The R Project SVN R

/* The graphics engine will only accept locations and dimensions 
 * in native device coordinates, but it provides the following functions
 * for converting between a couple of simple alternative coordinate 
 * systems and device coordinates:
 *    DEVICE = native units of the device
 *    NDC = Normalised device coordinates 
 *    INCHES = inches (!)
 *    CM = centimetres (!!)
 */

typedef enum {
 GE_DEVICE  = 0,    /* native device coordinates (rasters) */
 GE_NDC = 1,    /* normalised device coordinates x=(0,1), y=(0,1) */
 GE_INCHES = 2,
 GE_CM     = 3
} GEUnit;

#define MAX_GRAPHICS_SYSTEMS 24

typedef enum {
    /* In response to this event, the registered graphics system
     * should allocate and initialise the systemSpecific structure
     */
    GE_InitState = 0,
    /* This event gives the registered system a chance to undo
     * anything done in the initialisation.
     */
    GE_FinaliseState = 1,
    /* This event means that the graphics system should do a redraw.
     */
    GE_Redraw = 2
} GEevent;

/* The full definition should be ...
 *    typedef void (* GEcallback)(GEvent, *GEDevDesc);
 *
 * ... but I could not figure out how to use *GEDevDesc before
 * the definition of GEDevDesc.
 */
typedef void (* GEcallback)();

typedef struct {
    /* An array of information about each graphics system that
     * has registered with the graphics engine.
     * This is used to store graphics state for each graphics
     * system on each device.
     */
    void *systemSpecific;
    /* 
     * An array of function pointers, one per graphics system that
     * has registered with the graphics engine.
     *
     * system_Callback is called when the graphics engine wants
     * to give a graphics system the chance to play with its
     * device-specific information (stored in systemSpecific)
     * There are two parameters:  an "event" to tell the graphics
     * system why the graphics engine has called this function,
     * and the systemSpecific pointer.  The graphics engine
     * has to pass the systemSpecific pointer because only
     * the graphics engine will know what array index to use.
     */
    GEcallback callback;
} GESystemDesc;

typedef struct {
    int newDevStruct;
    NewDevDesc *dev;
    /* Information about a device which has nothing to do with
     * R's concept of a graphics engine.
     */
    GESystemDesc *gesd[MAX_GRAPHICS_SYSTEMS];
} GEDevDesc;

GEDevDesc* GEcreateDevDesc(NewDevDesc* dev);
void GEdestroyDevDesc(GEDevDesc* dd);
void* GEsystemState(GEDevDesc *dd, int index);
void GEregisterWithDevice(GEDevDesc *dd);
int GEregisterSystem(GEcallback callback);
void GEunregisterSystem(int registerIndex);

void GEHandleEvent(GEevent event, NewDevDesc *dev);

double fromDeviceX(double value, GEUnit to, GEDevDesc *dd); 
double toDeviceX(double value, GEUnit from, GEDevDesc *dd);
double fromDeviceY(double value, GEUnit to, GEDevDesc *dd); 
double toDeviceY(double value, GEUnit from, GEDevDesc *dd);
double fromDeviceWidth(double value, GEUnit to, GEDevDesc *dd); 
double toDeviceWidth(double value, GEUnit from, GEDevDesc *dd);
double fromDeviceHeight(double value, GEUnit to, GEDevDesc *dd); 
double toDeviceHeight(double value, GEUnit from, GEDevDesc *dd);

/*
 *  Some Notes on Line Textures
 *
 *  Line textures are stored as an array of 4-bit integers within
 *  a single 32-bit word.  These integers contain the lengths of
 *  lines to be drawn with the pen alternately down and then up.
 *  The device should try to arrange that these values are measured
 *  in points if possible, although pixels is ok on most displays.
 *
 *  If newlty contains a line texture description it is decoded
 *  as follows:
 *
 *      ndash = 0;
 *      for(i=0 ; i<8 && newlty & 15 ; i++) {
 *          dashlist[ndash++] = newlty & 15;
 *          newlty = newlty>>4;
 *      }
 *      dashlist[0] = length of pen-down segment
 *      dashlist[1] = length of pen-up segment
 *      etc
 *
 *  An integer containing a zero terminates the pattern.  Hence
 *  ndash in this code fragment gives the length of the texture
 *  description.  If a description contains an odd number of
 *  elements it is replicated to create a pattern with an
 *  even number of elements.  (If this is a pain, do something
 *  different its not crucial).
 *
 */

/*--- The basic numbered & names line types; Here device-independent:
  e.g. "dashed" == "44",  "dotdash" == "1343"
*/

#define LTY_BLANK   -1
#define LTY_SOLID   0
#define LTY_DASHED  4 + (4<<4)
#define LTY_DOTTED  1 + (3<<4)
#define LTY_DOTDASH 1 + (3<<4) + (4<<8) + (3<<12)
#define LTY_LONGDASH    7 + (3<<4)
#define LTY_TWODASH 2 + (2<<4) + (6<<8) + (2<<12)

void GESetClip(double x1, double y1, double x2, double y2, GEDevDesc *dd);
void GELine(double x1, double y1, double x2, double y2, 
        int col, int lty, double lwd,
        GEDevDesc *dd);
void GEPolyline(int n, double *x, double *y, 
        int col, int lty, double lwd,
        GEDevDesc *dd);
void GEPolygon(int n, double *x, double *y, 
           int col, int fill, int lty, double lwd,
           GEDevDesc *dd);
void GECircle(double x, double y, double radius,
         int col, int fill, int lty, double lwd,
         GEDevDesc *dd);
void GERect(double x0, double y0, double x1, double y1,
        int col, int fill, int lty, double lwd,
        GEDevDesc *dd);
void GEText(double x, double y, char *str,
        double xc, double yc, double rot, 
        int col, int font, double cex, double ps,
        GEDevDesc *dd);
void GEMode(int mode, GEDevDesc* dd);
void GESymbol(double x, double y, int pch, double size,
          int col, int fill, double lty, double lwd,
          int font, double cex, double ps,
          GEDevDesc *dd);
void GEPretty(double *lo, double *up, int *ndiv);
void GEMetricInfo(int c, int font, double cex, double ps,
          double *ascent, double *descent, double *width,
          GEDevDesc *dd);
double GEStrWidth(char *str, int font, double cex, double ps, GEDevDesc *dd);
double GEStrHeight(char *str, int font, double cex, double ps, GEDevDesc *dd);

#define DEG2RAD 0.01745329251994329576

NewDevDesc* GEcurrentDevice();