<pre class='metadata'>

Title: CSS Shapes Module Level 1

Status: ED

Prepare for TR: no

Work Status: Testing

Shortname: css-shapes

Level: 1

Group: csswg

TR: https://www.w3.org/TR/css-shapes/

ED: https://drafts.csswg.org/css-shapes/

Previous Version: https://www.w3.org/TR/2025/CRD-css-shapes-1-20250612/

Editor: Rossen Atanassov, Microsoft Corporation, [email protected], w3cid 49885

Editor: Alan Stearns, Adobe, [email protected], w3cid 46659

Editor: Noam Rosenthal, Google, w3cid 121539

Former Editor: Vincent Hardy

Implementation Report: https://wpt.fyi/results/css/css-shapes

Abstract: CSS Shapes describe geometric shapes for use in CSS. For Level 1, CSS Shapes can be applied to floats. A circle shape on a float will cause inline content to <a>wrap</a> around the circle shape instead of the float's bounding box.

Repository: w3c/csswg-drafts

WPT Path Prefix: css/css-shapes/

WPT Display: open

</pre>

<pre class='link-defaults'>

spec:css2; type:property; text:margin

spec:css-backgrounds-3; type:property; text:border-radius

spec:css-inline; type:dfn; text:initial letter box

spec:css-masking-1; type: value

text: nonzero

text: evenodd

spec:css-shapes; type: value

text: closest-side

text: farthest-side

spec:svg2; type:property;

text:fill-rule

spec:css-values-5; type:value;

text:top;

text:right;

text:bottom;

text:left;

text:center;

text:x-start;

text:y-start;

text:x-end;

text:y-end;

</pre>

<style>

.singleImgExample {

display: block;

margin: auto;

}

</style>

<h2 id="intro">

Introduction</h2>

<em>This section is not normative.</em>

Shapes define arbitrary geometries

that can be used as CSS values.

This specification defines properties

to control the geometry

of an element's <a>float area</a>.

The 'shape-outside' property uses shape values

to define the <a>float area</a> for a float.

Note: Future levels of CSS Shapes will allow use of shapes

on elements other than floats.

Other CSS modules can make use of shapes as well,

such as CSS Masking [[CSS-MASKING]]

and CSS Exclusions [[CSS3-EXCLUSIONS]].

Note: If a user agent implements both CSS Shapes

and CSS Exclusions,

the 'shape-outside' property defines

the exclusion area for an exclusion.

Note: A future level of CSS Shapes will define a shape-inside property,

which will define a shape to <a>wrap</a> content within the element.

<h3 id="module-interactions">

Module Interactions</h3>

This module extends the float features defined in [[!CSS2]] chapter 9.

<h3 id="values">Values</h3>

This specification follows the <a href="https://www.w3.org/TR/CSS2/about.html#property-defs">CSS property definition conventions</a> from [[!CSS2]]

using the <a href="https://www.w3.org/TR/css-values-3/#value-defs">value definition syntax</a> from [[!CSS-VALUES-3]].

Value types not defined in this specification are defined in CSS Values &amp; Units [[!CSS-VALUES-3]].

Combination with other CSS modules may expand the definitions of these value types.

In addition to the property-specific values listed in their definitions,

all properties defined in this specification

also accept the <a>CSS-wide keywords</a> as their property value.

For readability they have not been repeated explicitly.

<h3 id="terminology">

Terminology</h3>

<dfn data-lt="wrap|wrapping">Wrap</dfn>

This specification uses the term <a>wrap</a>

to refer to flowing content

around the sides of a <a>float area</a>,

defined in [[!CSS2]] chapter 9.

Content <a>wraps</a> around the right side

of a left-floated box,

and content <a>wraps</a> around the left side

of a right-floated box.

One result of this <a>wrapping</a>

is that line boxes next to a float

are shortened as necessary

to avoid intersections with the <a>float area</a>.

<dfn>Float area</dfn>

The area used

for <a>wrapping</a> content

around a float element.

The rules for float behavior

use the sides of the <a>float area</a>

to determine where content flows.

By default,

the <a>float area</a> is the float element's

<a>margin box</a>

(note this can be different than

the <a>float area</a> produced

by the ''margin-box'' value,

which includes border-radius curvature).

This specification's 'shape-outside'

and 'shape-margin' properties

can be used to define an arbitrary,

non-rectangular <a>float area</a>.

<dfn>direction-agnostic size</dfn>

The [=direction-agnostic size=] of a box is equal to the length of the diagonal of the box,

divided by sqrt(2).

