13 Gradients and Patterns
Contents
13.1 Introduction
With SVG, you can fill (i.e., paint the interior) or stroke (i.e.,
paint the outline) of shapes and text using one of the following:
- color (using <color> or the
  ‘solidColor’ element)
- gradients (linear or radial)
- patterns (vector or image, possibly tiled)
SVG uses the general notion of a paint server.
Gradients and patterns are just specific types of built-in paint
servers. The ‘solidColor’
element is another built-in paint server, described in Color.
Paint servers are referenced using a
URI reference on a ‘fill’ or
‘stroke’ property.
13.2 Gradients
13.2.1 Introduction
Gradients consist of continuously smooth color transitions
along a vector from one color to another, possibly
followed by additional transitions along the same vector
to other colors. SVG provides for two types of gradients:
linear
gradients and radial
gradients.
Once defined, gradients are then referenced using ‘fill’ or
‘stroke’ properties on a given
graphics element to indicate that
the given element shall be filled or stroked with the referenced gradient.
The angle of the color transitions along the gradient vector is defined by the
gradient normal. Before any transforms are applied to the gradient or its
referencing graphics element, the
gradient normal is perpendicular with the gradient vector. If a
graphics element references a
gradient, conceptually the graphics
element should take a copy of the gradient vector and gradient normal 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 normal. Any gradient transforms
that are specified on the reference gradient are applied before any
graphics element transformations
are applied to the gradient.
 
13.2.2 Linear gradients
Linear gradients are defined by a
‘linearGradient’ element.
‘linearGradient’
- Categories:
- Gradient element
- Content model:
- Any number of the following elements, in any order:
                
- Attributes:
- core attributes — ‘id’, ‘xml:base’, ‘xml:lang’, ‘xml:space’
- presentation attributes — ‘alignment-baseline’, ‘baseline-shift’, ‘clip’, ‘clip-path’, ‘clip-rule’, ‘color’, ‘color-interpolation’, ‘color-interpolation-filters’, ‘color-profile’, ‘color-rendering’, ‘cursor’, ‘direction’, ‘display’, ‘dominant-baseline’, ‘enable-background’, ‘fill’, ‘fill-opacity’, ‘fill-rule’, ‘filter’, ‘flood-color’, ‘flood-opacity’, ‘font-family’, ‘font-size’, ‘font-size-adjust’, ‘font-stretch’, ‘font-style’, ‘font-variant’, ‘font-weight’, ‘glyph-orientation-horizontal’, ‘glyph-orientation-vertical’, ‘image-rendering’, ‘kerning’, ‘letter-spacing’, ‘lighting-color’, ‘marker-end’, ‘marker-mid’, ‘marker-start’, ‘mask’, ‘opacity’, ‘overflow’, ‘pointer-events’, ‘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-rendering’, ‘unicode-bidi’, ‘visibility’, ‘word-spacing’, ‘writing-mode’
- xlink attributes — ‘xlink:href’, ‘xlink:show’, ‘xlink:actuate’, ‘xlink:type’, ‘xlink:role’, ‘xlink:arcrole’, ‘xlink:title’
- ‘class’
- ‘style’
- ‘externalResourcesRequired’
- ‘x1’
- ‘y1’
- ‘x2’
- ‘y2’
- ‘gradientUnits’
- ‘gradientTransform’
- ‘spreadMethod’
- ‘xlink:href’
 
