drafts of the graphics, which look lovely, and I decided to dig into the underlying code, confident that I could trim down the file size and thus help browser performance.

My personal graphical editor of choice is Inkscape, which is a fine tool for all its warts (though it’s a little painful on Mac, where it is hosted as an X-11 application); typically, though, I create SVG either programmatically with a script or manually with a text editor (yes, I know that’s crazy… but it can be done).  Michael, being a professional designer, uses Adobe Illustrator, and I am keen to have him use the tools he is most comfortable with.  Since I want SVG to be used by mainstream designers, I want to understand how their tools work and what their workflow is like.

So, in order to make sure that we can roundtrip the files as seamlessly as possible, while still leveraging the features of SVG, I set about today to establish a workflow with Illustrator, TextMate (my go-to text editor, with a custom SVG code template bundle), Firefox, and its native debugger extension Firebug (with its handy “Inspect Element” context-menu selection).  My goal: to make reusable icons out of some of the graphical assets in the larger image, to be referenced by SVG’s <use> element. Read the rest of this entry »

I attended Google I/O a couple weeks ago, and had a great time.  They really put the “hype” in HyperText Markup Language 5, identifying things like the Geolocation API and some of the WebApps Working Group deliverables as part of “HTML5″.  Not quite accurate, but it was a branding exercise, not a technical one.  Notably absent from the things they rolled into HTML5 during the keynote, though, was SVG… in fact, they seemed to go out of their way to avoid it.

But it’s in there. Read the rest of this entry »

While answering a question about styling SVG with CSS in the Freenode #svg IRC channel (yes, people still use IRC), I threw together a simple example to illustrate.  I like to do this, since in keeps me in practice, and gives me a chance to check the state of current implementations in the fast-changing world of SVG browser support.

The question was how to use CSS stylesheets, both internal and external, with SVG in Inkscape.  While I know that Inkscape makes heavy use of CSS inline style declarations on elements (more than is to my personal taste, to be honest), I didn’t (and don’t) know if it has any UI features for adding internal stylesheet blocks, or links to external stylesheets.  So I made a little test…

svgstyle.svg

<?xml-stylesheet type="text/css" href="svgstyle.css" ?>
<svg xmlns="http://www.w3.org/2000/svg"
     xmlns:xlink="http://www.w3.org/1999/xlink"
     width="100%" height="100%" viewBox="40 0 145 70">

  <style type="text/css"><![CDATA[
     ellipse
     {
       fill: lime;
       stroke: green;
       stroke-width: 10px;
     }
  ]]></style>

  <rect id="inline" x="50" y="10" width="30" height="50"
        rx="5" ry="5"
        style="fill:lime; stroke:green; stroke-width:3px;"/>
  <ellipse id="internal" cx="103" cy="35" rx="15" ry="25"
        style="stroke-width:3px;"/>
  <circle id="external" cx="150" cy="35" r="25"
        style="stroke-width:3px;"/>
</svg>

svgstyle.css

circle
{
   fill: lime;
   stroke: green;
   stroke-width: 10px;
}

Which looks like this (at least, in Firefox, Opera, Safari, and presumably Chrome):

Both internal styles worked fine in Inkscape, but the external reference did not, showing just a black circle.  I’m not really surprised.  Note the clunky way that you have to link to external stylesheets in SVG:

<?xml-stylesheet type="text/css" href="svgstyle.css" ?>

That’s really XSLT-licious. I have to confess, I don’t really care for PIs (insert dated Magnum PI joke here), or XML prologs in general… they seem somehow clumsy and un-XMLy, like a throwback to SGML. And as far as I know, they can’t be created or changed dynamically via clientside script. Compare that to the relatively easy and straightforward X/HTML way of linking to external stylesheets:

<link href="svgstyle.css" rel="stylesheet" type="text/css"/>

In the SVG WG, we intend to allow authors to reference external stylesheets in a manner a little more modern and consistent with what authors are already used to using, in some upcoming spec. We could do that a couple of different ways. We could allow them to use an xlink:href attribute on the <style> element, in the same way we currently treat the <script> element (that is, if there’s a resolvable external link, we use that, otherwise we use the child content of the element), or we could add a <link> element like X/HTML, or both. I kinda like the idea of allowing either.

To that end, I made a couple of tests, just playing around, to see if any browsers accidentally supported either of those options, by merit of having some shared codebase with X/HTML in their implementations. Unsurprisingly, neither worked.

But then I had another idea… use the an <xhtml:link> element in the XHTML namespace…

<xhtml:link href="svgstyle.css" rel="stylesheet" type="text/css"/>

With this rather happy result, which works in at least Firefox, Opera, and Safari.
external-link-xhtml.svg:

I don’t know if this is by design, or if it just fell out of the model, but I have to say I’m pleased as punch that it works. If nothing else, it’s a great proof of concept for adding more ways of linking to CSS in the SVG spec. This one goes in my toolkit, and I’m going to try to ensure that it gets standardized, if it’s not already there in some corner of some other spec. Probably somebody already knows about this (hell, probably everybody does, and I’m late to the party), but for me it was a w00ty discovery.

Update: heycam speculated that you might also be able to use @import rules, and indeed you can:

<style type="text/css">@import url(svgstyle.css);</style>

Wow.  After a ridiculously long time in preparation, with political battles along the way, and a long slog of making tests and maintaining older versions of the spec, as well as working on supporting specs like Element Traversal and DOM3 Events, SVG Tiny 1.2 is finally a W3C Recommendation.  Whew!

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