Chapter 21. API compatibility definition

Table of Contents
What is in the API?
Regression test for backwards compatibility

This chapter presents the formal definition of what is considered to be in the PLplot library API. It is assumed that major new releases of PLplot will have substantial backwards incompatible changes in the API, but the PLplot developers commit to introducing as few as possible of such incompatibilities between minor releases such that stability across those minor releases is practically guaranteed. In all cases where backwards incompatible changes have been introduced, then the library soname will be changed (for operating systems such as Linux that support versioned shared libraries).

The information in this chapter regards version 5.9.0 of PLplot, released on 2007-11-18.

What is in the API?

The formal definition of the PLplot C API is everything that is defined in the include file plplot.h. This includes all the function prototypes, the defined structures and the semantics of the constants. The list of symbols currently exported by the shared library libplplot.h that are declared in plplot.h is the following:

plAlloc2dGrid          plgdiori               plscmap1la
plClearOpts            plgdiplt               plscmap1n
plFindCommand          plgesc                 plscol0
plFindName             plgfam                 plscol0a
plFree2dGrid           plgfci                 plscolbg
plGetCursor            plgfile                plscolbga
plGetFlt               plgfnam                plscolor
plGetInt               plglevel               plscompression
plGetName              plgpage                plsdev
plHLS_RGB              plgra                  plsdidev
plMergeOpts            plgriddata             plsdimap
plMinMax2dGrid         plgspa                 plsdiori
plOptUsage             plgstrm                plsdiplt
plParseOpts            plgver                 plsdiplz
plRGB_HLS              plgvpd                 plseopH
plResetOpts            plgvpw                 plsesc
plSetOpt               plgxax                 plsetopt
plSetUsage             plgyax                 plsexit
plTranslateCursor      plgzax                 plsfam
pl_cmd                 plhist                 plsfci
pl_setcontlabelformat  plhls                  plsfile
pl_setcontlabelparam   plhlsrgb               plsfnam
pladv                  plimage                plshade
plarrows               plinit                 plshade1
plaxes                 pljoin                 plshades
plbin                  pllab                  plsmaj
plbop                  pllightsource          plsmem
plbox                  plline                 plsmin
plbox3                 plline3                plsori
plcalc_world           pllsty                 plspage
plclear                plmap                  plspause
plcol0                 plmeridians            plsstrm
plcol1                 plmesh                 plssub
plcont                 plmeshc                plssym
plcpstrm               plmkstrm               plstar
pldid2pc               plmtex                 plstart
pldip2dc               plmtex3                plstr
plend                  plot3d                 plstripa
plend1                 plot3dc                plstripc
plenv                  plot3dcl               plstripd
plenv0                 plparseopts            plstyl
pleop                  plpat                  plsurf3d
plerrx                 plpoin                 plsurf3dl
plerry                 plpoin3                plsvect
plf2eval               plpoly3                plsvpa
plf2eval2              plprec                 plsxax
plf2evalr              plpsty                 plsxwin
plfamadv               plptex                 plsyax
plfcont                plptex3                plsym
plfill                 plreplot               plszax
plfill3                plrgb                  pltext
plflush                plrgb1                 pltimefmt
plfont                 plrgbhls               pltr0
plfontld               plsButtonEH            pltr1
plfshade               plsError               pltr2
plgDevs                plsKeyEH               pltr2p
plgFileDevs            plsabort               plvasp
plgchr                 plsbopH                plvect
plgcol0                plschr                 plvpas
plgcol0a               plscmap0               plvpor
plgcolbg               plscmap0a              plvsta
plgcolbga              plscmap0n              plw3d
plgcompression         plscmap1               plwid
plgdev                 plscmap1a              plwind
plgdidev               plscmap1l              plxormod

Another important aspect of compatibility regard the Application Binary Interface (ABI). Backwards compatibility can be broken by changes in the C structures made public through plplot.h. Currently, they are:

typedef struct {
    const char *opt;
    int  (*handler)	(const char *, const char *, void *);
    void *client_data;
    void *var;
    long mode;
    const char *syntax;
    const char *desc;
} PLOptionTable;

typedef struct {
    int type;			/* of event (CURRENTLY UNUSED) */
    unsigned int state;		/* key or button mask */
    unsigned int keysym;	/* key selected */
    unsigned int button;	/* mouse button selected */
    PLINT subwindow;            /* subwindow (alias subpage, alias subplot) number */
    char string[PL_MAXKEY];	/* translated string */
    int pX, pY;			/* absolute device coordinates of pointer */
    PLFLT dX, dY;		/* relative device coordinates of pointer */
    PLFLT wX, wY;		/* world coordinates of pointer */
} PLGraphicsIn;

typedef struct {
    PLFLT dxmi, dxma, dymi, dyma;	/* min, max window rel dev coords */
    PLFLT wxmi, wxma, wymi, wyma;	/* min, max window world coords */
} PLWindow;

typedef struct {
    unsigned int x, y;			/* upper left hand corner */
    unsigned int width, height;		/* window dimensions */
} PLDisplay;

typedef struct {
    PLFLT *f;
    PLINT nx, ny, nz;
} PLfGrid;

typedef struct {
    PLFLT **f;
    PLINT nx, ny;
} PLfGrid2;

typedef struct {
    PLFLT *xg, *yg, *zg;
    PLINT nx, ny, nz;
} PLcGrid;

typedef struct {
    PLFLT **xg, **yg, **zg;
    PLINT nx, ny;
} PLcGrid2;

typedef struct {
    unsigned char r;		/* red */
    unsigned char g;		/* green */
    unsigned char b;		/* blue */
    PLFLT a;                    /* alpha (or transparency) */
    const char *name;
} PLColor;

typedef struct {
    PLFLT h;			/* hue */
    PLFLT l;			/* lightness */
    PLFLT s;			/* saturation */
    PLFLT p;			/* position */
    PLFLT a;                    /* alpha (or transparency) */
    int rev;			/* if set, interpolate through h=0 */
} PLControlPt;

typedef struct {
    PLINT cmd;
    PLINT result;
} PLBufferingCB;