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
image-rendering
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 2023/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

[1] (1,2,3,4,5,6,7,8,9,10,11,12,13)

These structural pseudo-classes are implemented in rust-selectors, which librsvg uses.