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MyPNG.c


/* 
A* -------------------------------------------------------------------
B* This file contains source code for the PyMOL computer program
C* copyright 1998-2000 by Warren Lyford Delano of DeLano Scientific. 
D* -------------------------------------------------------------------
E* It is unlawful to modify or remove this copyright notice.
F* -------------------------------------------------------------------
G* Please see the accompanying LICENSE file for further information. 
H* -------------------------------------------------------------------
I* Additional authors of this source file include:
-* TJO: TJ O'Donnell, under contract for DeLano Scientific LLC
-* 
-*
Z* -------------------------------------------------------------------
*/

#include"os_predef.h"
#include"MemoryDebug.h"


/* backwards compatibility */

#ifdef _HAVE_LIBPNG
#ifndef _PYMOL_LIBPNG
#define _PYMOL_LIBPNG
#endif
#endif


/* do we have libpng? */

#ifdef _PYMOL_LIBPNG
#include<png.h>


/* The png_jmpbuf() macro, used in error handling, became available in

 * libpng version 1.0.6.  If you want to be able to run your code with older

 * versions of libpng, you must define the macro yourself (but only if it

 * is not already defined by libpng!).

 */

#ifndef png_jmpbuf
#  define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
#endif

#endif

#include"os_std.h"

#include"Base.h"
#include "MyPNG.h"
#include"MemoryDebug.h"
#include "Setting.h"

int MyPNGWrite(PyMOLGlobals * G, char *file_name, unsigned char *data_ptr,
               unsigned int width, unsigned int height, float dpi, int format, int quiet)
{
  switch (format) {
  case cMyPNG_FormatPNG:
    {
#ifdef _PYMOL_LIBPNG
      int ok = true;
      FILE *fp = NULL;
      png_structp png_ptr;
      png_infop info_ptr;
      int bit_depth = 8;
      int bytes_per_pixel = 4;
      png_uint_32 k;
      png_byte *image = (png_byte *) data_ptr;
      png_bytep *row_pointers;
      int fd = 0;

      row_pointers = Alloc(png_bytep, height);

      /* open the file, allowing use of an encoded file descriptor, with
         approach adapted from TJO: chr(1) followed by ascii-format integer */
      if(file_name[0] == 1) {
        if(sscanf(file_name + 1, "%d", &fd) == 1) {
          fp = fdopen(fd, "wb");
        }
      } else {
        fp = fopen(file_name, "wb");
      }
      if(fp == NULL) {
        ok = false;
        goto cleanup;
      } else if(feof(fp)) {
        ok = false;
        goto cleanup;
      }
      /* Create and initialize the png_struct with the desired error handler
       * functions.  If you want to use the default stderr and longjump method,
       * you can supply NULL for the last three parameters.  We also check that
       * the library version is compatible with the one used at compile time,
       * in case we are using dynamically linked libraries.  REQUIRED.
       */
      png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);

      if(png_ptr == NULL) {
        ok = false;
        goto cleanup;
      }

      /* Allocate/initialize the image information data.  REQUIRED */
      info_ptr = png_create_info_struct(png_ptr);
      if(info_ptr == NULL) {
        png_destroy_write_struct(&png_ptr, (png_infopp) NULL);
        ok = false;
        goto cleanup;
      }

      /* Set error handling.  REQUIRED if you aren't supplying your own
       * error handling functions in the png_create_write_struct() call.
       */
      if(setjmp(png_jmpbuf(png_ptr))) {
        /* If we get here, we had a problem reading the file */
        png_destroy_write_struct(&png_ptr, (png_infopp) NULL);
        ok = false;
        goto cleanup;
      }

      /* set up the output control if you are using standard C streams */
      png_init_io(png_ptr, fp);

