Updates the PNG library to 1.2.37, enables some functionality for O3D

third_party/libpng/pngwrite.c

 
 /* pngwrite.c - general routines to write a PNG file
  *
- * Last changed in libpng 1.2.34 [December 18, 2008]
+ * Last changed in libpng 1.2.37 [June 4, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
- * Copyright (c) 1998-2008 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  */
 
-/* get internal access to png.h */
+/* Get internal access to png.h */
 #define PNG_INTERNAL
 #include "png.h"
 #ifdef PNG_WRITE_SUPPORTED
 
 /* Writes all the PNG information.  This is the suggested way to use the
  * library.  If you have a new chunk to add, make a function to write it,
  * and put it in the correct location here.  If you want the chunk written
  * after the image data, put it in png_write_end().  I strongly encourage
  * you to supply a PNG_INFO_ flag, and check info_ptr->valid before writing
  * the chunk, as that will keep the code from breaking if you want to just
  * write a plain PNG file.  If you have long comments, I suggest writing
  * them in png_write_end(), and compressing them.
  */
 void PNGAPI
 png_write_info_before_PLTE(png_structp png_ptr, png_infop info_ptr)
 {
    png_debug(1, "in png_write_info_before_PLTE");
    if (png_ptr == NULL || info_ptr == NULL)
       return;
    if (!(png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE))
    {
-   png_write_sig(png_ptr); /* write PNG signature */
+   png_write_sig(png_ptr); /* Write PNG signature */
 #if defined(PNG_MNG_FEATURES_SUPPORTED)
    if ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE)&&(png_ptr->mng_features_permitted))
    {
       png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
       png_ptr->mng_features_permitted=0;
    }
 #endif
-   /* write IHDR information. */
+   /* Write IHDR information. */
    png_write_IHDR(png_ptr, info_ptr->width, info_ptr->height,
       info_ptr->bit_depth, info_ptr->color_type, info_ptr->compression_type,
       info_ptr->filter_type,
 #if defined(PNG_WRITE_INTERLACING_SUPPORTED)
       info_ptr->interlace_type);
 #else
       0);
 #endif
-   /* the rest of these check to see if the valid field has the appropriate
-      flag set, and if it does, writes the chunk. */
+   /* The rest of these check to see if the valid field has the appropriate
+    * flag set, and if it does, writes the chunk.
+    */
 #if defined(PNG_WRITE_gAMA_SUPPORTED)
    if (info_ptr->valid & PNG_INFO_gAMA)
    {
 #  ifdef PNG_FLOATING_POINT_SUPPORTED
       png_write_gAMA(png_ptr, info_ptr->gamma);
 #else
 #ifdef PNG_FIXED_POINT_SUPPORTED
       png_write_gAMA_fixed(png_ptr, info_ptr->int_gamma);
 #  endif
 #endif
@@ skipping 28 matching lines @@
          info_ptr->int_x_red, info_ptr->int_y_red,
          info_ptr->int_x_green, info_ptr->int_y_green,
          info_ptr->int_x_blue, info_ptr->int_y_blue);
 #  endif
 #endif
    }
 #endif
 #if defined(PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED)
    if (info_ptr->unknown_chunks_num)
    {
-       png_unknown_chunk *up;
+      png_unknown_chunk *up;
 
-       png_debug(5, "writing extra chunks");
+      png_debug(5, "writing extra chunks");
 
-       for (up = info_ptr->unknown_chunks;
-            up < info_ptr->unknown_chunks + info_ptr->unknown_chunks_num;
-            up++)
-       {
+      for (up = info_ptr->unknown_chunks;
+           up < info_ptr->unknown_chunks + info_ptr->unknown_chunks_num;
+           up++)
+      {
          int keep=png_handle_as_unknown(png_ptr, up->name);
          if (keep != PNG_HANDLE_CHUNK_NEVER &&
             up->location && !(up->location & PNG_HAVE_PLTE) &&
             !(up->location & PNG_HAVE_IDAT) &&
             ((up->name[3] & 0x20) || keep == PNG_HANDLE_CHUNK_ALWAYS ||
             (png_ptr->flags & PNG_FLAG_KEEP_UNSAFE_CHUNKS)))
          {
             if (up->size == 0)
                png_warning(png_ptr, "Writing zero-length unknown chunk");
             png_write_chunk(png_ptr, up->name, up->data, up->size);
          }
-       }
+      }
    }
 #endif
       png_ptr->mode |= PNG_WROTE_INFO_BEFORE_PLTE;
    }
 }
 
 void PNGAPI
 png_write_info(png_structp png_ptr, png_infop info_ptr)
 {
 #if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
    int i;
 #endif
 
    png_debug(1, "in png_write_info");
 
    if (png_ptr == NULL || info_ptr == NULL)
       return;
 
    png_write_info_before_PLTE(png_ptr, info_ptr);
 
    if (info_ptr->valid & PNG_INFO_PLTE)
       png_write_PLTE(png_ptr, info_ptr->palette,
          (png_uint_32)info_ptr->num_palette);
    else if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       png_error(png_ptr, "Valid palette required for paletted images");
 
