Hello world
The following is a small sample GEGL application that animates a zoom on a mandelbrot fractal. compile it with:
$ gcc hello-world.c `pkg-config --libs --cflags gegl` -o hello-worldThis example and others can be found in the examples subdirectory of the GEGL source tree.
hello-world.c
#include <gegl.h>
#include <glib/gprintf.h>
gint
main (gint argc,
gchar **argv)
{
gegl_init (&argc, &argv); /* initialize the GEGL library */
/* license for this application, needed by fractal-explorer */
g_object_set (gegl_config (),
"application-license", "GPL3",
NULL);
{
/* instantiate a graph */
GeglNode *gegl = gegl_node_new ();
/*
This is the graph we're going to construct:
.-----------.
| display |
`-----------'
|
.--------.
| crop |
`--------'
|
.--------.
| over |
`--------'
| \
| \
| \
| |
| .------.
| | text |
| `------'
.------------------.
| fractal-explorer |
`------------------'
*/
/*< The image nodes representing operations we want to perform */
GeglNode *display = gegl_node_create_child (gegl, "gegl:display");
GeglNode *crop = gegl_node_new_child (gegl,
"operation", "gegl:crop",
"width", 512.0,
"height", 384.0,
NULL);
GeglNode *over = gegl_node_new_child (gegl,
"operation", "gegl:over",
NULL);
GeglNode *text = gegl_node_new_child (gegl,
"operation", "gegl:text",
"size", 10.0,
"color", gegl_color_new ("rgb(1.0,1.0,1.0)"),
NULL);
GeglNode *mandelbrot = gegl_node_new_child (gegl,
"operation", "gegl:fractal-explorer",
"shiftx", -256.0,
NULL);
gegl_node_link_many (mandelbrot, over, crop, display, NULL);
gegl_node_connect_to (text, "output", over, "aux");
/* request that the save node is processed, all dependencies will
* be processed as well
*/
{
gint frame;
gint frames = 200;
for (frame=0; frame<frames; frame++)
{
gchar string[512];
gdouble t = frame * 1.0/frames;
#define INTERPOLATE(min,max) ((max)*(t)+(min)*(1.0-t))
gdouble shiftx = INTERPOLATE(-256.0, -512.0);
gdouble shifty = INTERPOLATE(0.0, -256.0);
gdouble zoom = INTERPOLATE(300.0, 400.0);
gegl_node_set (mandelbrot, "shiftx", shiftx,
"shifty", shifty,
"zoom", zoom,
NULL);
g_sprintf (string, "x=%1.3f y=%1.3f z=%1.3f", shiftx, shifty, zoom);
gegl_node_set (text, "string", string, NULL);
gegl_node_process (display);
}
}
/* free resources used by the graph and the nodes it owns */
g_object_unref (gegl);
}
/* free resources globally used by GEGL */
gegl_exit ();
return 0;
}