Chapter 14: Paint Servers: Solid Colors, Gradients, and Patterns

14.1. Introduction

This section covers Paint Servers, a method which allows the fill or stroke of an object to be defined by a resource found elsewhere. It allows resources to be reused throughout a document. See the section Painting: Filling and Stroking for a general discussion of filling and stroking objects.

SVG defines several types of paint servers:

SVG 2 Requirement: Arbitrary fills for shapes.
Resolution: SVG 2 shall support filling and stroking from arbitrary elements.
Purpose: To allow for example videos or images to be used as a fill source.
Owner: Alex? (no action)
Image of two types of paint servers.

Two types of paint servers. From left to right: A linear gradient. A pattern.

Paint servers are used by including a URL reference in a fill or stroke property (i.e. fill="url(#MyLightPurple)").

properties inherit into a paint-server element from its ancestors; properties do not inherit from the element referencing the paint server element.

Paint-server elements are never rendered directly; their only usage is as something that can be referenced using the fill and stroke properties. The display value for these elements must always be set to none by the user agent style sheet, and this declaration must have importance over any other CSS rule or presentation attribute. Paint-server elements are available for referencing even when the display property on the paint-server element or any of its ancestors is set to none.

14.1.1. Using paint servers as templates

Most paint server elements accept an ‘href’ attribute, which can be used to define a compatible paint server element as a template. Attributes defined for the template element are used instead of the initial value if corresponding attributes are not specified on the current element. Furthermore, if the current element does not have any child content other than descriptive elements, than the child content of the template element is cloned to replace it.

The exclusion of descriptive content is new in SVG 2 for pattern, consistent with the behavior of gradients, and with changes to make descriptive content valid for any SVG element.

Also new: template cross-references may be to external file resources (different chapters in SVG 1.1 had inconsistent guidance on this point), and the "inheritance" of child elements is represented through a shadow tree.

Templating can be indirect to an arbitrary level (subject to security limits on external file resources, which can make a reference invalid). Thus, if the referenced template element does not have relevant child content or does not define the specified attribute, then the attribute value or cloned content is derived from another element referenced by the template's own ‘href’ attribute.

The description of each ‘href’ attribute in this chapter defines the limits of the templating process, as follows:

If any of the specified attributes are not defined on the current element, or if the current element has no child elements other than descriptive elements, the user agent must process the URL to identify the referenced resource. If the URL reference is not invalid, then the URL's target element is used as the template element, as follows:

When a paint-server element has a shadow tree, the element instances in that tree must be used in rendering the paint server effect, as if they were the paint server element's own children.

The use-element shadow tree model for templating allows cloned content to inherit different styles than the original. This behavior is newly defined in SVG 2; SVG 1.1 did not define how styles applied to inherited paint server content.

14.2. Gradients

Gradients consist of smooth color transitions between points on a drawing surface. SVG provides for three types of gradients:

Once a gradient is defined, a graphics element can be filled or stroked with the gradient by setting the fill or stroke properties to reference the gradient.

Color transitions for linear and radial gradients are defined by a series of color stops along a gradient vector. A gradient normal defines how the colors in a vector are painted to the surface. For a linear gradient, a normal is a line perpendicular to the vector. For a radial gradient, a normal is a circle intersecting the vector at a right angle. Each gradient normal is painted with one color determined by the vector.

Image of linear and radial gradients with vectors and normals indicated.

Linear and radial gradients with the gradient vector indicated. The vector consists of three stops shown by small circles. One gradient normal is shown for each gradient.

For linear and radial gradients, the color value between two stops along the gradient vector is the linear interpolation, per channel, of the color for each stop, weighted by the distance from each stop.

V = C0 + ( C1 - C0 ) ( D - O0 O1 - O0 )
    $V = C0.rgba + (C1.rgba - C0.rgba) * ((D - C0.offset) / (C1.offset - C0.offset));
  

Where, for each channel:

When a graphics element references a gradient, conceptually the graphics element should take a copy of the gradient vector with gradient normals and treat it as part of its own geometry. Any transformations applied to the graphics element geometry also apply to the copied gradient vector and gradient normals. Any gradient transforms that are specified on the reference gradient are applied before any graphics element transformations are applied to the gradient.