- DOM Interfaces:
      Attribute definitions:
      - gradientUnits =
        "userSpaceOnUse | objectBoundingBox"
- Defines the coordinate system for attributes ‘x1’,
        ‘y1’, ‘x2’ and ‘y2’.
 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’.
 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’.
 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 user space.
 If attribute ‘gradientUnits’
        is not specified, then the effect is as if a value of 'objectBoundingBox' were
        specified.
 Animatable:
        yes.
- 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 user space.
 If attribute ‘gradientTransform’ is not
        specified, then the effect is as if an identity transform
        were specified.
 Animatable:
        yes.
- x1 = "<coordinate>"
- ‘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.
 If the attribute is not specified, the effect is as if a
        value of '0%' were specified.
 Animatable:
        yes.
- y1 = "<coordinate>"
- See ‘x1’.
 If the attribute is not specified, the effect is as if a
        value of '0%' were specified.
 Animatable:
        yes.
- x2 = "<coordinate>"
- See ‘x1’.
 If the attribute is not specified, the effect is as if a
        value of '100%' were specified.
 Animatable:
        yes.
- y2 = "<coordinate>"
- See ‘x1’.
 If the attribute is not specified, the effect is as if a
        value of '0%' were specified.
 Animatable:
        yes.
- spreadMethod = "pad | reflect |
        repeat"
- Indicates what happens if the gradient starts or ends
        inside the bounds of the target rectangle.
        Possible values are: 'pad', which says to use the
        terminal colors of the gradient to fill the remainder of
        the target region, 'reflect', which says to reflect
        the gradient pattern start-to-end, end-to-start,
        start-to-end, etc. continuously until the target
        rectangle is filled, and repeat, which says
        to repeat the gradient pattern start-to-end, start-to-end,
        start-to-end, etc. continuously until the target region is
        filled.
 If the attribute is not specified, the effect is as if a
        value of 'pad' were specified.
 Animatable:
        yes.
- xlink:href = "<iri>"
- A URI
        reference to a different ‘linearGradient’ or
        ‘radialGradient’ element within
        the current SVG document fragment. Any ‘linearGradient’ attributes
        which are defined on the referenced element which are not
        defined on this element are inherited by this element. If
        this element has no defined gradient stops, and the
        referenced element does (possibly due to its own ‘xlink:href’
        attribute), then this element
        inherits the gradient stop from the referenced element.
        Inheritance can be indirect to an arbitrary level; thus, if
        the referenced element inherits attribute or gradient stops
        due to its own ‘xlink:href’
        attribute, then the current element can inherit those
        attributes or gradient stops.
 Animatable:
        yes.
 
Percentages are allowed for ‘x1’,
‘y1’, ‘x2’ and ‘y2’. For
gradientUnits="userSpaceOnUse",
percentages represent values relative to the current viewport. For
gradientUnits="objectBoundingBox",
percentages represent values relative to the bounding box for the
object.
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.
Properties inherit
into the ‘linearGradient’ element from its ancestors;
properties do not inherit from the element referencing the
‘linearGradient’ element.
‘linearGradient’ elements are never rendered directly;
their only usage is as something that can be referenced using the
‘fill’ and ‘stroke’ properties. The ‘display’
property does not apply to the ‘linearGradient’ element; thus,
‘linearGradient’ elements are not directly rendered even if
the ‘display’ property is set to a value other than
none, and ‘linearGradient’
elements are available for referencing even when the ‘display’
property on the ‘linearGradient’ element or any of its ancestors
is set to none.
Example lingrad01
shows how to fill a rectangle by referencing a linear gradient paint
server.
<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" 
  "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg width="8cm" height="4cm" viewBox="0 0 800 400" version="1.1"
     xmlns="http://www.w3.org/2000/svg">
  <desc>Example lingrad01 - fill a rectangle using a 
           linear gradient paint server</desc>
  <g>
    <defs>
      <linearGradient id="MyGradient">
        <stop offset="5%" stop-color="#F60" />
        <stop offset="95%" stop-color="#FF6" />
      </linearGradient>
    </defs>
    <!-- Outline the drawing area in blue -->
    <rect fill="none" stroke="blue" 
          x="1" y="1" width="798" height="398"/>
    <!-- The rectangle is filled using a linear gradient paint server -->
    <rect fill="url(#MyGradient)" stroke="black" stroke-width="5"  
          x="100" y="100" width="600" height="200"/>
  </g>
</svg>Example lingrad01|  | 
View this example as SVG (SVG-enabled browsers only)
13.2.3 Radial gradients
Radial gradients are defined by a
‘radialGradient’ element.
‘radialGradient’
- Categories:
- Gradient element
- Content model:
- Any number of the following elements, in any order:
                