Note: This is a method of averaging the width and height of a box

used by SVG in some cases,

when a percentage of a box's size is desired

but the context doesn't specifically favor the width or the height.

For square boxes, this is the same as the width/height.

<h2 id="relation-to-box-model-and-float-behavior">

Relation to the box model and float behavior</h2>

While the boundaries used

for <a>wrapping</a> inline flow content

outside a float

can be defined using shapes,

the actual box model does not change.

If the element has specified

margins, borders or padding

they will be computed and rendered

according to the [[!CSS3BOX]] module.

Also, float positioning and stacking are not affected

by defining a <a>float area</a> with a shape.

When a shape is used to define

a <a>float area</a>,

the shape is clipped

to the float's margin box.

In other words,

a shape can only ever reduce

a <a>float area</a>,

not increase it.

A reduced <a>float area</a> may have no effect

on some line boxes

that would normally be affected by the float.

If a shape does not enclose any area,

the shape’s edges are still used

to define the <a>float area</a>.

A <a>float area</a> defined by a shape

may reduce the normal <a>float area</a> on all sides,

but this does not allow content to <a>wrap</a>

on both sides of a float.

Left floats with a 'shape-outside' still

only allow content <a>wrapping</a> on the right side,

and right floats only allow <a>wrapping</a> on the left.

<div class="example">

In the following example

the left and right floating

<code class="html">img</code> elements

specify a triangular shape

using the 'shape-outside' property.

<pre><code>

&lt;img class="left" src="hand.svg"/&gt;

&lt;img class="right" src="hand.svg"/&gt;

&lt;p&gt;

Sometimes a web page's text content appears to be

funneling your attention towards a spot on the page

to drive you to follow a particular link. Sometimes

you don't notice.

&lt;/p&gt;

&lt;style type="text/css"&gt;

.left {

shape-outside: polygon(0 0, 100% 100%, 0 100%);

float: left;

width: 40%;

height: 12ex;

transform: scaleX(-1);

}

.right {

shape-outside: polygon(100% 0, 100% 100%, 0 100%);

float: right;

width: 40%;

height: 12ex;

}

p {

text-align: center;

}

&lt;/style&gt;

</code>

</pre>

<img class="singleImgExample" src="images/hand-funnel.png" alt="Using the shape-outside property with floats">

</div>

<div class="example">

Since shapes are clipped to the float's margin box,

adding this shape to the left float above

would result in the same rendering.

<pre><code>

shape-outside: polygon(0 0, 500% 500%, 0 500%);

</code>

</pre>

</div>

<div class="example">

A shape that does not enclose any area

still has edges that contribute to the <a>float area</a>.

This inset shape is a vertical line positioned

at the midpoint of the reference box.

This midpoint edge is used as the edge

of the float area for wrapping content.

<pre><code>

shape-outside: inset(0% 50% 0% 50%);

</code></pre>

If inset values add up to more than the width,

[[css-backgrounds-3#corner-overlap]] rules are used to determine

the edges of the rectangle.

This shape results in a vertical edge

25% from the left side of the reference box.

<pre><code>

shape-outside: inset(0% 150% 50% 0%);

</code></pre>

If the shape is only a horizontal line,

then it is an empty float area and has no effect on wrapping.

Note that in this example shape-margin must be 0px

(otherwise the line would expand to enclose an area).

<pre><code>

shape-outside: inset(50% 0% 0% 50%);

shape-margin: 0px;

</code></pre>

</div>

<div class="example">

A 'shape-outside' can create open areas

on both the left and right

of a <a>float area</a>.

Content still <a>wraps</a> only on one side

of a float in this case.

In the picture,

the shape is rendered in blue,

and the content area outside the shape in mauve.

<pre><code>

shape-outside: polygon(50px 0px, 100px 100px, 0px 100px);

</code>

</pre>

<img class="singleImgExample" src="images/float-side-example.png" alt="wrapping around right side of a left-float float area">

</div>

<div class="example">

The following styling creates

a shape much smaller than

the float's content area,

and adds a margin-top to the float.

In the picture,

the shape is rendered in blue,

the content area outside the shape in mauve,

and the margin area of the float box in yellow.

The inline content only <a>wraps</a> around the shape,

and otherwise overlays the rest

of the float margin box.