14.2.1. Definitions

gradient element
A gradient element is one that defines a gradient paint server. This specification defines the following gradient elements: linearGradient and radialGradient.

14.2.2. Linear gradients

Linear gradients are defined by a linearGradient element.

linearGradient
Categories:
Gradient element, never-rendered element, paint server element
Content model:
Any number of the following elements, in any order:animate, animateTransform, script, set, stop, style
Attributes:
DOM Interfaces:

14.2.2.1. Attributes

Note that the x1,y1, x2 and y2 attributes on a linearGradient are not presentation attributes; the used value is not affected by CSS styles. The gradientTransform attribute is a presentation attribute for the transform property.

gradientUnits

Defines the coordinate system for attributes x1, y1, x2 and y2.

Value
userSpaceOnUse | objectBoundingBox
initial value
objectBoundingBox
Animatable
yes
userSpaceOnUse

If gradientUnits="userSpaceOnUse", x1, y1, x2, and y2 represent values in the coordinate system that results from taking the current user coordinate system in place at the time when the gradient element is referenced (i.e., the user coordinate system for the element referencing the gradient element via a fill or stroke property) and then applying the transform specified by attribute gradientTransform. Percentages represent values relative to the current SVG viewport.

objectBoundingBox

If gradientUnits="objectBoundingBox", the user coordinate system for attributes x1, y1, x2 and y2 is established using the bounding box of the element to which the gradient is applied (see Object bounding box units) and then applying the transform specified by attribute gradientTransform. Percentages represent values relative to the bounding box for the object.

When gradientUnits="objectBoundingBox" and gradientTransform is the identity matrix, the normal of the linear gradient is perpendicular to the gradient vector in object bounding box space (i.e., the abstract coordinate system where (0,0) is at the top/left of the object bounding box and (1,1) is at the bottom/right of the object bounding box). When the object's bounding box is not square, the gradient normal which is initially perpendicular to the gradient vector within object bounding box space may render non-perpendicular relative to the gradient vector in user space. If the gradient vector is parallel to one of the axes of the bounding box, the gradient normal will remain perpendicular. This transformation is due to application of the non-uniform scaling transformation from bounding box space to local coordinate system.

gradientTransform

Contains the definition of an optional additional transformation from the gradient coordinate system onto the target coordinate system (i.e., 'userSpaceOnUse' or 'objectBoundingBox'). This allows for things such as skewing the gradient. This additional transformation matrix is post-multiplied to (i.e., inserted to the right of) any previously defined transformations, including the implicit transformation necessary to convert from object bounding box units to local coordinate system.

Value
<transform-list>
initial value
identity transform
Animatable
yes
x1

x1, y1, x2 and y2 define a gradient vector for the linear gradient. This gradient vector provides starting and ending points onto which the gradient stops are mapped. The values of x1, y1, x2 and y2 can be either numbers or percentages.

Value
<length>
initial value
0%
Animatable
yes
y1

See x1.

Value
<length>
initial value
0%
Animatable
yes
x2

See x1.

Value
<length>
initial value
100%
Animatable
yes
y2

See x1.

Value
<length>
initial value
0%
Animatable
yes
spreadMethod

Indicates what happens if the gradient starts or ends inside the bounds of the target rectangle.

Value
pad | reflect | repeat
initial value
pad
Animatable
yes
pad
Use the terminal colors of the gradient to fill the remainder of the target region.
reflect
Reflect the gradient pattern start-to-end, end-to-start, start-to-end, etc. continuously until the target rectangle is filled.
repeat
Repeat the gradient pattern start-to-end, start-to-end, start-to-end, etc. continuously until the target region is filled.
Image of the three possible values for 'spreadMethod'.

Illustration of the three possible values for spreadMethod, from left to right: pad, reflect, repeat. The gradient vector spans from 40% to 60% of the bounding box width.

href

A URL reference to a template gradient element; to be valid, the reference must be to a different linearGradient or a radialGradient element.

