Supported SVG and CSS features

Librsvg tries to be a mostly complete renderer for SVG1.1 and SVG2.

In terms of processing external references, librsvg is a bit more strict than SVG’s “static mode” and a bit more lenient than “secure static mode”. See “Security and locations of referenced files” in the reference documentation for details.

Animation, interactivity, and scripting are not supported.

The SVG1.2 specification never made it past draft status in the W3C’s process, and librsvg does not support it. Note that SVG2 removed some of the features proposed for SVG1.2.

Generally, librsvg tries to keep up with features in the SVG2 Candidate Recommendation spec. It ignores features in the SVG2 drafts that are not finalized yet.

Alternative versions of SVG (SVG Tiny, SVG Basic, SVG Native) are not explicitly supported. Their features which are a subset of SVG1.1 or SVG2 are supported if they are equivalent to the ones listed below.

SVG2 offloads many of its features to the family of CSS3 specifications. Librsvg does not try to support them exhaustively (there are too many features in CSS!). Instead, we try to prioritize new features based on the needs which people express in librsvg’s bug tracker. Do you want a feature? File an issue!

Attributes supported by all elements

Attribute

Notes

class

id

requiredExtensions

Used in children of the switch element.

requiredFeatures

Used in children of the switch element.

systemLanguage

Used in children of the switch element.

style

transform

The transform attribute has a different syntax than the CSS transform property.

xml:lang

xml:space

Elements and their specific attributes

Element

Attributes

Notes

a

xlink:href

Needs xlink namespace

href

SVG2

circle

cx

cy

r

clipPath

clipPathUnits

defs

ellipse

cx

cy

rx

ry

feBlend

See “Filter effects”

in

in2

mode

feColorMatrix

See “Filter effects”

in

type

values

feComponentTransfer

See “Filter effects”

in

feComposite

See “Filter effects”

in

in2

operator

k1

k2

k3

k4

feConvolveMatrix

See “Filter effects”

in

order

divisor

bias

targetX

targetY

edgeMode

kernelMatrix

kernelUnitLength

preserveAlpha

feDiffuseLighting

See “Filter effects”

in

surfaceScale

kernelUnitLength

diffuseConstant

feDisplacementMap

See “Filter effects”

in

in2

scale

xChannelSelector

yChannelSelector

feDistantLight

azimuth

elevation

feDropShadow

See “Filter effects”.

Also takes the flood-color and flood-opacity properties.

in

dx

dy

stdDeviation

feFuncA

See “Filter effect feComponentTransfer”

feFuncB

See “Filter effect feComponentTransfer”

feFuncG

See “Filter effect feComponentTransfer”

feFuncR

See “Filter effect feComponentTransfer”

feFlood

See “Filter effects”

Parameters come from the flood-color and flood-opacity properties.

feGaussianBlur

See “Filter effects”

in

stdDeviation

feImage

See “Filter effects”

xlink:href

Needs xlink namespace

href

SVG2

path

Non-standard; used by old Adobe Illustrator versions.

preserveAspectRatio

feMerge

See “Filter effects”

feMergeNode

in

feMorphology

See “Filter effects”

in

operator

radius

feOffset

See “Filter effects”

in

dx

dy

fePointLight

x

y

z

feSpecularLighting

See “Filter effects”

in

surfaceScale

kernelUnitLength

specularConstant

specularExponent

feSpotLight

x

y

z

pointsAtX

pointsAtY

pointsAtZ

specularExponent

limitingConeAngle

feTile

See “Filter effects”

in

feTurbulence

See “Filter effects”

baseFrequency

numOctaves

seed

stitchTiles

type

filter

filterUnits

primitiveUnits

x

y

width

height

g

image

xlink:href

Needs xlink namespace

href

SVG2

path

Non-standard; used by old Adobe Illustrator versions.

x

y

width

height

preserveAspectRatio

line

x1

y1

x2

y2

linearGradient

gradientUnits

gradientTransform

spreadMethod

x1

y1

x2

y2

marker

markerUnits

refX

refY

markerWidth

markerHeight

orient

preserveAspectRatio

viewBox

mask

x

y

width

height

maskUnits

maskContentUnits

path

d

pattern

xlink:href

Needs xlink namespace

href

SVG2

patternUnits

patternContentUnits

patternTransform

preserveAspectRatio

viewBox

x

y

width

height

polygon

points

polyline

points

radialGradient

gradientUnits

gradientTransform

spreadMethod

cx

cy

r

fx

fx

fr

rect

x

y

width

height

rx

ry

stop

offset

style

type

svg

x

y

width

height

viewBox

preserveAspectRatio

switch

symbol

preserveAspectRatio

viewBox

text

x

y

dx

dy

tref

xlink:href

Needs xlink namespace

tspan

x

y

dx

dy

use

xlink:href

Needs xlink namespace

href

SVG2

x

y

width

height

CSS properties

The following are shorthand properties. They are not available as presentation attributes, only as style properties, so for example you have to use <path style="marker: url(#foo);"/>, since there is no marker attribute.