<pre><code>

.float-left {

shape-outside: polygon(0% 50%, 50% 100%, 0 100%);

float: left;

width: 100px;

height: 100px;

margin-top: 20px;

}

</code></pre>

<img class="singleImgExample" src="images/float-margin-example.png" alt="Adding margin-top to a float with a small shape-outside">

The next picture shows a possible result

if two of these floats

were stacked next to each other.

Note that the floats are positioned

using their margin boxes,

not the <a>float area</a>.

<img class="singleImgExample" src="images/stacked-float-example.png" alt="Stacking two floats with a small shape-outside">

</div>

<h2 id="basic-shape-functions">

Basic Shapes</h2>

The <dfn>&lt;basic-shape&gt;</dfn> type

can be specified using basic shape functions.

When using this syntax

to define shapes,

the <dfn for="<basic-shape>" export>reference box</dfn> is defined

by each property that uses

<<basic-shape>> values.

The coordinate system for the shape

has its origin on the top-left corner of the

<a>reference box</a> with the x-axis

running to the right

and the y-axis running downwards.

All the lengths expressed in percentages

are resolved from the used dimensions

of the <a>reference box</a>.

<h3 id="supported-basic-shapes">

Supported Shapes</h3>

The <<basic-shape>> functions are:

<pre class=prod>

<<inset()>> = inset(

<<length-percentage>>{1,4}

[ round <<'border-radius'>> ]?

)

<<xywh()>> = xywh(

<<length-percentage>>{2} <<length-percentage [0, ∞]>>{2}

[ round <<'border-radius'>> ]?

)

<<rect()>> = rect(

[ <<length-percentage>> | auto ]{4}

[ round <<'border-radius'>> ]?

)

<dfn>&lt;basic-shape-rect></dfn> = <<inset()>> | <<rect()>> | <<xywh()>>

<<circle()>> = circle(

<<radial-size>>?

[ at <<position>> ]?

)

<<ellipse()>> = ellipse(

<<radial-size>>?

[ at <<position>> ]?

)

<<polygon()>> = polygon(

<<'fill-rule'>>?

[ round <<length>> ]? ,

[<<length-percentage>> <<length-percentage>>]#

)

<<path()>> = path(

<<'fill-rule'>>? ,

<<string>>

)

<<shape()>> = shape(

<<'fill-rule'>>?

from <<position>> ,

<<shape-command>>#

)

</pre>

<dl dfn-for="<basic-shape>">

<dt><dfn>inset()</dfn>

<dd>

Defines an inset rectangle

via insets from each edge of the [=reference box=].

If less than four <<length-percentage>> values are provided,

the omitted values default in the same way as the 'margin' shorthand:

an omitted second or third value defaults to the first,

and an omitted fourth value defaults to the second.

The four <<length-percentage>>s

define the position of the top, right, bottom, and left edges of a rectangle,

respectively,

as insets from the corresponding edges of the [=reference box=].

A pair of insets in either dimension

that add up to more than the used dimension

(such as left and right insets of 75% apiece)

use the [[css-backgrounds-3#corner-overlap]] rules

to proportionally reduce the inset effect to 100%.

<div class=example>

For example, specifying ''inset(75% 0 50% 0)''

has the top+bottom edges summing to 125%

of the [=reference box's=] height.

They're proportionally reduced to sum to 100%,

identical to specifying ''inset(60% 0 40% 0)''.

</div>

The optional <<'border-radius'>> argument(s)

define rounded corners for the rectangle

using the 'border-radius' shorthand syntax.

<wpt>

shape-functions/inset-function-computed.html

shape-functions/inset-function-invalid.html

shape-functions/inset-function-valid.html

</wpt>

<dt><dfn>xywh()</dfn>

<dd>

Defines a rectangle

via offsets from the top and left edge of the [=reference box=],

and a specified width and height.

The four <<length-percentage>>s define,

respectively,

the inset from the left edge of the [=reference box=],

the inset from the top edge of the [=reference box=],

the width of the rectangle,

and the height of the rectangle.

Note: This syntax is inspired by the <{svg/viewBox}> attribute from SVG.

The optional <<'border-radius'>> argument(s)

define rounded corners for the inset rectangle

using the 'border-radius' shorthand syntax.

<wpt>

shape-functions/xywh-function-computed.html

shape-functions/xywh-function-invalid.html

shape-functions/xywh-function-valid.html

</wpt>

<dt><dfn>rect()</dfn> =

<dd>

Defines a rectangle

via insets from the top and left edges of the [=reference box=].