Refer to the process for using paint servers as templates, and to the common handling defined for URL reference attributes and deprecated XLink attributes.

The specified attributes that will be copied from the template are:

Value
URL [URL]
initial value
empty
Animatable
yes

14.2.2.2. Notes on linear gradients

If x1 = x2 and y1 = y2, then the area to be painted will be painted as a single color using the color and opacity of the last gradient stop.

Example lingrad01 shows how to fill a rectangle by referencing a linear gradient paint server.

<?xml version="1.0" standalone="no"?>
<svg xmlns="http://www.w3.org/2000/svg"
     version="1.1"
     viewBox="0 0 300 200" >

  <title>Example lingrag01</title>
  <desc>Fill a rectangle using a linear-gradient paint server.</desc>

  <defs>
    <linearGradient id="MyGradient">
      <stop offset="5%" stop-color="#A8F" />
      <stop offset="95%" stop-color="#FDC" />
    </linearGradient>
  </defs>

  <!-- The rectangle is filled using a linear-gradient paint server -->
  <rect fill="url(#MyGradient)"
	stroke="black"
	stroke-width="2"
	x="25" y="25" width="250" height="150"/>
</svg>
Example lingrad01 — Fill a rectangle by referencing a linear gradient paint server

Example lingrad01

View this example as SVG (SVG-enabled browsers only)

14.2.3. Radial gradients

Radial gradients are defined by a radialGradient element.

radialGradient
Categories:
Gradient element, never-rendered element, paint server element
Content model:
Any number of the following elements, in any order:animate, animateTransform, script, set, stop, style
Attributes:
DOM Interfaces:

14.2.3.1. Attributes

Note that the cx,cy, and r attributes on a radialGradient are not presentation attributes; the used value is not affected by CSS styles. The gradientTransform attribute is a presentation attribute for the transform property.

gradientUnits = "userSpaceOnUse | objectBoundingBox"

Defines the coordinate system for attributes cx, cy, r, fx, fy, and fr.

initial value
objectBoundingBox
Animatable
yes
userSpaceOnUse

If gradientUnits="userSpaceOnUse", cx, cy, r, fx, fy, and fr represent values in the coordinate system that results from taking the current user coordinate system in place at the time when the gradient element is referenced (i.e., the user coordinate system for the element referencing the gradient element via a fill or stroke property) and then applying the transform specified by attribute gradientTransform. Percentages represent values relative to the current SVG viewport.

objectBoundingBox

If gradientUnits="objectBoundingBox", the user coordinate system for attributes cx, cy, r, fx, fy, and fr is established using the bounding box of the element to which the gradient is applied (see Object bounding box units) and then applying the transform specified by attribute gradientTransform. Percentages represent values relative to the bounding box for the object.

When gradientUnits="objectBoundingBox" and gradientTransform is the identity matrix, then the rings of the radial gradient are circular with respect to the object bounding box space (i.e., the abstract coordinate system where (0,0) is at the top/left of the object bounding box and (1,1) is at the bottom/right of the object bounding box). When the object's bounding box is not square, the rings that are conceptually circular within object bounding box space will render as elliptical due to application of the non-uniform scaling transformation from bounding box space to local coordinate system.

gradientTransform = "<transform-list>"

Contains the definition of an optional additional transformation from the gradient coordinate system onto the target coordinate system (i.e., 'userSpaceOnUse' or 'objectBoundingBox'). This allows for things such as skewing the gradient. This additional transformation matrix is post-multiplied to (i.e., inserted to the right of) any previously defined transformations, including the implicit transformation necessary to convert from object bounding box units to local coordinate system.

initial value
identity transform
Animatable
yes
cx = "<length>"

cx, cy and r define the end circle for the radial gradient. The gradient will be drawn such that the 100% gradient stop is mapped to the perimeter of this end circle.

initial value
50%
Animatable
yes
cy = "<length>"

See cx.

initial value
50%
Animatable
yes
r = "<length>"

See cx.