      /* Set the image information here.  Width and height are up to 2^31,
       * bit_depth is one of 1, 2, 4, 8, or 16, but valid values also depend on
       * the color_type selected. color_type is one of PNG_COLOR_TYPE_GRAY,
       * PNG_COLOR_TYPE_GRAY_ALPHA, PNG_COLOR_TYPE_PALETTE, PNG_COLOR_TYPE_RGB,
       * or PNG_COLOR_TYPE_RGB_ALPHA.  interlace is either PNG_INTERLACE_NONE or
       * PNG_INTERLACE_ADAM7, and the compression_type and filter_type MUST
       * currently be PNG_COMPRESSION_TYPE_BASE and PNG_FILTER_TYPE_BASE. REQUIRED
       */
      png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, PNG_COLOR_TYPE_RGB_ALPHA,
                   PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);

      if(dpi > 0.0F) {          /* only set resolution if dpi is positive */
        int dots_per_meter = (int) (dpi * 39.3700787);
        png_set_pHYs(png_ptr, info_ptr, dots_per_meter, dots_per_meter,
                     PNG_RESOLUTION_METER);
      }

      png_set_gamma(png_ptr, SettingGet(G, cSetting_png_screen_gamma),
                    SettingGet(G, cSetting_png_file_gamma));

      /* stamp the image as being created by PyMOL we could consider
       * supporting optional annotations as well: PDB codes, canonical
       * smiles, INCHIs, and other common identifiers */

      {
        png_text text;
        text.compression = PNG_TEXT_COMPRESSION_NONE;
        text.key = (png_charp) "Software";
        text.text = (png_charp) "PyMOL";
        text.text_length = 5;
        png_set_text(png_ptr, info_ptr, &text, 1);
      }
      {
        png_text text;
        text.compression = PNG_TEXT_COMPRESSION_NONE;
        text.key = (png_charp) "URL";
        text.text = (png_charp) "http://www.pymol.org";
        text.text_length = 5;
        png_set_text(png_ptr, info_ptr, &text, 1);
      }

      /* Write the file header information.  REQUIRED */
      png_write_info(png_ptr, info_ptr);

      /* The easiest way to write the image (you may have a different memory
       * layout, however, so choose what fits your needs best).  You need to
       * use the first method if you aren't handling interlacing yourself.
       */
      for(k = 0; k < height; k++)
        row_pointers[(height - k) - 1] = image + k * width * bytes_per_pixel;

      png_write_image(png_ptr, row_pointers);

      /* It is REQUIRED to call this to finish writing the rest of the file */
      png_write_end(png_ptr, info_ptr);

      /* clean up after the write, and free any memory allocated */
      png_destroy_write_struct(&png_ptr, (png_infopp) NULL);

    cleanup:
      if(fp) {
        /* close the file */
        fclose(fp);
      }

      mfree(row_pointers);
      /* that's it */

      return ok;
#else

      return 0;
#endif
    }
    break;
  case cMyPNG_FormatPPM:
    {
      FILE *fil = fopen(file_name, "wb");
      unsigned char *buffer = Alloc(unsigned char, 3 * width * height);

      if(fil && buffer) {
        fprintf(fil, "P6\n");
        fprintf(fil, "%d %d\n", width, height);
        fprintf(fil, "255\n");
        {
          int a, b;
          unsigned char *q = buffer, *p;
          p = data_ptr + width * 4 * (height - 1);
          for(b = 0; b < height; b++) {
            for(a = 0; a < width; a++) {
              *(q++) = *(p++);  /* platform-specific ordering? */
              *(q++) = *(p++);
              *(q++) = *(p++);
              p++;
            }
            p -= width * 8;
          }
          fwrite(buffer, width, height * 3, fil);
        }
      }
      if(fil) {
        fclose(fil);
      }
      FreeP(buffer);
    }
    return 1;
    break;
  }
  return 0;
}

int MyPNGRead(char *file_name, unsigned char **p_ptr, unsigned int *width_ptr,
              unsigned int *height_ptr)
{

#ifdef _PYMOL_LIBPNG

  FILE *png_file = NULL;
  png_struct *png_ptr = NULL;
  png_info *info_ptr = NULL;
  png_byte buf[8];
  png_byte *png_pixels = NULL;
  png_byte **row_pointers = NULL;
  png_byte *pix_ptr = NULL;
  png_uint_32 row_bytes = 0;

  png_uint_32 width;
  png_uint_32 height;
  int bit_depth;
  int color_type;
  int row, col;
  int ret;
  int i;
  int ok = true;
  unsigned char *p = NULL;
  double file_gamma;

  if(!file_name)
    return 0;

  png_file = fopen(file_name, "rb");
  if(png_file == NULL)
    return 0;