 #if defined(PNG_WRITE_tRNS_SUPPORTED)
    if (info_ptr->valid & PNG_INFO_tRNS)
+   {
+#if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
+      /* Invert the alpha channel (in tRNS) */
+      if ((png_ptr->transformations & PNG_INVERT_ALPHA) &&
+         info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       {
-#if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
-         /* invert the alpha channel (in tRNS) */
-         if ((png_ptr->transformations & PNG_INVERT_ALPHA) &&
-            info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
-         {
-            int j;
-            for (j=0; j<(int)info_ptr->num_trans; j++)
-               info_ptr->trans[j] = (png_byte)(255 - info_ptr->trans[j]);
-         }
+         int j;
+         for (j=0; j<(int)info_ptr->num_trans; j++)
+            info_ptr->trans[j] = (png_byte)(255 - info_ptr->trans[j]);
+      }
 #endif
       png_write_tRNS(png_ptr, info_ptr->trans, &(info_ptr->trans_values),
          info_ptr->num_trans, info_ptr->color_type);
-      }
+   }
 #endif
 #if defined(PNG_WRITE_bKGD_SUPPORTED)
    if (info_ptr->valid & PNG_INFO_bKGD)
       png_write_bKGD(png_ptr, &(info_ptr->background), info_ptr->color_type);
 #endif
 #if defined(PNG_WRITE_hIST_SUPPORTED)
    if (info_ptr->valid & PNG_INFO_hIST)
       png_write_hIST(png_ptr, info_ptr->hist, info_ptr->num_palette);
 #endif
 #if defined(PNG_WRITE_oFFs_SUPPORTED)
    if (info_ptr->valid & PNG_INFO_oFFs)
       png_write_oFFs(png_ptr, info_ptr->x_offset, info_ptr->y_offset,
          info_ptr->offset_unit_type);
 #endif
 #if defined(PNG_WRITE_pCAL_SUPPORTED)
    if (info_ptr->valid & PNG_INFO_pCAL)
       png_write_pCAL(png_ptr, info_ptr->pcal_purpose, info_ptr->pcal_X0,
          info_ptr->pcal_X1, info_ptr->pcal_type, info_ptr->pcal_nparams,
          info_ptr->pcal_units, info_ptr->pcal_params);
 #endif
+
+#if defined(PNG_sCAL_SUPPORTED)
+   if (info_ptr->valid & PNG_INFO_sCAL)
 #if defined(PNG_WRITE_sCAL_SUPPORTED)
-   if (info_ptr->valid & PNG_INFO_sCAL)
 #if defined(PNG_FLOATING_POINT_SUPPORTED) && !defined(PNG_NO_STDIO)
       png_write_sCAL(png_ptr, (int)info_ptr->scal_unit,
           info_ptr->scal_pixel_width, info_ptr->scal_pixel_height);
-#else
+#else /* !FLOATING_POINT */
 #ifdef PNG_FIXED_POINT_SUPPORTED
       png_write_sCAL_s(png_ptr, (int)info_ptr->scal_unit,
           info_ptr->scal_s_width, info_ptr->scal_s_height);
-#else
+#endif /* FIXED_POINT */
+#endif /* FLOATING_POINT */
+#else  /* !WRITE_sCAL */
       png_warning(png_ptr,
           "png_write_sCAL not supported; sCAL chunk not written.");
-#endif
-#endif
-#endif
+#endif /* WRITE_sCAL */
+#endif /* sCAL */
+
 #if defined(PNG_WRITE_pHYs_SUPPORTED)
    if (info_ptr->valid & PNG_INFO_pHYs)
       png_write_pHYs(png_ptr, info_ptr->x_pixels_per_unit,
          info_ptr->y_pixels_per_unit, info_ptr->phys_unit_type);
-#endif
+#endif /* pHYs */
+
 #if defined(PNG_WRITE_tIME_SUPPORTED)
    if (info_ptr->valid & PNG_INFO_tIME)
    {
       png_write_tIME(png_ptr, &(info_ptr->mod_time));
       png_ptr->mode |= PNG_WROTE_tIME;
    }
-#endif
+#endif /* tIME */
+
 #if defined(PNG_WRITE_sPLT_SUPPORTED)
    if (info_ptr->valid & PNG_INFO_sPLT)
      for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)
        png_write_sPLT(png_ptr, info_ptr->splt_palettes + i);
-#endif
+#endif /* sPLT */
+
 #if defined(PNG_WRITE_TEXT_SUPPORTED)
    /* Check to see if we need to write text chunks */
    for (i = 0; i < info_ptr->num_text; i++)
    {
       png_debug2(2, "Writing header text chunk %d, type %d", i,
          info_ptr->text[i].compression);
-      /* an internationalized chunk? */
+      /* An internationalized chunk? */
       if (info_ptr->text[i].compression > 0)
       {
 #if defined(PNG_WRITE_iTXt_SUPPORTED)
-          /* write international chunk */
+          /* Write international chunk */
           png_write_iTXt(png_ptr,
                          info_ptr->text[i].compression,
                          info_ptr->text[i].key,
                          info_ptr->text[i].lang,
                          info_ptr->text[i].lang_key,
                          info_ptr->text[i].text);
 #else
           png_warning(png_ptr, "Unable to write international text");
 #endif
           /* Mark this chunk as written */
           info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
       }
       /* If we want a compressed text chunk */
       else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_zTXt)
       {
 #if defined(PNG_WRITE_zTXt_SUPPORTED)
-         /* write compressed chunk */
+         /* Write compressed chunk */
          png_write_zTXt(png_ptr, info_ptr->text[i].key,
             info_ptr->text[i].text, 0,
             info_ptr->text[i].compression);
 #else
          png_warning(png_ptr, "Unable to write compressed text");
 #endif
          /* Mark this chunk as written */
          info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
       }
       else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
       {
 #if defined(PNG_WRITE_tEXt_SUPPORTED)
-         /* write uncompressed chunk */
+         /* Write uncompressed chunk */
          png_write_tEXt(png_ptr, info_ptr->text[i].key,
                          info_ptr->text[i].text,
                          0);
+         /* Mark this chunk as written */
+         info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
 #else
+         /* Can't get here */
          png_warning(png_ptr, "Unable to write uncompressed text");
 #endif
-         /* Mark this chunk as written */
-         info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
       }
    }
-#endif
+#endif /* tEXt */
+
 #if defined(PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED)
    if (info_ptr->unknown_chunks_num)
    {
        png_unknown_chunk *up;
 