A negative value is an error (see Error processing).

initial value
50%
Animatable
yes
fx = "<length>"

fx, fy, and fr define the start circle for the radial gradient. The gradient will be drawn such that the 0% gradient stop is mapped to the perimeter of this start circle.

initial value
see below
Animatable
yes

If attribute fx is not specified, fx will coincide with the presentational value of cx for the element whether the value for 'cx' was inherited or not. If the element references an element that specifies a value for 'fx', then the value of 'fx' is inherited from the referenced element.

Diagram of various radial gradient attributes.

This diagram shows how the geometric attributes are defined for the case where fr is 50% of r. The small circle marks the center of the outermost circle (cx,cy), while the cross marks the center of the innermost circle (fx,fy). The dashed lines show two gradient vectors. Vectors connect corresponding points on the inner and outer most circles. The region outside the outer circle is painted with the last stop-color while the region inside the inner circle is painted with the first stop-color.

fy = "<length>"

See fx.

initial value
see below
Animatable
yes

If attribute fy is not specified, fy will coincide with the presentational value of cy for the element whether the value for 'cy' was inherited or not. If the element references an element that specifies a value for 'fy', then the value of 'fy' is inherited from the referenced element.

fr = "<length>"

New in SVG 2. Added to align with Canvas.

fr is the radius of the focal circle. See fx.

A negative value is an error (see Error processing).

initial value
0%, see below
Animatable
yes

If the attribute is not specified, the effect is as if a value of '0%' were specified. If the element references an element that specifies a value for 'fr', then the value of 'fr' is inherited from the referenced element.

SVG 2 Requirement: Allow specifying focal circle radius in radial gradients.
Resolution: Add an ‘fr’ attribute to ‘radialGradient’> for SVG 2.
Purpose: To align with Canvas. The zero-offset stop would be along the circle defined by the ‘fx’, ‘fy’ and ‘fr’ attributes.
Owner: Erik (ACTION-3098)
spreadMethod = "pad | reflect | repeat"

Indicates what happens if the gradient starts or ends inside the bounds of the object(s) being painted by the gradient. Has the same values and meanings as the spreadMethod attribute on linearGradient element.

initial value
pad
Animatable
yes
href = [URL]

A URL reference to a template gradient element; to be valid, the reference must be to a linearGradient element or a different radialGradient element.

Refer to the process for using paint servers as templates, and to the common handling defined for URL reference attributes and deprecated XLink attributes.

The specified attributes that will be copied from the template are:

Refer to the common handling defined for URL reference attributes and deprecated XLink attributes.

initial value
empty
Animatable
yes
SVG 2 Requirement: Clarify radial gradients with focal point on the circle.
Resolution: When the focal point is on the circle edge, with repeat, then the distance between the first and last stop for the repeating colors is 0 and the paint should generate a color that is the average of all the gradient stops.
Purpose: To improve interoperability of radial gradients.
Owner: Erik (ACTION-3097)
Note: SVG 1.1 does not define what to do when the focal point is on the circle edge, with 'repeat'. The distance between the first and last stop for the repeating colors is 0. It was resolved that the paint should generate a color that is the weighted average (by offset) of all the gradient stops.

14.2.3.2. Notes on radial gradients

Changed in SVG 2. SVG 1.1 required that the focal point, if outside the end circle, be moved to be on the end circle. The change was made to align with Canvas.

Allowing the focal point to lie outside the end circle was resolved at the Rigi Kaltbad working group meeting.

If the start circle defined by fx, fy and fr lies outside the end circle defined by cx, cy, and r, effectively a cone is created, touched by the two circles. Areas outside the cone stay untouched by the gradient (transparent black).

If the start circle fully overlaps with the end circle, no gradient is drawn. The area stays untouched (transparent black).

Image of a radial gradient with the focal (start circle) outside
	  the start circle.

A radial gradient with the focal (start) circle outside the end circle. The focal circle is the smaller circle on the right. The gradient has spreadMethod="reflect".

Image of two radial gradients, one with the focus just inside the circumference
    and one with the focus on the circumference.

Two radial gradients with spreadMethod="repeat". On the left, the focal point is just inside the right side of the circle defined by cx, cy, and r. On the right, the focal point is on the circle. In this case, the area painted to the right of the circumference has a fill equal to the weighted average of the colors in the gradient vector.