The four <<length-percentage>>s

define the position of the top, right, bottom, and left edges of a rectangle,

respectively,

as insets from the top edge of the [=reference box=]

(for the first and third values)

or the left edge of the [=reference box=]

(for the second and fourth values).

An <css>auto</css> value makes the edge of the box

coincide with the corresponding edge of the [=reference box=]:

it's equivalent to ''0%''

as the first (top) or fourth (left) value,

and equivalent to ''100%''

as the second (right) or third (bottom) value.

The second (right) and third (bottom) values are floored

by the fourth (left) and second (top) values, respectively.

<div class='example'>

For example, specifying ''rect(10px 0 0 20px)''

would place the bottom edge higher than the top edge,

and the right edge further left than the left edge,

so both are corrected to not cross over the other edge,

identical to specifying ''rect(10px 20px 10px 20px)''.

</div>

Note: This syntax is similar,

but not quite identical,

to the legacy ''rect()'' function

used solely by the 'clip' property.

The optional <<'border-radius'>> argument(s)

define rounded corners for the rectangle

using the 'border-radius' shorthand syntax.)

<wpt>

shape-functions/rect-function-computed.html

shape-functions/rect-function-invalid.html

shape-functions/rect-function-valid.html

</wpt>

<dt><dfn>circle()</dfn>

<dd>

* The <<radial-size>> argument defines

the circle's radius.

Rather than referring to the [=gradient box=],

values are resolved against the [=reference box=].

Two <<length-percentage>> values are invalid.

If omitted it defaults to ''<radial-size>/closest-side''.

* The <<position>> argument defines

the center of the circle.

Unless otherwise specified,

this defaults to <css>center</css> if omitted.

<wpt>

shape-functions/circle-function-computed.html

shape-functions/circle-function-invalid.html

shape-functions/circle-function-valid.html

</wpt>

<dt><dfn>ellipse()</dfn>

<dd>

* The <<radial-size>> argument defines

the horizontal and vertical radiuses of the ellipse.

Rather than referring to the [=gradient box=],

values are resolved against the [=reference box=].

If omitted it defaults to ''<radial-size>/closest-side''.

* The <<position>> argument defines

the center of the ellipse.

Unless otherwise specified,

this defaults to <css>center</css> if omitted.

<wpt>

shape-functions/ellipse-function-computed.html

shape-functions/ellipse-function-invalid.html

shape-functions/ellipse-function-valid.html

</wpt>

<dt><dfn>polygon()</dfn>

<dd>

* The <<'fill-rule'>> specifies the filling rule used

to determine the interior.

Defaults to ''nonzero'' if omitted.

* An optional <<length>> after a <css>round</css> keyword

defines rounding for each vertex of the polygon.

The length is the radius of a circle

whose center lies on the bisector

of the smaller angle of the vertex,

and that is tangential

to both sides of the vertex.

<div class="example">

<figure>

<img src="images/vertex-rounding.png" alt="rounding concave and convex polygon vertices">

<figcaption>

Rounding polygon vertices that are both convex and concave.

</figcaption>

</figure>

</div>

To avoid rounding more

than half of any line segment,

the rounding of each vertex

must be clamped separately

such that the radius is never more than

the smaller of <code>tan(angle/2) segment / 2</code>

evaluated against both vertex line segments.

<div class="example">

<figure>

<img src="images/clamp-explanation.png" alt="visualization of clamp formula">

<figcaption>

This diagram shows the intent of the clamping formula.

</figcaption>

</figure>

</div>

* Each <<length-percentage>> pair

specifies a vertex of the polygon,

as a horizontal and vertical offset

from the left and top edges of the [=reference box=].

The UA must close a polygon

by connecting the last vertex

with the first vertex of the list.

<wpt>

shape-functions/polygon-function-computed.html

shape-functions/polygon-function-invalid.html

shape-functions/polygon-function-valid.html

</wpt>

<dt><dfn>path()</dfn>

<dd dfn-type=value dfn-for="path()">

* The <<'fill-rule'>> specifies the filling rule used

to determine the interior.

Defaults to ''nonzero'' if omitted,

unless the function is being used

in a context such as SVG shapes

where the 'fill-rule' property is relevant.

In that case an omitted value will use

the computed value of the 'fill-rule' property.

* The <<string>> represents an

<a href="https://www.w3.org/TR/SVG11/paths.html#PathData">SVG Path data string</a>.

A path data string that does not conform to the

to the grammar and parsing rules of SVG 1.1,

or that does conform but defines an empty path,

is [=invalid=] and causes the entire ''path()'' to be [=invalid=].