  /* read and check signature in PNG file */
  ret = fread(buf, 1, 8, png_file);
  if(ret != 8)
    ok = false;

  if(ok) {
    ret = png_check_sig(buf, 8);
    if(!ret)
      ok = false;
  }
  /* create png and info structures */
  if(ok) {
    png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if(!png_ptr)
      ok = false;
  }

  if(ok) {
    info_ptr = png_create_info_struct(png_ptr);
    if(!info_ptr)
      ok = false;
  }

  if(setjmp(png_jmpbuf(png_ptr)))
    ok = false;

  if(ok) {
    /* set up the input control for C streams */
    png_init_io(png_ptr, png_file);
    png_set_sig_bytes(png_ptr, 8);      /* we already read the 8 signature bytes */

    /* read the file information */
    png_read_info(png_ptr, info_ptr);

    /* get size and bit-depth of the PNG-image */
    png_get_IHDR(png_ptr, info_ptr,
                 &width, &height, &bit_depth, &color_type, NULL, NULL, NULL);

    /* set-up the transformations */

    if(color_type != PNG_COLOR_TYPE_RGB_ALPHA) {
      png_set_expand(png_ptr);
      png_set_filler(png_ptr, 0xFF, PNG_FILLER_AFTER);
    }

    if(color_type == PNG_COLOR_TYPE_GRAY || color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
      png_set_gray_to_rgb(png_ptr);
    /* only if file has a file gamma, we do a correction */
    if(png_get_gAMA(png_ptr, info_ptr, &file_gamma))
      png_set_gamma(png_ptr, (double) 2.2, file_gamma);

    /* all transformations have been registered; now update info_ptr data,
     * get rowbytes and channels, and allocate image memory */

    png_read_update_info(png_ptr, info_ptr);

    /* get the new color-type and bit-depth (after expansion/stripping) */
    png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
                 NULL, NULL, NULL);

    /* row_bytes is the width x number of channels x (bit-depth / 8) */
    row_bytes = png_get_rowbytes(png_ptr, info_ptr);
    if((png_pixels = (png_byte *) malloc(row_bytes * height * sizeof(png_byte))) == NULL) {
      ok = false;
    }
  }

  if(ok) {

    if((row_pointers = (png_byte **) malloc(height * sizeof(png_bytep))) == NULL) {
      png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
      free(png_pixels);
      png_pixels = NULL;
      ok = false;
    }
  }

  if(ok) {

    /* set the individual row_pointers to point at the correct offsets */
    for(i = 0; i < ((signed) height); i++)
      row_pointers[i] = png_pixels + i * row_bytes;

    /* now we can go ahead and just read the whole image */
    png_read_image(png_ptr, row_pointers);

    /* read rest of file, and get additional chunks in info_ptr - REQUIRED */
    png_read_end(png_ptr, info_ptr);
  }

  if(ok) {
    /* now reformat image into PyMOL format */

    p = (unsigned char *) mmalloc(4 * width * height);
    if(!p)
      ok = false;
  }
  if(ok) {
    *(p_ptr) = p;
    *(width_ptr) = width;
    *(height_ptr) = height;

    for(row = 0; row < (signed) height; row++) {
      pix_ptr = row_pointers[(height - 1) - row];
      for(col = 0; col < (signed) width; col++) {
        *p++ = *pix_ptr++;
        *p++ = *pix_ptr++;
        *p++ = *pix_ptr++;
        *p++ = *pix_ptr++;
      }
    }

  }

  if(row_pointers != (unsigned char **) NULL)
    free(row_pointers);
  if(png_pixels != (unsigned char *) NULL)
    free(png_pixels);

  if(png_ptr) {
    png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp) NULL);
  }
  if(png_file)
    fclose(png_file);

  return (ok);
#else
  return (false);
#endif

}                               /* end of source */

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