Diff of /v3p/png/pngwrite.c [b8853e] .. [1fae15] Maximize Restore

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--- a/v3p/png/pngwrite.c
+++ b/v3p/png/pngwrite.c
@@ -1,16 +1,18 @@
 
 /* pngwrite.c - general routines to write a PNG file
  *
- * libpng 1.2.8rc5 - November 29, 2004
- * For conditions of distribution and use, see copyright notice in png.h
- * Copyright (c) 1998-2004 Glenn Randers-Pehrson
+ * Last changed in libpng 1.5.10 [March 8, 2012]
+ * Copyright (c) 1998-2012 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
-#include "png.h"
+#include "pngpriv.h"
+
 #ifdef PNG_WRITE_SUPPORTED
 
 /* Writes all the PNG information.  This is the suggested way to use the
@@ -25,258 +27,264 @@
 void PNGAPI
 png_write_info_before_PLTE(png_structp png_ptr, png_infop info_ptr)
 {
-   png_debug(1, "in png_write_info_before_PLTE\n");
+   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))
-   {
-      png_warning(png_ptr,"MNG features are not allowed in a PNG datastream\n");
-      png_ptr->mng_features_permitted=0;
-   }
-#endif
-   /* write IHDR information. */
+   /* 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;
+   }
+#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)
-      info_ptr->interlace_type);
+       info_ptr->bit_depth, info_ptr->color_type, info_ptr->compression_type,
+       info_ptr->filter_type,
+#ifdef 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. */
-#if defined(PNG_WRITE_gAMA_SUPPORTED)
+       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.
+    */
+#ifdef 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
-   }
-#endif
-#if defined(PNG_WRITE_sRGB_SUPPORTED)
+      png_write_gAMA_fixed(png_ptr, info_ptr->gamma);
+#endif
+#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)
+          (png_charp)info_ptr->iccp_profile, (int)info_ptr->iccp_proflen);
+#endif
+#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
-      png_write_cHRM(png_ptr,
-         info_ptr->x_white, info_ptr->y_white,
-         info_ptr->x_red, info_ptr->y_red,
-         info_ptr->x_green, info_ptr->y_green,
-         info_ptr->x_blue, info_ptr->y_blue);
+      png_write_cHRM_fixed(png_ptr,
+          info_ptr->x_white, info_ptr->y_white,
+          info_ptr->x_red, info_ptr->y_red,
+          info_ptr->x_green, info_ptr->y_green,
+          info_ptr->x_blue, info_ptr->y_blue);
+#endif
+
+#ifdef 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++)
+      {
+         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->location & PNG_AFTER_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");
+
+#ifdef PNG_WRITE_tRNS_SUPPORTED
+   if (info_ptr->valid & PNG_INFO_tRNS)
+   {
+#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++)
+            info_ptr->trans_alpha[j] =
+               (png_byte)(255 - info_ptr->trans_alpha[j]);
+      }
+#endif
+      png_write_tRNS(png_ptr, info_ptr->trans_alpha, &(info_ptr->trans_color),
+          info_ptr->num_trans, info_ptr->color_type);
+   }
+#endif
+#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
+
+#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
+
+#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
+
+#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
+
+#ifdef PNG_WRITE_sCAL_SUPPORTED
+   if (info_ptr->valid & PNG_INFO_sCAL)
+      png_write_sCAL_s(png_ptr, (int)info_ptr->scal_unit,
+          info_ptr->scal_s_width, info_ptr->scal_s_height);
+#endif /* sCAL */
+
+#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 */
+
+#ifdef 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 /* tIME */
+
+#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 */
+
+#ifdef 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? */
+      if (info_ptr->text[i].compression > 0)
+      {
+#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
-#  ifdef PNG_FIXED_POINT_SUPPORTED
-      png_write_cHRM_fixed(png_ptr,
-         info_ptr->int_x_white, info_ptr->int_y_white,
-         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)
+          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)
+      {
+#ifdef PNG_WRITE_zTXt_SUPPORTED
+         /* 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)
+      {
+#ifdef PNG_WRITE_tEXt_SUPPORTED
+         /* 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
+      }
+   }
+#endif /* tEXt */
+
+#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
    if (info_ptr->unknown_chunks_num)
    {
-       png_unknown_chunk *up;
-
-       png_debug(5, "writing extra chunks\n");
-
-       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);
+      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++)
+      {
+         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)))
+             up->location &&
+             (up->location & PNG_HAVE_PLTE) &&
+             !(up->location & PNG_HAVE_IDAT) &&
+             !(up->location & PNG_AFTER_IDAT) &&
+             ((up->name[3] & 0x20) || keep == PNG_HANDLE_CHUNK_ALWAYS ||
+             (png_ptr->flags & PNG_FLAG_KEEP_UNSAFE_CHUNKS)))
          {
             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\n");
-
-   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\n");
-
-#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)
-         {
-            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_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
-#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
-      png_warning(png_ptr,
-          "png_write_sCAL not supported; sCAL chunk not written.\n");
-#endif
-#endif
-#endif
-#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
-#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
-#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
-#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\n", i,
-         info_ptr->text[i].compression);
-      /* 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);
-#else
-          png_warning(png_ptr, "Unable to write international text\n");
-#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 */
-         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\n");
-#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 */
-         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\n");
-#endif
-         /* Mark this chunk as written */
-         info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
-      }
-   }
-#endif
-#if defined(PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED)
-   if (info_ptr->unknown_chunks_num)
-   {
-       png_unknown_chunk *up;
-
-       png_debug(5, "writing extra chunks\n");
-
-       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)))
-         {
-            png_write_chunk(png_ptr, up->name, up->data, up->size);
-         }
-       }
+      }
    }
 #endif
 }
@@ -289,66 +297,78 @@
 void PNGAPI
 png_write_end(png_structp png_ptr, png_infop info_ptr)
 {
-   png_debug(1, "in png_write_end\n");
+   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 */
+#ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
+   if (png_ptr->num_palette_max > png_ptr->num_palette)
+      png_benign_error(png_ptr, "Wrote palette index exceeding num_palette");
+#endif
+
+   /* See if user wants us to write information chunks */
    if (info_ptr != NULL)
    {
-#if defined(PNG_WRITE_TEXT_SUPPORTED)
+#ifdef PNG_WRITE_TEXT_SUPPORTED
       int i; /* local index variable */
 #endif
-#if defined(PNG_WRITE_tIME_SUPPORTED)
-      /* check to see if user has supplied a time chunk */
+#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_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 */
+
+#endif
+#ifdef PNG_WRITE_TEXT_SUPPORTED
+      /* Loop through comment chunks */
       for (i = 0; i < info_ptr->num_text; i++)
       {
-         png_debug2(2, "Writing trailer text chunk %d, type %d\n", 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 */
-             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\n");
-#endif
-             /* Mark this chunk as written */
-             info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
+            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 */
+#ifdef PNG_WRITE_zTXt_SUPPORTED
+            /* Write compressed chunk */
             png_write_zTXt(png_ptr, info_ptr->text[i].key,
-               info_ptr->text[i].text, 0,
-               info_ptr->text[i].compression);
+                info_ptr->text[i].text, 0,
+                info_ptr->text[i].compression);
 #else
-            png_warning(png_ptr, "Unable to write compressed text\n");
+            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 */
+#ifdef PNG_WRITE_tEXt_SUPPORTED
+            /* Write uncompressed chunk */
             png_write_tEXt(png_ptr, info_ptr->text[i].key,
-               info_ptr->text[i].text, 0);
+                info_ptr->text[i].text, 0);
 #else
-            png_warning(png_ptr, "Unable to write uncompressed text\n");
+            png_warning(png_ptr, "Unable to write uncompressed text");
 #endif
 
