Set an internal control point of the current patch.
Valid values for point_num are from 0 to 3 and identify the
control points as explained in cairo_pattern_create_mesh().
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 point_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
Set an internal control point of the current patch. Valid values for point_num are from 0 to 3 and identify the control points as explained in cairo_pattern_create_mesh(). 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 point_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