The initial position is defined

by the first “move to” argument

in the path string.

For the initial direction follow SVG 1.1.

The UA must close a path

with an implicit

closepath command ("z" or "Z")

if it is not present in the string

for properties that require a closed loop

(such as 'shape-outside' and 'clip-path').

<wpt>

shape-functions/path-function-computed.html

shape-functions/path-function-invalid.html

shape-functions/path-function-valid.html

</wpt>

<dt><dfn>shape()</dfn>

<dd dfn-type=value dfn-for="shape()">

See <a href="#shape-function">The shape() function</a>.

<wpt>

shape-functions/shape-function-computed.html

shape-functions/shape-function-invalid.html

shape-functions/shape-function-valid.html

</wpt>

</dl>

<h4 id='shape-function'>

The ''shape()'' Function</h4>

While the ''path()'' function allows reuse of the SVG path syntax

to define more arbitrary shapes than allowed by more specialized shape functions,

it requires writing a path as a single string

(which is not compatible with, for example, building a path piecemeal with ''var()''),

and inherits a number of limitations from SVG,

such as implicitly only allowing the ''px'' unit.

The ''shape()'' function uses a set of commands roughly equivalent to the ones used by ''path()'',

but does so with more standard CSS syntax,

and allows the full range of CSS functionality,

such as additional units and math functions.

The commands used by ''shape()'' are dynamically turned into path segments when it is used for rendering,

e.g., when computing the rendered 'clip-path'.

In that sense, ''shape()'' is a superset of ''path()''. A ''path()'' can be easily converted to a ''shape()'',

but to convert a ''shape()'' back to a ''path()'' or to SVG requires information about the CSS environment (e.g.

current values of CSS custom properties, current font size for ''em'' units, etc).

The <<'fill-rule'>> is interpreted identically to the same argument in ''path()''.

The rest of the arguments define a list of path data commands,

identical to that of an <a href="https://www.w3.org/TR/SVG11/paths.html#PathData">SVG Path</a>,

which the function represents.

The <css>from <<coordinate-pair>></css> represents the starting point for the first shape-command.

It adds an initial <a href="https://www.w3.org/TR/SVG/paths.html#PathDataMovetoCommands">absolute moveto</a>

to the list of path data commands.

The sequence of <dfn><<shape-command>></dfn>s represent

further <a href="https://www.w3.org/TR/SVG11/paths.html#PathData">path data commands</a>.

Each command's starting point is the previous command's ending point.

<pre class=prod>

<<shape-command>> = <<move-command>> | <<line-command>> | close |

<<horizontal-line-command>> | <<vertical-line-command>> |

<<curve-command>> | <<smooth-command>> | <<arc-command>>

<<move-command>> = move <<command-end-point>>

<<line-command>> = line <<command-end-point>>

<<horizontal-line-command>> = hline

[ to [ <<length-percentage>> | left | center | right | x-start | x-end ]

| by <<length-percentage>> ]

<<vertical-line-command>> = vline

[ to [ <<length-percentage>> | top | center | bottom | y-start | y-end ]

| by <<length-percentage>> ]

<<curve-command>> = curve

[ [ to <<position>> with <<control-point>> [ / <<control-point>> ]? ]

| [ by <<coordinate-pair>> with <<relative-control-point>> [ / <<relative-control-point>> ]? ] ]

<<smooth-command>> = smooth

[ [ to <<position>> [ with <<control-point>> ]? ]

| [ by <<coordinate-pair>> [ with <<relative-control-point>> ]? ] ]

<<arc-command>> = arc <<command-end-point>>

[ [ of <<length-percentage>>{1,2} ]

&& <<arc-sweep>>? && <<arc-size>>? && [rotate <<angle>>]? ]

<<command-end-point>> = [ to <<position>> | by <<coordinate-pair>> ]

<<control-point>> = [ <<position>> | <<relative-control-point>> ]

<<relative-control-point>> = <<coordinate-pair>> [ from [ start | end | origin ] ]?

<<coordinate-pair>> = <<length-percentage>>{2}

<<arc-sweep>> = cw | ccw

<<arc-size>> = large | small

</pre>

<dl dfn-for="shape()">

<dt><dfn><<coordinate-pair>></dfn> = <<length-percentage>>{2}

<dd>Defines a pair of coordinates,

representing a rightward and downward offset, respectively,

from a specified reference point.

Percentages are resolved against the width or height, respectively,

of the [=reference box=].

