libpng: update to 1.2.43

third_party/libpng/pngwutil.c

 
 /* pngwutil.c - utilities to write a PNG file
  *
- * Last changed in libpng 1.2.36 [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 1.2.43 [February 25, 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
  */
 
 #define PNG_INTERNAL
+#define PNG_NO_PEDANTIC_WARNINGS
 #include "png.h"
 #ifdef PNG_WRITE_SUPPORTED
 
 /* Place a 32-bit number into a buffer in PNG byte order.  We work
  * with unsigned numbers for convenience, although one supported
  * ancillary chunk uses signed (two's complement) numbers.
  */
 void PNGAPI
 png_save_uint_32(png_bytep buf, png_uint_32 i)
 {
@@ skipping 70 matching lines @@
  * passing in png_write_chunk_data().
  */
 void PNGAPI
 png_write_chunk_start(png_structp png_ptr, png_bytep chunk_name,
    png_uint_32 length)
 {
    png_byte buf[8];
 
    png_debug2(0, "Writing %s chunk, length = %lu", chunk_name,
       (unsigned long)length);
+
    if (png_ptr == NULL)
       return;
 
+
    /* Write the length and the chunk name */
    png_save_uint_32(buf, length);
    png_memcpy(buf + 4, chunk_name, 4);
    png_write_data(png_ptr, buf, (png_size_t)8);
    /* Put the chunk name into png_ptr->chunk_name */
    png_memcpy(png_ptr->chunk_name, chunk_name, 4);
    /* Reset the crc and run it over the chunk name */
    png_reset_crc(png_ptr);
    png_calculate_crc(png_ptr, chunk_name, (png_size_t)4);
 }
@@ skipping 66 matching lines @@
    /* We may just want to pass the text right through */
    if (compression == PNG_TEXT_COMPRESSION_NONE)
    {
        comp->input = text;
        comp->input_len = text_len;
        return((int)text_len);
    }
 
    if (compression >= PNG_TEXT_COMPRESSION_LAST)
    {
-#if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
+#if defined(PNG_STDIO_SUPPORTED) && !defined(_WIN32_WCE)
       char msg[50];
       png_snprintf(msg, 50, "Unknown compression type %d", compression);
       png_warning(png_ptr, msg);
 #else
       png_warning(png_ptr, "Unknown compression type");
 #endif
    }
 
    /* We can't write the chunk until we find out how much data we have,
     * which means we need to run the compressor first and save the
@@ skipping 186 matching lines @@
    int interlace_type)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_IHDR;
 #endif
    int ret;
 
    png_byte buf[13]; /* Buffer to store the IHDR info */
 
    png_debug(1, "in png_write_IHDR");
+
    /* Check that we have valid input data from the application info */
    switch (color_type)
    {
       case PNG_COLOR_TYPE_GRAY:
          switch (bit_depth)
          {
             case 1:
             case 2:
             case 4:
             case 8:
             case 16: png_ptr->channels = 1; break;
-            default: png_error(png_ptr, "Invalid bit depth for grayscale image");
+            default: png_error(png_ptr,
+                         "Invalid bit depth for grayscale image");
          }
          break;
       case PNG_COLOR_TYPE_RGB:
          if (bit_depth != 8 && bit_depth != 16)
             png_error(png_ptr, "Invalid bit depth for RGB image");
          png_ptr->channels = 3;
          break;
       case PNG_COLOR_TYPE_PALETTE:
          switch (bit_depth)
          {
@@ skipping 27 matching lines @@
    /* Write filter_method 64 (intrapixel differencing) only if
     * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
     * 2. Libpng did not write a PNG signature (this filter_method is only
     *    used in PNG datastreams that are embedded in MNG datastreams) and
     * 3. The application called png_permit_mng_features with a mask that
     *    included PNG_FLAG_MNG_FILTER_64 and
     * 4. The filter_method is 64 and
     * 5. The color_type is RGB or RGBA
     */
    if (
-#if defined(PNG_MNG_FEATURES_SUPPORTED)
+#ifdef PNG_MNG_FEATURES_SUPPORTED
       !((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
       ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) == 0) &&
       (color_type == PNG_COLOR_TYPE_RGB ||
        color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
       (filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
 #endif
       filter_type != PNG_FILTER_TYPE_BASE)
    {
       png_warning(png_ptr, "Invalid filter type specified");
       filter_type = PNG_FILTER_TYPE_BASE;
    }
 
 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
    if (interlace_type != PNG_INTERLACE_NONE &&
       interlace_type != PNG_INTERLACE_ADAM7)
    {
       png_warning(png_ptr, "Invalid interlace type specified");
       interlace_type = PNG_INTERLACE_ADAM7;
    }
 #else
    interlace_type=PNG_INTERLACE_NONE;
 #endif
 
    /* Save the relevent information */
    png_ptr->bit_depth = (png_byte)bit_depth;
    png_ptr->color_type = (png_byte)color_type;
    png_ptr->interlaced = (png_byte)interlace_type;
-#if defined(PNG_MNG_FEATURES_SUPPORTED)
+#ifdef PNG_MNG_FEATURES_SUPPORTED
    png_ptr->filter_type = (png_byte)filter_type;
 #endif
    png_ptr->compression_type = (png_byte)compression_type;
    png_ptr->width = width;
    png_ptr->height = height;
 
    png_ptr->pixel_depth = (png_byte)(bit_depth * png_ptr->channels);
    png_ptr->rowbytes = PNG_ROWBYTES(png_ptr->pixel_depth, width);
    /* Set the usr info, so any transformations can modify it */
    png_ptr->usr_width = png_ptr->width;
@@ skipping 69 matching lines @@
 png_write_PLTE(png_structp png_ptr, png_colorp palette, png_uint_32 num_pal)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_PLTE;
 #endif
    png_uint_32 i;
    png_colorp pal_ptr;
    png_byte buf[3];
 
    png_debug(1, "in png_write_PLTE");
+
    if ((
-#if defined(PNG_MNG_FEATURES_SUPPORTED)
+#ifdef PNG_MNG_FEATURES_SUPPORTED
         !(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) &&
 #endif
         num_pal == 0) || num_pal > 256)
    {
      if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
      {
         png_error(png_ptr, "Invalid number of colors in palette");
      }
      else
      {
         png_warning(png_ptr, "Invalid number of colors in palette");
         return;
      }
    }
 