             /* Mark this chunk as written */
@@ -356,48 +376,56 @@
          }
       }
 #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_debug(5, "writing extra chunks\n");
-
-       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);
+      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++)
+      {
+         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 ||
-            (png_ptr->flags & PNG_FLAG_KEEP_UNSAFE_CHUNKS)))
+             up->location &&
+             (up->location & PNG_AFTER_IDAT) &&
+             ((up->name[3] & 0x20) || keep == PNG_HANDLE_CHUNK_ALWAYS ||
+             (png_ptr->flags & PNG_FLAG_KEEP_UNSAFE_CHUNKS)))
          {
             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);
-#if 0
-/* This flush, added in libpng-1.0.8,  causes some applications to crash
-   because they do not set png_ptr->output_flush_fn */
+   /* 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 .
+    */
+#ifdef PNG_WRITE_FLUSH_SUPPORTED
+#  ifdef PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED
    png_flush(png_ptr);
-#endif
-}
-
-#if defined(PNG_WRITE_tIME_SUPPORTED)
-#if !defined(_WIN32_WCE)
-/* "time.h" functions are 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\n");
+#  endif
+#endif
+}
+
+#ifdef PNG_CONVERT_tIME_SUPPORTED
+/* "tm" structure is not supported on WindowsCE */
+void PNGAPI
+png_convert_from_struct_tm(png_timep ptime, PNG_CONST 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;
@@ -411,74 +439,74 @@
 {
    struct tm *tbuf;
 
-   png_debug(1, "in png_convert_from_time_t\n");
+   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
-png_create_write_struct(png_const_charp user_png_ver, png_voidp error_ptr,
-                        png_error_ptr error_fn, png_error_ptr warn_fn)
+PNG_FUNCTION(png_structp,PNGAPI
+png_create_write_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
+    png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
 {
 #ifdef PNG_USER_MEM_SUPPORTED
-   return png_create_write_struct_2(user_png_ver, error_ptr, error_fn,
-               warn_fn, png_voidp_NULL, png_malloc_ptr_NULL, png_free_ptr_NULL);
+   return (png_create_write_struct_2(user_png_ver, error_ptr, error_fn,
+       warn_fn, NULL, NULL, NULL));
 }
 
 /* Alternate initialize png_ptr structure, and allocate any memory needed */
-png_structp PNGAPI
-png_create_write_struct_2(png_const_charp user_png_ver, png_voidp error_ptr,
-   png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
-   png_malloc_ptr malloc_fn, png_free_ptr free_fn)
+static void png_reset_filter_heuristics(png_structp png_ptr); /* forward decl */
+
+PNG_FUNCTION(png_structp,PNGAPI
+png_create_write_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
+    png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
+    png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
 {
 #endif /* PNG_USER_MEM_SUPPORTED */
+   volatile int png_cleanup_needed = 0;
+#ifdef PNG_SETJMP_SUPPORTED
+   volatile
+#endif
    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\n");
+   jmp_buf tmp_jmpbuf;
+#endif
+#endif
+
+   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);
+       (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;
-
-#if !defined(PNG_1_0_X)
-#ifdef PNG_ASSEMBLER_CODE_SUPPORTED
-   png_init_mmx_flags(png_ptr);   /* 1.2.0 addition */
-#endif
-#endif /* PNG_1_0_X */
-
-   /* added at libpng-1.2.6 */
+      return (NULL);
+
+   /* 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
+/* 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))
+   if (setjmp(tmp_jmpbuf))
 #else
-   if (setjmp(png_ptr->jmpbuf))
-#endif
-   {
-      png_free(png_ptr, png_ptr->zbuf);
-      png_ptr->zbuf=NULL;
-      png_destroy_struct(png_ptr);
-      return NULL;
-   }
+   if (setjmp(png_jmpbuf(png_ptr))) /* sets longjmp to match setjmp */
+#endif
 #ifdef USE_FAR_KEYWORD
-   png_memcpy(png_ptr->jmpbuf,jmpbuf,png_sizeof(jmp_buf));
-#endif
+   png_memcpy(png_jmpbuf(png_ptr), tmp_jmpbuf, png_sizeof(jmp_buf));
+#endif
+      PNG_ABORT();
 #endif
 
 #ifdef PNG_USER_MEM_SUPPORTED
@@ -486,197 +514,43 @@
 #endif /* PNG_USER_MEM_SUPPORTED */
    png_set_error_fn(png_ptr, error_ptr, error_fn, warn_fn);
 