- Attributes:
- core attributes — ‘id’, ‘xml:base’, ‘xml:lang’, ‘xml:space’
- presentation attributes — ‘alignment-baseline’, ‘baseline-shift’, ‘clip’, ‘clip-path’, ‘clip-rule’, ‘color’, ‘color-interpolation’, ‘color-interpolation-filters’, ‘color-profile’, ‘color-rendering’, ‘cursor’, ‘direction’, ‘display’, ‘dominant-baseline’, ‘enable-background’, ‘fill’, ‘fill-opacity’, ‘fill-rule’, ‘filter’, ‘flood-color’, ‘flood-opacity’, ‘font-family’, ‘font-size’, ‘font-size-adjust’, ‘font-stretch’, ‘font-style’, ‘font-variant’, ‘font-weight’, ‘glyph-orientation-horizontal’, ‘glyph-orientation-vertical’, ‘image-rendering’, ‘kerning’, ‘letter-spacing’, ‘lighting-color’, ‘marker-end’, ‘marker-mid’, ‘marker-start’, ‘mask’, ‘opacity’, ‘overflow’, ‘pointer-events’, ‘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-rendering’, ‘unicode-bidi’, ‘visibility’, ‘word-spacing’, ‘writing-mode’
- xlink attributes — ‘xlink:href’, ‘xlink:show’, ‘xlink:actuate’, ‘xlink:type’, ‘xlink:role’, ‘xlink:arcrole’, ‘xlink:title’
- ‘class’
- ‘style’
- ‘externalResourcesRequired’
- ‘cx’
- ‘cy’
- ‘r’
- ‘fx’
- ‘fy’
- ‘gradientUnits’
- ‘gradientTransform’
- ‘spreadMethod’
- ‘xlink:href’
 
- DOM Interfaces:
      Attribute definitions:
      - gradientUnits =
        "userSpaceOnUse | objectBoundingBox"
- Defines the coordinate system for attributes
        ‘cx’, ‘cy’, ‘r’, ‘fx’ and ‘fy’.
 If gradientUnits="userSpaceOnUse",
        ‘cx’, ‘cy’, ‘r’, ‘fx’ and ‘fy’
        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’.
 If gradientUnits="objectBoundingBox",
        the user coordinate system for attributes
        ‘cx’, ‘cy’, ‘r’, ‘fx’ and ‘fy’
         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’.
 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 user space.
 If attribute ‘gradientUnits’
        is not specified, then the effect is as if a value of 'objectBoundingBox' were
        specified.
 Animatable:
        yes.
- gradientTransform = "<transform-list>"
- Contains the definitions 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 user space.
 If attribute ‘gradientTransform’ is not
        specified, then the effect is as if an identity transform
        were specified.
 Animatable:
        yes.
- cx = "<coordinate>"
- ‘cx’, ‘cy’ and ‘r’ define the largest (i.e.,
        outermost) circle for the radial gradient. The gradient
        will be drawn such that the 100% gradient stop is mapped to the
        perimeter of this largest (i.e., outermost) circle.
 If the attribute is not specified, the effect is as if a
        value of '50%' were specified.
 Animatable:
        yes.
- cy = "<coordinate>"
- See ‘cx’.
 If the attribute is not specified, the effect is as if a
        value of '50%' were specified.
 Animatable:
        yes.
- r = "<length>"
- See ‘cx’.
 A negative value is an error (see Error processing).
        A value of zero will cause the area to be painted as a
        single color using the color and opacity of the last gradient stop.
 If the attribute is not specified, the effect is as if a
        value of '50%' were specified.
 Animatable:
        yes.
- fx = "<coordinate>"
- ‘fx’ and ‘fy’ define the focal point for the
        radial gradient. The gradient will be drawn such that the
        0% gradient stop is mapped to
        (fx, fy).
 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.
 Animatable:
        yes.
- fy = "<coordinate>"
- See ‘fx’.
 If attribute ‘fy’ is not specified, ‘fy’ will coincide
        with the presentational vlaue 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.
 Animatable:
        yes.
- 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.
 Animatable:
        yes.
- xlink:href = "<iri>"
- A URI
        reference to a different ‘linearGradient’ or
        ‘radialGradient’ element within
        the current SVG document fragment. Any ‘radialGradient’ attributes
        which are defined on the referenced element which are not
        defined on this element are inherited by this element. If
        this element has no defined gradient stops, and the
        referenced element does (possibly due to its own ‘xlink:href’
        attribute), then this element inherits the gradient stop from the referenced element.
        Inheritance can be indirect to an arbitrary level; thus, if
        the referenced element inherits attribute or gradient stops
        due to its own ‘xlink:href’
        attribute, then the current element can inherit those
        attributes or gradient stops.
 Animatable:
        yes.
 