    if (!(png_ptr->color_type&PNG_COLOR_MASK_COLOR))
    {
       png_warning(png_ptr,
         "Ignoring request to write a PLTE chunk in grayscale PNG");
       return;
    }
 
    png_ptr->num_palette = (png_uint_16)num_pal;
    png_debug1(3, "num_palette = %d", png_ptr->num_palette);
 
    png_write_chunk_start(png_ptr, (png_bytep)png_PLTE,
      (png_uint_32)(num_pal * 3));
-#ifndef PNG_NO_POINTER_INDEXING
+#ifdef PNG_POINTER_INDEXING_SUPPORTED
    for (i = 0, pal_ptr = palette; i < num_pal; i++, pal_ptr++)
    {
       buf[0] = pal_ptr->red;
       buf[1] = pal_ptr->green;
       buf[2] = pal_ptr->blue;
       png_write_chunk_data(png_ptr, buf, (png_size_t)3);
    }
 #else
-   /* This is a little slower but some buggy compilers need to do this instead */
+   /* This is a little slower but some buggy compilers need to do this
+    * instead
+    */
    pal_ptr=palette;
    for (i = 0; i < num_pal; i++)
    {
       buf[0] = pal_ptr[i].red;
       buf[1] = pal_ptr[i].green;
       buf[2] = pal_ptr[i].blue;
       png_write_chunk_data(png_ptr, buf, (png_size_t)3);
    }
 #endif
    png_write_chunk_end(png_ptr);
    png_ptr->mode |= PNG_HAVE_PLTE;
 }
 
 /* Write an IDAT chunk */
 void /* PRIVATE */
 png_write_IDAT(png_structp png_ptr, png_bytep data, png_size_t length)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_IDAT;
 #endif
+
    png_debug(1, "in png_write_IDAT");
 
    /* Optimize the CMF field in the zlib stream. */
    /* This hack of the zlib stream is compliant to the stream specification. */
    if (!(png_ptr->mode & PNG_HAVE_IDAT) &&
        png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
    {
       unsigned int z_cmf = data[0];  /* zlib compression method and flags */
       if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
       {
@@ skipping 34 matching lines @@
    png_ptr->mode |= PNG_HAVE_IDAT;
 }
 
 /* Write an IEND chunk */
 void /* PRIVATE */
 png_write_IEND(png_structp png_ptr)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_IEND;
 #endif
+
    png_debug(1, "in png_write_IEND");
+
    png_write_chunk(png_ptr, (png_bytep)png_IEND, png_bytep_NULL,
      (png_size_t)0);
    png_ptr->mode |= PNG_HAVE_IEND;
 }
 
-#if defined(PNG_WRITE_gAMA_SUPPORTED)
+#ifdef PNG_WRITE_gAMA_SUPPORTED
 /* Write a gAMA chunk */
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 void /* PRIVATE */
 png_write_gAMA(png_structp png_ptr, double file_gamma)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_gAMA;
 #endif
    png_uint_32 igamma;
    png_byte buf[4];
 
    png_debug(1, "in png_write_gAMA");
+
    /* file_gamma is saved in 1/100,000ths */
    igamma = (png_uint_32)(file_gamma * 100000.0 + 0.5);
    png_save_uint_32(buf, igamma);
    png_write_chunk(png_ptr, (png_bytep)png_gAMA, buf, (png_size_t)4);
 }
 #endif
 #ifdef PNG_FIXED_POINT_SUPPORTED
 void /* PRIVATE */
 png_write_gAMA_fixed(png_structp png_ptr, png_fixed_point file_gamma)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_gAMA;
 #endif
    png_byte buf[4];
 
    png_debug(1, "in png_write_gAMA");
+
    /* file_gamma is saved in 1/100,000ths */
    png_save_uint_32(buf, (png_uint_32)file_gamma);
    png_write_chunk(png_ptr, (png_bytep)png_gAMA, buf, (png_size_t)4);
 }
 #endif
 #endif
 
-#if defined(PNG_WRITE_sRGB_SUPPORTED)
+#ifdef PNG_WRITE_sRGB_SUPPORTED
 /* Write a sRGB chunk */
 void /* PRIVATE */
 png_write_sRGB(png_structp png_ptr, int srgb_intent)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_sRGB;
 #endif
    png_byte buf[1];
 
    png_debug(1, "in png_write_sRGB");
+
    if (srgb_intent >= PNG_sRGB_INTENT_LAST)
          png_warning(png_ptr,
             "Invalid sRGB rendering intent specified");
    buf[0]=(png_byte)srgb_intent;
    png_write_chunk(png_ptr, (png_bytep)png_sRGB, buf, (png_size_t)1);
 }
 #endif
 
-#if defined(PNG_WRITE_iCCP_SUPPORTED)
+#ifdef PNG_WRITE_iCCP_SUPPORTED
 /* Write an iCCP chunk */
 void /* PRIVATE */
 png_write_iCCP(png_structp png_ptr, png_charp name, int compression_type,
    png_charp profile, int profile_len)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_iCCP;
 #endif
    png_size_t name_len;
    png_charp new_name;
@@ skipping 18 matching lines @@
    if (profile == NULL)
       profile_len = 0;
 
    if (profile_len > 3)
       embedded_profile_len =
           ((*( (png_bytep)profile    ))<<24) |
           ((*( (png_bytep)profile + 1))<<16) |
           ((*( (png_bytep)profile + 2))<< 8) |
           ((*( (png_bytep)profile + 3))    );
 