<dt><dfn><<command-end-point>></dfn> = [ <dfn value for="shape(), <command-end-point>">to</dfn> <<position>> | <dfn value for="shape(), <command-end-point>">by</dfn> <<coordinate-pair>> ]

<dd>

Every command can be specified in "absolute" or "relative" coordinates,

determined by their ''shape()/by'' or ''shape()/to'' component.

''shape()/to'' indicates that any <<coordinate-pair>>s in the command

are relative to the top-left corner of the [=reference box=],

while ''shape()/by'' indicates that the <<coordinate-pair>>s

are relative to the command's starting point.

<<relative-control-point>> defines how ''shape()/by'' and ''shape()/to'' are interpreted for curve control points,

while <<horizontal-line-command>> and <<vertical-line-command>> define how ''shape()/by'' and ''shape()/to'' are

interpreted for horizontal and vertical lines, respectively.

When ''shape()/to'' is used, the coordinates can be specified as <<position>>s instead of <<coordinate-pair>>s.

Note: In either case, <<percentage>> values in <<coordinate-pair>>s

are always computed relative to the [=reference box's=] size.

<dt><dfn><<move-command>></dfn> = <dfn value>move</dfn> <<command-end-point>>

<dd>

Adds a <a href="https://www.w3.org/TR/SVG/paths.html#PathDataMovetoCommands">moveto</a> command

to the list of path data commands,

with an ending point specified by the <<coordinate-pair>>.

This draws nothing,

and merely "moves the pen" for the next command.

Note: This starts a new subpath,

for the purpose of the ''close'' command.

<dt><dfn><<line-command>></dfn> = <dfn value>line</dfn> <<command-end-point>>

<dd>

Adds a <a href="https://www.w3.org/TR/SVG/paths.html#PathDataLinetoCommands">lineto</a> command

to the list of path data commands,

with an ending point specified by the <<coordinate-pair>>.

This draws a straight line from the command's starting point to its ending point.

<dt><dfn><<horizontal-line-command>></dfn> = hline [ to [ <<length-percentage>> | left | center | right | x-start | x-end ]

| by <<length-percentage>> ]

<dd>

Adds a horizontal

<a href="https://www.w3.org/TR/SVG/paths.html#PathDataLinetoCommands">lineto</a> command

to the list of path data commands.

This is equivalent to a ''line'' command

with the <<length-percentage>> given as the horizontal component of the <<coordinate-pair>>.

Specifying the horizontal component of <<position>> instead of a <<length-percentage>> (''left'', ''center'', ''right'', ''x-start'', or ''x-end''),

would draw a line to that <<position>>, with the <<position>>'s vertical component remaining the same as the starting point.

<dt><dfn><<vertical-line-command>></dfn> = vline [ to [ <<length-percentage>> | top | center | bottom | y-start | y-end ] | by <<length-percentage>> ]

<dd>

Adds a vertical

<a href="https://www.w3.org/TR/SVG/paths.html#PathDataLinetoCommands">lineto</a> command

to the list of path data commands.

This is equivalent to a ''line'' command

with the <<length-percentage>> given as the vertical component of the <<coordinate-pair>>.

Specifying the horizontal component of <<position>>

(''top'', ''center'', ''bottom'', ''y-start'', or ''y-end'')

instead of a <<length-percentage>>,

would draw a line to that <<position>>, with the <<position>>'s horizontal component remaining the same as the starting point.

<dt><dfn><<curve-command>></dfn> = <dfn value>curve</dfn> [ [ to <<position>> with <<control-point>> [ / <<control-point>> ]? ]

| [ by <<coordinate-pair>> with <<relative-control-point>> [ / <<relative-control-point>> ]? ] ]

<dd>

Adds a Bézier curve command to the list of path data commands,

ending at the point specified by the <<position>> following the ''shape()/to'' keyword,

or the <<coordinate-pair>> following the ''shape()/by'' keyword, as specified by <<command-end-point>>.

The <css>with</css> component specifies control points for the curve:

if a single <<control-point>> or <<relative-control-point>> is provided,

the command specifies a <a href="https://www.w3.org/TR/SVG/paths.html#PathDataQuadraticBezierCommands">quadratic curve</a>;

if two <<control-point>>s or <<relative-control-point>>s are provided,

it specifies a <a href="https://www.w3.org/TR/SVG/paths.html#PathDataCubicBezierCommands">cubic curve</a>.