The treatment of the area to the right of the gradient in the right-hand side of the above figure is different from that of Canvas where the area would be transparent black. The difference is to maintain compatibility with SVG 1.1.

The color space for the weighted average is the same as in which the gradient is interpolated. See Rigi Kaltbad working group meeting.

Example radgrad01 shows how to fill a rectangle by referencing a radial gradient paint server.

<?xml version="1.0" standalone="no"?>
<svg xmlns="http://www.w3.org/2000/svg"
     viewBox="0 0 300 200" >
  <title>Example radgrad01</title>
  <desc>Fill a rectangle by referencing a radial gradient paint server.</desc>

  <defs>
    <radialGradient id="MyGradient"
		    gradientUnits="userSpaceOnUse"
		    cx="150" cy="100"
		    r="100">
      <stop offset="0%"   stop-color="#A8F" />
      <stop offset="50%"  stop-color="#FDC" />
      <stop offset="100%" stop-color="#A8F" />
    </radialGradient>
  </defs>

  <!-- The rectangle is filled using a radial gradient paint server -->
  <rect fill="url(#MyGradient)"
	stroke="black"
	stroke-width="2"
	x="25" y="25" width="250" height="150"/>
</svg>
Example radgrad01 — Fill a rectangle by referencing a radial gradient paint server

Example radgrad01

View this example as SVG (SVG-enabled browsers only)

14.2.4. Gradient stops

The vector of colors to use in a gradient is defined by the stop elements that are child elements to a linearGradient, or radialGradient element.

In SVG 1.1, the above read: "The ramp of colors..." but "ramp" is used nowhere else in this section.

stop
Categories:
None
Content model:
Any number of the following elements, in any order:
    animate, script, set, style
    Attributes:
    DOM Interfaces:

    14.2.4.1. Attributes

    offset

    Indicates were the gradient stop is placed. For linear gradients, the offset attribute represents a location along the gradient vector. For radial gradients, it represents a fractional distance from the edge of the innermost/smallest circle to the edge of the outermost/largest circle.

    Value
    <number> | <percentage>
    initial value
    0
    Animatable
    yes
    <number>
    A number usually ranging from 0 to 1.
    <percentage>
    A percentage usually ranging from 0% to 100%.

    14.2.4.2. Properties

    stop-color

    The stop-color property indicates what color to use at that gradient stop. The keyword currentColor and ICC colors can be specified in the same manner as within a <paint> specification for the fill and stroke properties.

    With respect to gradients, SVG treats the 'transparent' keyword differently than CSS. SVG does not calculate gradients in pre-multiplied space, so 'transparent' really means transparent black. Specifying a stop-color with the value 'transparent' is equivalent to specifying a stop-color with the value 'black' and a stop-opacity with the value '0'.

    Value
    currentColor | <color> <icccolor>
    Initial
    black
    Applies to
    stop elements
    Inherited
    no
    Percentages
    N/A
    Media
    visual
    Animatable
    yes
    stop-opacity

    The stop-opacity property defines the opacity of a given gradient stop. The opacity value used for the gradient calculation is the product of the value of stop-opacity and the opacity of the value of stop-color. For stop-color value types of that don't include explicit opacity information, the opacity of that component must be treated as 1.

    Value
    <alpha-value>
    Initial
    1
    Applies to
    stop elements
    Inherited
    no
    Percentages
    N/A
    Media
    visual
    Animatable
    yes
    <number>
    The opacity of the stop-color. Any values outside the range 0.0 (fully transparent) to 1.0 (fully opaque) must be clamped to this range.
    <percentage>
    The opacity of the stop-color expressed as a percentage of the range 0 to 1.

    14.2.4.3. Notes on gradient stops

    14.3. Patterns

    A pattern is used to fill or stroke an object using a pre-defined graphic object which can be replicated ("tiled") at fixed intervals in x and y to cover the areas to be painted. Patterns are defined using a pattern element and then referenced by properties fill and stroke on a given graphics element to indicate that the given element shall be filled or stroked with the pattern.

