9 Basic Shapes


Contents


 

9.1 Introduction

SVG contains the following set of basic shape elements:

Mathematically, these shape elements are equivalent to a 'path' element that would construct the same shape. The basic shapes may be stroked, filled and used as clip paths. All of the properties available for 'path' elements also apply to the basic shapes.

9.2 The 'rect' element

The 'rect' element defines a rectangle which is axis-aligned with the current user coordinate system. Rounded rectangles can be achieved by setting appropriate values for attributes rx and ry.

<!ENTITY % rectExt "" >
<!ELEMENT rect (%descTitle;,(animate|set|animateMotion|animateColor|animateTransform
                %geExt;%rectExt;)*) >
<!ATTLIST rect
  id ID #IMPLIED
  xml:lang NMTOKEN #IMPLIED
  xml:space (default|preserve) #IMPLIED
  class NMTOKENS #IMPLIED
  style CDATA #IMPLIED
  transform CDATA #IMPLIED
  %graphicsElementEvents;
  system-required NMTOKEN #IMPLIED
  system-language CDATA #IMPLIED
  x CDATA #IMPLIED
  y CDATA #IMPLIED
  width CDATA #REQUIRED
  height CDATA #REQUIRED
  rx CDATA #IMPLIED
  ry CDATA #IMPLIED >

Attribute definitions:

x = "<coordinate>"
The X-axis coordinate of the side of the rectangle which has the smaller X-axis coordinate value in the current user coordinate system.
The default value is "0".
Animatable: yes.
y = "<coordinate>"
The Y-axis coordinate of the side of the rectangle which has the smaller Y-axis coordinate value in the current user coordinate system.
The default value is "0".
Animatable: yes.
width = "<length>"
The width of the rectangle.
Animatable: yes.
height = "<length>"
The height of the rectangle.
Animatable: yes.
rx = "<length>"
For rounded rectangles, the x-axis radius of the ellipse used to round off the corners of the rectangle.
The default value is "0".
Animatable: yes.
ry = "<length>"
For rounded rectangles, the y-axis radius of the ellipse used to round off the corners of the rectangle.
The default value is "0".
Animatable: yes.
Attributes defined elsewhere:
id, xml:lang, xml:space, class, style, transform, %graphicsElementEvents;, system-required, system-language.

If a properly specified value is provided for rx but not for ry, then the user agent processes the 'rect' element with the effective value for ry as equal to rx. If a properly specified value is provided for ry but not for rx, then the user agent processes the 'rect' element with the effective value for rx as equal to ry. If neither rx nor ry has a properly specified value, then the user agent processes the 'rect' element as if no rounding had been specified, resulting in square corners. If rx is greater than half of the width of the rectangle, then the user agent processes the 'rect' element with the effective value for rx as half of the width of the rectangle. If ry is greater than half of the height of the rectangle, then the user agent processes the 'rect' element with the effective value for ry as half of the height of the rectangle. If rx or ry is negative, then the user agent processes the 'rect' element as if the given attribute had a value of zero.

Mathematically, a 'rect' element can be mapped to an equivalent 'path' element as follows.

Example rect01 below expresses all values in physical units (centimeters, in this case). The 'rect' element is filled with yellow and stroked with navy.

<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG December 1999//EN" 
  "http://www.w3.org/Graphics/SVG/SVG-19991203.dtd">
<svg width="12cm" height="4cm">
  <desc>Example rect01 - rectangle expressed in physical units</desc>

  <rect x="4cm" y="1cm" width="4cm" height="2cm"
        style="fill:yellow; stroke:navy; stroke-width:0.1cm" />
</svg>
Example rect01
Example rect01 - rectangle expressed in physical units

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

Example rect02 below specifies the coordinates of the two rounded rectangles in the user coordinate system established by the viewBox attribute on the 'svg' element and the transform attribute on the 'g' element. The rx specifies how to round the corners of the rectangles. Note that since no value has been specified for the ry attribute, it will be assigned the same value as the rx attribute.