<dt><dfn><<smooth-command>></dfn> = <dfn value>smooth</dfn> [ [ to <<position>> [with <<control-point>> ]? ]

| [ by <<coordinate-pair>> [ with <<relative-control-point>> ]? ] ]

<dd>

Adds a smooth Bézier curve command to the list of path data commands,

ending at the point specified by the <<position>> following the ''shape()/to'' keyword, or the <<coordinate-pair>> following the ''shape()/by'' keyword, as specified by <<command-end-point>>.

The <css>with</css> component specifies control points for the curve:

if it's omitted,

the command specifies a <a href="https://www.w3.org/TR/SVG/paths.html#PathDataQuadraticBezierCommands">smooth quadratic curve</a>;

if it's provided,

if specifies a <a href="https://www.w3.org/TR/SVG/paths.html#PathDataCubicBezierCommands">smooth cubic curve</a>.

Note: A ''smooth'' command is equivalent to a ''curve'' command

with the first control point automatically specified

as the reflection of the previous curve's second control point

around the starting point,

or as the starting point if the previous path data command wasn't a curve.

This ensures G1 continuity with the previous command,

so the curve appears to smoothly continue from the previous command,

rather than possibly making a sudden direction change.

<dt><dfn><<control-point>></dfn> = [ <<position>> | <<relative-control-point>> ]

<dd>

Provides a control point to a quadratic or cubic Bézier curve.

<dt><dfn><<relative-control-point>></dfn> = <<coordinate-pair>> [ from [ start | end | origin ] ]?

<dd>

Provides a control point to a quadratic or cubic Bézier curve.

When a <css>from</css> keyword is specified followed by <css>start</css>, <css>end</css>, or <css>origin</css>,

the given <<coordinate-pair>> is relative to

the command's starting point, the command's end point, or the [=reference box=], respectively.

If such component is not provided, the <<coordinate-pair>> is relative to the segment's start.

<dt><dfn><<arc-command>></dfn> = <dfn value>arc</dfn> <<command-end-point>> [of <<length-percentage>>{1,2}] && <<arc-sweep>>? && <<arc-size>>? && rotate <<angle>>? ]

<dd>

Add an <a href="https://www.w3.org/TR/SVG/paths.html#PathDataEllipticalArcCommands">elliptical arc</a> command

to the list of path data commands,

ending at the <<command-end-point>>.

The <css>of</css> component specifies the size of the ellipse that the arc is taken from.

The first <<length-percentage>> provides the horizontal radius of the ellipse

and the second provides the vertical radius.

Like for <<coordinate-pair>>s,

<<percentage>> values are resolved against the width or height of the [=reference box=],

as appropriate.

If only one <<length-percentage>> is provided,

both radiuses use the provided value.

In that case, <<percentage>> values are resolved against the [=direction-agnostic size=] of the [=reference box=]

(similar to the ''circle()'' function).

<div class=note>

Note that SVG has [[svg2#ArcOutOfRangeParameters|some specific error-handling for the ellipse radiuses]]:

* if the endpoint is the same as the starting point, the command does nothing

* if either radius is zero, the command is equivalent to a <<line-command>> to the ending point

* if either radius is negative, its absolute value is used instead

* if the radiuses don't describe an ellipse large enough

to intersect both the starting point and ending point

(after rotation by the specified <<angle>>),

they are scaled up uniformly until the ellipse is just large enough to reach.

</div>

The ellipse described by the specified radiuses defaults to being axis-aligned,

but can be rotated by specifying an <<angle>>.

Similar to the ''rotate()'' transform function,

positive angles specify a clockwise rotation,

and negative angles specify a counterclockwise rotation.

If omitted, this defaults to ''0deg''.

The ending point, radiuses, and angle,

taken together,

usually define two possible ellipses

that intersect the starting point and ending point,

and each ellipse can be traced in either direction,

for a total of four possible arcs.

The <<arc-sweep>> and <<arc-size>> components specify which of these arcs is desired:

* <dfn><<arc-sweep>></dfn> can be <dfn value for="shape(), arc">cw</dfn> or <dfn value for="shape(), arc">ccw</dfn>,

indicating that the arc that is traced around the ellipse clockwise or counter-clockwise from the center, respectively,

must be chosen.

If omitted, this defaults to ''ccw''.

Note: In the SVG arc command, ''cw'' corresponds to the value 1 for the sweep flag, and ''ccw'' to the value 0.

* <dfn><<arc-size>></dfn> can be <dfn value for="shape(), arc">large</dfn> or <dfn value for="shape(), arc">small</dfn>,

indicating that the larger or smaller, respectively, of the two possible arcs

must be chosen.

