viz.c

#include "cdt.h"
#include "gvc.h"

extern gvplugin_library_t gvplugin_dot_layout_LTX_library;
extern gvplugin_library_t gvplugin_neato_layout_LTX_library;
extern gvplugin_library_t gvplugin_core_LTX_library;

GVC_t *context = NULL;
char *last_result = NULL;

__attribute__((used)) char* vizRenderFromString(const char *string,
                                                const char *format,
                                                const char *engine) {
  if (context == NULL) {
    context = gvContext();
    gvAddLibrary(context, &gvplugin_core_LTX_library);
    gvAddLibrary(context, &gvplugin_dot_layout_LTX_library);
    gvAddLibrary(context, &gvplugin_neato_layout_LTX_library);
  }

  Agraph_t *graph = agmemread((char*)string);
  gvLayout(context, graph, engine);

  char *result = NULL;
  unsigned int length;
  gvRenderData(context, graph, format, &result, &length);

  gvFreeLayout(context, graph);
  agclose(graph);

  if (last_result != NULL) {
    gvFreeRenderData(last_result);
  }
  last_result = result;

  return result;
}