root/src/modules/loaders/loader_png.c

DEFINITIONS

1. comment_free
2. load
3. save
4. formats

#include "loader_common.h"
#include <png.h>

/* this is a quick sample png loader module... nice and small isn't it? */

/* PNG stuff */
#define PNG_BYTES_TO_CHECK 4

static void
comment_free(ImlibImage * im, void *data)
{
   free(data);
}

char
load(ImlibImage * im, ImlibProgressFunction progress,
     char progress_granularity, char immediate_load)
{
   png_uint_32         w32, h32;
   int                 w, h;
   char                hasa = 0;
   FILE               *f;
   png_structp         png_ptr = NULL;
   png_infop           info_ptr = NULL;
   int                 bit_depth, color_type, interlace_type;

   /* if immediate_load is 1, then don't delay image loading as below, or */
   /* already data in this image - don't load it again */
   if (im->data)
      return 0;
   f = fopen(im->real_file, "rb");
   if (!f)
      return 0;
   /* read header */
   if (!im->data)
     {
        unsigned char       buf[PNG_BYTES_TO_CHECK];

        /* if we haven't read the header before, set the header data */
        fread(buf, 1, PNG_BYTES_TO_CHECK, f);
        if (png_sig_cmp(buf, 0, PNG_BYTES_TO_CHECK))
          {
             fclose(f);
             return 0;
          }
        rewind(f);
        png_ptr =
           png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
        if (!png_ptr)
          {
             fclose(f);
             return 0;
          }
        info_ptr = png_create_info_struct(png_ptr);
        if (!info_ptr)
          {
             png_destroy_read_struct(&png_ptr, NULL, NULL);
             fclose(f);
             return 0;
          }
        if (setjmp(png_jmpbuf(png_ptr)))
          {
             png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
             fclose(f);
             return 0;
          }
        png_init_io(png_ptr, f);
        png_read_info(png_ptr, info_ptr);
        png_get_IHDR(png_ptr, info_ptr, (png_uint_32 *) (&w32),
                     (png_uint_32 *) (&h32), &bit_depth, &color_type,
                     &interlace_type, NULL, NULL);
        im->w = (int)w32;
        im->h = (int)h32;
        if (!IMAGE_DIMENSIONS_OK(w32, h32))
          {
             png_read_end(png_ptr, info_ptr);
             png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp) NULL);
             fclose(f);
             return 0;
          }
        if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
           hasa = 1;
        if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
           hasa = 1;
        if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
           hasa = 1;
        if (hasa)
           SET_FLAG(im->flags, F_HAS_ALPHA);
        else
           UNSET_FLAG(im->flags, F_HAS_ALPHA);
        /* set the format string member to the lower-case full extension */
        /* name for the format - so example names would be: */
        /* "png", "jpeg", "tiff", "ppm", "pgm", "pbm", "gif", "xpm" ... */
        if (!im->loader)
           im->format = strdup("png");
     }
   /* if its the second phase load OR its immediate load or a progress */
   /* callback is set then load the data */
   if ((im->loader) || (immediate_load) || (progress))
     {
        unsigned char     **lines;
        int                 i;

        w = im->w;
        h = im->h;

        /* Prep for transformations...  ultimately we want ARGB */
        /* expand palette -> RGB if necessary */
        if (color_type == PNG_COLOR_TYPE_PALETTE)
           png_set_palette_to_rgb(png_ptr);
        /* expand gray (w/reduced bits) -> 8-bit RGB if necessary */
        if ((color_type == PNG_COLOR_TYPE_GRAY) ||
            (color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
          {
             png_set_gray_to_rgb(png_ptr);
             if (bit_depth < 8)
                png_set_expand_gray_1_2_4_to_8(png_ptr);
          }
        /* expand transparency entry -> alpha channel if present */
        if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
           png_set_tRNS_to_alpha(png_ptr);
        /* reduce 16bit color -> 8bit color if necessary */
        if (bit_depth > 8)
           png_set_strip_16(png_ptr);
        /* pack all pixels to byte boundaries */
        png_set_packing(png_ptr);