If omitted, this defaults to ''small''.

Note: In the SVG arc command, ''large'' corresponds to the value 1 for the large flag, and ''small'' to the 0.

Note: If the starting and ending points are on exactly opposite sides of the ellipse,

both possible arcs are the same size,

but also there is only one possible ellipse.

In this case, the <<arc-sweep>> distinguishes which of the two possible arcs will be chosen,

and <<arc-size>> has no effect.

<figure>

<img src="images/four-arcs.svg" alt="a depiction of four possible arcs given a start and end point">

<figcaption>

A depiction of the two possible ellipses,

and four possible arcs,

that can be chosen between.

</figcaption>

</figure>

<dt><dfn value>close</dfn>

<dd>

Adds a <a href="https://www.w3.org/TR/SVG/paths.html#PathDataClosePathCommand">closepath</a> command

to the list of path data commands.

Note: This is similar to a ''line'' command

with its ending point set to the starting point of the subpath.

When specifying a raw shape, they're identical,

but if the path is stroked,

the ending point of the ''close'' command is smoothly joined

with the start of the subpath,

which affects how line-joins and line-caps are rendered.

</dl>

<h5 id=shape-examples>Using ''shape()'' to create responsive, parametric speech bubble</h5>

<div class=example>

The ''shape()'' function enables shapes that are responsive, rather than scalable.

While the ''polygon()'' shape is also responsive, it only support simple rounded corners and not complex curves.

To demonstrate, let's start with a speech bubble, such as the following:

<img src="images/bubble.svg" width=300 style="background: unset" alt="A speech bubble shape">

Using this shape with a ''clip-path'' can be done by using the ''path()'' function:

<pre highlight="css">

.bubble { clip-path: path("m 5 0 H 95 Q 100 0 100 5 V 92 Q 100 97 95 97 H 70 l -2 3 l -2 -3 H 5 Q 0 97 0 92 V 5 Q 0 0 5 0") };

</pre>

Altohugh this path can easily scale, the scaled results are not always desirable. e.g. when scaled to a small balloon, the arrow and corners are scaled to become almost invisible:

<img src="images/bubble.svg" width=100 style="background: unset" alt="scled-down speech bubble shape">

To construct this shape using the ''shape()'' function, let's start by turning all the pixel values from the ''path'' function to percentages.

Note that the ''shape()'' function begins with <css>from</css>:

<pre highlight="css">

.bubble { clip-path: shape( from 5% 0%,

hline to 95%,

curve to 100% 5% with 100% 0%,

vline to 92%,

curve to 95% 97% with 100% 97%,

hline to 70%,

line by -2% 3%,

line by -2% -3%,

hline to 5%,

curve to 0% 92% with 0% 97%,

vline to 5%,

curve to 5% 0% with 0% 0%); }

</pre>

To make this path responsive, as in, respond well to size changes, we will convert some of its units to ''px'' values,

specifically the ones the control the curves and arrows:

<pre highlight="css">

.bubble { clip-path: shape( from 5px 0%,

hline to calc(100% - 5px),

curve to 100% 5px with 100% 0%,

vline to calc(100% - 8px),

curve to calc(100% - 5px) calc(100% - 3px) with 100% calc(100% - 3px),

hline to 70%,

line by -2px 3px,

line by -2px -3px,

hline to 5px,

curve to 0% calc(100% - 8px) with 0% calc(100% - 3px),

vline to 5px,

curve to 5px 0% with 0% 0%); }

</pre>

When applied as ''clip-path'', it would looks like the following:

<p>

<img src="images/bubble-50.svg" width=150 style="background: unset" alt="A speech bubble shape, using clip-path">

</p>

The whole speech bubble is scaled to the reference box, while the curves and arrows stay more constant.

Since ''shape()'' uses CSS units, we can replace some of the edges with ''position'' values:

<pre highlight="css">

.bubble { clip-path: shape(from 5px 0,

hline to calc(100% - 5px),

curve to right 5px with right top,

vline to calc(100% - 8px),

curve to calc(100% - 5px) calc(100% - 3px) with right calc(100% - 3px),

hline to 70%,

line by -2px 3px,

line by -2px -3px,

hline to 5px,

curve to left calc(100% - 8px) with left calc(100% - 3px),

vline to 5px,

curve to 5px top with left top); }

</pre>

Another useful feature of ''shape()'' is that it can be used alongside CSS properties. In this case,