11. XAS graphics

• The typical commands which the user accesses are clients
• These clients are linked with high level graphics routines (the xasgraph library)
• These routines in turn use low level graphics routines (the graphserv library) to send an opcode and eventual operands to a graphics server over a pair of communication channels : one for sending command, and one for receiving server replies.
• Up to this level everything is device independent
• The various server instances contain into themselves all device specific stuff.

Most of the details (inclusive of the server implementation) are kept in two separate paper documents. We recall here only some basic facts and give some idioms about the construction of graphics clients.

opcode	function	operands
none	Reconnect implemented at server level
-2	server specific directives	subcode suboperands
-1	Terminate implemented in deleteserver
0	Disconnect see y_closeplot
1	ClearPage see y_page
2	Move see y_move	x y
3	Draw see y_draw	x y
4	PolyLine see y_lines	n x(n) y(n)
5	PolyMarker (psserver side only)	n x(n) y(n)
6	PolyFill see y_fill	n x(n) y(n)
7	Text see y_text	nchar string(nchar)
8	ClearView see y_clear_viewport
9	WriteImage see y_write_image	nbyte data(nbyte)
10	WriteLut see y_writelut	start ncolor red(ncolor) green(ncolor) blue(ncolor)
11	ReadCursor see y_get_cursor [*]	none ; returns x y key
12	ReadImage [*]	none ; returns nbyte data(nbyte)
13	ReadLut see y_readlut	none ; returns start ncolor red(ncolor) green(ncolor) blue(ncolor)
101	Viewport see y_viewport	xlow xup ylow yup
102	Window see y_window	xlow xup ylow yup
103	Coord see y_coordinates and y_window	ncoord
104	Scale see y_scale	xscale yscale
105	Pen see y_colour	colour
106	LineWidth see y_width	width
107	LineStyle	style + TBD
108	Bkg	colour
109	Marker (psserver side only)	n
110	TextFont see y_text	n
111	TextSize (psserver side only)	size
112	TextOrient (psserver side only)	angle
113	TextMode (psserver side only)	n
201	QueryViewport	returns xlow xup ylow yup
202	QueryWindow	returns xlow xup ylow yup
203	QueryCoord	returns ncoord
204	QueryScale	returns xscale yscale
205	QueryPen	returns colour
206	QueryLineWidth>	returns width
207	QueryLineStyle	returns style + TBD
208	QueryBkg	returns colour
209	QueryMarker	returns n
210	QueryTextFont	returns n
211	QueryTextSize	returns size
212	QueryTextOrient	returns angle
213	QueryTextMode	returns n

• Typical very high level graphics clients in XAS are the display and overtrace commands. These programs do not do any plotting themselves, but are just dispatchers to other clients. Dispatchers are explained in section 4.

• Typical high level graphics clients (used to plot a XAS data file in a standard way) use xasgraph utility routines and have a basic structure like this :

  CALL CHECK_OVERTRACE(CLEAR) verify if plotting over preexisting plot get program specific options open and read data file CALL GET_DATASTYLE(ISTYLE) retrieve plotting style from environment LUS(1)=1 LUS(2)=2 CALL Y_OPENPLOT(LUS,' ',0) open plotting connection CALL DF_PEN_COLOURS(LUS,CLEAR) take pen colours from environment CALL DF_VIEWPORT(LUS,BUFFER,ANNOTATE) arrange default viewport CALL DF_WINDOW(LUS,CLEAR ,REPLOTAXES, ...) arrange default window IF(CLEAR.OR.REPLOTAXES)THEN CALL DF_AXES(LUS, XLINLOG, YLINLOG, ...) ENDIF plot axis frame .... CALL Y_COORDINATES(LUS,2) use world coordinates CALL PLOT_XXY_xxx(LUS, ...) use high level call to plot data .... CALL Y_COORDINATES(LUS,1) use NDC coordinates CALL Y_VIEWPORT(LUS,0.0,1.0,0.0,0.5) viewport for annotations CALL Y_COLOUR(LUS,PENCOMMON_TXT) pen colour for annotations CALL ANNOTATE_NEW(LUS, ...) custom annotations IF (CLEAR) CALL Z_SET_GLOBAL ('LASTPLOT', 'spectrum'//PLOTTYPE//' '//NAME1) save plot type to environment CALL Y_CLOSEPLOT(LUS) close plotting connection

• Plain lower level graphics clients use graphserv routines directly and may have a basic structure like this :

  LUS(1)=1 LUS(2)=2 CALL Y_OPENPLOT(LUS,' ',0) open plotting connection CALL Y_VIEWPORT(LUS,0.0,1.0,0.0,0.5) set viewport CALL Y_WINDOW(LUS,XVL,XVU,YVL,YVU) set plotting window CALL Y_COORDINATES(LUS,2) use world coordinates CALL Y_SCALE(LUS,'LIN','LOG') set axis scales .... CALL Y_COLOUR(LUS,ICOL) set pen colour CALL Y_LINES(LUs,2,AX,AY) use low level call to plot data .... CALL Y_CLOSEPLOT(LUS) close plotting connection

• Programs needing graphics input may have a basic structure like this. The trick with DF_VIEWPORT, DF_WINDOW (with dummy arguments) and the xyaxis environment variable is to be regarded as a workaround to make sure this program uses the last axis setting available in the server and in the environment (in a future the "query calls" will allow to get the data directly from the server) and therefore returns consistent coordinates.

  LUS(1)=1 LUS(2)=2 CALL Y_OPENPLOT(LUG,' ',0) open plotting connection CALL DF_VIEWPORT(LUG,BUFFER,BUFFER2) recover current viewport CALL DF_WINDOW(LUG,.FALSE.,.FALSE. ,BUFFER, BUFFER ,BUFFER2, E,E,E,E,E,E) recover plotting window CALL Z_GET_GLOBAL('XYAXIS',BUFFER) READ(BUFFER,*,IOSTAT=IERR)X1,X2,Y1,Y2 retrieve actual window extrema .... CALL Y_GET_CURSOR(LUG,A1,E1,BUFFER(1:1)) CALL Y_GET_CURSOR(LUG,A2,E2,BUFFER(1:1)) read two cursor points .... CALL Y_CLOSEPLOT(LUG) close plotting connection .... IF(E2.LT.E1)THEN ... better check points are in order

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