Here are the classes, structs, unions and interfaces with brief descriptions:

Nplplot
C_N1
C_N10
C_N11
C_N2
C_N3
C_N4
C_N5
C_N6
C_N7
C_N8
C_N9
Cinterface_plparseopts
Cpl_setcontlabelformat
Cpladv
Cplbop
CPLcGrid
CPLcGrid2
Cplclear
Cplcol0
Cplcpstrm
Cplend
Cplend1
Cpleop
Cplfamadv
Cplflush
Cplfont
Cplfontld
Cplgcol0
Cplgcolbg
Cplgcompression
Cplgdev
Cplgdrawmode
Cplget_arguments
Cplgfam
Cplgfci
Cplgfnam
Cplgfont
Cplglevel
Cplgra
Cplgstrm
Cplgver
Cplgxax
Cplgyax
Cplgzax
Cplinit
Cpllab
Cpllsty
Cplmkstrm
Cplparseopts
Cplpat
Cplprec
Cplpsty
Cplreplot
Cplscmap0
Cplscmap0n
Cplscmap1
Cplscmap1n
Cplscol0
Cplscolbg
Cplscolor
Cplscompression
Cplsdev
Cplsdrawmode
Cplseed
Cplsesc
Cplsetopt
Cplsfam
Cplsfci
Cplsfnam
Cplsfont
Cplsmem
Cplsmema
Cplsori
Cplspal0
Cplspal1
Cplspause
Cplsstrm
Cplssub
Cplstar
Cplstart
Cplstripd
Cplstyl
Cplsvect
Cplsxax
Cplsyax
Cplszax
Cpltext
Cpltimefmt
Cplvsta
Cplxormod
Mplplot_double
Cinterface_plslabelfunc
Cinterface_plstransform
Cplrandd
Cplslabelfunc
Cplstransform
Mplplot_graphics
Cplgraphicsin
Cplgetcursor
Mplplot_private_utilities
Cinterface_strlen
Mplplot_types
Cplfgrid
Cplcgrid
Nplplotc
C_SwigNonDynamicMeta
CPLGraphicsIn
NPltk_init
C_SwigNonDynamicMeta
C__dlhandle
C_plm_format
C_plm_version
C_pyqt4ClassPluginDef
C_pyqt4QtSignal
C_pyqt5ClassPluginDef
C_pyqt5QtSignal
C_sipAPIDef
C_sipBufferDef
C_sipBufferInfoDef
C_sipCFunctionDef
C_sipCharInstanceDef
C_sipClassTypeDef
C_sipContainerDef
C_sipDateDef
C_sipDelayedDtor
C_sipDoubleInstanceDef
C_sipEncodedTypeDef
C_sipEnumMemberDef
C_sipEnumTypeDef
C_sipEnumTypeObject
C_sipExportedModuleDef
C_sipExternalTypeDef
C_sipImportedExceptionDef
C_sipImportedModuleDef
C_sipImportedTypeDef
C_sipImportedVirtErrorHandlerDef
C_sipInitExtenderDef
C_sipInstancesDef
C_sipIntInstanceDef
C_sipIntTypeClassMap
C_sipLicenseDef
C_sipLongInstanceDef
C_sipLongLongInstanceDef
C_sipMappedTypeDef
C_sipMethodDef
C_sipPyMethod
C_sipPySlotDef
C_sipPySlotExtenderDef
C_sipQtAPI
C_sipSimpleWrapper
C_sipSlot
C_sipStringInstanceDef
C_sipStringTypeClassMap
C_sipSubClassConvertorDef
C_sipTimeDef
C_sipTypeDef
C_sipTypedefDef
C_sipTypeInstanceDef
C_sipUnsignedLongInstanceDef
C_sipUnsignedLongLongInstanceDef
C_sipVariableDef
C_sipVersionedFunctionDef
C_sipVirtErrorHandlerDef
C_sipVoidPtrInstanceDef
C_sipWrapper
C_sipWrapperType
C_state
Carc_struct
CcdImageStruct
CcdPointStruct
Ccircle
CClipper
CCmdInfo
CCommand
Ccont_level
Ccont_line
CContourable_Data
CCoord_2d
CCoord_Xformer
Ccsa
Ccxx_pltr2
Cdelaunay
Cdev_entry
CDIR
Cdirent
CDrawingObjectsChanger
CDrvOpt
CDrvOptCmd
CEscText
CFCI_to_FontName_Table
CFont
CFontGrabber
Chashtable
CHershey_to_Unicode_table
Cht_bucket
CIMG_DT
Cistack
Cline
Clpi
Clweights
CMasterHandler
CMemoryMapHeader
CMJDtimeStruct
Cnn_weights
Cnnai
Cnnhpi
Cnnpi
Coctave_swig_packed
Coctave_swig_ref
Coctave_swig_type
Ccpp_ptr
Coctave_value_ref
COriginChanger
Cpattern
CPDFstrm
Cplbuffer
CPLBufferingCB
CPLCairo
CPLcGrid
CPLcGrid2
CPLColor
CPLControlPt
CPLDev
CPlDevice
CPLDispatchTable
CPLDisplay
Cplf2ops_t
CPLfGrid
CPLfGrid2
CPlFrame
CPLGraphicsIn
CPLiodev
CPLLabelDefaults
CPLmDev
CPLMemoryMap
CPLmIndex
CPLNamedMutex
CPLNamedMutexLocker
CPLOptionInfo
CPLOptionTable
CPlPlotter
CPLRDev
CPLS
CPLStream
Cplstream
CPLStrip
CPLWindow
Cpoint
CPSDev
Cpt
CQGlobalSpace
CQSASConfigStruct
Cqt_meta_stringdata_MasterHandler_t
Cqt_meta_stringdata_QtExtWidget_t
Cqt_meta_stringdata_QtPLWidget_t
CQtPLDriver
CRand
CScaler
CsipQtExtWidget
CsipQtPLDriver
CsipQtPLWidget
Csquare
CSVG
Cswig_cast_info
Cswig_const_info
Cswig_globalvar
Cswig_lua_attribute
Cswig_lua_class
Cswig_lua_const_info
Cswig_lua_namespace
Cswig_lua_rawdata
Cswig_lua_userdata
Cswig_lua_var_info
Cswig_module_info
Cswig_octave_class
Cswig_octave_member
Cswig_type_info
Cswig_varlinkobject
CSwigPyClientData
CSwigPyObject
CSwigPyPacked
CTAI_UTC
CtclMatrix
CtclMatrixXtnsnDescr
CTextObjectsChanger
CTextObjectsSaver
CTextSizeInfo
CTkDev
CTkwDev
CTkwDisplay
Ctriangle
Ctriangle_neighbours
CUnicode_to_Type1_table
CwxPLDevice
CwxPLplotstream	WxPLplotstream is inherited from plstream, which is the C++ interface
CwxPLplotwindow
CXwDev
CXwDisplay