+   if (embedded_profile_len < 0)
+   {
+      png_warning(png_ptr,
+        "Embedded profile length in iCCP chunk is negative");
+      png_free(png_ptr, new_name);
+      return;
+   }
+
    if (profile_len < embedded_profile_len)
    {
       png_warning(png_ptr,
         "Embedded profile length too large in iCCP chunk");
       png_free(png_ptr, new_name);
       return;
    }
 
    if (profile_len > embedded_profile_len)
    {
@@ skipping 14 matching lines @@
      (png_size_t)(name_len + 2));
 
    if (profile_len)
       png_write_compressed_data_out(png_ptr, &comp);
 
    png_write_chunk_end(png_ptr);
    png_free(png_ptr, new_name);
 }
 #endif
 
-#if defined(PNG_WRITE_sPLT_SUPPORTED)
+#ifdef PNG_WRITE_sPLT_SUPPORTED
 /* Write a sPLT chunk */
 void /* PRIVATE */
 png_write_sPLT(png_structp png_ptr, png_sPLT_tp spalette)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_sPLT;
 #endif
    png_size_t name_len;
    png_charp new_name;
    png_byte entrybuf[10];
    int entry_size = (spalette->depth == 8 ? 6 : 10);
    int palette_size = entry_size * spalette->nentries;
    png_sPLT_entryp ep;
-#ifdef PNG_NO_POINTER_INDEXING
+#ifndef PNG_POINTER_INDEXING_SUPPORTED
    int i;
 #endif
 
    png_debug(1, "in png_write_sPLT");
+
    if ((name_len = png_check_keyword(png_ptr,spalette->name, &new_name))==0)
       return;
 
    /* Make sure we include the NULL after the name */
    png_write_chunk_start(png_ptr, (png_bytep)png_sPLT,
      (png_uint_32)(name_len + 2 + palette_size));
    png_write_chunk_data(png_ptr, (png_bytep)new_name,
      (png_size_t)(name_len + 1));
    png_write_chunk_data(png_ptr, (png_bytep)&spalette->depth, (png_size_t)1);
 
    /* Loop through each palette entry, writing appropriately */
-#ifndef PNG_NO_POINTER_INDEXING
+#ifdef PNG_POINTER_INDEXING_SUPPORTED
    for (ep = spalette->entries; ep<spalette->entries + spalette->nentries; ep++)
    {
       if (spalette->depth == 8)
       {
           entrybuf[0] = (png_byte)ep->red;
           entrybuf[1] = (png_byte)ep->green;
           entrybuf[2] = (png_byte)ep->blue;
           entrybuf[3] = (png_byte)ep->alpha;
           png_save_uint_16(entrybuf + 4, ep->frequency);
       }
@@ skipping 29 matching lines @@
       }
       png_write_chunk_data(png_ptr, entrybuf, (png_size_t)entry_size);
    }
 #endif
 
    png_write_chunk_end(png_ptr);
    png_free(png_ptr, new_name);
 }
 #endif
 
-#if defined(PNG_WRITE_sBIT_SUPPORTED)
+#ifdef PNG_WRITE_sBIT_SUPPORTED
 /* Write the sBIT chunk */
 void /* PRIVATE */
 png_write_sBIT(png_structp png_ptr, png_color_8p sbit, int color_type)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_sBIT;
 #endif
    png_byte buf[4];
    png_size_t size;
 
    png_debug(1, "in png_write_sBIT");
+
    /* Make sure we don't depend upon the order of PNG_COLOR_8 */
    if (color_type & PNG_COLOR_MASK_COLOR)
    {
       png_byte maxbits;
 
       maxbits = (png_byte)(color_type==PNG_COLOR_TYPE_PALETTE ? 8 :
                 png_ptr->usr_bit_depth);
       if (sbit->red == 0 || sbit->red > maxbits ||
           sbit->green == 0 || sbit->green > maxbits ||
           sbit->blue == 0 || sbit->blue > maxbits)
@@ skipping 24 matching lines @@
          png_warning(png_ptr, "Invalid sBIT depth specified");
          return;
       }
       buf[size++] = sbit->alpha;
    }
 
    png_write_chunk(png_ptr, (png_bytep)png_sBIT, buf, size);
 }
 #endif
 
-#if defined(PNG_WRITE_cHRM_SUPPORTED)
+#ifdef PNG_WRITE_cHRM_SUPPORTED
 /* Write the cHRM chunk */
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 void /* PRIVATE */
 png_write_cHRM(png_structp png_ptr, double white_x, double white_y,
    double red_x, double red_y, double green_x, double green_y,
    double blue_x, double blue_y)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_cHRM;
 #endif
    png_byte buf[32];
 
    png_fixed_point int_white_x, int_white_y, int_red_x, int_red_y,
       int_green_x, int_green_y, int_blue_x, int_blue_y;
 
    png_debug(1, "in png_write_cHRM");
 
    int_white_x = (png_uint_32)(white_x * 100000.0 + 0.5);
    int_white_y = (png_uint_32)(white_y * 100000.0 + 0.5);
    int_red_x   = (png_uint_32)(red_x   * 100000.0 + 0.5);
    int_red_y   = (png_uint_32)(red_y   * 100000.0 + 0.5);
    int_green_x = (png_uint_32)(green_x * 100000.0 + 0.5);
    int_green_y = (png_uint_32)(green_y * 100000.0 + 0.5);
    int_blue_x  = (png_uint_32)(blue_x  * 100000.0 + 0.5);
    int_blue_y  = (png_uint_32)(blue_y  * 100000.0 + 0.5);
 
-#if !defined(PNG_NO_CHECK_cHRM)
+#ifdef PNG_CHECK_cHRM_SUPPORTED
    if (png_check_cHRM_fixed(png_ptr, int_white_x, int_white_y,
       int_red_x, int_red_y, int_green_x, int_green_y, int_blue_x, int_blue_y))
 #endif
    {
       /* Each value is saved in 1/100,000ths */
-    
+
       png_save_uint_32(buf, int_white_x);
       png_save_uint_32(buf + 4, int_white_y);
 
       png_save_uint_32(buf + 8, int_red_x);
       png_save_uint_32(buf + 12, int_red_y);
 
       png_save_uint_32(buf + 16, int_green_x);
       png_save_uint_32(buf + 20, int_green_y);
 
       png_save_uint_32(buf + 24, int_blue_x);
       png_save_uint_32(buf + 28, int_blue_y);
 
       png_write_chunk(png_ptr, (png_bytep)png_cHRM, buf, (png_size_t)32);
    }
 }
 #endif
 #ifdef PNG_FIXED_POINT_SUPPORTED
 void /* PRIVATE */
 png_write_cHRM_fixed(png_structp png_ptr, png_fixed_point white_x,
    png_fixed_point white_y, png_fixed_point red_x, png_fixed_point red_y,
    png_fixed_point green_x, png_fixed_point green_y, png_fixed_point blue_x,
    png_fixed_point blue_y)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_cHRM;
 #endif
    png_byte buf[32];
 
