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Mozilla SVG Project


Since you have come this far, you probably already know that SVG stands for Scalable Vector Graphics, and that it is an XML language for sophisticated 2-dimensional graphics. SVG is to graphics what XHTML is to text, MathML is to mathematical equations and CML is to the description of chemical molecules.

SVG is similar in scope to Macromedia's proprietary Flash technology: among other things it offers anti-aliased rendering, pattern and gradient fills, sophisticated filter-effects, clipping to arbitrary paths, text and animations. What distinguishes SVG from Flash, is that it is a W3C recommendation (i.e. a standard for all intents and purposes) and that it is XML-based as opposed to a closed binary format. It is explicitly designed to work with other W3C standards such as CSS, DOM and SMIL.

A simple example

In case you're curious what SVG looks like, here's an example:

<svg xmlns=""
  <g fill-opacity="0.7" stroke="black" stroke-width="0.1cm">
    <circle cx="6cm" cy="2cm" r="100" fill="red"
                    transform="translate(0,50)" />
    <circle cx="6cm" cy="2cm" r="100" fill="blue"
                    transform="translate(70,150)" />
    <circle cx="6cm" cy="2cm" r="100" fill="green"
                    transform="translate(-70,150)" />

And this is what it looks like when rendered by Mozilla Firefox 1.5:

Native SVG vs. plug-in SVG

The Mozilla SVG implementation is a native SVG implementation. This is as opposed to plug-in SVG viewers such as the Adobe viewer (which is currently the most popular SVG viewer).

Some of the implications of this are:

  • Mozilla can handle documents that contain SVG, MathML, XHTML, XUL, etc. all mixed together in the same 'compound' document. This is being made possible by using XML namespaces.
  • Mozilla is 'aware' of the SVG content. It can be accessed through the SVG DOM (which is compatible with the XML DOM) and manipulated by Mozilla's script engine.
  • Other Mozilla technologies can be used with SVG. XBL coupled with SVG is a particular interesting combination. It can be used to create graphical widgets (I wonder when we'll see the first SVG-based chrome!) or extend Mozilla to recognize other specialized languages such as e.g. CML (chemical markup language). There are samples of these kinds of more advanced usage patterns on


SVG support is now included in the latest version of Mozilla Firefox!

The goal we're working towards with Mozilla's SVG implementation is SVG 1.1 Full. What exists now in the tree should be treated as a technology preview. As we implement more of the specification, content written against Mozilla's SVG implementation might break if it unintentionally relies on bugs that are fixed. We realize this is not ideal, but ask you be patient as we continue implementing an extremely large specification that lacks a comprehensive test suite.

Our goal is specification conformance. Where the specification and other implementations of SVG differ, we will conform to the specification. Where the specification is ambiguous, we will make an informed decision, consulting the SVG working group and other experts as appropriate.

While we are still a long way away from full SVG support, the subset currently implemented is already pretty usable. We have support for all basic shapes including beziers, stroking and filling with opacity, gradients, scripting, events, and much of the DOM.

Big areas of the SVG specification where we're still lacking include filters, svg defined fonts, and declarative animations. A page listing the current implementation status of svg elements and the rendering backends can be found at

Getting Involved

SVG 1.1 is a big specification and we still have a lot of work to do to fully implement it. If you think you can help us by e.g. tracking down bugs, writing some test-cases or implementing some outstanding features, please get in touch.

We have an IRC chat channel, #svg, on

There is also newsgroup/mailing list dedicated to SVG in Mozilla. It's called

If reporting bugs, the best place for them is in bugzilla so that we can track them and you can monitor the progress. File them in the "Core" product with the "SVG" component. If you have a testcase (which we love to have), please use the attachment feature of bugzilla to include it rather than pasting it in the bug.


SVG support is now included in the latest version of Mozilla Firefox and in the developer/tester nightly builds (using the cairo renderer backend on all platforms). For most people it is no longer necessary to download special "SVG enabled" builds. The only exception is if you are running Microsoft Windows 98 or older. In this case we recommend you download a GDI+ enabled SVG build. You will also need to install GDI+.


If, for whatever reason, you want to build your own version of a Mozilla product with SVG support instead of downloading a build from the links in the previous section, then see our Mozilla+SVG build page.

Frequently Asked Questions

Before asking us questions directly, please take a look at the FAQ to see if your question has already been answered. If your question hasn't been answered there, try asking in our newsgroup or IRC channel.


Mozilla-specific SVG sites

General resources