-   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)
-   {
-     /* Libpng 0.90 and later are binary incompatible with libpng 0.89, so
-      * we must recompile any applications that use any older library version.
-      * For versions after libpng 1.0, we will be compatible, so we need
-      * only check the first digit.
-      */
-     if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0] ||
-         (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)
-        char msg[80];
-        if (user_png_ver)
-        {
-          sprintf(msg, "Application was compiled with png.h from libpng-%.20s",
-             user_png_ver);
-          png_warning(png_ptr, msg);
-        }
-        sprintf(msg, "Application  is  running with png.c from libpng-%.20s",
-           png_libpng_ver);
-        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 */
+   if (!png_user_version_check(png_ptr, user_png_ver))
+      png_cleanup_needed = 1;
+
+   /* 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);
-#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. */
-#ifdef USE_FAR_KEYWORD
-   if (setjmp(jmpbuf))
-      PNG_ABORT();
-   png_memcpy(png_ptr->jmpbuf,jmpbuf,png_sizeof(jmp_buf));
+
+   if (!png_cleanup_needed)
+   {
+      png_ptr->zbuf = (png_bytep)png_malloc_warn(png_ptr,
+          png_ptr->zbuf_size);
+      if (png_ptr->zbuf == NULL)
+         png_cleanup_needed = 1;
+   }
+
+   if (png_cleanup_needed)
+   {
+       /* Clean up PNG structure and deallocate any memory. */
+       png_free(png_ptr, png_ptr->zbuf);
+       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
-   if (setjmp(png_ptr->jmpbuf))
-      PNG_ABORT();
-#endif
-#endif
-   return png_ptr;
-}
-
-/* Initialize png_ptr structure, and allocate any memory needed */
-#undef png_write_init
-void PNGAPI
-png_write_init(png_structp png_ptr)
-{
-   /* We only come here via pre-1.0.7-compiled applications */
-   png_write_init_2(png_ptr, "1.0.6 or earlier", 0, 0);
-}
-
-void PNGAPI
-png_write_init_2(png_structp png_ptr, png_const_charp user_png_ver,
-                 png_size_t png_struct_size, png_size_t png_info_size)
-{
-   /* We only come here via pre-1.0.12-compiled applications */
-#if !defined(PNG_NO_STDIO) && !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;
-      if (user_png_ver)
-      {
-        sprintf(msg, "Application was compiled with png.h from libpng-%.20s",
-           user_png_ver);
-        png_warning(png_ptr, msg);
-      }
-      sprintf(msg, "Application  is  running with png.c from libpng-%.20s",
-         png_libpng_ver);
-      png_warning(png_ptr, msg);
-   }
-#endif
-   if (png_sizeof(png_struct) > png_struct_size)
-     {
-       png_ptr->error_fn=NULL;
-#ifdef PNG_ERROR_NUMBERS_SUPPORTED
-       png_ptr->flags=0;
-#endif
-       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;
-#ifdef PNG_ERROR_NUMBERS_SUPPORTED
-       png_ptr->flags=0;
-#endif
-       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);
-}
-
-
-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 */
-#endif
-   int i = 0;
-   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\n");
-
-#ifdef PNG_SETJMP_SUPPORTED
-   /* 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 */
-   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;
-#endif
-
-#if !defined(PNG_1_0_X)
-#ifdef PNG_ASSEMBLER_CODE_SUPPORTED
-   png_init_mmx_flags(png_ptr);   /* 1.2.0 addition */
-#endif
-#endif /* PNG_1_0_X */
-
-#ifdef PNG_SETJMP_SUPPORTED
-   /* 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 */
-   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
-}
+       png_destroy_struct((png_voidp)png_ptr);
+#endif
+       return (NULL);
+   }
+
+   png_set_write_fn(png_ptr, NULL, NULL, NULL);
+
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+   png_reset_filter_heuristics(png_ptr);
+#endif
+
+   return (png_ptr);
+}
+
 
 /* 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
@@ -685,13 +559,17 @@
  */
 void PNGAPI
 png_write_rows(png_structp png_ptr, png_bytepp row,
-               png_uint_32 num_rows)
+    png_uint_32 num_rows)
 {
    png_uint_32 i; /* row counter */
    png_bytepp rp; /* row pointer */
 
-   png_debug(1, "in png_write_rows\n");
-   /* loop through the rows */
+   png_debug(1, "in png_write_rows");
+
+   if (png_ptr == NULL)
+      return;
+
+   /* Loop through the rows */
    for (i = 0, rp = row; i < num_rows; i++, rp++)
    {
       png_write_row(png_ptr, *rp);
@@ -708,18 +586,23 @@
    int pass, num_pass; /* pass variables */
    png_bytepp rp; /* points to current row */
 
-   png_debug(1, "in png_write_image\n");
-#if defined(PNG_WRITE_INTERLACING_SUPPORTED)
-   /* initialize interlace handling.  If image is not interlaced,
-      this will set pass to 1 */
+   if (png_ptr == NULL)
+      return;
+
+   png_debug(1, "in png_write_image");
+
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
+   /* 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);
@@ -727,55 +610,69 @@
    }
 }
 