        png_debug(5, "writing extra chunks");
 
        for (up = info_ptr->unknown_chunks;
             up < info_ptr->unknown_chunks + info_ptr->unknown_chunks_num;
             up++)
@@ skipping 19 matching lines @@
  */
 void PNGAPI
 png_write_end(png_structp png_ptr, png_infop info_ptr)
 {
    png_debug(1, "in png_write_end");
    if (png_ptr == NULL)
       return;
    if (!(png_ptr->mode & PNG_HAVE_IDAT))
       png_error(png_ptr, "No IDATs written into file");
 
-   /* see if user wants us to write information chunks */
+   /* See if user wants us to write information chunks */
    if (info_ptr != NULL)
    {
 #if defined(PNG_WRITE_TEXT_SUPPORTED)
-      int i; /* local index variable */
+      int i; /* Local index variable */
 #endif
 #if defined(PNG_WRITE_tIME_SUPPORTED)
-      /* check to see if user has supplied a time chunk */
+      /* Check to see if user has supplied a time chunk */
       if ((info_ptr->valid & PNG_INFO_tIME) &&
          !(png_ptr->mode & PNG_WROTE_tIME))
          png_write_tIME(png_ptr, &(info_ptr->mod_time));
 #endif
 #if defined(PNG_WRITE_TEXT_SUPPORTED)
-      /* loop through comment chunks */
+      /* Loop through comment chunks */
       for (i = 0; i < info_ptr->num_text; i++)
       {
          png_debug2(2, "Writing trailer text chunk %d, type %d", i,
             info_ptr->text[i].compression);
-         /* an internationalized chunk? */
+         /* An internationalized chunk? */
          if (info_ptr->text[i].compression > 0)
          {
 #if defined(PNG_WRITE_iTXt_SUPPORTED)
-             /* write international chunk */
+             /* Write international chunk */
              png_write_iTXt(png_ptr,
                          info_ptr->text[i].compression,
                          info_ptr->text[i].key,
                          info_ptr->text[i].lang,
                          info_ptr->text[i].lang_key,
                          info_ptr->text[i].text);
 #else
              png_warning(png_ptr, "Unable to write international text");
 #endif
              /* Mark this chunk as written */
              info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
          }
          else if (info_ptr->text[i].compression >= PNG_TEXT_COMPRESSION_zTXt)
          {
 #if defined(PNG_WRITE_zTXt_SUPPORTED)
-            /* write compressed chunk */
+            /* Write compressed chunk */
             png_write_zTXt(png_ptr, info_ptr->text[i].key,
                info_ptr->text[i].text, 0,
                info_ptr->text[i].compression);
 #else
             png_warning(png_ptr, "Unable to write compressed text");
 #endif
             /* Mark this chunk as written */
             info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
          }
          else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
          {
 #if defined(PNG_WRITE_tEXt_SUPPORTED)
-            /* write uncompressed chunk */
+            /* Write uncompressed chunk */
             png_write_tEXt(png_ptr, info_ptr->text[i].key,
                info_ptr->text[i].text, 0);
 #else
             png_warning(png_ptr, "Unable to write uncompressed text");
 #endif
 
             /* Mark this chunk as written */
             info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
          }
       }
@@ skipping 17 matching lines @@
          {
             png_write_chunk(png_ptr, up->name, up->data, up->size);
          }
        }
    }
 #endif
    }
 
    png_ptr->mode |= PNG_AFTER_IDAT;
 