    png_debug(1, "in png_write_cHRM");
+
    /* Each value is saved in 1/100,000ths */
-#if !defined(PNG_NO_CHECK_cHRM)
+#ifdef PNG_CHECK_cHRM_SUPPORTED
    if (png_check_cHRM_fixed(png_ptr, white_x, white_y, red_x, red_y,
       green_x, green_y, blue_x, blue_y))
 #endif
    {
       png_save_uint_32(buf, (png_uint_32)white_x);
       png_save_uint_32(buf + 4, (png_uint_32)white_y);
 
       png_save_uint_32(buf + 8, (png_uint_32)red_x);
       png_save_uint_32(buf + 12, (png_uint_32)red_y);
 
       png_save_uint_32(buf + 16, (png_uint_32)green_x);
       png_save_uint_32(buf + 20, (png_uint_32)green_y);
 
       png_save_uint_32(buf + 24, (png_uint_32)blue_x);
       png_save_uint_32(buf + 28, (png_uint_32)blue_y);
 
       png_write_chunk(png_ptr, (png_bytep)png_cHRM, buf, (png_size_t)32);
    }
 }
 #endif
 #endif
 
-#if defined(PNG_WRITE_tRNS_SUPPORTED)
+#ifdef PNG_WRITE_tRNS_SUPPORTED
 /* Write the tRNS chunk */
 void /* PRIVATE */
 png_write_tRNS(png_structp png_ptr, png_bytep trans, png_color_16p tran,
    int num_trans, int color_type)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_tRNS;
 #endif
    png_byte buf[6];
 
    png_debug(1, "in png_write_tRNS");
+
    if (color_type == PNG_COLOR_TYPE_PALETTE)
    {
       if (num_trans <= 0 || num_trans > (int)png_ptr->num_palette)
       {
          png_warning(png_ptr, "Invalid number of transparent colors specified");
          return;
       }
       /* Write the chunk out as it is */
       png_write_chunk(png_ptr, (png_bytep)png_tRNS, trans,
         (png_size_t)num_trans);
@@ skipping 24 matching lines @@
       }
       png_write_chunk(png_ptr, (png_bytep)png_tRNS, buf, (png_size_t)6);
    }
    else
    {
       png_warning(png_ptr, "Can't write tRNS with an alpha channel");
    }
 }
 #endif
 
-#if defined(PNG_WRITE_bKGD_SUPPORTED)
+#ifdef PNG_WRITE_bKGD_SUPPORTED
 /* Write the background chunk */
 void /* PRIVATE */
 png_write_bKGD(png_structp png_ptr, png_color_16p back, int color_type)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_bKGD;
 #endif
    png_byte buf[6];
 
    png_debug(1, "in png_write_bKGD");
+
    if (color_type == PNG_COLOR_TYPE_PALETTE)
    {
       if (
-#if defined(PNG_MNG_FEATURES_SUPPORTED)
+#ifdef PNG_MNG_FEATURES_SUPPORTED
           (png_ptr->num_palette ||
           (!(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE))) &&
 #endif
          back->index >= png_ptr->num_palette)
       {
          png_warning(png_ptr, "Invalid background palette index");
          return;
       }
       buf[0] = back->index;
       png_write_chunk(png_ptr, (png_bytep)png_bKGD, buf, (png_size_t)1);
@@ skipping 18 matching lines @@
          png_warning(png_ptr,
            "Ignoring attempt to write bKGD chunk out-of-range for bit_depth");
          return;
       }
       png_save_uint_16(buf, back->gray);
       png_write_chunk(png_ptr, (png_bytep)png_bKGD, buf, (png_size_t)2);
    }
 }
 #endif
 
-#if defined(PNG_WRITE_hIST_SUPPORTED)
+#ifdef PNG_WRITE_hIST_SUPPORTED
 /* Write the histogram */
 void /* PRIVATE */
 png_write_hIST(png_structp png_ptr, png_uint_16p hist, int num_hist)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_hIST;
 #endif
    int i;
    png_byte buf[3];
 
    png_debug(1, "in png_write_hIST");
+
    if (num_hist > (int)png_ptr->num_palette)
    {
       png_debug2(3, "num_hist = %d, num_palette = %d", num_hist,
          png_ptr->num_palette);
       png_warning(png_ptr, "Invalid number of histogram entries specified");
       return;
    }
 
    png_write_chunk_start(png_ptr, (png_bytep)png_hIST,
      (png_uint_32)(num_hist * 2));
@@ skipping 20 matching lines @@
  */
 png_size_t /* PRIVATE */
 png_check_keyword(png_structp png_ptr, png_charp key, png_charpp new_key)
 {
    png_size_t key_len;
    png_charp kp, dp;
    int kflag;
    int kwarn=0;
 
    png_debug(1, "in png_check_keyword");
+
    *new_key = NULL;
 
    if (key == NULL || (key_len = png_strlen(key)) == 0)
    {
       png_warning(png_ptr, "zero length keyword");
       return ((png_size_t)0);
    }
 
    png_debug1(2, "Keyword to be checked is '%s'", key);
 
    *new_key = (png_charp)png_malloc_warn(png_ptr, (png_uint_32)(key_len + 2));
    if (*new_key == NULL)
    {
       png_warning(png_ptr, "Out of memory while procesing keyword");
       return ((png_size_t)0);
    }
 
