SVG Tiny 1.2 - 20050413

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.

Schema: rect
  <define name='rect'>
    <element name='rect'>
      <ref name='rect.AT'/>
      <zeroOrMore><ref name='shapeCommon.CM'/></zeroOrMore>
    </element>
  </define>

  <define name='rect.AT' combine='interleave'>
    <ref name='svg.ShapeCommon.attr'/>
    <ref name='svg.XYWH.attr'/>
    <ref name='svg.RxRyCommon.attr'/>
  </define>
    

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.

If the attribute is not specified, the effect is as if a value of "0" were specified.

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.

If the attribute is not specified, the effect is as if a value of "0" were specified.

Animatable: yes.
width = "<length>"
The width of the rectangle.

A negative value is an error (see Error processing). A value of zero disables rendering of the element.

Animatable: yes.
height = "<length>"
The height of the rectangle.

A negative value is an error (see Error processing). A value of zero disables rendering of the element.

Animatable: yes.
rx = "<length>"
For rounded rectangles, the x-axis radius of the ellipse used to round off the corners of the rectangle.

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

See the notes below about what happens if the attribute is not specified.

Animatable: yes.
ry = "<length>"
For rounded rectangles, the y-axis radius of the ellipse used to round off the corners of the rectangle.

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

See the notes below about what happens if the attribute is not specified.

Animatable: yes.

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.

Mathematically, a 'rect' element can be mapped to an equivalent 'path' element as follows: (Note: all coordinate and length values are first converted into user space coordinates according to Units.)

Example 09_01 shows a rectangle with sharp corners. The 'rect' element is filled with yellow and stroked with navy.

Example: 09_01.svg
<?xml version="1.0" standalone="no"?>
<svg width="12cm" height="4cm" viewBox="0 0 1200 400"
     xmlns="http://www.w3.org/2000/svg" version="1.2" baseProfile="tiny">
  <desc>Example rect01 - rectangle with sharp corners</desc>
  <!-- Show outline of canvas using 'rect' element -->
  <rect x="1" y="1" width="1198" height="398"
        fill="none" stroke="blue" stroke-width="2"/>
  <rect x="400" y="100" width="400" height="200"
        fill="yellow" stroke="navy" stroke-width="10"  />
</svg>
    
Rendering of 09_01.svg

Example 09_02 shows two rounded rectangles. 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.

Example: 09_02.svg
<?xml version="1.0" standalone="no"?>
<svg width="12cm" height="4cm" viewBox="0 0 1200 400"
     xmlns="http://www.w3.org/2000/svg" version="1.2" baseProfile="tiny">
  <desc>Example rect02 - rounded rectangles</desc>
  <!-- Show outline of canvas using 'rect' element -->
  <rect x="1" y="1" width="1198" height="398"
        fill="none" stroke="blue" stroke-width="2"/>
  <rect x="100" y="100" width="400" height="200" rx="50"
        fill="green" />
  <g transform="translate(700 210) rotate(-30)">
    <rect x="0" y="0" width="400" height="200" rx="50"
          fill="none" stroke="purple" stroke-width="30" />
  </g>
</svg>
    
Rendering of 09_02.svg

9.3 The 'circle' element

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

Schema: circle
  <define name='circle'>
    <element name='circle'>
      <ref name='circle.AT'/>
      <zeroOrMore><ref name='shapeCommon.CM'/></zeroOrMore>
    </element>
  </define>

  <define name='circle.AT' combine='interleave'>
    <ref name='svg.ShapeCommon.attr'/>
    <ref name='svg.CxCy.attr'/>
    <ref name='svg.R.attr'/>
  </define>
    

Attribute definitions:

cx = "<coordinate>"
The x-axis coordinate of the center of the circle.

If the attribute is not specified, the effect is as if a value of "0" were specified.

Animatable: yes.
cy = "<coordinate>"
The y-axis coordinate of the center of the circle.

If the attribute is not specified, the effect is as if a value of "0" were specified.

Animatable: yes.
r = "<length>"
The radius of the circle.

A negative value is an error (see Error processing). A value of zero disables rendering of the element.

Animatable: yes.


The arc of a 'circle' element begins at the "3 o'clock" point on the radius and progresses towards the "9 o'clock" point. The starting point and direction of the arc are affected by the user space transform in the same manner as the geometry of the element.