-   /* write end of PNG file */
+   /* Write end of PNG file */
    png_write_IEND(png_ptr);
    /* This flush, added in libpng-1.0.8, removed from libpng-1.0.9beta03,
     * and restored again in libpng-1.2.30, may cause some applications that
     * do not set png_ptr->output_flush_fn to crash.  If your application
     * experiences a problem, please try building libpng with
     * PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED defined, and report the event to
     * png-mng-implement at lists.sf.net .  This kludge will be removed
     * from libpng-1.4.0.
     */
 #if defined(PNG_WRITE_FLUSH_SUPPORTED) && \
@@ skipping 59 matching lines @@
    png_debug(1, "in png_create_write_struct");
 #ifdef PNG_USER_MEM_SUPPORTED
    png_ptr = (png_structp)png_create_struct_2(PNG_STRUCT_PNG,
       (png_malloc_ptr)malloc_fn, (png_voidp)mem_ptr);
 #else
    png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG);
 #endif /* PNG_USER_MEM_SUPPORTED */
    if (png_ptr == NULL)
       return (NULL);
 
-   /* added at libpng-1.2.6 */
+   /* Added at libpng-1.2.6 */
 #ifdef PNG_SET_USER_LIMITS_SUPPORTED
    png_ptr->user_width_max=PNG_USER_WIDTH_MAX;
    png_ptr->user_height_max=PNG_USER_HEIGHT_MAX;
 #endif
 
 #ifdef PNG_SETJMP_SUPPORTED
 #ifdef USE_FAR_KEYWORD
    if (setjmp(jmpbuf))
 #else
    if (setjmp(png_ptr->jmpbuf))
@@ skipping 50 matching lines @@
         png_warning(png_ptr, msg);
 #endif
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
         png_ptr->flags=0;
 #endif
         png_error(png_ptr,
            "Incompatible libpng version in application and library");
      }
    }
 
-   /* initialize zbuf - compression buffer */
+   /* Initialize zbuf - compression buffer */
    png_ptr->zbuf_size = PNG_ZBUF_SIZE;
    png_ptr->zbuf = (png_bytep)png_malloc(png_ptr,
       (png_uint_32)png_ptr->zbuf_size);
 
    png_set_write_fn(png_ptr, png_voidp_NULL, png_rw_ptr_NULL,
       png_flush_ptr_NULL);
 
 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
    png_set_filter_heuristics(png_ptr, PNG_FILTER_HEURISTIC_DEFAULT,
       1, png_doublep_NULL, png_doublep_NULL);
@@ skipping 73 matching lines @@
 }
 #endif /* PNG_1_0_X || PNG_1_2_X */
 
 
 void PNGAPI
 png_write_init_3(png_structpp ptr_ptr, png_const_charp user_png_ver,
    png_size_t png_struct_size)
 {
    png_structp png_ptr=*ptr_ptr;
 #ifdef PNG_SETJMP_SUPPORTED
-   jmp_buf tmp_jmp; /* to save current jump buffer */
+   jmp_buf tmp_jmp; /* To save current jump buffer */
 #endif
 
    int i = 0;
 
    if (png_ptr == NULL)
       return;
 
    do
    {
      if (user_png_ver[i] != png_libpng_ver[i])
      {
 #ifdef PNG_LEGACY_SUPPORTED
        png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
 #else
        png_ptr->warning_fn=NULL;
        png_warning(png_ptr,
  "Application uses deprecated png_write_init() and should be recompiled.");
        break;
 #endif
      }
    } while (png_libpng_ver[i++]);
 
    png_debug(1, "in png_write_init_3");
 
 #ifdef PNG_SETJMP_SUPPORTED
-   /* save jump buffer and error functions */
+   /* Save jump buffer and error functions */
    png_memcpy(tmp_jmp, png_ptr->jmpbuf, png_sizeof(jmp_buf));
 #endif
 
    if (png_sizeof(png_struct) > png_struct_size)
      {
        png_destroy_struct(png_ptr);
        png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG);
        *ptr_ptr = png_ptr;
      }
 
-   /* reset all variables to 0 */
+   /* Reset all variables to 0 */
    png_memset(png_ptr, 0, png_sizeof(png_struct));
 
-   /* added at libpng-1.2.6 */
+   /* Added at libpng-1.2.6 */
 #ifdef PNG_SET_USER_LIMITS_SUPPORTED
    png_ptr->user_width_max=PNG_USER_WIDTH_MAX;
    png_ptr->user_height_max=PNG_USER_HEIGHT_MAX;
 #endif
 
 #ifdef PNG_SETJMP_SUPPORTED
-   /* restore jump buffer */
+   /* Restore jump buffer */
    png_memcpy(png_ptr->jmpbuf, tmp_jmp, png_sizeof(jmp_buf));
 #endif
 
    png_set_write_fn(png_ptr, png_voidp_NULL, png_rw_ptr_NULL,
       png_flush_ptr_NULL);
 
-   /* initialize zbuf - compression buffer */
+   /* Initialize zbuf - compression buffer */
    png_ptr->zbuf_size = PNG_ZBUF_SIZE;
    png_ptr->zbuf = (png_bytep)png_malloc(png_ptr,
       (png_uint_32)png_ptr->zbuf_size);
 