-/* called by user to write a row of image data */
-void PNGAPI
-png_write_row(png_structp png_ptr, png_bytep row)
-{
-   png_debug2(1, "in png_write_row (row %ld, pass %d)\n",
+/* Called by user to write a row of image data */
+void PNGAPI
+png_write_row(png_structp png_ptr, png_const_bytep row)
+{
+   /* 1.5.6: moved from png_struct to be a local structure: */
+   png_row_info row_info;
+
+   if (png_ptr == NULL)
+      return;
+
+   png_debug2(1, "in png_write_row (row %u, 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.");
-
-   /* check for transforms that have been set but were defined out */
+      /* 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 */
 #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.");
-#endif
+      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.");
-#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.");
-#endif
+      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");
+#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.");
-#endif
+      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.");
-#endif
+      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.");
-#endif
+      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 */
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
+   /* If interlaced and not interested in row, return */
    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
    {
       switch (png_ptr->pass)
@@ -787,6 +684,7 @@
                return;
             }
             break;
+
          case 1:
             if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
             {
@@ -794,6 +692,7 @@
                return;
             }
             break;
+
          case 2:
             if ((png_ptr->row_number & 0x07) != 4)
             {
@@ -801,6 +700,7 @@
                return;
             }
             break;
+
          case 3:
             if ((png_ptr->row_number & 0x03) || png_ptr->width < 3)
             {
@@ -808,6 +708,7 @@
                return;
             }
             break;
+
          case 4:
             if ((png_ptr->row_number & 0x03) != 2)
             {
@@ -815,6 +716,7 @@
                return;
             }
             break;
+
          case 5:
             if ((png_ptr->row_number & 0x01) || png_ptr->width < 2)
             {
@@ -822,6 +724,7 @@
                return;
             }
             break;
+
          case 6:
             if (!(png_ptr->row_number & 0x01))
             {
@@ -829,41 +732,39 @@
                return;
             }
             break;
-      }
-   }
-#endif
-
-   /* 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\n", png_ptr->row_info.color_type);
-   png_debug1(3, "row_info->width = %lu\n", png_ptr->row_info.width);
-   png_debug1(3, "row_info->channels = %d\n", png_ptr->row_info.channels);
-   png_debug1(3, "row_info->bit_depth = %d\n", png_ptr->row_info.bit_depth);
-   png_debug1(3, "row_info->pixel_depth = %d\n", png_ptr->row_info.pixel_depth);
-   png_debug1(3, "row_info->rowbytes = %lu\n", png_ptr->row_info.rowbytes);
+
+         default: /* error: ignore it */
+            break;
+      }
+   }
+#endif
+
+   /* Set up row info for transformations */
+   row_info.color_type = png_ptr->color_type;
+   row_info.width = png_ptr->usr_width;
+   row_info.channels = png_ptr->usr_channels;
+   row_info.bit_depth = png_ptr->usr_bit_depth;
+   row_info.pixel_depth = (png_byte)(row_info.bit_depth * row_info.channels);
+   row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
+
+   png_debug1(3, "row_info->color_type = %d", row_info.color_type);
+   png_debug1(3, "row_info->width = %u", row_info.width);
+   png_debug1(3, "row_info->channels = %d", row_info.channels);
+   png_debug1(3, "row_info->bit_depth = %d", row_info.bit_depth);
+   png_debug1(3, "row_info->pixel_depth = %d", row_info.pixel_depth);
+   png_debug1(3, "row_info->rowbytes = %lu", (unsigned long)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 */
+   png_memcpy(png_ptr->row_buf + 1, row, row_info.rowbytes);
+
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
+   /* 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 ... */
-      if (!(png_ptr->row_info.width))
+       (png_ptr->transformations & PNG_INTERLACE))
+   {
+      png_do_write_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass);
+      /* This should always get caught above, but still ... */
+      if (!(row_info.width))
       {
          png_write_finish_row(png_ptr);
          return;
@@ -871,11 +772,20 @@
    }
 #endif
 
-   /* handle other transformations */
+#ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
+   /* Handle other transformations */
    if (png_ptr->transformations)
-      png_do_write_transformations(png_ptr);
-
-#if defined(PNG_MNG_FEATURES_SUPPORTED)
+      png_do_write_transformations(png_ptr, &row_info);
+#endif
+
+   /* At this point the row_info pixel depth must match the 'transformed' depth,
+    * which is also the output depth.
+    */
+   if (row_info.pixel_depth != png_ptr->pixel_depth ||
+      row_info.pixel_depth != png_ptr->transformed_pixel_depth)
+      png_error(png_ptr, "internal write transform logic error");
+
+#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
@@ -889,61 +799,74 @@
        (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
    {
       /* Intrapixel differencing */
-      png_do_write_intrapixel(&(png_ptr->row_info), png_ptr->row_buf + 1);
-   }
+      png_do_write_intrapixel(&row_info, png_ptr->row_buf + 1);
+   }
+#endif
+
+/* Added at libpng-1.5.10 */
+#ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
+   /* Check for out-of-range palette index */
+   if(row_info.color_type == PNG_COLOR_TYPE_PALETTE)
+      png_do_check_palette_indexes(png_ptr, &row_info);
 #endif
 
    /* Find a filter if necessary, filter the row and write it out. */
-   png_write_find_filter(png_ptr, &(png_ptr->row_info));
+   png_write_find_filter(png_ptr, &row_info);
 
    if (png_ptr->write_row_fn != NULL)
       (*(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\n");
+   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\n");
+   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 */
-         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;
+         /* Write the IDAT and reset the zlib output buffer */
+         png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
          wrote_IDAT = 1;
       }
    } while (wrote_IDAT == 1);
@@ -951,18 +874,16 @@
    /* 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->zbuf_size - png_ptr->zstream.avail_out);
    }
    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)
 {
@@ -973,35 +894,40 @@
    png_voidp mem_ptr = NULL;
 #endif
 
-   png_debug(1, "in png_destroy_write_struct\n");
+   png_debug(1, "in png_destroy_write_struct");
+
    if (png_ptr_ptr != NULL)
-   {
       png_ptr = *png_ptr_ptr;
+
 #ifdef PNG_USER_MEM_SUPPORTED
+   if (png_ptr != NULL)
+   {
       free_fn = png_ptr->free_fn;
       mem_ptr = png_ptr->mem_ptr;
-#endif
-   }
+   }
+#endif
 
    if (info_ptr_ptr != NULL)
       info_ptr = *info_ptr_ptr;
 
    if (info_ptr != NULL)
    {
-      png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
-
-#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
-      if (png_ptr->num_chunk_list)
-      {
-         png_free(png_ptr, png_ptr->chunk_list);
-         png_ptr->chunk_list=NULL;
-         png_ptr->num_chunk_list=0;
-      }
-#endif
+      if (png_ptr != NULL)
+      {
+         png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
+
+#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+         if (png_ptr->num_chunk_list)
+         {
+            png_free(png_ptr, png_ptr->chunk_list);
+            png_ptr->num_chunk_list = 0;
+         }
+#endif
+      }
 
 #ifdef PNG_USER_MEM_SUPPORTED
       png_destroy_struct_2((png_voidp)info_ptr, (png_free_ptr)free_fn,
-         (png_voidp)mem_ptr);
+          (png_voidp)mem_ptr);
 #else
       png_destroy_struct((png_voidp)info_ptr);
 #endif
@@ -1013,7 +939,7 @@
       png_write_destroy(png_ptr);
 #ifdef PNG_USER_MEM_SUPPORTED
       png_destroy_struct_2((png_voidp)png_ptr, (png_free_ptr)free_fn,
-         (png_voidp)mem_ptr);
+          (png_voidp)mem_ptr);
 #else
       png_destroy_struct((png_voidp)png_ptr);
 #endif
@@ -1027,63 +953,68 @@
 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;
+#ifdef PNG_WARNINGS_SUPPORTED
    png_error_ptr warning_fn;
+#endif
    png_voidp error_ptr;
 #ifdef PNG_USER_MEM_SUPPORTED
    png_free_ptr free_fn;
 #endif
 