    Attributes x, y, width, height and patternUnits define a reference rectangle somewhere on the infinite canvas. The reference rectangle has its top/left at (xy) and its bottom/right at (x + widthy + height). The tiling theoretically extends a series of such rectangles to infinity in X and Y (positive and negative), with rectangles starting at (x + m*widthy + n* height) for each possible integer value for m and n.

    pattern
    Categories:
    Container element, never-rendered element, paint server element
    Content model:
    Any number of the following elements, in any order:a, audio, canvas, clipPath, filter, foreignObject, iframe, image, marker, mask, script, style, switch, text, video, view
    Attributes:
    DOM Interfaces:

    14.3.1. Attributes

    Note that the x,y, width and height attributes on a pattern are not presentation attributes; the used value is not affected by CSS styles. The patternTransform attribute is a presentation attribute for the transform property.

    patternUnits

    Defines the coordinate system for attributes x, y, width and height.

    Value
    userSpaceOnUse | objectBoundingBox
    initial value
    objectBoundingBox
    Animatable
    yes
    userSpaceOnUse

    If patternUnits="userSpaceOnUse", x, y, width and height represent values in the coordinate system that results from taking the current user coordinate system in place at the time when the pattern element is referenced (i.e., the user coordinate system for the element referencing the pattern element via a fill or stroke property) and then applying the transform specified by attribute patternTransform. Percentages represent values relative to the current SVG viewport.

    objectBoundingBox

    If patternUnits="objectBoundingBox", the user coordinate system for attributes x, y, width and height is established using the bounding box of the element to which the pattern is applied (see Object bounding box units) and then applying the transform specified by attribute patternTransform. Percentages represent values relative to the bounding box for the object.

    patternContentUnits

    Defines the coordinate system for the contents of the pattern. Note that this attribute has no effect if attribute viewBox is specified.

    Value
    userSpaceOnUse | objectBoundingBox
    initial value
    userSpaceOnUse
    Animatable
    yes
    userSpaceOnUse

    If patternContentUnits="userSpaceOnUse", the user coordinate system for the contents of the pattern element is the coordinate system that results from taking the current user coordinate system in place at the time when the pattern element is referenced (i.e., the user coordinate system for the element referencing the pattern element via a fill or stroke property) and then applying the transform specified by attribute patternTransform.

    objectBoundingBox

    If patternContentUnits="objectBoundingBox", the user coordinate system for the contents of the pattern element is established using the bounding box of the element to which the pattern is applied (see Object bounding box units) and then applying the transform specified by attribute patternTransform.

    patternTransform

    Contains the definition of an optional additional transformation from the pattern coordinate system onto the target coordinate system (i.e., 'userSpaceOnUse' or 'objectBoundingBox'). This allows for things such as skewing the pattern tiles. This additional transformation matrix is post-multiplied to (i.e., inserted to the right of) any previously defined transformations, including the implicit transformation necessary to convert from object bounding box units to local coordinate system.

    Value
    <transform-list>
    initial value
    identity transform
    Animatable
    yes
    x

    x, y, width and height indicate how the pattern tiles are placed and spaced. These attributes represent coordinates and values in the coordinate space specified by the combination of attributes patternUnits and patternTransform.

    Value
    <length>
    initial value
    0
    Animatable
    yes
    y

    See x.

    Value
    <length>
    initial value
    0
    Animatable
    yes
    width

    See x.

    Value
    <length>
    initial value
    0
    Animatable
    yes

    A negative value is an error (see Error processing). A value of zero disables rendering of the element (i.e., no paint is applied).

    height

    See x.

    Value
    <length>
    initial value
    0
    Animatable
    yes

    A negative value is an error (see Error processing). A value of zero disables rendering of the element (i.e., no paint is applied).

    href

    A URL reference to a template element, which must be a different pattern element to be valid.

    Refer to the process for using paint servers as templates, and to the common handling defined for URL reference attributes and deprecated XLink attributes.

