Beside SVG's styling properties, SVG also defines geometry properties. Geometry properties describe the position and dimension of the graphics elements ‘circle’, ‘ellipse’, ‘rect’, ‘image’, ‘foreignObject’ and the ‘svg’ element.
The cx, cy, x and y properties accept negative values. The r, rx, ry, width and height properties do not: a negative <length-percentage> is invalid. When an invalid negative value is specified for one of these properties, whether through a presentation attribute or a CSS declaration, it must be treated as if the property's initial value had been specified: auto for rx, ry, width and height, and 0 for r. A negative value therefore never puts the element into an error state; the @@ unknown term "used value" is determined by the property's normal resolution rules. The following table summarizes this handling.
| Property | Value | Initial | Negative allowed? | Negative computes to | Used value of a negative value |
|---|---|---|---|---|---|
| cx, cy | <length-percentage> | 0 | yes | the specified value (kept as-is) | the negative value (translates the shape) |
| r | <length-percentage> | 0 | no | 0 | 0; a ‘circle’ with r = 0 is not rendered |
| rx, ry | <length-percentage> | auto | auto | no | auto | resolved as auto: equal to the used value of the other radius, or 0 if the other radius is also auto or negative. An ‘ellipse’ with a resolved radius of 0 is not rendered. |
| width, height | <length-percentage> | auto | auto | no | auto | resolved as auto per the sizing table: 100% for the outermost ‘svg’, the intrinsic size for ‘image’, and 0 for all other elements. |
| Name: | cx |
|---|---|
| Value: | <length-percentage> |
| Initial: | 0 |
| Applies to: | ‘circle’ and ‘ellipse’ elements |
| Inherited: | no |
| Percentages: | refer to the width of the current SVG viewport (see Units) |
| Media: | visual |
| Computed value: | an absolute length or percentage |
| Animation type: | by computed value |
The cx property describes the horizontal center coordinate of the position of the element.
Negative values are permitted for cx; a negative value translates the center of the shape and does not disable rendering, unlike r, rx and ry (see the handling of negative values).
| Name: | cy |
|---|---|
| Value: | <length-percentage> |
| Initial: | 0 |
| Applies to: | ‘circle’ and ‘ellipse’ elements |
| Inherited: | no |
| Percentages: | refer to the height of the current SVG viewport (see Units) |
| Media: | visual |
| Computed value: | an absolute length or percentage |
| Animation type: | by computed value |
The cy property describes the vertical center coordinate of the position of the element.
Negative values are permitted for cy; a negative value translates the center of the shape and does not disable rendering (see the handling of negative values).
| Name: | r |
|---|---|
| Value: | <length-percentage> |
| Initial: | 0 |
| Applies to: | ‘circle’ element |
| Inherited: | no |
| Percentages: | refer to the normalized diagonal of the current SVG viewport (see Units) |
| Media: | visual |
| Computed value: | an absolute length or percentage |
| Animation type: | by computed value |
The r property describes the radius of the ‘circle’ element.
A negative value for r is invalid; it is treated as if 0 had been specified (see the handling of negative values), so the ‘circle’ is not rendered.
| Name: | rx |
|---|---|
| Value: | <length-percentage> | auto |
| Initial: | auto |
| Applies to: | ‘ellipse’, ‘rect’ elements |
| Inherited: | no |
| Percentages: | refer to the width of the current SVG viewport (see Units) |
| Media: | visual |
| Computed value: | an absolute length or percentage |
| Animation type: | by computed value |
The rx property describes the horizontal radius of the ‘ellipse’ element and the curve radius of the ‘rect’ element. When the computed value of ‘rx’ is auto, the used radius is equal to the absolute length used for ry, creating a circular arc. If both ‘rx’ and ‘ry’ have a computed value of auto, the used value is 0.
Regardless of how the value is calculated, the used value of ‘rx’ for a ‘rect’ is never more than 50% of the used value of width for the same shape.
The auto behavior is new in SVG 2 for ‘ellipse’, matching the behavior for ‘rect’ elements when rx was not specified.
A negative value for rx is invalid; it is treated as if auto had been specified (see the handling of negative values). It therefore resolves like auto: to the used value of ry, or to 0 if ry is also auto or negative.
| Name: | ry |
|---|---|
| Value: | <length-percentage> | auto |
| Initial: | auto |
| Applies to: | ‘ellipse’, ‘rect’ |
| Inherited: | no |
| Percentages: | refer to the height of the current SVG viewport (see Units) |
| Media: | visual |
| Computed value: | an absolute length or percentage |
| Animatable type: | by computed value |
The ry property describes the vertical radius of the ‘ellipse’ element and the vertical curve radius of the ‘rect’ element. When the computed value of ‘ry’ is auto, the used radius is equal to the absolute length used for rx, creating a circular arc. If both ‘rx’ and ‘ry’ have a computed value of auto, the used value is 0.
Regardless of how the value is calculated, the used value of ‘ry’ for a ‘rect’ is never more than 50% of the used value of height for the same shape.
The auto behavior is new in SVG 2 for ‘ellipse’, matching the behavior for ‘rect’ elements when ry was not specified.
A negative value for ry is invalid; it is treated as if auto had been specified (see the handling of negative values). It therefore resolves like auto: to the used value of rx, or to 0 if rx is also auto or negative.
| Name: | x |
|---|---|
| Value: | <length-percentage> |
| Initial: | 0 |
| Applies to: | ‘svg’, ‘rect’, ‘image’, ‘foreignObject’ elements |
| Inherited: | no |
| Percentages: | refer to the width of the current SVG viewport (see Units) |
| Media: | visual |
| Computed value: | an absolute length or percentage |
| Animation type: | by computed value |
The x property describes the horizontal coordinate of the position of the element.
| Name: | y |
|---|---|
| Value: | <length-percentage> |
| Initial: | 0 |
| Applies to: | ‘svg’, ‘rect’, ‘image’, ‘foreignObject’ elements |
| Inherited: | no |
| Percentages: | refer to the height of the current SVG viewport (see Units) |
| Media: | visual |
| Computed value: | an absolute length or percentage |
| Animation type: | by computed value |
The y property describes the vertical coordinate of the position of the element.
See the CSS 2.1 specification for the definitions of width and height.
The CSS width and height properties are used for sizing some SVG elements. Specifically, they are used to size ‘rect’, ‘image’, ‘foreignObject’, and the outermost ‘svg’ element. All of these elements have ‘width’ and ‘height’ presentation attributes. The properties are also used for laying out embedded elements from the HTML namespace.
Other SVG elements, such as nested ‘svg’ elements, the ‘use’ element, and the ‘symbol’ element, also have ‘width’ and ‘height’ attributes, but do not accept them as CSS properties. On these elements, the width and height must be specified as XML attributes; CSS properties with the same names are ignored.
The used value of width may be constrained by the value of the max-width and min-width properties. The used value of height may be constrained by the value of the max-height and min-height properties.
The following table summarizes how the value auto for width and height is treated on different elements:
| Element | Value | Treated as |
|---|---|---|
| ‘svg’ | auto | 100% |
| ‘image’ | auto | Calculated from the referenced image's intrinsic dimensions and aspect ratio, according to the CSS Default Sizing Algorithm |
| All other elements | auto | 0 |
New in SVG 2. Images embedded in SVG can now be auto-sized to the intrinsic size, or scaled to a fixed height or width according to the intrinsic aspect ratio. This matches the behavior of embedded images in HTML.
This means that, for example, a ‘foreignObject’ object element will not shrink-wrap to its contents if auto is used.