-   png_debug(1, "in png_write_destroy\n");
-   /* free any memory zlib uses */
-   deflateEnd(&png_ptr->zstream);
-
-   /* free our memory.  png_free checks NULL for us. */
+   png_debug(1, "in png_write_destroy");
+
+   /* Free any memory zlib uses */
+   if (png_ptr->zlib_state != PNG_ZLIB_UNINITIALIZED)
+      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);
+#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);
    png_free(png_ptr, png_ptr->avg_row);
    png_free(png_ptr, png_ptr->paeth_row);
-
-#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);
+#endif
+
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+   /* Use this to save a little code space, it doesn't free the filter_costs */
+   png_reset_filter_heuristics(png_ptr);
    png_free(png_ptr, png_ptr->filter_costs);
    png_free(png_ptr, png_ptr->inv_filter_costs);
 #endif
 
 #ifdef PNG_SETJMP_SUPPORTED
-   /* reset structure */
-   png_memcpy(tmp_jmp, png_ptr->jmpbuf, png_sizeof (jmp_buf));
+   /* Reset structure */
+   png_memcpy(tmp_jmp, png_ptr->longjmp_buffer, png_sizeof(jmp_buf));
 #endif
 
    error_fn = png_ptr->error_fn;
+#ifdef PNG_WARNINGS_SUPPORTED
    warning_fn = png_ptr->warning_fn;
+#endif
    error_ptr = png_ptr->error_ptr;
 #ifdef PNG_USER_MEM_SUPPORTED
    free_fn = png_ptr->free_fn;
 #endif
 
-   png_memset(png_ptr, 0, png_sizeof (png_struct));
+   png_memset(png_ptr, 0, png_sizeof(png_struct));
 
    png_ptr->error_fn = error_fn;
+#ifdef PNG_WARNINGS_SUPPORTED
    png_ptr->warning_fn = warning_fn;
+#endif
    png_ptr->error_ptr = error_ptr;
 #ifdef PNG_USER_MEM_SUPPORTED
    png_ptr->free_fn = free_fn;
 #endif
 
 #ifdef PNG_SETJMP_SUPPORTED
-   png_memcpy(png_ptr->jmpbuf, tmp_jmp, png_sizeof (jmp_buf));
+   png_memcpy(png_ptr->longjmp_buffer, tmp_jmp, png_sizeof(jmp_buf));
 #endif
 }
 
@@ -1091,25 +1022,48 @@
 void PNGAPI
 png_set_filter(png_structp png_ptr, int method, int filters)
 {
-   png_debug(1, "in png_set_filter\n");
-#if defined(PNG_MNG_FEATURES_SUPPORTED)
+   png_debug(1, "in png_set_filter");
+
+   if (png_ptr == NULL)
+      return;
+
+#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;
+      method = PNG_FILTER_TYPE_BASE;
+
 #endif
    if (method == PNG_FILTER_TYPE_BASE)
    {
       switch (filters & (PNG_ALL_FILTERS | 0x07))
       {
+#ifdef PNG_WRITE_FILTER_SUPPORTED
          case 5:
          case 6:
          case 7: png_warning(png_ptr, "Unknown row filter for method 0");
-         case PNG_FILTER_VALUE_NONE:  png_ptr->do_filter=PNG_FILTER_NONE; break;
-         case PNG_FILTER_VALUE_SUB:   png_ptr->do_filter=PNG_FILTER_SUB;  break;
-         case PNG_FILTER_VALUE_UP:    png_ptr->do_filter=PNG_FILTER_UP;   break;
-         case PNG_FILTER_VALUE_AVG:   png_ptr->do_filter=PNG_FILTER_AVG;  break;
-         case PNG_FILTER_VALUE_PAETH: png_ptr->do_filter=PNG_FILTER_PAETH;break;
-         default: png_ptr->do_filter = (png_byte)filters; break;
+#endif /* PNG_WRITE_FILTER_SUPPORTED */
+         case PNG_FILTER_VALUE_NONE:
+            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;
+
+         case PNG_FILTER_VALUE_UP:
+            png_ptr->do_filter = PNG_FILTER_UP; break;
+
+         case PNG_FILTER_VALUE_AVG:
+            png_ptr->do_filter = PNG_FILTER_AVG; break;
+
+         case PNG_FILTER_VALUE_PAETH:
+            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_WRITE_FILTER_SUPPORTED */
       }
 
       /* If we have allocated the row_buf, this means we have already started
@@ -1123,10 +1077,11 @@
        */
       if (png_ptr->row_buf != NULL)
       {
+#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,
-              (png_ptr->rowbytes + 1));
+                (png_ptr->rowbytes + 1));
             png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
          }
 
@@ -1135,12 +1090,14 @@
             if (png_ptr->prev_row == NULL)
             {
                png_warning(png_ptr, "Can't add Up filter after starting");
-               png_ptr->do_filter &= ~PNG_FILTER_UP;
+               png_ptr->do_filter = (png_byte)(png_ptr->do_filter &
+                   ~PNG_FILTER_UP);
             }
+
             else
             {
                png_ptr->up_row = (png_bytep)png_malloc(png_ptr,
-                  (png_ptr->rowbytes + 1));
+                   (png_ptr->rowbytes + 1));
                png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
             }
          }
@@ -1150,12 +1107,14 @@
             if (png_ptr->prev_row == NULL)
             {
                png_warning(png_ptr, "Can't add Average filter after starting");
-               png_ptr->do_filter &= ~PNG_FILTER_AVG;
+               png_ptr->do_filter = (png_byte)(png_ptr->do_filter &
+                   ~PNG_FILTER_AVG);
             }
+
             else
             {
                png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
-                  (png_ptr->rowbytes + 1));
+                   (png_ptr->rowbytes + 1));
                png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
             }
          }
@@ -1168,15 +1127,17 @@
                png_warning(png_ptr, "Can't add Paeth filter after starting");
                png_ptr->do_filter &= (png_byte)(~PNG_FILTER_PAETH);
             }
+
             else
             {
                png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr,
-                  (png_ptr->rowbytes + 1));
+                   (png_ptr->rowbytes + 1));
                png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
             }
          }
 