Percentages are allowed for attributes ‘cx’, ‘cy’,
‘r’, ‘fx’ and ‘fy’. For
gradientUnits="userSpaceOnUse", percentages
represent values relative to the current viewport.  For
gradientUnits="objectBoundingBox", percentages
represent values relative to the bounding box for the object.
If the point defined by ‘fx’ and ‘fy’ lies outside the
circle defined by ‘cx’, ‘cy’ and ‘r’, then the user
agent shall set the focal point to the intersection of the line from
(‘cx’, ‘cy’) to (‘fx’, ‘fy’) with the circle
defined by ‘cx’, ‘cy’ and ‘r’.
Properties
inherit into the ‘radialGradient’ element from its ancestors;
properties do not inherit from the element referencing the
‘radialGradient’ element.
‘radialGradient’ elements are never rendered directly;
their only usage is as something that can be referenced using the
‘fill’ and ‘stroke’ properties. The ‘display’
property does not apply to the ‘radialGradient’ element; thus,
‘radialGradient’ elements are not directly rendered even if
the ‘display’ property is set to a value other than
none, and ‘radialGradient’ elements
are available for referencing even when the ‘display’ property on
the ‘radialGradient’ element or any of its ancestors is set to
none.
Example radgrad01
shows how to fill a rectangle by referencing a radial gradient paint
server.
<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" 
  "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg width="8cm" height="4cm" viewBox="0 0 800 400" version="1.1"
     xmlns="http://www.w3.org/2000/svg">
  <desc>Example radgrad01 - fill a rectangle by referencing a 
           radial gradient paint server</desc>
  <g>
    <defs>
      <radialGradient id="MyGradient" gradientUnits="userSpaceOnUse"
                      cx="400" cy="200" r="300" fx="400" fy="200">
        <stop offset="0%" stop-color="red" />
        <stop offset="50%" stop-color="blue" />
        <stop offset="100%" stop-color="red" />
      </radialGradient>
    </defs>
    <!-- Outline the drawing area in blue -->
    <rect fill="none" stroke="blue" 
          x="1" y="1" width="798" height="398"/>
    <!-- The rectangle is filled using a radial gradient paint server -->
    <rect fill="url(#MyGradient)" stroke="black" stroke-width="5"  
          x="100" y="100" width="600" height="200"/>
  </g>
</svg>Example radgrad01|  | 
View this example as SVG (SVG-enabled browsers only)
13.2.4 Gradient stops
The ramp of colors to use on a gradient is defined
by the ‘stop’ elements that are child elements to either the
‘linearGradient’ element or the ‘radialGradient’
element.
‘stop’
- Categories:
- None
- Content model:
- Any number of the following elements, in any order:
                