 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
    png_set_filter_heuristics(png_ptr, PNG_FILTER_HEURISTIC_DEFAULT,
       1, png_doublep_NULL, png_doublep_NULL);
 #endif
 }
 
 /* Write a few rows of image data.  If the image is interlaced,
  * either you will have to write the 7 sub images, or, if you
  * have called png_set_interlace_handling(), you will have to
  * "write" the image seven times.
  */
 void PNGAPI
 png_write_rows(png_structp png_ptr, png_bytepp row,
    png_uint_32 num_rows)
 {
-   png_uint_32 i; /* row counter */
-   png_bytepp rp; /* row pointer */
+   png_uint_32 i; /* Row counter */
+   png_bytepp rp; /* Row pointer */
 
    png_debug(1, "in png_write_rows");
 
    if (png_ptr == NULL)
       return;
 
-   /* loop through the rows */
+   /* Loop through the rows */
    for (i = 0, rp = row; i < num_rows; i++, rp++)
    {
       png_write_row(png_ptr, *rp);
    }
 }
 
 /* Write the image.  You only need to call this function once, even
  * if you are writing an interlaced image.
  */
 void PNGAPI
 png_write_image(png_structp png_ptr, png_bytepp image)
 {
-   png_uint_32 i; /* row index */
-   int pass, num_pass; /* pass variables */
-   png_bytepp rp; /* points to current row */
+   png_uint_32 i; /* Row index */
+   int pass, num_pass; /* Pass variables */
+   png_bytepp rp; /* Points to current row */
 
    if (png_ptr == NULL)
       return;
 
    png_debug(1, "in png_write_image");
 #if defined(PNG_WRITE_INTERLACING_SUPPORTED)
-   /* intialize interlace handling.  If image is not interlaced,
-      this will set pass to 1 */
+   /* Initialize interlace handling.  If image is not interlaced,
+    * this will set pass to 1
+    */
    num_pass = png_set_interlace_handling(png_ptr);
 #else
    num_pass = 1;
 #endif
-   /* loop through passes */
+   /* Loop through passes */
    for (pass = 0; pass < num_pass; pass++)
    {
-      /* loop through image */
+      /* Loop through image */
       for (i = 0, rp = image; i < png_ptr->height; i++, rp++)
       {
          png_write_row(png_ptr, *rp);
       }
    }
 }
 
-/* called by user to write a row of image data */
+/* Called by user to write a row of image data */
 void PNGAPI
 png_write_row(png_structp png_ptr, png_bytep row)
 {
    if (png_ptr == NULL)
       return;
    png_debug2(1, "in png_write_row (row %ld, pass %d)",
       png_ptr->row_number, png_ptr->pass);
 
-   /* initialize transformations and other stuff if first time */
+   /* Initialize transformations and other stuff if first time */
    if (png_ptr->row_number == 0 && png_ptr->pass == 0)
    {
-   /* make sure we wrote the header info */
-   if (!(png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE))
-      png_error(png_ptr,
-         "png_write_info was never called before png_write_row.");
+      /* Make sure we wrote the header info */
+      if (!(png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE))
+         png_error(png_ptr,
+            "png_write_info was never called before png_write_row.");
 
-   /* check for transforms that have been set but were defined out */
+      /* Check for transforms that have been set but were defined out */
 #if !defined(PNG_WRITE_INVERT_SUPPORTED) && defined(PNG_READ_INVERT_SUPPORTED)
-   if (png_ptr->transformations & PNG_INVERT_MONO)
-      png_warning(png_ptr, "PNG_WRITE_INVERT_SUPPORTED is not defined.");
+      if (png_ptr->transformations & PNG_INVERT_MONO)
+         png_warning(png_ptr, "PNG_WRITE_INVERT_SUPPORTED is not defined.");
 #endif
 #if !defined(PNG_WRITE_FILLER_SUPPORTED) && defined(PNG_READ_FILLER_SUPPORTED)
-   if (png_ptr->transformations & PNG_FILLER)
-      png_warning(png_ptr, "PNG_WRITE_FILLER_SUPPORTED is not defined.");
+      if (png_ptr->transformations & PNG_FILLER)
+         png_warning(png_ptr, "PNG_WRITE_FILLER_SUPPORTED is not defined.");
 #endif
 #if !defined(PNG_WRITE_PACKSWAP_SUPPORTED) && defined(PNG_READ_PACKSWAP_SUPPORTED)
-   if (png_ptr->transformations & PNG_PACKSWAP)
-      png_warning(png_ptr, "PNG_WRITE_PACKSWAP_SUPPORTED is not defined.");
+      if (png_ptr->transformations & PNG_PACKSWAP)
+         png_warning(png_ptr, "PNG_WRITE_PACKSWAP_SUPPORTED is not defined.");
 #endif
 #if !defined(PNG_WRITE_PACK_SUPPORTED) && defined(PNG_READ_PACK_SUPPORTED)
-   if (png_ptr->transformations & PNG_PACK)
-      png_warning(png_ptr, "PNG_WRITE_PACK_SUPPORTED is not defined.");
+      if (png_ptr->transformations & PNG_PACK)
+         png_warning(png_ptr, "PNG_WRITE_PACK_SUPPORTED is not defined.");
 #endif
 #if !defined(PNG_WRITE_SHIFT_SUPPORTED) && defined(PNG_READ_SHIFT_SUPPORTED)
-   if (png_ptr->transformations & PNG_SHIFT)
-      png_warning(png_ptr, "PNG_WRITE_SHIFT_SUPPORTED is not defined.");
+      if (png_ptr->transformations & PNG_SHIFT)
+         png_warning(png_ptr, "PNG_WRITE_SHIFT_SUPPORTED is not defined.");
 #endif
 #if !defined(PNG_WRITE_BGR_SUPPORTED) && defined(PNG_READ_BGR_SUPPORTED)
-   if (png_ptr->transformations & PNG_BGR)
-      png_warning(png_ptr, "PNG_WRITE_BGR_SUPPORTED is not defined.");
+      if (png_ptr->transformations & PNG_BGR)
+         png_warning(png_ptr, "PNG_WRITE_BGR_SUPPORTED is not defined.");
 #endif
 #if !defined(PNG_WRITE_SWAP_SUPPORTED) && defined(PNG_READ_SWAP_SUPPORTED)
-   if (png_ptr->transformations & PNG_SWAP_BYTES)
-      png_warning(png_ptr, "PNG_WRITE_SWAP_SUPPORTED is not defined.");
+      if (png_ptr->transformations & PNG_SWAP_BYTES)
+         png_warning(png_ptr, "PNG_WRITE_SWAP_SUPPORTED is not defined.");
 #endif
 