<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG December 1999//EN" 
  "http://www.w3.org/Graphics/SVG/SVG-19991203.dtd">
<svg width="12cm" height="4cm" viewBox="0 0 1200 400">
  <desc>Example rect02 - rounded rectangles expressed in user coordinates</desc>

  <rect x="100" y="100" width="400" height="200" rx="50"
        style="fill:green;" />

  <g transform="translate(700 300); rotate(-30)">
    <rect x="0" y="0" width="400" height="200" rx="50"
          style="fill:none; stroke:purple; stroke-width:30" />
  </g>
</svg>
Example rect02
Example rect02 - rounded rectangles expressed in user coordinates

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

9.3 The 'circle' element

The 'circle' element defines a circle based on a center point and a radius.

<!ENTITY % circleExt "" >
<!ELEMENT circle (%descTitle;,(animate|set|animateMotion|animateColor|animateTransform
                %geExt;%circleExt;)*) >
<!ATTLIST circle
  id ID #IMPLIED
  xml:lang NMTOKEN #IMPLIED
  xml:space (default|preserve) #IMPLIED
  class NMTOKENS #IMPLIED
  style CDATA #IMPLIED
  transform CDATA #IMPLIED
  %graphicsElementEvents;
  system-required NMTOKEN #IMPLIED
  system-language CDATA #IMPLIED
  cx CDATA "0"
  cy CDATA "0"
  r CDATA #REQUIRED >

Attribute definitions:

cx = "<coordinate>"
The X-axis coordinate of the center of the circle.
The default value is "0".
Animatable: yes.
cy = "<coordinate>"
The Y-axis coordinate of the center of the circle.
The default value is "0".
Animatable: yes.
r = "<length>"
The radius of the circle.
Animatable: yes.

Attributes defined elsewhere:
id, xml:lang, xml:space, class, style, transform, %graphicsElementEvents;, system-required, system-language.

Mathematically, a 'circle' element can be mapped to an equivalent 'path' element as follows.

Example circle01 below expresses all values in physical units (centimeters, in this case). The 'circle' element is filled with red and stroked with blue.

<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG December 1999//EN" 
  "http://www.w3.org/Graphics/SVG/SVG-19991203.dtd">
<svg width="12cm" height="4cm">
  <desc>Example circle01 - circle expressed in physical units</desc>

  <circle cx="6cm" cy="2cm" r="1cm"
        style="fill:red; stroke:blue; stroke-width:0.1cm" />
</svg>
Example circle01
Example circle01 - circle expressed in physical units

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

9.4 The 'ellipse' element

The 'ellipse' element defines an ellipse which is axis-aligned with the current user coordinate system based on a center point and two radii.

<!ENTITY % ellipseExt "" >
<!ELEMENT ellipse (%descTitle;,(animate|set|animateMotion|animateColor|animateTransform
                %geExt;%ellipseExt;)*) >
<!ATTLIST ellipse
  id ID #IMPLIED
  xml:lang NMTOKEN #IMPLIED
  xml:space (default|preserve) #IMPLIED
  class NMTOKENS #IMPLIED
  style CDATA #IMPLIED
  transform CDATA #IMPLIED
  %graphicsElementEvents;
  system-required NMTOKEN #IMPLIED
  system-language CDATA #IMPLIED
  cx CDATA "0"
  cy CDATA "0"
  rx CDATA #REQUIRED
  ry CDATA #REQUIRED >

Attribute definitions:

cx = "<coordinate>"
The X-axis coordinate of the center of the ellipse.
The default value is "0".
Animatable: yes.
cy = "<coordinate>"
The Y-axis coordinate of the center of the ellipse.
The default value is "0".
Animatable: yes.
rx = "<length>"
The X-axis radius of the ellipse.
Animatable: yes.
ry = "<length>"
The Y-axis radius of the ellipse.
Animatable: yes.