- Attributes:
- core attributes — ‘id’, ‘xml:base’, ‘xml:lang’, ‘xml:space’
- presentation attributes — ‘alignment-baseline’, ‘baseline-shift’, ‘clip’, ‘clip-path’, ‘clip-rule’, ‘color’, ‘color-interpolation’, ‘color-interpolation-filters’, ‘color-profile’, ‘color-rendering’, ‘cursor’, ‘direction’, ‘display’, ‘dominant-baseline’, ‘enable-background’, ‘fill’, ‘fill-opacity’, ‘fill-rule’, ‘filter’, ‘flood-color’, ‘flood-opacity’, ‘font-family’, ‘font-size’, ‘font-size-adjust’, ‘font-stretch’, ‘font-style’, ‘font-variant’, ‘font-weight’, ‘glyph-orientation-horizontal’, ‘glyph-orientation-vertical’, ‘image-rendering’, ‘kerning’, ‘letter-spacing’, ‘lighting-color’, ‘marker-end’, ‘marker-mid’, ‘marker-start’, ‘mask’, ‘opacity’, ‘overflow’, ‘pointer-events’, ‘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-rendering’, ‘unicode-bidi’, ‘visibility’, ‘word-spacing’, ‘writing-mode’
- ‘class’
- ‘style’
- ‘offset’
 
- DOM Interfaces:
      Attribute definitions:
      - offset = "<number> | <percentage>"
- The ‘offset’ attribute is
        either a <number>
        (usually ranging from 0 to 1) or a <percentage>
        (usually ranging from 0% to 100%) which indicates where the
        gradient stop is placed. For linear gradients, the ‘offset’ attribute represents a
        location along the gradient vector. For radial
        gradients, it represents a percentage distance from (fx,fy)
        to the edge of the outermost/largest circle.
 Animatable:
        yes.
 
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.
    
The ‘stop-opacity’ property defines the opacity of a given
gradient stop.
    
      - ‘stop-opacity’
- 
          | Value: | <opacity-value> | 
              inherit |  | Initial: | 1 |  | Applies to: | ‘stop’ elements |  | Inherited: | no |  | Percentages: | N/A |  | Media: | visual |  | Animatable: | yes |  
 
 
Some notes on gradients:
- Gradient offset values less than 0 (or less than 0%) are
  rounded up to 0%. Gradient offset values greater than 1 (or
  greater than 100%) are rounded down to 100%.
- It is necessary that at least two stops defined to have a
  gradient effect. If no stops are defined, then painting shall
  occur as if 'none' were specified as the paint style. If one
  stop is defined, then paint with the solid color fill using
  the color defined for that gradient stop.
- Each gradient offset value is required to be equal to or
  greater than the previous gradient stop's offset value. If a
  given gradient stop's offset value is not equal to or greater
  than all previous offset values, then the offset value is
  adjusted to be equal to the largest of all previous offset
  values.
- 
    If two gradient stops have the same offset value, then the
    latter gradient stop controls the color value at the
    overlap point. In particular: 
<stop offset="0" stop-color="white"/>
<stop offset=".2" stop-color="red"/>
<stop offset=".2" stop-color="blue"/>
<stop offset="1" stop-color="black"/>
 will have approximately the same effect as:
<stop offset="0" stop-color="white"/>
<stop offset=".1999999999" stop-color="red"/>
<stop offset=".2" stop-color="blue"/>
<stop offset="1" stop-color="black"/>
 which is a gradient that goes smoothly from white to red,
    then abruptly shifts from red to blue, and then goes
    smoothly from blue to black.
13.3 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 referenced
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 (x, y) and its bottom/right at
(x + width, y + 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*width, y + n*
height) for each possible integer value for m and
n.
‘pattern’
- Categories:
- Container element
- Content model:
- Any number of the following elements, in any order:
                - animation elements — ‘animate’, ‘animateColor’, ‘animateMotion’, ‘animateTransform’, ‘set’
- descriptive elements — ‘desc’, ‘metadata’, ‘title’
- shape elements — ‘circle’, ‘ellipse’, ‘line’, ‘path’, ‘polygon’, ‘polyline’, ‘rect’
- structural elements — ‘defs’, ‘g’, ‘svg’, ‘symbol’, ‘use’
- gradient elements — ‘linearGradient’, ‘radialGradient’
- ‘a’
- ‘altGlyphDef’
- ‘clipPath’
- ‘color-profile’
- ‘cursor’
- ‘filter’
- ‘font’
- ‘font-face’
- ‘foreignObject’
- ‘image’
- ‘marker’
- ‘mask’
- ‘pattern’
- ‘script’
- ‘style’
- ‘switch’
- ‘text’
- ‘view’
 
