Function:cs2sdhcb

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cs2sdhcb

Set the handle dragging callback.

Prototype

void cs2sdhcb(void *cbfn);

Description

Set the drag handle callback function; use NULL argument to cancel callback.

The callback function must be of the form:

void dragfn(int *id, XYZ *pos)

where id is the identifier of the chosen handle and pos is a pointer to XYZ variable containing new coordinates.

A handle is dragged by pressing and holding the SHIFT key, while pressing and holding the RIGHT MOUSE BUTTON.

See Also

ds2ahAdd a handle to allow interactive picking of objects.
cs2scbSet the callback function.
struct_XYZData structure for (x,y,z) coordinates.

Code Example

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include "s2plot.h"

#define N 10                    /* Number of points */

XYZ xyz[N];                     /* Global variable: positions */
COLOUR col[N];                  /* Colour of the point */
int sel[N];                     /* Global varibale: selected data */

void drag(int *id, XYZ *p)      /* The drag callback */
{
   xyz[*id] = *p;               /* Update the dragged point's location */
}

void cb(double *t, int *kc)
{
   COLOUR hilite = { 1.0, 1.0, 1.0 };           /* Highlight colour */
   float hsize = 0.02;                          /* Size of handle */
   int i;                                       /* Loop variable */

   for (i=0;i<N;i++) {
      ns2vthpoint(xyz[i], col[i], 3);                   /* Draw thick point */
      ds2ah(xyz[i], hsize, col[i], hilite, i, sel[i]);  /* Draw handles */
   }
}

int main(int argc, char *argv[])
{
   int i;                                       /* Loop varibale */

   srand48((long)time(NULL));                   /* Seed random numbers */

   fprintf(stderr,"Shift and right mouse click to drag a handle\n");
   s2opend("/?",argc, argv);                    /* Open the display */
   s2swin(-1.,1., -1.,1., -1.,1.);              /* Set the window coordinates */
   s2box("BCDET",0,0,"BCDET",0,0,"BCDET",0,0);  /* Draw coordinate box */

   for (i=0;i<N;i++) {                          /* Set-up globals */
      xyz[i].x = drand48()*2.0 - 1.0;           /* Random position */
      xyz[i].y = drand48()*2.0 - 1.0;
      xyz[i].z = drand48()*2.0 - 1.0;
      col[i].r = drand48();                     /* Random colour */
      col[i].g = drand48();
      col[i].b = drand48();
      sel[i]   = 0;                             /* Not currently selected */
   }

   cs2scb(&cb);                                 /* Install dynamic callback */
   cs2sdhcb(&drag);                          /* Install handle dragging callback */

   cs2thv(1);                                   /* Make handles visible */
   ss2txh(1);                                   /* Make crosshairs visible */

   s2show(1);                                   /* Open the s2plot window */

   return 1;
}

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