/* note from raster:                                                         */
/* thanks to mustapha for helping debug this on PPC Linux remotely by        */
/* sending across screenshots all the time and me figuring out from them     */
/* what the hell was up with the colors                                      */
/* now png loading should work on big-endian machines nicely                 */
#ifdef WORDS_BIGENDIAN
        png_set_swap_alpha(png_ptr);
        if (!hasa)
           png_set_filler(png_ptr, 0xff, PNG_FILLER_BEFORE);
#else
        png_set_bgr(png_ptr);
        if (!hasa)
           png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
#endif

        if (im->data)
           free(im->data);
        im->data = malloc(w * h * sizeof(DATA32));
        if (!im->data)
          {
             png_read_end(png_ptr, info_ptr);
             png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp) NULL);
             fclose(f);
             return 0;
          }
        lines = (unsigned char **)malloc(h * sizeof(unsigned char *));

        if (!lines)
          {
             free(im->data);
             im->data = NULL;
             png_read_end(png_ptr, info_ptr);
             png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp) NULL);
             fclose(f);
             return 0;
          }
        for (i = 0; i < h; i++)
           lines[i] = ((unsigned char *)(im->data)) + (i * w * sizeof(DATA32));
        if (progress)
          {
             int                 y, count, prevy, pass, number_passes, per,
                nrows = 1;

             count = 0;
             number_passes = png_set_interlace_handling(png_ptr);
             for (pass = 0; pass < number_passes; pass++)
               {
                  prevy = 0;
                  per = 0;
                  for (y = 0; y < h; y += nrows)
                    {
                       png_read_rows(png_ptr, &lines[y], NULL, nrows);

                       per = (((pass * h) + y) * 100) / (h * number_passes);
                       if ((per - count) >= progress_granularity)
                         {
                            count = per;
                            if (!progress(im, per, 0, prevy, w, y - prevy + 1))
                              {
                                 free(lines);
                                 png_read_end(png_ptr, info_ptr);
                                 png_destroy_read_struct(&png_ptr, &info_ptr,
                                                         (png_infopp) NULL);
                                 fclose(f);
                                 return 2;
                              }
                            prevy = y + 1;
                         }
                    }
                  if (!progress(im, per, 0, prevy, w, y - prevy + 1))
                    {
                       free(lines);
                       png_read_end(png_ptr, info_ptr);
                       png_destroy_read_struct(&png_ptr, &info_ptr,
                                               (png_infopp) NULL);
                       fclose(f);
                       return 2;
                    }
               }
          }
        else
           png_read_image(png_ptr, lines);
        free(lines);
        png_read_end(png_ptr, info_ptr);
     }
#ifdef PNG_TEXT_SUPPORTED
   {
      png_textp           text;
      int                 num;
      int                 i;

      num = 0;
      png_get_text(png_ptr, info_ptr, &text, &num);
      for (i = 0; i < num; i++)
        {
           if (!strcmp(text[i].key, "Imlib2-Comment"))
              __imlib_AttachTag(im, "comment", 0, strdup(text[i].text),
                                comment_free);
        }
   }
#endif
   png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp) NULL);
   fclose(f);
   return 1;
}

char
save(ImlibImage * im, ImlibProgressFunction progress, char progress_granularity)
{
   FILE               *f;
   png_structp         png_ptr;
   png_infop           info_ptr;
   DATA32             *ptr;
   int                 x, y, j, interlace;
   png_bytep           row_ptr, data = NULL;
   png_color_8         sig_bit;
   int                 pl = 0;
   char                pper = 0;
   ImlibImageTag      *tag;
   int                 quality = 75, compression = 3, num_passes = 1, pass;

   if (!im->data)
      return 0;

   f = fopen(im->real_file, "wb");
   if (!f)
      return 0;
   png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
   if (!png_ptr)
     {
        fclose(f);
        return 0;
     }
   info_ptr = png_create_info_struct(png_ptr);
   if (!info_ptr)
     {
        fclose(f);
        png_destroy_write_struct(&png_ptr, (png_infopp) NULL);
        return 0;
     }
   if (setjmp(png_jmpbuf(png_ptr)))
     {
        fclose(f);
        png_destroy_write_struct(&png_ptr, (png_infopp) & info_ptr);
        png_destroy_info_struct(png_ptr, (png_infopp) & info_ptr);
        return 0;
     }