- Attributes:
- conditional processing attributes — ‘requiredFeatures’, ‘requiredExtensions’, ‘systemLanguage’
- core attributes — ‘id’, ‘xml:base’, ‘xml:lang’, ‘xml:space’
- presentation attributes — ‘alignment-baseline’, ‘baseline-shift’, ‘clip’, ‘clip-path’, ‘clip-rule’, ‘color’, ‘color-interpolation’, ‘color-interpolation-filters’, ‘color-profile’, ‘color-rendering’, ‘cursor’, ‘direction’, ‘display’, ‘dominant-baseline’, ‘enable-background’, ‘fill’, ‘fill-opacity’, ‘fill-rule’, ‘filter’, ‘flood-color’, ‘flood-opacity’, ‘font-family’, ‘font-size’, ‘font-size-adjust’, ‘font-stretch’, ‘font-style’, ‘font-variant’, ‘font-weight’, ‘glyph-orientation-horizontal’, ‘glyph-orientation-vertical’, ‘image-rendering’, ‘kerning’, ‘letter-spacing’, ‘lighting-color’, ‘marker-end’, ‘marker-mid’, ‘marker-start’, ‘mask’, ‘opacity’, ‘overflow’, ‘pointer-events’, ‘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-rendering’, ‘unicode-bidi’, ‘visibility’, ‘word-spacing’, ‘writing-mode’
- xlink attributes — ‘xlink:href’, ‘xlink:show’, ‘xlink:actuate’, ‘xlink:type’, ‘xlink:role’, ‘xlink:arcrole’, ‘xlink:title’
- ‘class’
- ‘style’
- ‘externalResourcesRequired’
- ‘viewBox’
- ‘preserveAspectRatio’
- ‘x’
- ‘y’
- ‘width’
- ‘height’
- ‘patternUnits’
- ‘patternContentUnits’
- ‘patternTransform’
- ‘xlink:href’
 
- DOM Interfaces:
      Attribute definitions:
      - patternUnits = "userSpaceOnUse
        | objectBoundingBox"
- Defines the coordinate system for attributes
        ‘x’, ‘y’, ‘width’ and ‘height’.
 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’.
 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’.
 If attribute ‘patternUnits’
        is not specified, then the effect is as if a value of 'objectBoundingBox' were
        specified.
 Animatable:
        yes.
- patternContentUnits =
        "userSpaceOnUse | objectBoundingBox"
- Defines the coordinate system for the contents of the
        ‘pattern’. Note that this
        attribute has no effect if attribute ‘viewBox’ is specified.
 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’.
 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’.
 If attribute ‘patternContentUnits’ is not
        specified, then the effect is as if a value of
        'userSpaceOnUse' were
        specified.
 Animatable:
        yes.
- patternTransform = "<transform-list>"
- 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 user space.
 If attribute ‘patternTransform’ is not specified,
        then the effect is as if an identity transform were
        specified.
 Animatable:
        yes.
- x = "<coordinate>"
- ‘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’.
 If the attribute is not specified, the effect is as if a
        value of zero were specified.
 Animatable:
        yes.
- y = "<coordinate>"
- See ‘x’.
 If the attribute is not specified, the effect is as if a
        value of zero were specified.
 Animatable:
        yes.
- width = "<length>"
- See ‘x’.
 A negative value is an error (see Error processing).
        A value of zero disables rendering of the element (i.e., no
        paint is applied).
 If the attribute is not specified, the effect is as if a
        value of zero were specified.
 Animatable:
        yes.
- height = "<length>"
- See ‘x’.
 A negative value is an error (see Error processing).
        A value of zero disables rendering of the element (i.e., no
        paint is applied).
 If the attribute is not specified, the effect is as if a
        value of zero were specified.
 Animatable:
        yes.
- xlink:href = "<iri>"
- A URI
        reference to a different ‘pattern’ element within the
        current SVG document fragment. Any attributes which are
        defined on the referenced element which are not defined on
        this element are inherited by this element. If this element
        has no children, and the referenced element does (possibly
        due to its own ‘xlink:href’
        attribute), then this element inherits the children from
        the referenced element. Inheritance can be indirect to an
        arbitrary level; thus, if the referenced element inherits
        attributes or children due to its own ‘xlink:href’ attribute, then the current
        element can inherit those attributes or children.
 Animatable:
        yes.
- 
          preserveAspectRatio = "[defer] <align> [<meetOrSlice>]"
        