    /* Replace non-printing characters with a blank and print a warning */
    for (kp = key, dp = *new_key; *kp != '\0'; kp++, dp++)
    {
       if ((png_byte)*kp < 0x20 ||
          ((png_byte)*kp > 0x7E && (png_byte)*kp < 0xA1))
       {
-#if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
+#if defined(PNG_STDIO_SUPPORTED) && !defined(_WIN32_WCE)
          char msg[40];
 
          png_snprintf(msg, 40,
            "invalid keyword character 0x%02X", (png_byte)*kp);
          png_warning(png_ptr, msg);
 #else
          png_warning(png_ptr, "invalid character in keyword");
 #endif
          *dp = ' ';
       }
@@ skipping 66 matching lines @@
    {
       png_warning(png_ptr, "keyword length must be 1 - 79 characters");
       (*new_key)[79] = '\0';
       key_len = 79;
    }
 
    return (key_len);
 }
 #endif
 
-#if defined(PNG_WRITE_tEXt_SUPPORTED)
+#ifdef PNG_WRITE_tEXt_SUPPORTED
 /* Write a tEXt chunk */
 void /* PRIVATE */
 png_write_tEXt(png_structp png_ptr, png_charp key, png_charp text,
    png_size_t text_len)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_tEXt;
 #endif
    png_size_t key_len;
    png_charp new_key;
 
    png_debug(1, "in png_write_tEXt");
+
    if ((key_len = png_check_keyword(png_ptr, key, &new_key))==0)
       return;
 
    if (text == NULL || *text == '\0')
       text_len = 0;
    else
       text_len = png_strlen(text);
 
    /* Make sure we include the 0 after the key */
    png_write_chunk_start(png_ptr, (png_bytep)png_tEXt,
       (png_uint_32)(key_len + text_len + 1));
    /*
     * We leave it to the application to meet PNG-1.0 requirements on the
     * contents of the text.  PNG-1.0 through PNG-1.2 discourage the use of
     * any non-Latin-1 characters except for NEWLINE.  ISO PNG will forbid them.
     * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
     */
    png_write_chunk_data(png_ptr, (png_bytep)new_key,
      (png_size_t)(key_len + 1));
    if (text_len)
       png_write_chunk_data(png_ptr, (png_bytep)text, (png_size_t)text_len);
 
    png_write_chunk_end(png_ptr);
    png_free(png_ptr, new_key);
 }
 #endif
 
-#if defined(PNG_WRITE_zTXt_SUPPORTED)
+#ifdef PNG_WRITE_zTXt_SUPPORTED
 /* Write a compressed text chunk */
 void /* PRIVATE */
 png_write_zTXt(png_structp png_ptr, png_charp key, png_charp text,
    png_size_t text_len, int compression)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_zTXt;
 #endif
    png_size_t key_len;
    char buf[1];
@@ skipping 39 matching lines @@
    /* Write compression */
    png_write_chunk_data(png_ptr, (png_bytep)buf, (png_size_t)1);
    /* Write the compressed data */
    png_write_compressed_data_out(png_ptr, &comp);
 
    /* Close the chunk */
    png_write_chunk_end(png_ptr);
 }
 #endif
 
-#if defined(PNG_WRITE_iTXt_SUPPORTED)
+#ifdef PNG_WRITE_iTXt_SUPPORTED
 /* Write an iTXt chunk */
 void /* PRIVATE */
 png_write_iTXt(png_structp png_ptr, int compression, png_charp key,
     png_charp lang, png_charp lang_key, png_charp text)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_iTXt;
 #endif
    png_size_t lang_len, key_len, lang_key_len, text_len;
    png_charp new_lang;
@@ skipping 68 matching lines @@
    png_write_chunk_data(png_ptr, (lang_key ? (png_bytep)lang_key : cbuf),
      (png_size_t)(lang_key_len + 1));
    png_write_compressed_data_out(png_ptr, &comp);
 
    png_write_chunk_end(png_ptr);
    png_free(png_ptr, new_key);
    png_free(png_ptr, new_lang);
 }
 #endif
 
-#if defined(PNG_WRITE_oFFs_SUPPORTED)
+#ifdef PNG_WRITE_oFFs_SUPPORTED
 /* Write the oFFs chunk */
 void /* PRIVATE */
 png_write_oFFs(png_structp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
    int unit_type)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_oFFs;
 #endif
    png_byte buf[9];
 
    png_debug(1, "in png_write_oFFs");
+
    if (unit_type >= PNG_OFFSET_LAST)
       png_warning(png_ptr, "Unrecognized unit type for oFFs chunk");
 
    png_save_int_32(buf, x_offset);
    png_save_int_32(buf + 4, y_offset);
    buf[8] = (png_byte)unit_type;
 
    png_write_chunk(png_ptr, (png_bytep)png_oFFs, buf, (png_size_t)9);
 }
 #endif
-#if defined(PNG_WRITE_pCAL_SUPPORTED)
+#ifdef PNG_WRITE_pCAL_SUPPORTED
 /* Write the pCAL chunk (described in the PNG extensions document) */
 void /* PRIVATE */
 png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
    png_int_32 X1, int type, int nparams, png_charp units, png_charpp params)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_pCAL;
 #endif
    png_size_t purpose_len, units_len, total_len;
    png_uint_32p params_len;
    png_byte buf[10];
    png_charp new_purpose;
    int i;
 
    png_debug1(1, "in png_write_pCAL (%d parameters)", nparams);
+
    if (type >= PNG_EQUATION_LAST)
       png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
 
    purpose_len = png_check_keyword(png_ptr, purpose, &new_purpose) + 1;
    png_debug1(3, "pCAL purpose length = %d", (int)purpose_len);
    units_len = png_strlen(units) + (nparams == 0 ? 0 : 1);
    png_debug1(3, "pCAL units length = %d", (int)units_len);
    total_len = purpose_len + units_len + 10;
 
    params_len = (png_uint_32p)png_malloc(png_ptr,
@@ skipping 26 matching lines @@
    {
       png_write_chunk_data(png_ptr, (png_bytep)params[i],
          (png_size_t)params_len[i]);
    }
 
    png_free(png_ptr, params_len);
    png_write_chunk_end(png_ptr);
 }
 #endif
 
-#if defined(PNG_WRITE_sCAL_SUPPORTED)
+#ifdef PNG_WRITE_sCAL_SUPPORTED
 /* Write the sCAL chunk */
-#if defined(PNG_FLOATING_POINT_SUPPORTED) && !defined(PNG_NO_STDIO)
+#if defined(PNG_FLOATING_POINT_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
 void /* PRIVATE */
 png_write_sCAL(png_structp png_ptr, int unit, double width, double height)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_sCAL;
 #endif
    char buf[64];
    png_size_t total_len;
 
    png_debug(1, "in png_write_sCAL");
 