          if (png_ptr->do_filter == PNG_NO_FILTERS)
+#endif /* PNG_WRITE_FILTER_SUPPORTED */
             png_ptr->do_filter = PNG_FILTER_NONE;
       }
    }
@@ -1191,127 +1152,253 @@
  * filtered data going to zlib more consistent, hopefully resulting in
  * better compression.
  */
-#if defined(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,
-                          png_doublep filter_costs)
-{
-   int i;
-
-   png_debug(1, "in png_set_filter_heuristics\n");
-   if (heuristic_method >= PNG_FILTER_HEURISTIC_LAST)
-   {
-      png_warning(png_ptr, "Unknown filter heuristic method");
-      return;
-   }
-
-   if (heuristic_method == PNG_FILTER_HEURISTIC_DEFAULT)
-   {
-      heuristic_method = PNG_FILTER_HEURISTIC_UNWEIGHTED;
-   }
-
-   if (num_weights < 0 || filter_weights == NULL ||
-      heuristic_method == PNG_FILTER_HEURISTIC_UNWEIGHTED)
-   {
-      num_weights = 0;
-   }
-
-   png_ptr->num_prev_filters = (png_byte)num_weights;
-   png_ptr->heuristic_method = (png_byte)heuristic_method;
-
-   if (num_weights > 0)
-   {
-      if (png_ptr->prev_filters == NULL)
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED      /* GRR 970116 */
+/* Convenience reset API. */
+static void
+png_reset_filter_heuristics(png_structp png_ptr)
+{
+   /* Clear out any old values in the 'weights' - this must be done because if
+    * the app calls set_filter_heuristics multiple times with different
+    * 'num_weights' values we would otherwise potentially have wrong sized
+    * arrays.
+    */
+   png_ptr->num_prev_filters = 0;
+   png_ptr->heuristic_method = PNG_FILTER_HEURISTIC_UNWEIGHTED;
+   if (png_ptr->prev_filters != NULL)
+   {
+      png_bytep old = png_ptr->prev_filters;
+      png_ptr->prev_filters = NULL;
+      png_free(png_ptr, old);
+   }
+   if (png_ptr->filter_weights != NULL)
+   {
+      png_uint_16p old = png_ptr->filter_weights;
+      png_ptr->filter_weights = NULL;
+      png_free(png_ptr, old);
+   }
+
+   if (png_ptr->inv_filter_weights != NULL)
+   {
+      png_uint_16p old = png_ptr->inv_filter_weights;
+      png_ptr->inv_filter_weights = NULL;
+      png_free(png_ptr, old);
+   }
+
+   /* Leave the filter_costs - this array is fixed size. */
+}
+
+static int
+png_init_filter_heuristics(png_structp png_ptr, int heuristic_method,
+   int num_weights)
+{
+   if (png_ptr == NULL)
+      return 0;
+
+   /* Clear out the arrays */
+   png_reset_filter_heuristics(png_ptr);
+
+   /* Check arguments; the 'reset' function makes the correct settings for the
+    * unweighted case, but we must handle the weight case by initializing the
+    * arrays for the caller.
+    */
+   if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
+   {
+      int i;
+
+      if (num_weights > 0)
       {
          png_ptr->prev_filters = (png_bytep)png_malloc(png_ptr,
-            (png_uint_32)(png_sizeof(png_byte) * num_weights));
+             (png_uint_32)(png_sizeof(png_byte) * num_weights));
 
          /* To make sure that the weighting starts out fairly */
          for (i = 0; i < num_weights; i++)
          {
             png_ptr->prev_filters[i] = 255;
          }
-      }
-
-      if (png_ptr->filter_weights == NULL)
-      {
+
          png_ptr->filter_weights = (png_uint_16p)png_malloc(png_ptr,
-            (png_uint_32)(png_sizeof(png_uint_16) * num_weights));
+             (png_uint_32)(png_sizeof(png_uint_16) * num_weights));
 