Attributes defined elsewhere:
id, xml:lang, xml:space, class, style, transform, %graphicsElementEvents;, system-required, system-language.

Mathematically, an 'ellipse' element can be mapped to an equivalent 'path' element as follows.

Example ellipse01 below specifies the coordinates of the two ellipses in the user coordinate system established by the viewBox attribute on the 'svg' element and the transform attribute on the 'g' 'ellipse' elements. Both ellipses uses the default values of zero for the cx and cy attributes (the center of the ellipse). The second ellipse is rotated.

<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG December 1999//EN" 
  "http://www.w3.org/Graphics/SVG/SVG-19991203.dtd">
<svg width="12cm" height="4cm" viewBox="0 0 1200 400">
  <desc>Example ellipse01 - ellipses expressed in user coordinates</desc>

  <g transform="translate(300 200)">
    <ellipse rx="250" ry="100"
          style="fill:red" />
  </g>

  <ellipse transform="translate(900 200); rotate(30)" 
        rx="250" ry="100"
        style="fill:none; stroke:blue; stroke-width: 20" />

</svg>
Example ellipse01
Example ellipse01 - ellipses expressed in user coordinates

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

9.5 The 'line' element

The 'line' element defines a line segment that starts at one point and ends at another.

<!ENTITY % lineExt "" >
<!ELEMENT line (%descTitle;,(animate|set|animateMotion|animateColor|animateTransform
                %geExt;%lineExt;)*) >
<!ATTLIST line
  id ID #IMPLIED
  xml:lang NMTOKEN #IMPLIED
  xml:space (default|preserve) #IMPLIED
  class NMTOKENS #IMPLIED
  style CDATA #IMPLIED
  transform CDATA #IMPLIED
  %graphicsElementEvents;
  system-required NMTOKEN #IMPLIED
  system-language CDATA #IMPLIED
  x1 CDATA "0"
  y1 CDATA "0"
  x2 CDATA "0"
  y2 CDATA "0" >

Attribute definitions:

x1 = "<coordinate>"
The X-axis coordinate of the start of the line.
The default value is "0".
Animatable: yes.
y1 = "<coordinate>"
The Y-axis coordinate of the start of the line.
The default value is "0".
Animatable: yes.
x2 = "<coordinate>"
The X-axis coordinate of the end of the line.
The default value is "0".
Animatable: yes.
y2 = "<coordinate>"
The Y-axis coordinate of the end of the line.
The default value is "0".
Animatable: yes.

Attributes defined elsewhere:
id, xml:lang, xml:space, class, style, transform, %graphicsElementEvents;, system-required, system-language.

Mathematically, an 'line' element can be mapped to an equivalent 'path' element as follows.

Example line01 below specifies the coordinates of the five lines in the user coordinate system established by the viewBox attribute on the 'svg' element. The lines have different thicknesses.

<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG December 1999//EN" 
  "http://www.w3.org/Graphics/SVG/SVG-19991203.dtd">
<svg width="12cm" height="4cm" viewBox="0 0 1200 400">
  <desc>Example line01 - lines expressed in user coordinates</desc>

  <g style="fill:none; stroke:green">
    <line x1="100" y1="300" x2="300" y2="100"
            style="stroke-width:5" />
    <line x1="300" y1="300" x2="500" y2="100"
            style="stroke-width:10" />
    <line x1="500" y1="300" x2="700" y2="100"
            style="stroke-width:15" />
    <line x1="700" y1="300" x2="900" y2="100"
            style="stroke-width:20" />
    <line x1="900" y1="300" x2="1100" y2="100"
            style="stroke-width:25" />
  </g>
</svg>
Example line01
Example line01 - lines expressed in user coordinates

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

9.6 The 'polyline' element

The 'polyline' element defines a set of connected straight line segments. Typically, 'polyline' elements define open shapes.