Property

Notes

font

glyph-orientation-vertical

Supports only CSS Writing Modes 3 values: auto, 0, 90, 0deg, 90deg

marker

The following are longhand properties. Most of them are available as presentation attributes, e.g. you can use <rect fill="blue"/> as well as <rect style="fill: blue;"/>. The Notes column indicates which properties are not available as presentation attributes.

Property

Notes

baseline-shift

clip-path

clip-rule

color

color- interpolation-filters

direction

display

enable-background

fill

fill-opacity

fill-rule

filter

flood-color

flood-opacity

font-family

font-size

font-stretch

font-style

font-variant

font-weight

isolation

Not available as a presentation attribute.

letter-spacing

lighting-color

line-height

Not available as a presentation attribute.

marker-end

marker-mid

marker-start

mask

mask-type

mix-blend-mode

Not available as a presentation attribute.

opacity

overflow

paint-order

shape-rendering

stop-color

stop-opacity

stroke

stroke-dasharray

stroke-dashoffset

stroke-linecap

stroke-linejoin

stroke-miterlimit

stroke-opacity

stroke-width

text-anchor

text-decoration

text-orientation

Not available as a presentation attribute.

text-rendering

transform

SVG2; different syntax from the transform attribute.

unicode-bidi

vector-effect

Only non-scaling-stroke is supported for paths.

visibility

writing-mode

Filter effects

The following elements are filter effects:

  • feBlend

  • feColorMatrix

  • feComponentTransfer

  • feComposite

  • feConvolveMatrix

  • feDiffuseLighting

  • feDisplacementMap

  • feDropShadow

  • feFlood

  • feGaussianBlur

  • feImage

  • feMerge

  • feMorphology

  • feOffset

  • feSpecularLighting

  • feTile

  • feTurbulence

All of those elements for filter effects support these attributes:

Attribute

Notes

x

y

width

height

result

Some filter effect elements take one input in the in attribute, and some others take two inputs in the in, in2 attributes. See the table of elements above for details.

Filter effect feComponentTransfer

The feComponentTransfer element can contain children feFuncA, feFuncR, feFuncG, feFuncB, and those all support these attributes:

Attribute

Notes

type

tableValues

slope

intercept

amplitude

exponent

offset

CSS features

Pseudo-classes

Pseudo-class

Notes

:link

:visited

Because librsvg does not maintain browser history, this is parsed, but never matches

:lang()

:not()

[1]

:first-child

[1]

:last-child

[1]

:only-child

[1]

:root

[1]

:empty

[1]

:nth-child()

[1]

:nth-last-child()

[1]

:nth-of-type()

[1]

:nth-last-of-type()

[1]

:first-of-type

[1]

:last-of-type

[1]

:only-of-type

[1]

FIXME: which selectors, combinators, at-rules.

XML features

XInclude

Librsvg supports the following subset of XML Inclusions (XInclude).

A document or element may declare the namespace for http://www.w3.org/2001/XInclude, conventionally as an attribute xmlns:xi="http://www.w3.org/2001/XInclude".

The following discussion assumes an xi: shorthand; your namespace declaration may use a different one, but xi: is conventional for XInclude.

The following are examples of valid inclusions:

<xi:include href="foo.xml" parse="xml"/>
<!-- If foo.xml cannot be read, parsing stops with an error -->

<xi:include href="foo.xml" parse="xml">
  <xi:fallback>
    <some_fallback_element/>
    <another_fallback_element/>
  </xi:fallback>
</xi:include>
<!-- If foo.xml cannot be read, the elements inside xi:fallback are used instead.
     If foo.xml has a syntax error, parsing stops with an error. -->

<xi:include href="foo.txt" parse="text" encoding="utf-8">
  <xi:fallback>
    Text to be included if foo.txt cannot be read.
  </xi:fallback>
</xi:include>

For the xi:include element, the href attribute is mandatory, and parse and encoding are optional:

  • href - mandatory for librsvg. This is different from the XInclude specification: the attribute is mandatory in librsvg, while the spec assumes that if it is not present, then an xpointer or fragid attributes are used instead. Librsvg does not support those. If there is no href attribute, librsvg will ignore the whole xi:include element.

  • parse - optional; supported values are xml and text; the default is xml.

  • encoding - optional; only used for including text files with parse="text". The value should be a WHATWG label for an encoding, for example, utf-8 or koi8-r.

Inside <xi:include>, there can be an <xi:fallback> element to specify what should be included if the href cannot be read.

xml:lang and xml:space

Individual elements can specify an xml:lang attribute to specify their language. This can be used in a <text> element for the main language of its content, or generally for the purposes of CSS selector matching. Note that this is different from the use of systemLanguage in children of the <switch> element, which is used to render different elements depending on the system’s language.

Librsvg supports the xml:space attribute and its handling per SVG1.1. Note that this has been superseded in SVG2 with CSS whitespace handling; librsvg does not support this yet as of 2013/Feb/10.

Explicitly Unsupported features

  • flowRoot element and its children - Inkscape, SVG 1.2 only.

  • glyph-orientation-horizontal property - SVG1.1 only, removed in SVG2

  • The pseudo-classes :is() and :where() are part of Selectors Level 4, which is still a working draft.

Footnotes