- 
          
            See ‘preserveAspectRatio’.
           
            If the attribute is not specified, then the effect is as if a value of xMidYMid meet were specified.
           Animatable: yes. 
 
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.  Note that if
the ‘overflow’ property is set to visible
the rendering behavior for the pattern is undefined. 
Example pattern01 below shows the
effect of clipping to the pattern tile.
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 (x, y),
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’.
Properties inherit into the
‘pattern’ element from its ancestors; properties do not
inherit from the element referencing the ‘pattern’ element.
‘pattern’ elements are never rendered directly; their only usage is
as something that can be referenced using the ‘fill’ and
‘stroke’ properties. The ‘display’ property does not apply to
the ‘pattern’ element; thus, ‘pattern’ elements are not directly
rendered even if the ‘display’ property is set to a value other than
none, and ‘pattern’ elements are
available for referencing even when the ‘display’ property on the
‘pattern’ element or any of its ancestors is set to
none.
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 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"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" 
  "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg width="8cm" height="4cm" viewBox="0 0 800 400" version="1.1"
     xmlns="http://www.w3.org/2000/svg">
  <defs>
    <pattern id="TrianglePattern" patternUnits="userSpaceOnUse"
             x="0" y="0" width="100" height="100"
             viewBox="0 0 10 10" >
      <path d="M 0 0 L 7 0 L 3.5 7 z" fill="red" stroke="blue" />
    </pattern> 
  </defs>
  <!-- Outline the drawing area in blue -->
  <rect fill="none" stroke="blue" 
        x="1" y="1" width="798" height="398"/>
  <!-- The ellipse is filled using a triangle pattern paint server
       and stroked with black -->
  <ellipse fill="url(#TrianglePattern)" stroke="black" stroke-width="5"  
           cx="400" cy="200" rx="350" ry="150" />
</svg>Example pattern01|  | 
View this example as SVG (SVG-enabled browsers only)
13.4 DOM interfaces
13.4.1 Interface SVGGradientElement
 The SVGGradientElement interface is a base interface used by
 SVGLinearGradientElement and SVGRadialGradientElement.
interface SVGGradientElement : SVGElement,
                               SVGURIReference,
                               SVGExternalResourcesRequired,
                               SVGStylable,
                               SVGUnitTypes {
  // 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;
  readonly attribute SVGAnimatedEnumeration gradientUnits;
  readonly attribute SVGAnimatedTransformList gradientTransform;
  readonly attribute SVGAnimatedEnumeration spreadMethod;
};- Constants in group “Spread Method Types”:
- 
- SVG_SPREADMETHOD_UNKNOWN (unsigned short)
- 
 The type is not one of predefined types. It is invalid to attempt to
 define a new value of this type or to attempt to switch an existing
 value to this type.
 
- SVG_SPREADMETHOD_PAD (unsigned short)
- 
 Corresponds to value 'pad'.
 