Example circle01 consists of a 'circle' element that is filled with red and stroked with blue.

Example: 09_03.svg
<?xml version="1.0" standalone="no"?>
<svg width="12cm" height="4cm" viewBox="0 0 1200 400"
     xmlns="http://www.w3.org/2000/svg" version="1.2" baseProfile="tiny">
  <desc>Example circle01 - circle filled with red and stroked with blue</desc>
  <!-- Show outline of canvas using 'rect' element -->
  <rect x="1" y="1" width="1198" height="398"
        fill="none" stroke="blue" stroke-width="2"/>
  <circle cx="600" cy="200" r="100"
        fill="red" stroke="blue" stroke-width="10"  />
</svg>
    
Rendering of 09_03.svg

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.

Schema: ellipse
  <define name='ellipse'>
    <element name='ellipse'>
      <ref name='ellipse.AT'/>
      <zeroOrMore><ref name='shapeCommon.CM'/></zeroOrMore>
    </element>
  </define>

  <define name='ellipse.AT' combine='interleave'>
    <ref name='svg.ShapeCommon.attr'/>
    <ref name='svg.RxRyCommon.attr'/>
    <ref name='svg.CxCy.attr'/>
  </define>
    

Attribute definitions:

cx = "<coordinate>"
The x-axis coordinate of the center of the ellipse.

If the attribute is not specified, the effect is as if a value of "0" were specified.

Animatable: yes.
cy = "<coordinate>"
The y-axis coordinate of the center of the ellipse.

If the attribute is not specified, the effect is as if a value of "0" were specified.

Animatable: yes.
rx = "<length>"
The x-axis radius of the ellipse.

A negative value is an error (see Error processing). A value of zero disables rendering of the element.

Animatable: yes.
ry = "<length>"
The y-axis radius of the ellipse.

A negative value is an error (see Error processing). A value of zero disables rendering of the element.

Animatable: yes.


The arc of an 'ellipse' element begins at the "3 o'clock" point on the radius and progresses towards the "9 o'clock" point. The starting point and direction of the arc are affected by the user space transform in the same manner as the geometry of the element.

Example 09_04 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' and 'ellipse' elements. Both ellipses use the default values of zero for the cx and cy attributes (the center of the ellipse). The second ellipse is rotated.

Example: 09_04.svg
<?xml version="1.0" standalone="no"?>
<svg width="12cm" height="4cm" viewBox="0 0 1200 400"
     xmlns="http://www.w3.org/2000/svg" version="1.2" baseProfile="tiny">
  <desc>Example ellipse01 - examples of ellipses</desc>
  <!-- Show outline of canvas using 'rect' element -->
  <rect x="1" y="1" width="1198" height="398"
        fill="none" stroke="blue" stroke-width="2" />
  <g transform="translate(300 200)">
    <ellipse rx="250" ry="100"
          fill="red"  />
  </g>
  <ellipse transform="translate(900 200) rotate(-30)" 
        rx="250" ry="100"
        fill="none" stroke="blue" stroke-width="20"  />
</svg>
    
Rendering of 09_04.svg

9.5 The 'line' element

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

Schema: line
  <define name='line'>
    <element name='line'>
      <ref name='line.AT'/>
      <zeroOrMore><ref name='shapeCommon.CM'/></zeroOrMore>
    </element>
  </define>

  <define name='line.AT' combine='interleave'>
    <ref name='svg.ShapeCommon.attr'/>
    <ref name='svg.X12Y12.attr'/>
  </define>

    

Attribute definitions:

x1 = "<coordinate>"
The x-axis coordinate of the start of the line.

If the attribute is not specified, the effect is as if a value of "0" were specified.

Animatable: yes.
y1 = "<coordinate>"
The y-axis coordinate of the start of the line.

If the attribute is not specified, the effect is as if a value of "0" were specified.

Animatable: yes.
x2 = "<coordinate>"
The x-axis coordinate of the end of the line.

If the attribute is not specified, the effect is as if a value of "0" were specified.

Animatable: yes.
y2 = "<coordinate>"
The y-axis coordinate of the end of the line.

If the attribute is not specified, the effect is as if a value of "0" were specified.

Animatable: yes.