    buf[0] = (char)unit;
-#if defined(_WIN32_WCE)
+#ifdef _WIN32_WCE
 /* sprintf() function is not supported on WindowsCE */
    {
       wchar_t wc_buf[32];
       size_t wc_len;
       swprintf(wc_buf, TEXT("%12.12e"), width);
       wc_len = wcslen(wc_buf);
-      WideCharToMultiByte(CP_ACP, 0, wc_buf, -1, buf + 1, wc_len, NULL, NULL);
+      WideCharToMultiByte(CP_ACP, 0, wc_buf, -1, buf + 1, wc_len, NULL,
+          NULL);
       total_len = wc_len + 2;
       swprintf(wc_buf, TEXT("%12.12e"), height);
       wc_len = wcslen(wc_buf);
       WideCharToMultiByte(CP_ACP, 0, wc_buf, -1, buf + total_len, wc_len,
          NULL, NULL);
       total_len += wc_len;
    }
 #else
    png_snprintf(buf + 1, 63, "%12.12e", width);
    total_len = 1 + png_strlen(buf + 1) + 1;
@@ skipping 31 matching lines @@
    png_memcpy(buf + 1, width, wlen + 1);      /* Append the '\0' here */
    png_memcpy(buf + wlen + 2, height, hlen);  /* Do NOT append the '\0' here */
 
    png_debug1(3, "sCAL total length = %u", (unsigned int)total_len);
    png_write_chunk(png_ptr, (png_bytep)png_sCAL, buf, total_len);
 }
 #endif
 #endif
 #endif
 
-#if defined(PNG_WRITE_pHYs_SUPPORTED)
+#ifdef PNG_WRITE_pHYs_SUPPORTED
 /* Write the pHYs chunk */
 void /* PRIVATE */
 png_write_pHYs(png_structp png_ptr, png_uint_32 x_pixels_per_unit,
    png_uint_32 y_pixels_per_unit,
    int unit_type)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_pHYs;
 #endif
    png_byte buf[9];
 
    png_debug(1, "in png_write_pHYs");
+
    if (unit_type >= PNG_RESOLUTION_LAST)
       png_warning(png_ptr, "Unrecognized unit type for pHYs chunk");
 
    png_save_uint_32(buf, x_pixels_per_unit);
    png_save_uint_32(buf + 4, y_pixels_per_unit);
    buf[8] = (png_byte)unit_type;
 
    png_write_chunk(png_ptr, (png_bytep)png_pHYs, buf, (png_size_t)9);
 }
 #endif
 
-#if defined(PNG_WRITE_tIME_SUPPORTED)
+#ifdef PNG_WRITE_tIME_SUPPORTED
 /* Write the tIME chunk.  Use either png_convert_from_struct_tm()
  * or png_convert_from_time_t(), or fill in the structure yourself.
  */
 void /* PRIVATE */
 png_write_tIME(png_structp png_ptr, png_timep mod_time)
 {
 #ifdef PNG_USE_LOCAL_ARRAYS
    PNG_tIME;
 #endif
    png_byte buf[7];
 
    png_debug(1, "in png_write_tIME");
+
    if (mod_time->month  > 12 || mod_time->month  < 1 ||
        mod_time->day    > 31 || mod_time->day    < 1 ||
        mod_time->hour   > 23 || mod_time->second > 60)
    {
       png_warning(png_ptr, "Invalid time specified for tIME chunk");
       return;
    }
 
    png_save_uint_16(buf, mod_time->year);
    buf[2] = mod_time->month;
    buf[3] = mod_time->day;
    buf[4] = mod_time->hour;
    buf[5] = mod_time->minute;
    buf[6] = mod_time->second;
 
    png_write_chunk(png_ptr, (png_bytep)png_tIME, buf, (png_size_t)7);
 }
 #endif
 
 /* Initializes the row writing capability of libpng */
 void /* PRIVATE */
 png_write_start_row(png_structp png_ptr)
 {
 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
-#ifdef PNG_USE_LOCAL_ARRAYS
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 
    /* Start of interlace block */
    int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
 
    /* Offset to next interlace block */
    int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
 
    /* Start of interlace block in the y direction */
    int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
 
    /* Offset to next interlace block in the y direction */
    int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
 #endif
-#endif
 
    png_size_t buf_size;
 
    png_debug(1, "in png_write_start_row");
+
    buf_size = (png_size_t)(PNG_ROWBYTES(
       png_ptr->usr_channels*png_ptr->usr_bit_depth, png_ptr->width) + 1);
 
    /* Set up row buffer */
    png_ptr->row_buf = (png_bytep)png_malloc(png_ptr,
      (png_uint_32)buf_size);
    png_ptr->row_buf[0] = PNG_FILTER_VALUE_NONE;
 
-#ifndef PNG_NO_WRITE_FILTER
+#ifdef PNG_WRITE_FILTER_SUPPORTED
    /* Set up filtering buffer, if using this filter */
    if (png_ptr->do_filter & PNG_FILTER_SUB)
    {
       png_ptr->sub_row = (png_bytep)png_malloc(png_ptr,
          (png_uint_32)(png_ptr->rowbytes + 1));
       png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
    }
 
    /* We only need to keep the previous row if we are using one of these. */
    if (png_ptr->do_filter & (PNG_FILTER_AVG | PNG_FILTER_UP | PNG_FILTER_PAETH))
    {
-     /* Set up previous row buffer */
-     png_ptr->prev_row = (png_bytep)png_malloc(png_ptr,
-        (png_uint_32)buf_size);
-     png_memset(png_ptr->prev_row, 0, buf_size);
+      /* Set up previous row buffer */
+      png_ptr->prev_row = (png_bytep)png_calloc(png_ptr,
+         (png_uint_32)buf_size);
 
       if (png_ptr->do_filter & PNG_FILTER_UP)
       {
          png_ptr->up_row = (png_bytep)png_malloc(png_ptr,
-           (png_uint_32)(png_ptr->rowbytes + 1));
+            (png_uint_32)(png_ptr->rowbytes + 1));
          png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
       }
 
       if (png_ptr->do_filter & PNG_FILTER_AVG)
       {
          png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
-           (png_uint_32)(png_ptr->rowbytes + 1));
+            (png_uint_32)(png_ptr->rowbytes + 1));
          png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
       }
 
       if (png_ptr->do_filter & PNG_FILTER_PAETH)
       {
          png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr,
-           (png_uint_32)(png_ptr->rowbytes + 1));
+            (png_uint_32)(png_ptr->rowbytes + 1));
          png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
       }
    }
-#endif /* PNG_NO_WRITE_FILTER */
+#endif /* PNG_WRITE_FILTER_SUPPORTED */
 
