cairo:mesh-pattern-set-corner-color-rgba (pattern index red green blue alpha)

pattern -- a cairo:pattern-t instance
corner -- an unsigned integer for the corner to set the color for
red -- a number for the red component of the color
green -- a number for the green component of the color
blue -- a number for the blue component of the color
alpha -- a number for the alpha component of the color

Sets the color of a corner of the current patch in a mesh pattern. The color is specified in the same way as for the cairo:set-source-rgba function.

Valid values for corner are from 0 to 3 and identify the corners as explained for the cairo:pattern-create-mesh function. If the pattern argument is not a mesh pattern then pattern will be put into an error status with a :pattern-type-mismatch value. If corner is not valid, pattern will be put into an error status with a :invalid-index value. If pattern has no current patch, pattern will be put into an error status with a :invalid-mesh-construction value. The arguments are coerced to double floats before being passed to the foreign C function.