   /* check whether we should use interlacing */
   interlace = PNG_INTERLACE_NONE;
   if ((tag = __imlib_GetTag(im, "interlacing")) && tag->val)
     {
#ifdef PNG_WRITE_INTERLACING_SUPPORTED
        interlace = PNG_INTERLACE_ADAM7;
#endif
     }

   png_init_io(png_ptr, f);
   if (im->flags & F_HAS_ALPHA)
     {
        png_set_IHDR(png_ptr, info_ptr, im->w, im->h, 8,
                     PNG_COLOR_TYPE_RGB_ALPHA, interlace,
                     PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
#ifdef WORDS_BIGENDIAN
        png_set_swap_alpha(png_ptr);
#else
        png_set_bgr(png_ptr);
#endif
     }
   else
     {
        png_set_IHDR(png_ptr, info_ptr, im->w, im->h, 8, PNG_COLOR_TYPE_RGB,
                     interlace, PNG_COMPRESSION_TYPE_BASE,
                     PNG_FILTER_TYPE_BASE);
        data = malloc(im->w * 3 * sizeof(char));
     }
   sig_bit.red = 8;
   sig_bit.green = 8;
   sig_bit.blue = 8;
   sig_bit.alpha = 8;
   png_set_sBIT(png_ptr, info_ptr, &sig_bit);
   /* quality */
   tag = __imlib_GetTag(im, "quality");
   if (tag)
     {
        quality = tag->val;
        if (quality < 1)
           quality = 1;
        if (quality > 99)
           quality = 99;
     }
   /* convert to compression */
   quality = quality / 10;
   compression = 9 - quality;
   /* compression */
   tag = __imlib_GetTag(im, "compression");
   if (tag)
      compression = tag->val;
   if (compression < 0)
      compression = 0;
   if (compression > 9)
      compression = 9;
   tag = __imlib_GetTag(im, "comment");
   if (tag)
     {
#ifdef PNG_TEXT_SUPPORTED
        png_text            text;

        text.key = "Imlib2-Comment";
        text.text = tag->data;
        text.compression = PNG_TEXT_COMPRESSION_zTXt;
        png_set_text(png_ptr, info_ptr, &(text), 1);
#endif
     }
   png_set_compression_level(png_ptr, compression);
   png_write_info(png_ptr, info_ptr);
   png_set_shift(png_ptr, &sig_bit);
   png_set_packing(png_ptr);

#ifdef PNG_WRITE_INTERLACING_SUPPORTED
   num_passes = png_set_interlace_handling(png_ptr);
#endif

   for (pass = 0; pass < num_passes; pass++)
     {
        ptr = im->data;

        for (y = 0; y < im->h; y++)
          {
             if (im->flags & F_HAS_ALPHA)
                row_ptr = (png_bytep) ptr;
             else
               {
                  for (j = 0, x = 0; x < im->w; x++)
                    {
                       data[j++] = (ptr[x] >> 16) & 0xff;
                       data[j++] = (ptr[x] >> 8) & 0xff;
                       data[j++] = (ptr[x]) & 0xff;
                    }
                  row_ptr = (png_bytep) data;
               }
             png_write_rows(png_ptr, &row_ptr, 1);
             if (progress)
               {
                  char                per;
                  int                 l;

                  per = 100 * (pass + y / (float)im->h) / num_passes;
                  if ((per - pper) >= progress_granularity)
                    {
                       l = y - pl;
                       if (!progress(im, per, 0, (y - l), im->w, l))
                         {
                            if (data)
                               free(data);
                            png_write_end(png_ptr, info_ptr);
                            png_destroy_write_struct(&png_ptr,
                                                     (png_infopp) & info_ptr);
                            png_destroy_info_struct(png_ptr,
                                                    (png_infopp) & info_ptr);
                            fclose(f);
                            return 2;
                         }
                       pper = per;
                       pl = y;
                    }
               }
             ptr += im->w;
          }
     }
   if (data)
      free(data);
   png_write_end(png_ptr, info_ptr);
   png_destroy_write_struct(&png_ptr, (png_infopp) & info_ptr);
   png_destroy_info_struct(png_ptr, (png_infopp) & info_ptr);

   fclose(f);
   return 1;
}

/* fills the ImlibLoader struct with a string array of format file */
/* extensions this loader can load. eg: */
/* loader->formats = { "jpeg", "jpg"}; */
/* giving permutations is a good idea. case sensitivity is irrelevant */
/* your loader CAN load more than one format if it likes - like: */
/* loader->formats = { "gif", "png", "jpeg", "jpg"} */
/* if it can load those formats. */
void
formats(ImlibLoader * l)
{
   /* this is the only bit you have to change... */
   char               *list_formats[] = { "png" };

   /* don't bother changing any of this - it just reads this in and sets */
   /* the struct values and makes copies */
   {
      int                 i;

      l->num_formats = (sizeof(list_formats) / sizeof(char *));
      l->formats = malloc(sizeof(char *) * l->num_formats);

      for (i = 0; i < l->num_formats; i++)
         l->formats[i] = strdup(list_formats[i]);
   }
}