GlyCreator

#include <glycin.h>

GlyCreator *creator = gly_creator_new("image/jpeg", NULL);

if (!creator)
  return;

// Create frame with a single red pixel
guint8 data[] = {255, 0, 0};
gsize length = sizeof(data);
GBytes *texture = g_bytes_new(data, length);
GlyNewFrame *new_frame = gly_creator_add_frame(creator, 1, 1, GLY_MEMORY_R8G8B8, texture);

// Create JPEG
GlyEncodedImage *encoded_image = gly_creator_create(creator, NULL);

if (encoded_image)
{
  GBytes *binary_data = gly_encoded_image_get_data(encoded_image);
  if (binary_data)
  {
    // Write image to file
    GFile *file = g_file_new_for_path("test.jpg");
    g_file_replace_contents(
        file,
        g_bytes_get_data(binary_data, NULL),
        g_bytes_get_size(binary_data),
        NULL,
        FALSE,
        G_FILE_CREATE_NONE,
        NULL,
        NULL,
        NULL);
  }
}