Table 81 – Additional Entries Specific to a Type 3 Shading Dictionary

Key

Type

Value

Coords

array

(Required) An array of six numbers [ x 0 y 0 r 0 x 1 y 1 r 1 ] specifying the centres and radii of the starting and ending circles, expressed in the shading’s target coordinate space. The radii r 0 and r 1 shall both be greater than or equal to 0. If one radius is 0, the corresponding circle shall be treated as a point; if both are 0, nothing shall be painted.

Domain

array

(Optional) An array of two numbers [ t 0 t 1 ] specifying the limiting values of a parametric variable t. The variable is considered to vary linearly between these two values as the colour gradient varies between the starting and ending circles. The variable t becomes the input argument to the colour function(s). Default value: [ 0.0 1.0 ].

Function

function

(Required) A 1-in, n-out function or an array of n 1-in, 1-out functions (where n is the number of colour components in the shading dictionary’s colour space). The function(s) shall be called with values of the parametric variable t in the domain defined by the shading dictionary’s Domain entry. Each function’s domain shall be a superset of that of the shading dictionary. If the value returned by the function for a given colour component is out of range, it shall be adjusted to the nearest valid value.

Extend

array

(Optional) An array of two boolean values specifying whether to extend the shading beyond the starting and ending circles, respectively. Default value: [ false false ].