       png_write_start_row(png_ptr);
    }
 
 #if defined(PNG_WRITE_INTERLACING_SUPPORTED)
-   /* if interlaced and not interested in row, return */
+   /* If interlaced and not interested in row, return */
    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
    {
       switch (png_ptr->pass)
       {
          case 0:
             if (png_ptr->row_number & 0x07)
             {
                png_write_finish_row(png_ptr);
                return;
             }
@@ skipping 37 matching lines @@
             if (!(png_ptr->row_number & 0x01))
             {
                png_write_finish_row(png_ptr);
                return;
             }
             break;
       }
    }
 #endif
 
-   /* set up row info for transformations */
+   /* Set up row info for transformations */
    png_ptr->row_info.color_type = png_ptr->color_type;
    png_ptr->row_info.width = png_ptr->usr_width;
    png_ptr->row_info.channels = png_ptr->usr_channels;
    png_ptr->row_info.bit_depth = png_ptr->usr_bit_depth;
    png_ptr->row_info.pixel_depth = (png_byte)(png_ptr->row_info.bit_depth *
       png_ptr->row_info.channels);
 
    png_ptr->row_info.rowbytes = PNG_ROWBYTES(png_ptr->row_info.pixel_depth,
       png_ptr->row_info.width);
 
    png_debug1(3, "row_info->color_type = %d", png_ptr->row_info.color_type);
    png_debug1(3, "row_info->width = %lu", png_ptr->row_info.width);
    png_debug1(3, "row_info->channels = %d", png_ptr->row_info.channels);
    png_debug1(3, "row_info->bit_depth = %d", png_ptr->row_info.bit_depth);
    png_debug1(3, "row_info->pixel_depth = %d", png_ptr->row_info.pixel_depth);
    png_debug1(3, "row_info->rowbytes = %lu", png_ptr->row_info.rowbytes);
 
    /* Copy user's row into buffer, leaving room for filter byte. */
    png_memcpy_check(png_ptr, png_ptr->row_buf + 1, row,
       png_ptr->row_info.rowbytes);
 
 #if defined(PNG_WRITE_INTERLACING_SUPPORTED)
-   /* handle interlacing */
+   /* Handle interlacing */
    if (png_ptr->interlaced && png_ptr->pass < 6 &&
       (png_ptr->transformations & PNG_INTERLACE))
    {
       png_do_write_interlace(&(png_ptr->row_info),
          png_ptr->row_buf + 1, png_ptr->pass);
-      /* this should always get caught above, but still ... */
+      /* This should always get caught above, but still ... */
       if (!(png_ptr->row_info.width))
       {
          png_write_finish_row(png_ptr);
          return;
       }
    }
 #endif
 
-   /* handle other transformations */
+   /* Handle other transformations */
    if (png_ptr->transformations)
       png_do_write_transformations(png_ptr);
 
 #if defined(PNG_MNG_FEATURES_SUPPORTED)
    /* Write filter_method 64 (intrapixel differencing) only if
     * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
     * 2. Libpng did not write a PNG signature (this filter_method is only
     *    used in PNG datastreams that are embedded in MNG datastreams) and
     * 3. The application called png_permit_mng_features with a mask that
     *    included PNG_FLAG_MNG_FILTER_64 and
@@ skipping 19 matching lines @@
 /* Set the automatic flush interval or 0 to turn flushing off */
 void PNGAPI
 png_set_flush(png_structp png_ptr, int nrows)
 {
    png_debug(1, "in png_set_flush");
    if (png_ptr == NULL)
       return;
    png_ptr->flush_dist = (nrows < 0 ? 0 : nrows);
 }
 
-/* flush the current output buffers now */
+/* Flush the current output buffers now */
 void PNGAPI
 png_write_flush(png_structp png_ptr)
 {
    int wrote_IDAT;
 
    png_debug(1, "in png_write_flush");
    if (png_ptr == NULL)
       return;
    /* We have already written out all of the data */
    if (png_ptr->row_number >= png_ptr->num_rows)
-     return;
+      return;
 
    do
    {
       int ret;
 
-      /* compress the data */
+      /* Compress the data */
       ret = deflate(&png_ptr->zstream, Z_SYNC_FLUSH);
       wrote_IDAT = 0;
 
-      /* check for compression errors */
+      /* Check for compression errors */
       if (ret != Z_OK)
       {
          if (png_ptr->zstream.msg != NULL)
             png_error(png_ptr, png_ptr->zstream.msg);
          else
             png_error(png_ptr, "zlib error");
       }
 
       if (!(png_ptr->zstream.avail_out))
       {
-         /* write the IDAT and reset the zlib output buffer */
+         /* Write the IDAT and reset the zlib output buffer */
          png_write_IDAT(png_ptr, png_ptr->zbuf,
                         png_ptr->zbuf_size);
          png_ptr->zstream.next_out = png_ptr->zbuf;
          png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
          wrote_IDAT = 1;
       }
    } while(wrote_IDAT == 1);
 
    /* If there is any data left to be output, write it into a new IDAT */
    if (png_ptr->zbuf_size != png_ptr->zstream.avail_out)
    {
-      /* write the IDAT and reset the zlib output buffer */
+      /* Write the IDAT and reset the zlib output buffer */
       png_write_IDAT(png_ptr, png_ptr->zbuf,
                      png_ptr->zbuf_size - png_ptr->zstream.avail_out);
       png_ptr->zstream.next_out = png_ptr->zbuf;
       png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
    }
    png_ptr->flush_rows = 0;
    png_flush(png_ptr);
 }
 #endif /* PNG_WRITE_FLUSH_SUPPORTED */
 
-/* free all memory used by the write */
+/* Free all memory used by the write */
 void PNGAPI
 png_destroy_write_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
 {
    png_structp png_ptr = NULL;
    png_infop info_ptr = NULL;
 #ifdef PNG_USER_MEM_SUPPORTED
    png_free_ptr free_fn = NULL;
    png_voidp mem_ptr = NULL;
 #endif
 
@@ skipping 55 matching lines @@
       *png_ptr_ptr = NULL;
    }
 }
 
 
 /* Free any memory used in png_ptr struct (old method) */
 void /* PRIVATE */
 png_write_destroy(png_structp png_ptr)
 {
 #ifdef PNG_SETJMP_SUPPORTED
-   jmp_buf tmp_jmp; /* save jump buffer */
+   jmp_buf tmp_jmp; /* Save jump buffer */
 #endif
    png_error_ptr error_fn;
    png_error_ptr warning_fn;
    png_voidp error_ptr;
 #ifdef PNG_USER_MEM_SUPPORTED
    png_free_ptr free_fn;
 #endif
 
    png_debug(1, "in png_write_destroy");
-   /* free any memory zlib uses */
+   /* Free any memory zlib uses */
    deflateEnd(&png_ptr->zstream);
 
-   /* free our memory.  png_free checks NULL for us. */
+   /* Free our memory.  png_free checks NULL for us. */
    png_free(png_ptr, png_ptr->zbuf);
    png_free(png_ptr, png_ptr->row_buf);
 #ifndef PNG_NO_WRITE_FILTER
    png_free(png_ptr, png_ptr->prev_row);
    png_free(png_ptr, png_ptr->sub_row);
    png_free(png_ptr, png_ptr->up_row);
    png_free(png_ptr, png_ptr->avg_row);
    png_free(png_ptr, png_ptr->paeth_row);
 #endif
 
 #if defined(PNG_TIME_RFC1123_SUPPORTED)
    png_free(png_ptr, png_ptr->time_buffer);
 #endif
 
 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
    png_free(png_ptr, png_ptr->prev_filters);
    png_free(png_ptr, png_ptr->filter_weights);
    png_free(png_ptr, png_ptr->inv_filter_weights);
    png_free(png_ptr, png_ptr->filter_costs);
    png_free(png_ptr, png_ptr->inv_filter_costs);
 #endif
 
 #ifdef PNG_SETJMP_SUPPORTED
-   /* reset structure */
+   /* Reset structure */
    png_memcpy(tmp_jmp, png_ptr->jmpbuf, png_sizeof(jmp_buf));
 #endif
 
    error_fn = png_ptr->error_fn;
    warning_fn = png_ptr->warning_fn;
    error_ptr = png_ptr->error_ptr;
 #ifdef PNG_USER_MEM_SUPPORTED
    free_fn = png_ptr->free_fn;
 #endif
 