 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
    /* If interlaced, we need to set up width and height of pass */
    if (png_ptr->interlaced)
    {
       if (!(png_ptr->transformations & PNG_INTERLACE))
       {
          png_ptr->num_rows = (png_ptr->height + png_pass_yinc[0] - 1 -
             png_pass_ystart[0]) / png_pass_yinc[0];
          png_ptr->usr_width = (png_ptr->width + png_pass_inc[0] - 1 -
@@ skipping 13 matching lines @@
    }
    png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
    png_ptr->zstream.next_out = png_ptr->zbuf;
 }
 
 /* Internal use only.  Called when finished processing a row of data. */
 void /* PRIVATE */
 png_write_finish_row(png_structp png_ptr)
 {
 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
-#ifdef PNG_USE_LOCAL_ARRAYS
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 
    /* Start of interlace block */
    int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
 
    /* Offset to next interlace block */
    int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
 
    /* Start of interlace block in the y direction */
    int png_pass_ystart[7] = {0, 0, 4, 0, 2, 0, 1};
 
    /* Offset to next interlace block in the y direction */
    int png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
 #endif
-#endif
 
    int ret;
 
    png_debug(1, "in png_write_finish_row");
+
    /* Next row */
    png_ptr->row_number++;
 
    /* See if we are done */
    if (png_ptr->row_number < png_ptr->num_rows)
       return;
 
 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
    /* If interlaced, go to next pass */
    if (png_ptr->interlaced)
@@ skipping 67 matching lines @@
    if (png_ptr->zstream.avail_out < png_ptr->zbuf_size)
    {
       png_write_IDAT(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size -
          png_ptr->zstream.avail_out);
    }
 
    deflateReset(&png_ptr->zstream);
    png_ptr->zstream.data_type = Z_BINARY;
 }
 
-#if defined(PNG_WRITE_INTERLACING_SUPPORTED)
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
 /* Pick out the correct pixels for the interlace pass.
  * The basic idea here is to go through the row with a source
  * pointer and a destination pointer (sp and dp), and copy the
  * correct pixels for the pass.  As the row gets compacted,
  * sp will always be >= dp, so we should never overwrite anything.
  * See the default: case for the easiest code to understand.
  */
 void /* PRIVATE */
 png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
 {
-#ifdef PNG_USE_LOCAL_ARRAYS
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
 
    /* Start of interlace block */
    int png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};
 
    /* Offset to next interlace block */
    int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
-#endif
 
    png_debug(1, "in png_do_write_interlace");
+
    /* We don't have to do anything on the last pass (6) */
-#if defined(PNG_USELESS_TESTS_SUPPORTED)
+#ifdef PNG_USELESS_TESTS_SUPPORTED
    if (row != NULL && row_info != NULL && pass < 6)
 #else
    if (pass < 6)
 #endif
    {
       /* Each pixel depth is handled separately */
       switch (row_info->pixel_depth)
       {
          case 1:
          {
@@ skipping 139 matching lines @@
  * chosen filter.
  */
 #define PNG_MAXSUM (((png_uint_32)(-1)) >> 1)
 #define PNG_HISHIFT 10
 #define PNG_LOMASK ((png_uint_32)0xffffL)
 #define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT))
 void /* PRIVATE */
 png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
 {
    png_bytep best_row;
-#ifndef PNG_NO_WRITE_FILTER
+#ifdef PNG_WRITE_FILTER_SUPPORTED
    png_bytep prev_row, row_buf;
    png_uint_32 mins, bpp;
    png_byte filter_to_do = png_ptr->do_filter;
    png_uint_32 row_bytes = row_info->rowbytes;
-#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
    int num_p_filters = (int)png_ptr->num_prev_filters;
-#endif
+#endif 
 
    png_debug(1, "in png_write_find_filter");
+
+#ifndef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+  if (png_ptr->row_number == 0 && filter_to_do == PNG_ALL_FILTERS)
+  {
+      /* These will never be selected so we need not test them. */
+      filter_to_do &= ~(PNG_FILTER_UP | PNG_FILTER_PAETH);
+  }
+#endif 
+
    /* Find out how many bytes offset each pixel is */
    bpp = (row_info->pixel_depth + 7) >> 3;
 
    prev_row = png_ptr->prev_row;
 #endif
    best_row = png_ptr->row_buf;
-#ifndef PNG_NO_WRITE_FILTER
+#ifdef PNG_WRITE_FILTER_SUPPORTED
    row_buf = best_row;
    mins = PNG_MAXSUM;
 
    /* The prediction method we use is to find which method provides the
     * smallest value when summing the absolute values of the distances
     * from zero, using anything >= 128 as negative numbers.  This is known
     * as the "minimum sum of absolute differences" heuristic.  Other
     * heuristics are the "weighted minimum sum of absolute differences"
     * (experimental and can in theory improve compression), and the "zlib
     * predictive" method (not implemented yet), which does test compressions
@@ skipping 22 matching lines @@
       png_uint_32 sum = 0;
       png_uint_32 i;
       int v;
 
       for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
       {
          v = *rp;
          sum += (v < 128) ? v : 256 - v;
       }
 
-#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
       {
          png_uint_32 sumhi, sumlo;
          int j;
          sumlo = sum & PNG_LOMASK;
          sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; /* Gives us some footroom */
 
          /* Reduce the sum if we match any of the previous rows */
          for (j = 0; j < num_p_filters; j++)
          {
@@ skipping 43 matching lines @@
       best_row = png_ptr->sub_row;
    }
 
    else if (filter_to_do & PNG_FILTER_SUB)
    {
       png_bytep rp, dp, lp;
       png_uint_32 sum = 0, lmins = mins;
       png_uint_32 i;
       int v;
 