<!ENTITY % polylineExt "" >
<!ELEMENT polyline (%descTitle;,(animate|set|animateMotion|animateColor|animateTransform
                %geExt;%polylineExt;)*) >
<!ATTLIST polyline
  id ID #IMPLIED
  xml:lang NMTOKEN #IMPLIED
  xml:space (default|preserve) #IMPLIED
  class NMTOKENS #IMPLIED
  style CDATA #IMPLIED
  transform CDATA #IMPLIED
  %graphicsElementEvents;
  system-required NMTOKEN #IMPLIED
  system-language CDATA #IMPLIED
  points CDATA #REQUIRED >

Attribute definitions:

points = "<list-of-points>"
The points that make up the polyline. All coordinate values are in the user coordinate system.
Animatable: yes.

Attributes defined elsewhere:
id, xml:lang, xml:space, class, style, transform, %graphicsElementEvents;, system-required, system-language.

If an odd number of points is provided, then the element is in error, with the same user agent behavior as occurs with an incorrectly specified 'path' element.

Mathematically, a 'polyline' element can be mapped to an equivalent 'path' element as follows.

Example polyline01 below specifies a polyline in the user coordinate system established by the viewBox attribute on the 'svg' element.

<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG December 1999//EN" 
  "http://www.w3.org/Graphics/SVG/SVG-19991203.dtd">
<svg width="12cm" height="4cm" viewBox="0 0 1200 400">
  <desc>Example polyline01 - increasingly larger bars</desc>

  <polyline style="fill:none; stroke:blue; stroke-width:10cm"
            points="50,375
                    150,375 150,325 250,325 250,375
                    350,375 350,250 450,250 450,375
                    550,375 550,175 650,175 650,375
                    750,375 750,100 850,100 850,375
                    950,375 950,25 1050,25 1050,375
                    1150,375" />
</svg>
Example polyline01
Example polyline01 - increasingly larger bars

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

9.7 The 'polygon' element

The 'polygon' element defines a closed shape consisting of a set of connected straight line segments.

<!ENTITY % polygonExt "" >
<!ELEMENT polygon (%descTitle;,(animate|set|animateMotion|animateColor|animateTransform
                %geExt;%polygonExt;)*) >
<!ATTLIST polygon
  id ID #IMPLIED
  xml:lang NMTOKEN #IMPLIED
  xml:space (default|preserve) #IMPLIED
  class NMTOKENS #IMPLIED
  style CDATA #IMPLIED
  transform CDATA #IMPLIED
  %graphicsElementEvents;
  system-required NMTOKEN #IMPLIED
  system-language CDATA #IMPLIED
  points CDATA #REQUIRED >

Attribute definitions:

points = "<list-of-points>"
The points that make up the polygon. All coordinate values are in the user coordinate system.
Animatable: yes.

Attributes defined elsewhere:
id, xml:lang, xml:space, class, style, transform, %graphicsElementEvents;, system-required, system-language.

If an odd number of points is provided, then the element is in error, with the same user agent behavior as occurs with an incorrectly specified 'path' element.

Mathematically, a 'polygon' element can be mapped to an equivalent 'path' element as follows.

Example polygon01 below specifies two polygons (a star and a hexagon) in the user coordinate system established by the viewBox attribute on the 'svg' element.

<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG December 1999//EN" 
  "http://www.w3.org/Graphics/SVG/SVG-19991203.dtd">
<svg width="12cm" height="4cm" viewBox="0 0 1200 400">
  <desc>Example polygon01 - star and hexagon</desc>

  <polygon style="fill:red; stroke:blue; stroke-width:10"
            points="350,75  379,161 469,161 397,215
                    423,301 350,250 277,301 303,215
                    231,161 321,161" />
  <polygon style="fill:lime; stroke:blue; stroke-width:10"
            points="850,75  958,137.5 958,262.5
                    850,325 742,262.6 742,137.5" />
</svg>
Example polygon01
Example polygon01 - star and hexagon