Mathematically, a 'line' element can be mapped to an equivalent 'path' element as follows: (Note: all coordinate and length values are first converted into user space coordinates according to Units.)

Because 'line' elements are single lines and thus are geometrically one-dimensional, they have no interior; thus, 'line' elements are never filled (see the 'fill' property).

Example 09_05 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.

Example: 09_05.svg
<?xml version="1.0" standalone="no"?>
<svg width="12cm" height="4cm" viewBox="0 0 1200 400"
     xmlns="http://www.w3.org/2000/svg" version="1.2" baseProfile="tiny">
  <desc>Example line01 - lines expressed in user coordinates</desc>
  <!-- Show outline of canvas using 'rect' element -->
  <rect x="1" y="1" width="1198" height="398"
        fill="none" stroke="blue" stroke-width="2" />
  <g stroke="green" >
    <line x1="100" y1="300" x2="300" y2="100"
            stroke-width="5"  />
    <line x1="300" y1="300" x2="500" y2="100"
            stroke-width="10"  />
    <line x1="500" y1="300" x2="700" y2="100"
            stroke-width="15"  />
    <line x1="700" y1="300" x2="900" y2="100"
            stroke-width="20"  />
    <line x1="900" y1="300" x2="1100" y2="100"
            stroke-width="25"  />
  </g>
</svg>
    
Rendering of 09_05.svg

9.6 The 'polyline' element

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

Schema: polyline
  <define name='polyline'>
    <element name='polyline'>
      <ref name='polyCommon.AT'/>
      <zeroOrMore><ref name='shapeCommon.CM'/></zeroOrMore>
    </element>
  </define>

  <define name='polyCommon.AT' combine='interleave'>
    <ref name='svg.ShapeCommon.attr'/>
    <attribute name='points' svg:animatable='true' svg:inheritable='false'>
      <ref name='Points.datatype'/>
    </attribute>
  </define>
    

Attribute definitions:

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

Animatable: yes.


If an odd number of coordinates 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 09_06 below specifies a polyline in the user coordinate system established by the viewBox attribute on the 'svg' element.

Example: 09_06.svg
<?xml version="1.0" standalone="no"?>
<svg width="12cm" height="4cm" viewBox="0 0 1200 400"
     xmlns="http://www.w3.org/2000/svg" version="1.2" baseProfile="tiny">
  <desc>Example polyline01 - increasingly larger bars</desc>
  <!-- Show outline of canvas using 'rect' element -->
  <rect x="1" y="1" width="1198" height="398"
        fill="none" stroke="blue" stroke-width="2" />
  <polyline fill="none" stroke="blue" stroke-width="10" 
            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>    
Rendering of 09_06.svg

9.7 The 'polygon' element

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

Schema: polygon
  <define name='polygon'>
    <element name='polygon'>
      <ref name='polyCommon.AT'/>
      <zeroOrMore><ref name='shapeCommon.CM'/></zeroOrMore>
    </element>
  </define>
    

Attribute definitions:

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

Animatable: yes.


If an odd number of coordinates 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 09_07 below specifies two polygons (a star and a hexagon) in the user coordinate system established by the viewBox attribute on the 'svg' element.

Example: 09_07.svg
<?xml version="1.0" standalone="no"?>
<svg width="12cm" height="4cm" viewBox="0 0 1200 400"
     xmlns="http://www.w3.org/2000/svg" version="1.2" baseProfile="tiny">
  <desc>Example polygon01 - star and hexagon</desc>
  <!-- Show outline of canvas using 'rect' element -->
  <rect x="1" y="1" width="1198" height="398"
        fill="none" stroke="blue" stroke-width="2" />
  <polygon 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 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>
    
Rendering of 09_07.svg

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

The following is the Backus-Naur Form (BNF) for points specifications in 'polyline' and 'polygon' elements. The following notation is used:

list-of-points:
    wsp* coordinate-pairs? wsp*
coordinate-pairs:
    coordinate-pair
    | coordinate-pair comma-wsp coordinate-pairs
coordinate-pair:
    coordinate comma-wsp coordinate
coordinate:
    number
number:
    sign? integer-constant
    | sign? floating-point-constant
comma-wsp:
    (wsp+ 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)+

9.8 Shape Module

The Shape Module contains the following elements: