libpng: update to 1.2.43

I unpacked libpng 1.2.43 and did:
 cd third_party/libpng
 for x in $(ls -1) ; do cp /tmp/libpng-1.2.43/$x .; done

The diffs appear to all be safe. The Chromium specific config is in pngusr.h
and isn't touched by this change.

1.2.43 fixes http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-0205

c7013d773eb45b8ed6a864e419e544106a0dd95d  /tmp/libpng-1.2.43.tar.xz

BUG=38512
TEST=none

http://codereview.chromium.org/1118002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@41972 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 217 insertions, 183 deletions

diff --git a/third_party/libpng/pngwrite.c b/third_party/libpng/pngwrite.c
index bd6263c..e411e81 100644
--- a/third_party/libpng/pngwrite.c
+++ b/third_party/libpng/pngwrite.c
@@ -1,15 +1,19 @@
 
 /* pngwrite.c - general routines to write a PNG file
  *
- * Last changed in libpng 1.2.37 [June 4, 2009]
- * For conditions of distribution and use, see copyright notice in png.h
- * Copyright (c) 1998-2009 Glenn Randers-Pehrson
+ * Last changed in libpng 1.2.42 [January 3, 2010]
+ * Copyright (c) 1998-2010 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.)
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
  */
 
 /* Get internal access to png.h */
 #define PNG_INTERNAL
+#define PNG_NO_PEDANTIC_WARNINGS
 #include "png.h"
 #ifdef PNG_WRITE_SUPPORTED
 
@@ -26,23 +30,26 @@ 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 */
-#if defined(PNG_MNG_FEATURES_SUPPORTED)
-   if ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE)&&(png_ptr->mng_features_permitted))
+   /* Write PNG signature */
+   png_write_sig(png_ptr);
+#ifdef 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;
+      png_ptr->mng_features_permitted = 0;
    }
 #endif
    /* 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)
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
       info_ptr->interlace_type);
 #else
       0);
@@ -50,7 +57,7 @@ png_write_info_before_PLTE(png_structp png_ptr, png_infop info_ptr)
    /* 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)
+#ifdef PNG_WRITE_gAMA_SUPPORTED
    if (info_ptr->valid & PNG_INFO_gAMA)
    {
 #  ifdef PNG_FLOATING_POINT_SUPPORTED
@@ -62,20 +69,20 @@ png_write_info_before_PLTE(png_structp png_ptr, png_infop info_ptr)
 #endif
    }
 #endif
-#if defined(PNG_WRITE_sRGB_SUPPORTED)
+#ifdef PNG_WRITE_sRGB_SUPPORTED
    if (info_ptr->valid & PNG_INFO_sRGB)
       png_write_sRGB(png_ptr, (int)info_ptr->srgb_intent);
 #endif
-#if defined(PNG_WRITE_iCCP_SUPPORTED)
+#ifdef PNG_WRITE_iCCP_SUPPORTED
    if (info_ptr->valid & PNG_INFO_iCCP)
       png_write_iCCP(png_ptr, info_ptr->iccp_name, PNG_COMPRESSION_TYPE_BASE,
                      info_ptr->iccp_profile, (int)info_ptr->iccp_proflen);
 #endif
-#if defined(PNG_WRITE_sBIT_SUPPORTED)
+#ifdef PNG_WRITE_sBIT_SUPPORTED
    if (info_ptr->valid & PNG_INFO_sBIT)
       png_write_sBIT(png_ptr, &(info_ptr->sig_bit), info_ptr->color_type);
 #endif
-#if defined(PNG_WRITE_cHRM_SUPPORTED)
+#ifdef PNG_WRITE_cHRM_SUPPORTED
    if (info_ptr->valid & PNG_INFO_cHRM)
    {
 #ifdef PNG_FLOATING_POINT_SUPPORTED
@@ -95,7 +102,7 @@ png_write_info_before_PLTE(png_structp png_ptr, png_infop info_ptr)
 #endif
    }
 #endif
-#if defined(PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED)
+#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
    if (info_ptr->unknown_chunks_num)
    {
       png_unknown_chunk *up;
@@ -106,7 +113,7 @@ png_write_info_before_PLTE(png_structp png_ptr, png_infop info_ptr)
            up < info_ptr->unknown_chunks + info_ptr->unknown_chunks_num;
            up++)
       {
-         int keep=png_handle_as_unknown(png_ptr, up->name);
+         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) &&
@@ -144,16 +151,16 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
    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)
+#ifdef PNG_WRITE_tRNS_SUPPORTED
    if (info_ptr->valid & PNG_INFO_tRNS)
    {
-#if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
+#ifdef 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++)
+         for (j = 0; j<(int)info_ptr->num_trans; j++)
             info_ptr->trans[j] = (png_byte)(255 - info_ptr->trans[j]);
       }
 #endif
@@ -161,30 +168,30 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
          info_ptr->num_trans, info_ptr->color_type);
    }
 #endif
-#if defined(PNG_WRITE_bKGD_SUPPORTED)
+#ifdef 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)
+#ifdef 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)
+#ifdef 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)
+#ifdef 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)
+#ifdef PNG_sCAL_SUPPORTED
    if (info_ptr->valid & PNG_INFO_sCAL)
-#if defined(PNG_WRITE_sCAL_SUPPORTED)
-#if defined(PNG_FLOATING_POINT_SUPPORTED) && !defined(PNG_NO_STDIO)
+#ifdef PNG_WRITE_sCAL_SUPPORTED
+#if defined(PNG_FLOATING_POINT_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
       png_write_sCAL(png_ptr, (int)info_ptr->scal_unit,
           info_ptr->scal_pixel_width, info_ptr->scal_pixel_height);
 #else /* !FLOATING_POINT */
@@ -199,13 +206,13 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
 #endif /* WRITE_sCAL */
 #endif /* sCAL */
 
-#if defined(PNG_WRITE_pHYs_SUPPORTED)
+#ifdef 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 /* pHYs */
 
-#if defined(PNG_WRITE_tIME_SUPPORTED)
+#ifdef PNG_WRITE_tIME_SUPPORTED
    if (info_ptr->valid & PNG_INFO_tIME)
    {
       png_write_tIME(png_ptr, &(info_ptr->mod_time));
@@ -213,13 +220,13 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
    }
 #endif /* tIME */
 
-#if defined(PNG_WRITE_sPLT_SUPPORTED)
+#ifdef 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 /* sPLT */
 
-#if defined(PNG_WRITE_TEXT_SUPPORTED)
+#ifdef PNG_WRITE_TEXT_SUPPORTED
    /* Check to see if we need to write text chunks */
    for (i = 0; i < info_ptr->num_text; i++)
    {
@@ -228,7 +235,7 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
       /* An internationalized chunk? */
       if (info_ptr->text[i].compression > 0)
       {
-#if defined(PNG_WRITE_iTXt_SUPPORTED)
+#ifdef PNG_WRITE_iTXt_SUPPORTED
           /* Write international chunk */
           png_write_iTXt(png_ptr,
                          info_ptr->text[i].compression,
@@ -245,7 +252,7 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
       /* If we want a compressed text chunk */
       else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_zTXt)
       {
-#if defined(PNG_WRITE_zTXt_SUPPORTED)
+#ifdef PNG_WRITE_zTXt_SUPPORTED
          /* Write compressed chunk */
          png_write_zTXt(png_ptr, info_ptr->text[i].key,
             info_ptr->text[i].text, 0,
@@ -258,7 +265,7 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
       }
       else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
       {
-#if defined(PNG_WRITE_tEXt_SUPPORTED)
+#ifdef PNG_WRITE_tEXt_SUPPORTED
          /* Write uncompressed chunk */
          png_write_tEXt(png_ptr, info_ptr->text[i].key,
                          info_ptr->text[i].text,
@@ -273,18 +280,18 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
    }
 #endif /* tEXt */
 
-#if defined(PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED)
+#ifdef 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++)
-       {
-         int keep=png_handle_as_unknown(png_ptr, up->name);
+      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) &&
@@ -293,7 +300,7 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
          {
             png_write_chunk(png_ptr, up->name, up->data, up->size);
          }
-       }
+      }
    }
 #endif
 }
@@ -307,6 +314,7 @@ 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))
@@ -315,16 +323,16 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
    /* See if user wants us to write information chunks */
    if (info_ptr != NULL)
    {
-#if defined(PNG_WRITE_TEXT_SUPPORTED)
-      int i; /* Local index variable */
+#ifdef PNG_WRITE_TEXT_SUPPORTED
+      int i; /* local index variable */
 #endif
-#if defined(PNG_WRITE_tIME_SUPPORTED)
+#ifdef PNG_WRITE_tIME_SUPPORTED
       /* 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)
+#ifdef PNG_WRITE_TEXT_SUPPORTED
       /* Loop through comment chunks */
       for (i = 0; i < info_ptr->num_text; i++)
       {
@@ -333,23 +341,23 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
          /* An internationalized chunk? */
          if (info_ptr->text[i].compression > 0)
          {
-#if defined(PNG_WRITE_iTXt_SUPPORTED)
-             /* 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);
+#ifdef PNG_WRITE_iTXt_SUPPORTED
+            /* 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");
+            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;
+            /* 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)
+#ifdef PNG_WRITE_zTXt_SUPPORTED
             /* Write compressed chunk */
             png_write_zTXt(png_ptr, info_ptr->text[i].key,
                info_ptr->text[i].text, 0,
@@ -362,7 +370,7 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
          }
          else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
          {
-#if defined(PNG_WRITE_tEXt_SUPPORTED)
+#ifdef PNG_WRITE_tEXt_SUPPORTED
             /* Write uncompressed chunk */
             png_write_tEXt(png_ptr, info_ptr->text[i].key,
                info_ptr->text[i].text, 0);
@@ -375,18 +383,18 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
          }
       }
 #endif
-#if defined(PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED)
+#ifdef 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++)
-       {
-         int keep=png_handle_as_unknown(png_ptr, up->name);
+      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_AFTER_IDAT) &&
             ((up->name[3] & 0x20) || keep == PNG_HANDLE_CHUNK_ALWAYS ||
@@ -394,7 +402,7 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
          {
             png_write_chunk(png_ptr, up->name, up->data, up->size);
          }
-       }
+      }
    }
 #endif
    }
@@ -408,22 +416,22 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
     * 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.
+    * png-mng-implement at lists.sf.net .
     */
-#if defined(PNG_WRITE_FLUSH_SUPPORTED) && \
-    defined(PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED)
+#ifdef PNG_WRITE_FLUSH_SUPPORTED
+#  ifdef PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED
    png_flush(png_ptr);
+#  endif
 #endif
 }
 
-#if defined(PNG_WRITE_tIME_SUPPORTED)
-#if !defined(_WIN32_WCE)
-/* "time.h" functions are not supported on WindowsCE */
+#ifdef PNG_CONVERT_tIME_SUPPORTED
+/* "tm" structure is not supported on WindowsCE */
 void PNGAPI
 png_convert_from_struct_tm(png_timep ptime, struct tm FAR * ttime)
 {
    png_debug(1, "in png_convert_from_struct_tm");
+
    ptime->year = (png_uint_16)(1900 + ttime->tm_year);
    ptime->month = (png_byte)(ttime->tm_mon + 1);
    ptime->day = (png_byte)ttime->tm_mday;
@@ -438,11 +446,11 @@ png_convert_from_time_t(png_timep ptime, time_t ttime)
    struct tm *tbuf;
 
    png_debug(1, "in png_convert_from_time_t");
+
    tbuf = gmtime(&ttime);
    png_convert_from_struct_tm(ptime, tbuf);
 }
 #endif
-#endif
 
 /* Initialize png_ptr structure, and allocate any memory needed */
 png_structp PNGAPI
@@ -462,16 +470,18 @@ png_create_write_struct_2(png_const_charp user_png_ver, png_voidp error_ptr,
 {
 #endif /* PNG_USER_MEM_SUPPORTED */
 #ifdef PNG_SETJMP_SUPPORTED
-    volatile
+   volatile
 #endif
-    png_structp png_ptr;
+   png_structp png_ptr;
 #ifdef PNG_SETJMP_SUPPORTED
 #ifdef USE_FAR_KEYWORD
    jmp_buf jmpbuf;
 #endif
 #endif
    int i;
+
    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);
@@ -483,8 +493,8 @@ png_create_write_struct_2(png_const_charp user_png_ver, png_voidp error_ptr,
 
    /* 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;
+   png_ptr->user_width_max = PNG_USER_WIDTH_MAX;
+   png_ptr->user_height_max = PNG_USER_HEIGHT_MAX;
 #endif
 
 #ifdef PNG_SETJMP_SUPPORTED
@@ -495,8 +505,13 @@ png_create_write_struct_2(png_const_charp user_png_ver, png_voidp error_ptr,
 #endif
    {
       png_free(png_ptr, png_ptr->zbuf);
-       png_ptr->zbuf=NULL;
-      png_destroy_struct(png_ptr);
+      png_ptr->zbuf = NULL;
+#ifdef PNG_USER_MEM_SUPPORTED
+      png_destroy_struct_2((png_voidp)png_ptr,
+         (png_free_ptr)free_fn, (png_voidp)mem_ptr);
+#else
+      png_destroy_struct((png_voidp)png_ptr);
+#endif
       return (NULL);
    }
 #ifdef USE_FAR_KEYWORD
@@ -511,12 +526,12 @@ png_create_write_struct_2(png_const_charp user_png_ver, png_voidp error_ptr,
 
    if (user_png_ver)
    {
-     i=0;
-     do
-     {
-       if (user_png_ver[i] != png_libpng_ver[i])
-          png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
-     } while (png_libpng_ver[i++]);
+      i = 0;
+      do
+      {
+         if (user_png_ver[i] != png_libpng_ver[i])
+            png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
+      } while (png_libpng_ver[i++]);
    }
 
    if (png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH)
@@ -530,14 +545,14 @@ png_create_write_struct_2(png_const_charp user_png_ver, png_voidp error_ptr,
          (user_png_ver[0] == '1' && user_png_ver[2] != png_libpng_ver[2]) ||
          (user_png_ver[0] == '0' && user_png_ver[2] < '9'))
      {
-#if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
+#if defined(PNG_STDIO_SUPPORTED) && !defined(_WIN32_WCE)
         char msg[80];
         if (user_png_ver)
         {
-          png_snprintf(msg, 80,
-             "Application was compiled with png.h from libpng-%.20s",
-             user_png_ver);
-          png_warning(png_ptr, msg);
+           png_snprintf(msg, 80,
+              "Application was compiled with png.h from libpng-%.20s",
+              user_png_ver);
+           png_warning(png_ptr, msg);
         }
         png_snprintf(msg, 80,
            "Application  is  running with png.c from libpng-%.20s",
@@ -545,7 +560,7 @@ png_create_write_struct_2(png_const_charp user_png_ver, png_voidp error_ptr,
         png_warning(png_ptr, msg);
 #endif
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
-        png_ptr->flags=0;
+        png_ptr->flags = 0;
 #endif
         png_error(png_ptr,
            "Incompatible libpng version in application and library");
@@ -555,20 +570,21 @@ png_create_write_struct_2(png_const_charp user_png_ver, png_voidp error_ptr,
    /* 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_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)
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
    png_set_filter_heuristics(png_ptr, PNG_FILTER_HEURISTIC_DEFAULT,
       1, png_doublep_NULL, png_doublep_NULL);
 #endif
 
 #ifdef PNG_SETJMP_SUPPORTED
-/* Applications that neglect to set up their own setjmp() and then encounter
-   a png_error() will longjmp here.  Since the jmpbuf is then meaningless we
-   abort instead of returning. */
+   /* Applications that neglect to set up their own setjmp() and then
+    * encounter a png_error() will longjmp here.  Since the jmpbuf is
+    * then meaningless we abort instead of returning.
+    */
 #ifdef USE_FAR_KEYWORD
    if (setjmp(jmpbuf))
       PNG_ABORT();
@@ -598,18 +614,18 @@ png_write_init_2(png_structp png_ptr, png_const_charp user_png_ver,
 {
    /* We only come here via pre-1.0.12-compiled applications */
    if (png_ptr == NULL) return;
-#if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
+#if defined(PNG_STDIO_SUPPORTED) && !defined(_WIN32_WCE)
    if (png_sizeof(png_struct) > png_struct_size ||
       png_sizeof(png_info) > png_info_size)
    {
       char msg[80];
-      png_ptr->warning_fn=NULL;
+      png_ptr->warning_fn = NULL;
       if (user_png_ver)
       {
-        png_snprintf(msg, 80,
-           "Application was compiled with png.h from libpng-%.20s",
-           user_png_ver);
-        png_warning(png_ptr, msg);
+         png_snprintf(msg, 80,
+            "Application was compiled with png.h from libpng-%.20s",
+            user_png_ver);
+         png_warning(png_ptr, msg);
       }
       png_snprintf(msg, 80,
          "Application  is  running with png.c from libpng-%.20s",
@@ -618,23 +634,25 @@ png_write_init_2(png_structp png_ptr, png_const_charp user_png_ver,
    }
 #endif
    if (png_sizeof(png_struct) > png_struct_size)
-     {
-       png_ptr->error_fn=NULL;
+   {
+      png_ptr->error_fn = NULL;
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
-       png_ptr->flags=0;
+      png_ptr->flags = 0;
 #endif
-       png_error(png_ptr,
-       "The png struct allocated by the application for writing is too small.");
-     }
+      png_error(png_ptr,
+      "The png struct allocated by the application for writing is"
+      " too small.");
+   }
    if (png_sizeof(png_info) > png_info_size)
-     {
-       png_ptr->error_fn=NULL;
+   {
+      png_ptr->error_fn = NULL;
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
-       png_ptr->flags=0;
+      png_ptr->flags = 0;
 #endif
-       png_error(png_ptr,
-       "The info struct allocated by the application for writing is too small.");
-     }
+      png_error(png_ptr,
+      "The info struct allocated by the application for writing is"
+      " too small.");
+   }
    png_write_init_3(&png_ptr, user_png_ver, png_struct_size);
 }
 #endif /* PNG_1_0_X || PNG_1_2_X */
@@ -644,9 +662,9 @@ 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;
+   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;
@@ -656,17 +674,16 @@ png_write_init_3(png_structpp ptr_ptr, png_const_charp user_png_ver,
 
    do
    {
-     if (user_png_ver[i] != png_libpng_ver[i])
-     {
+      if (user_png_ver[i] != png_libpng_ver[i])
+      {
 #ifdef PNG_LEGACY_SUPPORTED
-       png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
+         png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
 #else
-       png_ptr->warning_fn=NULL;
-       png_warning(png_ptr,
+         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");
@@ -677,19 +694,19 @@ png_write_init_3(png_structpp ptr_ptr, png_const_charp user_png_ver,
 #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;
-     }
+   {
+      png_destroy_struct(png_ptr);
+      png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG);
+      *ptr_ptr = png_ptr;
+   }
 
    /* Reset all variables to 0 */
    png_memset(png_ptr, 0, png_sizeof(png_struct));
 
    /* 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;
+   png_ptr->user_width_max = PNG_USER_WIDTH_MAX;
+   png_ptr->user_height_max = PNG_USER_HEIGHT_MAX;
 #endif
 
 #ifdef PNG_SETJMP_SUPPORTED
@@ -703,9 +720,8 @@ png_write_init_3(png_structpp ptr_ptr, png_const_charp user_png_ver,
    /* 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_uint_32)png_ptr->zbuf_size);
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
    png_set_filter_heuristics(png_ptr, PNG_FILTER_HEURISTIC_DEFAULT,
       1, png_doublep_NULL, png_doublep_NULL);
 #endif
@@ -720,8 +736,8 @@ 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");
 
@@ -741,15 +757,16 @@ png_write_rows(png_structp png_ptr, png_bytepp row,
 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)
+
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
    /* Initialize interlace handling.  If image is not interlaced,
     * this will set pass to 1
     */
@@ -774,6 +791,7 @@ 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);
 
@@ -788,15 +806,19 @@ png_write_row(png_structp png_ptr, png_bytep row)
       /* 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.");
+         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.");
+         png_warning(png_ptr,
+             "PNG_WRITE_FILLER_SUPPORTED is not defined.");
 #endif
-#if !defined(PNG_WRITE_PACKSWAP_SUPPORTED) && defined(PNG_READ_PACKSWAP_SUPPORTED)
+#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.");
+         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)
@@ -818,7 +840,7 @@ png_write_row(png_structp png_ptr, png_bytep row)
       png_write_start_row(png_ptr);
    }
 
-#if defined(PNG_WRITE_INTERLACING_SUPPORTED)
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
    /* If interlaced and not interested in row, return */
    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
    {
@@ -899,7 +921,7 @@ png_write_row(png_structp png_ptr, png_bytep row)
    png_memcpy_check(png_ptr, png_ptr->row_buf + 1, row,
       png_ptr->row_info.rowbytes);
 
-#if defined(PNG_WRITE_INTERLACING_SUPPORTED)
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
    /* Handle interlacing */
    if (png_ptr->interlaced && png_ptr->pass < 6 &&
       (png_ptr->transformations & PNG_INTERLACE))
@@ -919,7 +941,7 @@ png_write_row(png_structp png_ptr, png_bytep row)
    if (png_ptr->transformations)
       png_do_write_transformations(png_ptr);
 
-#if defined(PNG_MNG_FEATURES_SUPPORTED)
+#ifdef 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
@@ -944,12 +966,13 @@ png_write_row(png_structp png_ptr, png_bytep row)
       (*(png_ptr->write_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
 }
 
-#if defined(PNG_WRITE_FLUSH_SUPPORTED)
+#ifdef PNG_WRITE_FLUSH_SUPPORTED
 /* 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);
@@ -962,6 +985,7 @@ 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 */
@@ -1022,6 +1046,7 @@ png_destroy_write_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
 #endif
 
    png_debug(1, "in png_destroy_write_struct");
+
    if (png_ptr_ptr != NULL)
    {
       png_ptr = *png_ptr_ptr;
@@ -1048,11 +1073,11 @@ png_destroy_write_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
       {
         png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
 
-#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
+#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
         if (png_ptr->num_chunk_list)
         {
            png_free(png_ptr, png_ptr->chunk_list);
-           png_ptr->chunk_list=NULL;
+           png_ptr->chunk_list = NULL;
            png_ptr->num_chunk_list = 0;
         }
 #endif
@@ -1096,13 +1121,14 @@ png_write_destroy(png_structp png_ptr)
 #endif
 
    png_debug(1, "in png_write_destroy");
+
    /* Free any memory zlib uses */
    deflateEnd(&png_ptr->zstream);
 
    /* 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
+#ifdef PNG_WRITE_FILTER_SUPPORTED
    png_free(png_ptr, png_ptr->prev_row);
    png_free(png_ptr, png_ptr->sub_row);
    png_free(png_ptr, png_ptr->up_row);
@@ -1110,11 +1136,11 @@ png_write_destroy(png_structp png_ptr)
    png_free(png_ptr, png_ptr->paeth_row);
 #endif
 
-#if defined(PNG_TIME_RFC1123_SUPPORTED)
+#ifdef PNG_TIME_RFC1123_SUPPORTED
    png_free(png_ptr, png_ptr->time_buffer);
 #endif
 
-#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
+#ifdef 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);
@@ -1153,9 +1179,10 @@ void PNGAPI
 png_set_filter(png_structp png_ptr, int method, int filters)
 {
    png_debug(1, "in png_set_filter");
+
    if (png_ptr == NULL)
       return;
-#if defined(PNG_MNG_FEATURES_SUPPORTED)
+#ifdef PNG_MNG_FEATURES_SUPPORTED
    if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
       (method == PNG_INTRAPIXEL_DIFFERENCING))
          method = PNG_FILTER_TYPE_BASE;
@@ -1164,26 +1191,26 @@ png_set_filter(png_structp png_ptr, int method, int filters)
    {
       switch (filters & (PNG_ALL_FILTERS | 0x07))
       {
-#ifndef PNG_NO_WRITE_FILTER
+#ifdef PNG_WRITE_FILTER_SUPPORTED
          case 5:
          case 6:
          case 7: png_warning(png_ptr, "Unknown row filter for method 0");
-#endif /* PNG_NO_WRITE_FILTER */
+#endif /* PNG_WRITE_FILTER_SUPPORTED */
          case PNG_FILTER_VALUE_NONE:
-              png_ptr->do_filter=PNG_FILTER_NONE; break;
-#ifndef PNG_NO_WRITE_FILTER
+              png_ptr->do_filter = PNG_FILTER_NONE; break;
+#ifdef PNG_WRITE_FILTER_SUPPORTED
          case PNG_FILTER_VALUE_SUB:
-              png_ptr->do_filter=PNG_FILTER_SUB; break;
+              png_ptr->do_filter = PNG_FILTER_SUB; break;
          case PNG_FILTER_VALUE_UP:
-              png_ptr->do_filter=PNG_FILTER_UP; break;
+              png_ptr->do_filter = PNG_FILTER_UP; break;
          case PNG_FILTER_VALUE_AVG:
-              png_ptr->do_filter=PNG_FILTER_AVG; break;
+              png_ptr->do_filter = PNG_FILTER_AVG; break;
          case PNG_FILTER_VALUE_PAETH:
-              png_ptr->do_filter=PNG_FILTER_PAETH; break;
+              png_ptr->do_filter = PNG_FILTER_PAETH; break;
          default: png_ptr->do_filter = (png_byte)filters; break;
 #else
          default: png_warning(png_ptr, "Unknown row filter for method 0");
-#endif /* PNG_NO_WRITE_FILTER */
+#endif /* PNG_WRITE_FILTER_SUPPORTED */
       }
 
       /* If we have allocated the row_buf, this means we have already started
@@ -1197,7 +1224,7 @@ png_set_filter(png_structp png_ptr, int method, int filters)
        */
       if (png_ptr->row_buf != NULL)
       {
-#ifndef PNG_NO_WRITE_FILTER
+#ifdef PNG_WRITE_FILTER_SUPPORTED
          if ((png_ptr->do_filter & PNG_FILTER_SUB) && png_ptr->sub_row == NULL)
          {
             png_ptr->sub_row = (png_bytep)png_malloc(png_ptr,
@@ -1252,7 +1279,7 @@ png_set_filter(png_structp png_ptr, int method, int filters)
          }
 
          if (png_ptr->do_filter == PNG_NO_FILTERS)
-#endif /* PNG_NO_WRITE_FILTER */
+#endif /* PNG_WRITE_FILTER_SUPPORTED */
             png_ptr->do_filter = PNG_FILTER_NONE;
       }
    }
@@ -1267,7 +1294,7 @@ png_set_filter(png_structp png_ptr, int method, int filters)
  * filtered data going to zlib more consistent, hopefully resulting in
  * better compression.
  */
-#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)      /* GRR 970116 */
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED      /* GRR 970116 */
 void PNGAPI
 png_set_filter_heuristics(png_structp png_ptr, int heuristic_method,
    int num_weights, png_doublep filter_weights,
@@ -1276,6 +1303,7 @@ png_set_filter_heuristics(png_structp png_ptr, int heuristic_method,
    int i;
 
    png_debug(1, "in png_set_filter_heuristics");
+
    if (png_ptr == NULL)
       return;
    if (heuristic_method >= PNG_FILTER_HEURISTIC_LAST)
@@ -1390,6 +1418,7 @@ void PNGAPI
 png_set_compression_level(png_structp png_ptr, int level)
 {
    png_debug(1, "in png_set_compression_level");
+
    if (png_ptr == NULL)
       return;
    png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_LEVEL;
@@ -1400,6 +1429,7 @@ void PNGAPI
 png_set_compression_mem_level(png_structp png_ptr, int mem_level)
 {
    png_debug(1, "in png_set_compression_mem_level");
+
    if (png_ptr == NULL)
       return;
    png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL;
@@ -1410,6 +1440,7 @@ void PNGAPI
 png_set_compression_strategy(png_structp png_ptr, int strategy)
 {
    png_debug(1, "in png_set_compression_strategy");
+
    if (png_ptr == NULL)
       return;
    png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_STRATEGY;
@@ -1430,7 +1461,7 @@ png_set_compression_window_bits(png_structp png_ptr, int window_bits)
    if (window_bits == 8)
      {
        png_warning(png_ptr, "Compression window is being reset to 512");
-       window_bits=9;
+       window_bits = 9;
      }
 #endif
    png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS;
@@ -1441,6 +1472,7 @@ void PNGAPI
 png_set_compression_method(png_structp png_ptr, int method)
 {
    png_debug(1, "in png_set_compression_method");
+
    if (png_ptr == NULL)
       return;
    if (method != 8)
@@ -1457,12 +1489,13 @@ png_set_write_status_fn(png_structp png_ptr, png_write_status_ptr write_row_fn)
    png_ptr->write_row_fn = write_row_fn;
 }
 
-#if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
+#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
 void PNGAPI
 png_set_write_user_transform_fn(png_structp png_ptr, png_user_transform_ptr
    write_user_transform_fn)
 {
    png_debug(1, "in png_set_write_user_transform_fn");
+
    if (png_ptr == NULL)
       return;
    png_ptr->transformations |= PNG_USER_TRANSFORM;
@@ -1471,31 +1504,26 @@ png_set_write_user_transform_fn(png_structp png_ptr, png_user_transform_ptr
 #endif
 
 
-#if defined(PNG_INFO_IMAGE_SUPPORTED)
+#ifdef 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 */
-   if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
-      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)
+#ifdef PNG_WRITE_INVERT_SUPPORTED
    /* Invert monochrome pixels */
    if (transforms & PNG_TRANSFORM_INVERT_MONO)
       png_set_invert_mono(png_ptr);
 #endif
 
-#if defined(PNG_WRITE_SHIFT_SUPPORTED)
+#ifdef PNG_WRITE_SHIFT_SUPPORTED
    /* Shift the pixels up to a legal bit depth and fill in
     * as appropriate to correctly scale the image.
     */
@@ -1504,19 +1532,19 @@ png_write_png(png_structp png_ptr, png_infop info_ptr,
       png_set_shift(png_ptr, &info_ptr->sig_bit);
 #endif
 
-#if defined(PNG_WRITE_PACK_SUPPORTED)
+#ifdef PNG_WRITE_PACK_SUPPORTED
    /* Pack pixels into bytes */
    if (transforms & PNG_TRANSFORM_PACKING)
        png_set_packing(png_ptr);
 #endif
 
-#if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
+#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
    /* Swap location of alpha bytes from ARGB to RGBA */
    if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
       png_set_swap_alpha(png_ptr);
 #endif
 
-#if defined(PNG_WRITE_FILLER_SUPPORTED)
+#ifdef PNG_WRITE_FILLER_SUPPORTED
    /* Pack XRGB/RGBX/ARGB/RGBA into * RGB (4 channels -> 3 channels) */
    if (transforms & PNG_TRANSFORM_STRIP_FILLER_AFTER)
       png_set_filler(png_ptr, 0, PNG_FILLER_AFTER);
@@ -1524,24 +1552,30 @@ png_write_png(png_structp png_ptr, png_infop info_ptr,
       png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
 #endif
 
-#if defined(PNG_WRITE_BGR_SUPPORTED)
+#ifdef PNG_WRITE_BGR_SUPPORTED
    /* Flip BGR pixels to RGB */
    if (transforms & PNG_TRANSFORM_BGR)
       png_set_bgr(png_ptr);
 #endif
 
-#if defined(PNG_WRITE_SWAP_SUPPORTED)
+#ifdef PNG_WRITE_SWAP_SUPPORTED
    /* Swap bytes of 16-bit files to most significant byte first */
    if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
       png_set_swap(png_ptr);
 #endif
 
-#if defined(PNG_WRITE_PACKSWAP_SUPPORTED)
+#ifdef PNG_WRITE_PACKSWAP_SUPPORTED
    /* Swap bits of 1, 2, 4 bit packed pixel formats */
    if (transforms & PNG_TRANSFORM_PACKSWAP)
       png_set_packswap(png_ptr);
 #endif
 
+#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
+   /* Invert the alpha channel from opacity to transparency */
+   if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
+      png_set_invert_alpha(png_ptr);
+#endif
+
    /* ----------------------- end of transformations ------------------- */
 
    /* Write the bits */