@@ skipping 282 matching lines @@
 void PNGAPI
 png_set_compression_window_bits(png_structp png_ptr, int window_bits)
 {
    if (png_ptr == NULL)
       return;
    if (window_bits > 15)
       png_warning(png_ptr, "Only compression windows <= 32k supported by PNG");
    else if (window_bits < 8)
       png_warning(png_ptr, "Only compression windows >= 256 supported by PNG");
 #ifndef WBITS_8_OK
-   /* avoid libpng bug with 256-byte windows */
+   /* Avoid libpng bug with 256-byte windows */
    if (window_bits == 8)
      {
        png_warning(png_ptr, "Compression window is being reset to 512");
        window_bits=9;
      }
 #endif
    png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS;
    png_ptr->zlib_window_bits = window_bits;
 }
 
@@ skipping 32 matching lines @@
 
 
 #if defined(PNG_INFO_IMAGE_SUPPORTED)
 void PNGAPI
 png_write_png(png_structp png_ptr, png_infop info_ptr,
               int transforms, voidp params)
 {
    if (png_ptr == NULL || info_ptr == NULL)
       return;
 #if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
-   /* invert the alpha channel from opacity to transparency */
+   /* Invert the alpha channel from opacity to transparency */
    if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
-       png_set_invert_alpha(png_ptr);
+      png_set_invert_alpha(png_ptr);
 #endif
 
    /* Write the file header information. */
    png_write_info(png_ptr, info_ptr);
 
    /* ------ these transformations don't touch the info structure ------- */
 
 #if defined(PNG_WRITE_INVERT_SUPPORTED)
-   /* invert monochrome pixels */
+   /* Invert monochrome pixels */
    if (transforms & PNG_TRANSFORM_INVERT_MONO)
-       png_set_invert_mono(png_ptr);
+      png_set_invert_mono(png_ptr);
 #endif
 
 #if defined(PNG_WRITE_SHIFT_SUPPORTED)
    /* Shift the pixels up to a legal bit depth and fill in
     * as appropriate to correctly scale the image.
     */
    if ((transforms & PNG_TRANSFORM_SHIFT)
                && (info_ptr->valid & PNG_INFO_sBIT))
-       png_set_shift(png_ptr, &info_ptr->sig_bit);
+      png_set_shift(png_ptr, &info_ptr->sig_bit);
 #endif
 
 #if defined(PNG_WRITE_PACK_SUPPORTED)
-   /* pack pixels into bytes */
+   /* Pack pixels into bytes */
    if (transforms & PNG_TRANSFORM_PACKING)
        png_set_packing(png_ptr);
 #endif
 
 #if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
-   /* swap location of alpha bytes from ARGB to RGBA */
+   /* Swap location of alpha bytes from ARGB to RGBA */
    if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
-       png_set_swap_alpha(png_ptr);
+      png_set_swap_alpha(png_ptr);
 #endif
 
 #if defined(PNG_WRITE_FILLER_SUPPORTED)
    /* Pack XRGB/RGBX/ARGB/RGBA into * RGB (4 channels -> 3 channels) */
-  if (transforms & PNG_TRANSFORM_STRIP_FILLER_AFTER)
+   if (transforms & PNG_TRANSFORM_STRIP_FILLER_AFTER)
       png_set_filler(png_ptr, 0, PNG_FILLER_AFTER);
-  else if (transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE)
+   else if (transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE)
       png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
 #endif
 
 #if defined(PNG_WRITE_BGR_SUPPORTED)
-   /* flip BGR pixels to RGB */
+   /* Flip BGR pixels to RGB */
    if (transforms & PNG_TRANSFORM_BGR)
-       png_set_bgr(png_ptr);
+      png_set_bgr(png_ptr);
 #endif
 
 #if defined(PNG_WRITE_SWAP_SUPPORTED)
-   /* swap bytes of 16-bit files to most significant byte first */
+   /* Swap bytes of 16-bit files to most significant byte first */
    if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
-       png_set_swap(png_ptr);
+      png_set_swap(png_ptr);
 #endif
 
 #if defined(PNG_WRITE_PACKSWAP_SUPPORTED)
-   /* swap bits of 1, 2, 4 bit packed pixel formats */
+   /* Swap bits of 1, 2, 4 bit packed pixel formats */
    if (transforms & PNG_TRANSFORM_PACKSWAP)
-       png_set_packswap(png_ptr);
+      png_set_packswap(png_ptr);
 #endif
 
    /* ----------------------- end of transformations ------------------- */
 
-   /* write the bits */
+   /* Write the bits */
    if (info_ptr->valid & PNG_INFO_IDAT)
        png_write_image(png_ptr, info_ptr->row_pointers);
 
    /* It is REQUIRED to call this to finish writing the rest of the file */
    png_write_end(png_ptr, info_ptr);
 
-   transforms = transforms; /* quiet compiler warnings */
+   transforms = transforms; /* Quiet compiler warnings */
    params = params;
 }
 #endif
 #endif /* PNG_WRITE_SUPPORTED */