-#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
       /* We temporarily increase the "minimum sum" by the factor we
        * would reduce the sum of this filter, so that we can do the
        * early exit comparison without scaling the sum each time.
        */
       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
       {
          int j;
          png_uint_32 lmhi, lmlo;
          lmlo = lmins & PNG_LOMASK;
          lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
@@ skipping 32 matching lines @@
          i++, rp++, lp++, dp++)
       {
          v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
 
          sum += (v < 128) ? v : 256 - v;
 
          if (sum > lmins)  /* We are already worse, don't continue. */
             break;
       }
 
-#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
       {
          int j;
          png_uint_32 sumhi, sumlo;
          sumlo = sum & PNG_LOMASK;
          sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
 
          for (j = 0; j < num_p_filters; j++)
          {
             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB)
@@ skipping 40 matching lines @@
    }
 
    else if (filter_to_do & PNG_FILTER_UP)
    {
       png_bytep rp, dp, pp;
       png_uint_32 sum = 0, lmins = mins;
       png_uint_32 i;
       int v;
 
 
-#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
       {
          int j;
          png_uint_32 lmhi, lmlo;
          lmlo = lmins & PNG_LOMASK;
          lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
 
          for (j = 0; j < num_p_filters; j++)
          {
             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
@@ skipping 21 matching lines @@
            pp = prev_row + 1; i < row_bytes; i++)
       {
          v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
 
          sum += (v < 128) ? v : 256 - v;
 
          if (sum > lmins)  /* We are already worse, don't continue. */
             break;
       }
 
-#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
       {
          int j;
          png_uint_32 sumhi, sumlo;
          sumlo = sum & PNG_LOMASK;
          sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
 
          for (j = 0; j < num_p_filters; j++)
          {
             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP)
@@ skipping 42 matching lines @@
       best_row = png_ptr->avg_row;
    }
 
    else if (filter_to_do & PNG_FILTER_AVG)
    {
       png_bytep rp, dp, pp, lp;
       png_uint_32 sum = 0, lmins = mins;
       png_uint_32 i;
       int v;
 
-#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
       {
          int j;
          png_uint_32 lmhi, lmlo;
          lmlo = lmins & PNG_LOMASK;
          lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
 
          for (j = 0; j < num_p_filters; j++)
          {
             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_AVG)
@@ skipping 28 matching lines @@
       {
          v = *dp++ =
           (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) & 0xff);
 
          sum += (v < 128) ? v : 256 - v;
 
          if (sum > lmins)  /* We are already worse, don't continue. */
             break;
       }
 
-#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
       {
          int j;
          png_uint_32 sumhi, sumlo;
          sumlo = sum & PNG_LOMASK;
          sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
 
          for (j = 0; j < num_p_filters; j++)
          {
             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE)
@@ skipping 63 matching lines @@
       best_row = png_ptr->paeth_row;
    }
 
    else if (filter_to_do & PNG_FILTER_PAETH)
    {
       png_bytep rp, dp, pp, cp, lp;
       png_uint_32 sum = 0, lmins = mins;
       png_uint_32 i;
       int v;
 
-#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
       {
          int j;
          png_uint_32 lmhi, lmlo;
          lmlo = lmins & PNG_LOMASK;
          lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
 
          for (j = 0; j < num_p_filters; j++)
          {
             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
@@ skipping 60 matching lines @@
 #endif /* PNG_SLOW_PAETH */
 
          v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
 
          sum += (v < 128) ? v : 256 - v;
 
          if (sum > lmins)  /* We are already worse, don't continue. */
             break;
       }
 
-#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
       if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
       {
          int j;
          png_uint_32 sumhi, sumlo;
          sumlo = sum & PNG_LOMASK;
          sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
 
          for (j = 0; j < num_p_filters; j++)
          {
             if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH)
@@ skipping 15 matching lines @@
          else
             sum = (sumhi << PNG_HISHIFT) + sumlo;
       }
 #endif
 
       if (sum < mins)
       {
          best_row = png_ptr->paeth_row;
       }
    }
-#endif /* PNG_NO_WRITE_FILTER */
+#endif /* PNG_WRITE_FILTER_SUPPORTED */
    /* Do the actual writing of the filtered row data from the chosen filter. */
 
    png_write_filtered_row(png_ptr, best_row);
 
-#ifndef PNG_NO_WRITE_FILTER
-#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
+#ifdef PNG_WRITE_FILTER_SUPPORTED
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
    /* Save the type of filter we picked this time for future calculations */
    if (png_ptr->num_prev_filters > 0)
    {
       int j;
       for (j = 1; j < num_p_filters; j++)
       {
          png_ptr->prev_filters[j] = png_ptr->prev_filters[j - 1];
       }
       png_ptr->prev_filters[j] = best_row[0];
    }
 #endif
-#endif /* PNG_NO_WRITE_FILTER */
+#endif /* PNG_WRITE_FILTER_SUPPORTED */
 }
 
 
 /* Do the actual writing of a previously filtered row. */
 void /* PRIVATE */
 png_write_filtered_row(png_structp png_ptr, png_bytep filtered_row)
 {
    png_debug(1, "in png_write_filtered_row");
+
    png_debug1(2, "filter = %d", filtered_row[0]);
    /* Set up the zlib input buffer */
 
    png_ptr->zstream.next_in = filtered_row;
    png_ptr->zstream.avail_in = (uInt)png_ptr->row_info.rowbytes + 1;
    /* Repeat until we have compressed all the data */
    do
    {
       int ret; /* Return of zlib */
 
@@ skipping 25 matching lines @@
       png_bytep tptr;
 
       tptr = png_ptr->prev_row;
       png_ptr->prev_row = png_ptr->row_buf;
       png_ptr->row_buf = tptr;
    }
 
    /* Finish row - updates counters and flushes zlib if last row */
    png_write_finish_row(png_ptr);
 
-#if defined(PNG_WRITE_FLUSH_SUPPORTED)
+#ifdef PNG_WRITE_FLUSH_SUPPORTED
    png_ptr->flush_rows++;
 
    if (png_ptr->flush_dist > 0 &&
        png_ptr->flush_rows >= png_ptr->flush_dist)
    {
       png_write_flush(png_ptr);
    }
 #endif
 }
 #endif /* PNG_WRITE_SUPPORTED */