/******************************************************************************
  Copyright (C) Michael Still 2002
  
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
  
  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
******************************************************************************/

#include <stdio.h>
#include <png.h>
#include <libmplot.h>

int
main (int argc, char *argv[])
{
  FILE *image;
  unsigned int i, textx, texty;
  png_uint_32 rowbytes;
  png_structp png;
  png_infop info;
  png_bytepp row_pointers = NULL;
  plot_state *graph;
  char *raster;
  float angle;
  int x, count;

  if((graph = plot_newplot(400, 400)) == NULL){
    fprintf(stderr, "Could not allocate a new plot\n");
    exit(1);
  }

  // Draw the "frame" for the parabola
  plot_setlinestart (graph, 200, 200);
  plot_addcubiccurvesegment (graph, 300, 200, 225, 300, 275, 300);
  plot_strokeline (graph);
  plot_endline (graph);

  plot_setlinestart (graph, 200, 200);
  plot_addquadraticcurvesegmentone (graph, 300, 200, 200, 300);
  plot_strokeline (graph);
  plot_endline (graph);

  plot_setlinestart (graph, 200, 200);
  plot_addquadraticcurvesegmenttwo (graph, 300, 200, 300, 300);
  plot_strokeline (graph);
  plot_endline (graph);

  plot_setlinestart(graph, 200, 200);
  plot_addlinesegment(graph, 225, 300);
  plot_addlinesegment(graph, 275, 300);
  plot_addlinesegment(graph, 300, 200);
  plot_strokeline(graph);
  plot_endline(graph);



  // Write out the PNG file
  raster = plot_getraster(graph);

  if((image = fopen("graph.png", "wb")) == NULL){
    fprintf(stderr, "Could not open the output image\n");
    exit(42);
  }

  // Get ready for writing
  if ((png =
       png_create_write_struct (PNG_LIBPNG_VER_STRING, NULL, NULL,
                                NULL)) == NULL){
    fprintf(stderr, "Could not create write structure for PNG (out of memory?)");
    exit(42);
  }

  // Get ready to specify important stuff about the image
  if ((info = png_create_info_struct (png)) == NULL){
    fprintf(stderr,
            "Could not create PNG info structure for writing (out of memory?)");
    exit(42);
  }

  if (setjmp (png_jmpbuf (png))){
    fprintf(stderr, "Could not set the PNG jump value for writing");
    exit(42);
  }

  // This is needed before IO will work (unless you define callbacks)
  png_init_io(png, image);

  // Define important stuff about the image
  info->channels = 3;
  info->pixel_depth = 24;
  png_set_IHDR (png, info, 400, 400, 8, PNG_COLOR_TYPE_RGB,
                PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT,
                PNG_FILTER_TYPE_DEFAULT);
  png_write_info (png, info);

  // Write the image out
  if((row_pointers = malloc (400 * sizeof (png_bytep))) == NULL){
    fprintf(stderr, "Could not allocate memory\n");
    exit(42);
  }

  for(i = 0; i < 400; i++){
    row_pointers[i] = raster + (i * 400 * 3);
  }

  png_write_image (png, row_pointers);

  // Cleanup
  png_write_end (png, info);
  png_destroy_write_struct (&png, &info);
  fclose(image); 
}