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

9.8 The grammar for points specifications in 'polyline' and 'polygon' elements

The following is the BNF for points specifications in 'polyline' and 'polygon' elements. The following notation is used:

list-of-points:
    wsp* coordinate-pairs?

coordinate-pairs:
    coordinate-pair
    | coordinate-pair comma-wsp coordinate-pairs

coordinate-pair:
    coordinate comma-wsp coordinate

coordinate:
    number-wsp

number-wsp:
    number wsp*

number:
    sign? integer-constant
    | sign? floating-point-constant

comma-wsp:
    comma? wsp*

comma:
    ","

integer-constant:
    digit-sequence

floating-point-constant:
    fractional-constant exponent?
    | digit-sequence exponent

fractional-constant:
    digit-sequence? "." digit-sequence
    | digit-sequence "."

exponent:
    ( "e" | "E" ) sign? digit-sequence

sign:
    "+" | "-"

digit-sequence:
    digit
    | digit digit-sequence

digit:
    "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"

wsp:
    (#x20 | #x9 | #xD | #xA)+

9.9 DOM interfaces


9.9.1 Interface SVGRectElement

The SVGRectElement interface corresponds to the 'rect' element.

interface SVGRectElement : SVGStyledAndTransformedElement {
  attribute SVGLength x;
  attribute SVGLength y;
  attribute SVGLength width;
  attribute SVGLength height;
  attribute SVGLength rx;
  attribute SVGLength ry;
};

9.9.2 Interface SVGCircleElement

The SVGCircleElement interface corresponds to the 'circle' element.

interface SVGCircleElement : SVGStyledAndTransformedElement {
  attribute SVGLength cx;
  attribute SVGLength cy;
  attribute SVGLength r;
};

9.9.3 Interface SVGEllipseElement

The SVGEllipseElement interface corresponds to the 'ellipse' element.

interface SVGEllipseElement : SVGStyledAndTransformedElement {
  attribute SVGLength cx;
  attribute SVGLength cy;
  attribute SVGLength rx;
  attribute SVGLength ry;
};

9.9.4 Interface SVGLineElement

The SVGLineElement interface corresponds to the 'line' element.

interface SVGLineElement : SVGStyledAndTransformedElement {
  attribute SVGLength x1;
  attribute SVGLength y1;
  attribute SVGLength x2;
  attribute SVGLength y2;
};

9.9.5 Interface SVGPointList

The SVGPointList interface is a base interface used by SVGPolylineElement and SVGPolygonElement.

interface SVGPointList  {
  SVGPoint     createSVGPoint();     // Returns unattached point (0,0)

  readonly attribute  unsigned long number_of_lengths;
  SVGPoint      getSVGPoint(in unsigned long index);

  // Replace all existing entries with a single entry.
  void           initialize(in SVGPoint newSVGPoint)
                                           raises(DOMException);
  void           clear(); // Clear all entries, giving an empty list
  SVGPoint      insertBefore(in SVGPoint newSVGPoint,
                                           in unsigned long index)
                                           raises(DOMException);
  SVGPoint      replace(in SVGPoint newSVGPoint,
                                      in unsigned long index)
                                      raises(DOMException);
  SVGPoint      remove(in unsigned long index)
                                     raises(DOMException);
  SVGPoint      append(in SVGPoint newSVGLength)
                                     raises(DOMException);
};

9.9.6 Interface SVGPolylineElement

The SVGPolylineElement interface corresponds to the 'polyline' element.

interface SVGPolylineElement : SVGStyledAndTransformedElement {
  attribute SVGPointList points;
};

9.9.7 Interface SVGPolygonElement

The SVGPolygonElement interface corresponds to the 'polygon' element.

interface SVGPolygonElement : SVGStyledAndTransformedElement {
  attribute SVGPointList points;
};