Sets the color of a corner of the current patch in a mesh pattern.
The color is specified in the same way as in cairo_set_source_rgba().
Valid values for corner_num are from 0 to 3 and identify the
corners as explained in Pattern.createMesh.
Note: If pattern is not a mesh pattern then pattern will be put
into an error status with a status of
CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If corner_num is not valid,
pattern will be put into an error status with a status of
CAIRO_STATUS_INVALID_INDEX. If pattern has no current patch,
pattern will be put into an error status with a status of
CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
Since 1.12
Sets the color of a corner of the current patch in a mesh pattern. The color is specified in the same way as in cairo_set_source_rgba(). Valid values for corner_num are from 0 to 3 and identify the corners as explained in Pattern.createMesh. Note: If pattern is not a mesh pattern then pattern will be put into an error status with a status of CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If corner_num is not valid, pattern will be put into an error status with a status of CAIRO_STATUS_INVALID_INDEX. If pattern has no current patch, pattern will be put into an error status with a status of CAIRO_STATUS_INVALID_MESH_CONSTRUCTION. Since 1.12