Once a routine has been provided, the "null" routine AST_NULL can be supplied in a subsequent call to astGrfSet to reset the routine to the corresponding routine in the graphics interface selected at link-time. AST_NULL is defined in the AST_PAR include file.
The first argument (GRFCON) for each function is an AST KeyMap pointer that can be used by the called function to establish the context in which it is being called. The contents of the KeyMap are determined by the calling application, which should obtain a pointer to the KeyMap using the AST_GETGRFCONTEXT routine, and then store any necessary information in the KeyMap using the methods of the KeyMap class. Note, the functions listed below should never annul or delete the supplied KeyMap pointer.
INTEGER FUNCTION ATTR( GRFCON, ATT, VAL, OLDVAL, PRIM )
INTEGER FUNCTION BBUF( GRFCON )
INTEGER FUNCTION CAP( GRFCON, CAP, VALUE )
GRF__MJUST: This function should return a non-zero value if the "Text" and "TxExt" functions recognise "M" as a character in the justification string. If the first character of a justification string is "M", then the text should be justified with the given reference point at the bottom of the bounding box. This is different to "B" justification, which requests that the reference point be put on the baseline of the text, since some characters hang down below the baseline. If the "Text" or "TxExt" function cannot differentiate between "M" and "B", then this function should return zero, in which case "M" justification will never be requested by Plot. The supplied VALUE argument should be ignored.
GRF__ESC: This function should return a non-zero value if the "Text" and "TxExt" functions can recognise and interpret graphics escape sequences within the supplied string (see attribute Escape). Zero should be returned if escape sequences cannot be interpreted (in which case the Plot class will interpret them itself if needed). The supplied VALUE argument should be ignored only if escape sequences cannot be interpreted by "Text" and "TxExt". Otherwise, VALUE indicates whether "Text" and "TxExt" should interpret escape sequences in subsequent calls. If VALUE is non-zero then escape sequences should be interpreted by "Text" and "TxExt". Otherwise, they should be drawn as literal text.
INTEGER FUNCTION EBUF( GRFCON )
INTEGER FUNCTION FLUSH( GRFCON )
INTEGER FUNCTION LINE( GRFCON, N, X, Y )
INTEGER FUNCTION MARK( GRFCON, N, X, Y, TYPE )
INTEGER FUNCTION QCH( GRFCON, CHV, CHH )
INTEGER FUNCTION SCALES( GRFCON, ALPHA, BETA )
INTEGER FUNCTION TEXT( GRFCON, TEXT, X, Y, JUST, UPX, UPY )
INTEGER FUNCTION TXEXT( GRFCON, TEXT, X, Y, JUST, UPX, UPY, XB, YB )
AST A Library for Handling World Coordinate Systems in Astronomy