- SVG_SPREADMETHOD_REFLECT (unsigned short)
- 
 Corresponds to value 'reflect'.
 
- SVG_SPREADMETHOD_REPEAT (unsigned short)
- 
 Corresponds to value 'repeat'.
 
 
- Attributes:
- 
- gradientUnits (readonly SVGAnimatedEnumeration)
- 
 Corresponds to attribute  ‘gradientUnits’- 
 on the given element.  Takes one of the constants defined in
  SVGUnitTypes- .
 
- gradientTransform (readonly SVGAnimatedTransformList)
- 
 Corresponds to attribute ‘gradientTransform’
 on the given element.
 
- spreadMethod (readonly SVGAnimatedEnumeration)
- 
 Corresponds to attribute ‘spreadMethod’
 on the given element.  One of the Spread Method Types defined on
 this interface.
 
 
13.4.2 Interface SVGLinearGradientElement
 The SVGLinearGradientElement interface corresponds to the
 ‘linearGradient’ element.
interface SVGLinearGradientElement : SVGGradientElement {
  readonly attribute SVGAnimatedLength x1;
  readonly attribute SVGAnimatedLength y1;
  readonly attribute SVGAnimatedLength x2;
  readonly attribute SVGAnimatedLength y2;
};- Attributes:
- 
- x1 (readonly SVGAnimatedLength)
- y1 (readonly SVGAnimatedLength)
- x2 (readonly SVGAnimatedLength)
- y2 (readonly SVGAnimatedLength)
 
13.4.3 Interface SVGRadialGradientElement
 The SVGRadialGradientElement interface corresponds to the
 ‘radialGradient’ element.
interface SVGRadialGradientElement : SVGGradientElement {
  readonly attribute SVGAnimatedLength cx;
  readonly attribute SVGAnimatedLength cy;
  readonly attribute SVGAnimatedLength r;
  readonly attribute SVGAnimatedLength fx;
  readonly attribute SVGAnimatedLength fy;
};- Attributes:
- 
- cx (readonly SVGAnimatedLength)
- cy (readonly SVGAnimatedLength)
- r (readonly SVGAnimatedLength)
- fx (readonly SVGAnimatedLength)
- fy (readonly SVGAnimatedLength)
 
13.4.4 Interface SVGStopElement
 The SVGStopElement interface corresponds to the ‘stop’
 element.
interface SVGStopElement : SVGElement,
                           SVGStylable {
  readonly attribute SVGAnimatedNumber offset;
};- Attributes:
- 
- offset (readonly SVGAnimatedNumber)
 
13.4.5 Interface SVGPatternElement
 The SVGPatternElement interface corresponds to the ‘pattern’
 element.
interface SVGPatternElement : SVGElement,
                              SVGURIReference,
                              SVGTests,
                              SVGLangSpace,
                              SVGExternalResourcesRequired,
                              SVGStylable,
                              SVGFitToViewBox,
                              SVGUnitTypes {
  readonly attribute SVGAnimatedEnumeration patternUnits;
  readonly attribute SVGAnimatedEnumeration patternContentUnits;
  readonly attribute SVGAnimatedTransformList patternTransform;
  readonly attribute SVGAnimatedLength x;
  readonly attribute SVGAnimatedLength y;
  readonly attribute SVGAnimatedLength width;
  readonly attribute SVGAnimatedLength height;
};- Attributes:
- 
- patternUnits (readonly SVGAnimatedEnumeration)
- patternContentUnits (readonly SVGAnimatedEnumeration)
- patternTransform (readonly SVGAnimatedTransformList)
- x (readonly SVGAnimatedLength)
- 
 Corresponds to attribute  ‘x’-  on the given  ‘pattern’- 
 element.
 
- y (readonly SVGAnimatedLength)
- 
 Corresponds to attribute  ‘y’-  on the given  ‘pattern’- 
 element.
 
- width (readonly SVGAnimatedLength)
- height (readonly SVGAnimatedLength)