          png_ptr->inv_filter_weights = (png_uint_16p)png_malloc(png_ptr,
-            (png_uint_32)(png_sizeof(png_uint_16) * num_weights));
+             (png_uint_32)(png_sizeof(png_uint_16) * num_weights));
+
          for (i = 0; i < num_weights; i++)
          {
             png_ptr->inv_filter_weights[i] =
             png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
          }
-      }
-
+
+         /* Safe to set this now */
+         png_ptr->num_prev_filters = (png_byte)num_weights;
+      }
+
+      /* If, in the future, there are other filter methods, this would
+       * need to be based on png_ptr->filter.
+       */
+      if (png_ptr->filter_costs == NULL)
+      {
+         png_ptr->filter_costs = (png_uint_16p)png_malloc(png_ptr,
+             (png_uint_32)(png_sizeof(png_uint_16) * PNG_FILTER_VALUE_LAST));
+
+         png_ptr->inv_filter_costs = (png_uint_16p)png_malloc(png_ptr,
+             (png_uint_32)(png_sizeof(png_uint_16) * PNG_FILTER_VALUE_LAST));
+      }
+
+      for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
+      {
+         png_ptr->inv_filter_costs[i] =
+         png_ptr->filter_costs[i] = PNG_COST_FACTOR;
+      }
+
+      /* All the arrays are inited, safe to set this: */
+      png_ptr->heuristic_method = PNG_FILTER_HEURISTIC_WEIGHTED;
+
+      /* Return the 'ok' code. */
+      return 1;
+   }
+   else if (heuristic_method == PNG_FILTER_HEURISTIC_DEFAULT ||
+      heuristic_method == PNG_FILTER_HEURISTIC_UNWEIGHTED)
+   {
+      return 1;
+   }
+   else
+   {
+      png_warning(png_ptr, "Unknown filter heuristic method");
+      return 0;
+   }
+}
+
+/* Provide floating and fixed point APIs */
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+void PNGAPI
+png_set_filter_heuristics(png_structp png_ptr, int heuristic_method,
+    int num_weights, png_const_doublep filter_weights,
+    png_const_doublep filter_costs)
+{
+   png_debug(1, "in png_set_filter_heuristics");
+
+   /* The internal API allocates all the arrays and ensures that the elements of
+    * those arrays are set to the default value.
+    */
+   if (!png_init_filter_heuristics(png_ptr, heuristic_method, num_weights))
+      return;
+
+   /* If using the weighted method copy in the weights. */
+   if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
+   {
+      int i;
       for (i = 0; i < num_weights; i++)
       {
-         if (filter_weights[i] < 0.0)
+         if (filter_weights[i] <= 0.0)
          {
             png_ptr->inv_filter_weights[i] =
             png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
          }
+
          else
          {
             png_ptr->inv_filter_weights[i] =
-               (png_uint_16)((double)PNG_WEIGHT_FACTOR*filter_weights[i]+0.5);
+                (png_uint_16)(PNG_WEIGHT_FACTOR*filter_weights[i]+.5);
+
             png_ptr->filter_weights[i] =
-               (png_uint_16)((double)PNG_WEIGHT_FACTOR/filter_weights[i]+0.5);
+                (png_uint_16)(PNG_WEIGHT_FACTOR/filter_weights[i]+.5);
          }
       }
-   }
-
-   /* If, in the future, there are other filter methods, this would
-    * need to be based on png_ptr->filter.
+
+      /* Here is where we set the relative costs of the different filters.  We
+       * should take the desired compression level into account when setting
+       * the costs, so that Paeth, for instance, has a high relative cost at low
+       * compression levels, while it has a lower relative cost at higher
+       * compression settings.  The filter types are in order of increasing
+       * relative cost, so it would be possible to do this with an algorithm.
+       */
+      for (i = 0; i < PNG_FILTER_VALUE_LAST; i++) if (filter_costs[i] >= 1.0)
+      {
+         png_ptr->inv_filter_costs[i] =
+             (png_uint_16)(PNG_COST_FACTOR / filter_costs[i] + .5);
+
+         png_ptr->filter_costs[i] =
+             (png_uint_16)(PNG_COST_FACTOR * filter_costs[i] + .5);
+      }
+   }
+}
+#endif /* FLOATING_POINT */
+
+#ifdef PNG_FIXED_POINT_SUPPORTED
+void PNGAPI
+png_set_filter_heuristics_fixed(png_structp png_ptr, int heuristic_method,
+    int num_weights, png_const_fixed_point_p filter_weights,
+    png_const_fixed_point_p filter_costs)
+{
+   png_debug(1, "in png_set_filter_heuristics_fixed");
+
+   /* The internal API allocates all the arrays and ensures that the elements of
+    * those arrays are set to the default value.
     */
-   if (png_ptr->filter_costs == NULL)
-   {
-      png_ptr->filter_costs = (png_uint_16p)png_malloc(png_ptr,
-         (png_uint_32)(png_sizeof(png_uint_16) * PNG_FILTER_VALUE_LAST));
-
-      png_ptr->inv_filter_costs = (png_uint_16p)png_malloc(png_ptr,
-         (png_uint_32)(png_sizeof(png_uint_16) * PNG_FILTER_VALUE_LAST));
-
+   if (!png_init_filter_heuristics(png_ptr, heuristic_method, num_weights))
+      return;
+
+   /* If using the weighted method copy in the weights. */
+   if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
+   {
+      int i;
+      for (i = 0; i < num_weights; i++)
+      {
+         if (filter_weights[i] <= 0)
+         {
+            png_ptr->inv_filter_weights[i] =
+            png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
+         }
+
+         else
+         {
+            png_ptr->inv_filter_weights[i] = (png_uint_16)
+               ((PNG_WEIGHT_FACTOR*filter_weights[i]+PNG_FP_HALF)/PNG_FP_1);
+
+            png_ptr->filter_weights[i] = (png_uint_16)((PNG_WEIGHT_FACTOR*
+               PNG_FP_1+(filter_weights[i]/2))/filter_weights[i]);
+         }
+      }
+
+      /* Here is where we set the relative costs of the different filters.  We
+       * should take the desired compression level into account when setting
+       * the costs, so that Paeth, for instance, has a high relative cost at low
+       * compression levels, while it has a lower relative cost at higher
+       * compression settings.  The filter types are in order of increasing
+       * relative cost, so it would be possible to do this with an algorithm.
+       */
       for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
-      {
-         png_ptr->inv_filter_costs[i] =
-         png_ptr->filter_costs[i] = PNG_COST_FACTOR;
-      }
-   }
-
-   /* Here is where we set the relative costs of the different filters.  We
-    * should take the desired compression level into account when setting
-    * the costs, so that Paeth, for instance, has a high relative cost at low
-    * compression levels, while it has a lower relative cost at higher
-    * compression settings.  The filter types are in order of increasing
-    * relative cost, so it would be possible to do this with an algorithm.
-    */
-   for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
-   {
-      if (filter_costs == NULL || filter_costs[i] < 0.0)
-      {
-         png_ptr->inv_filter_costs[i] =
-         png_ptr->filter_costs[i] = PNG_COST_FACTOR;
-      }
-      else if (filter_costs[i] >= 1.0)
-      {
-         png_ptr->inv_filter_costs[i] =
-            (png_uint_16)((double)PNG_COST_FACTOR / filter_costs[i] + 0.5);
-         png_ptr->filter_costs[i] =
-            (png_uint_16)((double)PNG_COST_FACTOR * filter_costs[i] + 0.5);
-      }
-   }
-}
+         if (filter_costs[i] >= PNG_FP_1)
+      {
+         png_uint_32 tmp;
+
+         /* Use a 32 bit unsigned temporary here because otherwise the
+          * intermediate value will be a 32 bit *signed* integer (ANSI rules)
+          * and this will get the wrong answer on division.
+          */
+         tmp = PNG_COST_FACTOR*PNG_FP_1 + (filter_costs[i]/2);
+         tmp /= filter_costs[i];
+
+         png_ptr->inv_filter_costs[i] = (png_uint_16)tmp;
+
+         tmp = PNG_COST_FACTOR * filter_costs[i] + PNG_FP_HALF;
+         tmp /= PNG_FP_1;
+
+         png_ptr->filter_costs[i] = (png_uint_16)tmp;
+      }
+   }
+}
+#endif /* FIXED_POINT */
 #endif /* PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
 