    The specified attributes that will be copied from the template are:

    Value
    URL [URL]
    initial value
    empty
    Animatable
    yes

    14.3.2. Notes on patterns

    SVG's user agent style sheet sets the overflow property for pattern elements to hidden, which causes a rectangular clipping path to be created at the bounds of the pattern tile. Unless the overflow property is overridden, any graphics within the pattern which goes outside of the pattern rectangle will be clipped. Example pattern01 below shows the effect of clipping to the pattern tile.

    Note that if the overflow property is set to visible the rendering behavior for the pattern outside the bounds of the pattern is currently undefined. A future version of SVG may require the overflow to be shown. SVG implementers are encouraged to render the overflow as this is the behavior expected by authors. If overflow is rendered, the pattern tiles should be rendered left to right in rows and the rows from top to bottom.

    See GitHub Issue 129

    The contents of the pattern are relative to a new coordinate system. If there is a viewBox attribute, then the new coordinate system is fitted into the region defined by the x, y, width, height and patternUnits attributes on the pattern element using the standard rules for viewBox and preserveAspectRatio. If there is no viewBox attribute, then the new coordinate system has its origin at (xy), where x is established by the x attribute on the pattern element, and y is established by the y attribute on the pattern element. Thus, in the following example:

    <pattern x="10" y="10" width="20" height="20">
      <rect x="5" y="5" width="10" height="10"/>
    </pattern>
    

    the rectangle has its top/left located 5 units to the right and 5 units down from the origin of the pattern tile.

    The viewBox attribute introduces a supplemental transformation which is applied on top of any transformations necessary to create a new pattern coordinate system due to attributes x, y, width, height and patternUnits.

    Event attributes and event listeners attached to the contents of a pattern element are not processed; only the rendering aspects of pattern elements are processed.

    Example pattern01 shows how to fill a rectangle by referencing a pattern paint server. Note how the blue stroke of each triangle has been slightly clipped at the top and the left. This is due to SVG's user agent style sheet setting the overflow property for pattern elements to hidden, which causes the pattern to be clipped to the bounds of the pattern tile.

    <?xml version="1.0" standalone="no"?>
    <svg xmlns="http://www.w3.org/2000/svg"
         version="1.1"
         viewBox="0 0 300 200" >
    
      <title>Example pattern01</title>
      <desc>Fill an ellipse using a pattern paint server.</desc>
    
      <defs>
        <pattern id="TrianglePattern"
    	     patternUnits="userSpaceOnUse"
                 x="0" y="0" width="50" height="50"
                 viewBox="0 0 10 10" >
          <path d="M 0 0 L 7 0 L 3.5 7 z"
    	    fill="plum"
    	    stroke="blue" />
        </pattern> 
      </defs>
    
      <!-- The ellipse is filled using a triangle pattern paint server -->
      <ellipse fill="url(#TrianglePattern)"
    	   stroke="black"
    	   stroke-width="2"
               cx="150" cy="100" rx="125" ry="75" />
    </svg>
    Example pattern01 — fill a rectangle by referencing a pattern paint server

    Example pattern01

    View this example as SVG (SVG-enabled browsers only)

    14.4. DOM interfaces

    14.4.1. Interface SVGGradientElement

    The SVGGradientElement interface is used as a base interface for gradient paint server element interfaces.

    [Exposed=Window]
    interface SVGGradientElement : SVGElement {
    
      // Spread Method Types
      const unsigned short SVG_SPREADMETHOD_UNKNOWN = 0;
      const unsigned short SVG_SPREADMETHOD_PAD = 1;
      const unsigned short SVG_SPREADMETHOD_REFLECT = 2;
      const unsigned short SVG_SPREADMETHOD_REPEAT = 3;
    
      [SameObject] readonly attribute SVGAnimatedEnumeration gradientUnits;
      [SameObject] readonly attribute SVGAnimatedTransformList gradientTransform;
      [SameObject] readonly attribute SVGAnimatedEnumeration spreadMethod;
    };
    
    SVGGradientElement includes SVGURIReference;
    

    The numeric spread method type constants defined on SVGGradientElement are used to represent the keyword values that the ‘spreadMethod’ attribute can take. Their meanings are as follows:

    ConstantMeaning
    SVG_SPREADMETHOD_PADThe pad keyword.
    SVG_SPREADMETHOD_REFLECTThe reflect keyword.
    SVG_SPREADMETHOD_REPEATThe repeat keyword.
    SVG_SPREADMETHOD_UNKNOWNSome other value.

    The gradientUnits IDL attribute reflects the ‘gradientUnits’ content attribute. The numeric type values for ‘gradientUnits’ attributes on gradient elements are as follows:

    ValueNumeric type value
    userSpaceOnUse SVG_UNIT_TYPE_USERSPACEONUSE
    objectBoundingBox SVG_UNIT_TYPE_OBJECTBOUNDINGBOX

    The gradientTransform IDL attribute reflects the computed value of the transform property and the 'gradientTransform' presentation attribute for linearGradient and radialGradient elements.

    The spreadMethod IDL attribute reflects the ‘spreadMethod’ content attribute. The numeric type values for ‘spreadMethod’ attributes on gradient elements are as described above in the numeric spread type constant table.

    14.4.2. Interface SVGLinearGradientElement

    An SVGLinearGradientElement object represents an linearGradient in the DOM.

    [Exposed=Window]
    interface SVGLinearGradientElement : SVGGradientElement {
      [SameObject] readonly attribute SVGAnimatedLength x1;
      [SameObject] readonly attribute SVGAnimatedLength y1;
      [SameObject] readonly attribute SVGAnimatedLength x2;
      [SameObject] readonly attribute SVGAnimatedLength y2;
    };

    The x1, y1, x2 and y2 IDL attributes reflect the x1, y1, x2 and y2 content attributes, respectively

    14.4.3. Interface SVGRadialGradientElement

    An SVGRadialGradientElement object represents an radialGradient in the DOM.

    [Exposed=Window]
    interface SVGRadialGradientElement : SVGGradientElement {
      [SameObject] readonly attribute SVGAnimatedLength cx;
      [SameObject] readonly attribute SVGAnimatedLength cy;
      [SameObject] readonly attribute SVGAnimatedLength r;
      [SameObject] readonly attribute SVGAnimatedLength fx;
      [SameObject] readonly attribute SVGAnimatedLength fy;
      [SameObject] readonly attribute SVGAnimatedLength fr;
    };

    The cx, cy, r, fx, fy and fr IDL attributes reflect the cx, cy, r, fx, fy and fr content attributes, respectively

    14.4.4. Interface SVGStopElement

    An SVGStopElement object represents a stop element in the DOM.

    [Exposed=Window]
    interface SVGStopElement : SVGElement {
      [SameObject] readonly attribute SVGAnimatedNumber offset;
    };

    The offset IDL attribute reflects the offset content attribute.

    Note that SVGStopElement does not have a reflecting IDL attribute for its path attribute.

    14.4.5. Interface SVGPatternElement

    An SVGPatternElement object represents a pattern element in the DOM.

    [Exposed=Window]
    interface SVGPatternElement : SVGElement {
      [SameObject] readonly attribute SVGAnimatedEnumeration patternUnits;
      [SameObject] readonly attribute SVGAnimatedEnumeration patternContentUnits;
      [SameObject] readonly attribute SVGAnimatedTransformList patternTransform;
      [SameObject] readonly attribute SVGAnimatedLength x;
      [SameObject] readonly attribute SVGAnimatedLength y;
      [SameObject] readonly attribute SVGAnimatedLength width;
      [SameObject] readonly attribute SVGAnimatedLength height;
    };
    
    SVGPatternElement includes SVGFitToViewBox;
    SVGPatternElement includes SVGURIReference;
    

    The patternUnits and patternContentUnits IDL attributes reflect the patternUnits and patternContentUnits content attributes, respectively. The numeric type values for patternUnits and patternContentUnits are as follows:

    ValueNumeric type value
    userSpaceOnUse SVG_UNIT_TYPE_USERSPACEONUSE
    objectBoundingBox SVG_UNIT_TYPE_OBJECTBOUNDINGBOX

    The patternTransform IDL attribute reflects the computed value of the transform property and the ‘patternTransform’ presentation attribute.

    The x, y, width and height IDL attributes reflect the x, y, width and height content attributes, respectively.