 void PNGAPI
 png_set_compression_level(png_structp png_ptr, int level)
 {
-   png_debug(1, "in png_set_compression_level\n");
+   png_debug(1, "in png_set_compression_level");
+
+   if (png_ptr == NULL)
+      return;
+
    png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_LEVEL;
    png_ptr->zlib_level = level;
 }
@@ -1319,7 +1406,11 @@
 void PNGAPI
 png_set_compression_mem_level(png_structp png_ptr, int mem_level)
 {
-   png_debug(1, "in png_set_compression_mem_level\n");
+   png_debug(1, "in png_set_compression_mem_level");
+
+   if (png_ptr == NULL)
+      return;
+
    png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL;
    png_ptr->zlib_mem_level = mem_level;
 }
@@ -1327,25 +1418,38 @@
 void PNGAPI
 png_set_compression_strategy(png_structp png_ptr, int strategy)
 {
-   png_debug(1, "in png_set_compression_strategy\n");
+   png_debug(1, "in png_set_compression_strategy");
+
+   if (png_ptr == NULL)
+      return;
+
    png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_STRATEGY;
    png_ptr->zlib_strategy = strategy;
 }
 
+/* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
+ * smaller value of window_bits if it can do so safely.
+ */
 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;
-     }
+      {
+        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;
@@ -1354,111 +1458,210 @@
 void PNGAPI
 png_set_compression_method(png_structp png_ptr, int method)
 {
-   png_debug(1, "in png_set_compression_method\n");
+   png_debug(1, "in png_set_compression_method");
+
+   if (png_ptr == NULL)
+      return;
+
    if (method != 8)
       png_warning(png_ptr, "Only compression method 8 is supported by PNG");
+
    png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_METHOD;
    png_ptr->zlib_method = method;
 }
 
+/* The following were added to libpng-1.5.4 */
+#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
+void PNGAPI
+png_set_text_compression_level(png_structp png_ptr, int level)
+{
+   png_debug(1, "in png_set_text_compression_level");
+
+   if (png_ptr == NULL)
+      return;
+
+   png_ptr->flags |= PNG_FLAG_ZTXT_CUSTOM_LEVEL;
+   png_ptr->zlib_text_level = level;
+}
+
+void PNGAPI
+png_set_text_compression_mem_level(png_structp png_ptr, int mem_level)
+{
+   png_debug(1, "in png_set_text_compression_mem_level");
+
+   if (png_ptr == NULL)
+      return;
+
+   png_ptr->flags |= PNG_FLAG_ZTXT_CUSTOM_MEM_LEVEL;
+   png_ptr->zlib_text_mem_level = mem_level;
+}
+
+void PNGAPI
+png_set_text_compression_strategy(png_structp png_ptr, int strategy)
+{
+   png_debug(1, "in png_set_text_compression_strategy");
+
+   if (png_ptr == NULL)
+      return;
+
+   png_ptr->flags |= PNG_FLAG_ZTXT_CUSTOM_STRATEGY;
+   png_ptr->zlib_text_strategy = strategy;
+}
+
+/* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
+ * smaller value of window_bits if it can do so safely.
+ */
+void PNGAPI
+png_set_text_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 */
+   if (window_bits == 8)
+      {
+        png_warning(png_ptr, "Text compression window is being reset to 512");
+        window_bits = 9;
+      }
+
+#endif
+   png_ptr->flags |= PNG_FLAG_ZTXT_CUSTOM_WINDOW_BITS;
+   png_ptr->zlib_text_window_bits = window_bits;
+}
+
+void PNGAPI
+png_set_text_compression_method(png_structp png_ptr, int method)
+{
+   png_debug(1, "in png_set_text_compression_method");
+
+   if (png_ptr == NULL)
+      return;
+
+   if (method != 8)
+      png_warning(png_ptr, "Only compression method 8 is supported by PNG");
+
+   png_ptr->flags |= PNG_FLAG_ZTXT_CUSTOM_METHOD;
+   png_ptr->zlib_text_method = method;
+}
+#endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */
+/* end of API added to libpng-1.5.4 */
+
 void PNGAPI
 png_set_write_status_fn(png_structp png_ptr, png_write_status_ptr write_row_fn)
 {
+   if (png_ptr == NULL)
+      return;
+
    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\n");
+    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;
    png_ptr->write_user_transform_fn = write_user_transform_fn;
 }
 #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 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
+    int transforms, voidp params)
+{
+   if (png_ptr == NULL || info_ptr == NULL)
+      return;
 
    /* 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 */
+#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)
+      png_set_invert_mono(png_ptr);
+#endif
+
+#ifdef 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);
-#endif
-
-#if defined(PNG_WRITE_PACK_SUPPORTED)
-   /* pack pixels into bytes */
+       && (info_ptr->valid & PNG_INFO_sBIT))
+      png_set_shift(png_ptr, &info_ptr->sig_bit);
+#endif
+
+#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)
-   /* swap location of alpha bytes from ARGB to RGBA */
+#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)
-   /* Get rid of filler (OR ALPHA) bytes, pack XRGB/RGBX/ARGB/RGBA into
-    * RGB (4 channels -> 3 channels). The second parameter is not used.
-    */
-   if (transforms & PNG_TRANSFORM_STRIP_FILLER)
-       png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
-#endif
-
-#if defined(PNG_WRITE_BGR_SUPPORTED)
-   /* flip BGR pixels to RGB */
+      png_set_swap_alpha(png_ptr);
+#endif
+
+#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);
+
+   else if (transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE)
+      png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
+#endif
+
+#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)
-   /* swap bytes of 16-bit files to most significant byte first */
+      png_set_bgr(png_ptr);
+#endif
+
+#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)
-   /* swap bits of 1, 2, 4 bit packed pixel formats */
+      png_set_swap(png_ptr);
+#endif
+
+#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);
+      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 */
+   /* 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);
 
-   if (transforms == 0 || params == NULL)
-      /* quiet compiler warnings */ return;
+   PNG_UNUSED(transforms)   /* Quiet compiler warnings */
+   PNG_UNUSED(params)
 }
 #endif
 #endif /* PNG_WRITE_SUPPORTED */