Changeset 43 for vendor/libpng/pngrtran.c

Timestamp:

02/15/10 11:37:15 (2 years ago)

Author:

Carsten

Message:

Upgraded vendor/libpng from 1.2.40 to 1.2.42.

Files:

• vendor/libpng/pngrtran.c (modified) (106 diffs)

vendor/libpng/pngrtran.c

@@ -2 +2 @@
 /* pngrtran.c - transforms the data in a row for PNG readers
  *
- * Last changed in libpng 1.2.38 [July 16, 2009]
- * Copyright (c) 1998-2009 Glenn Randers-Pehrson
+ * Last changed in libpng 1.2.42 [January 3, 2010]
+ * Copyright (c) 1998-2010 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -18 +18 @@
 
 #define PNG_INTERNAL
+#define PNG_NO_PEDANTIC_WARNINGS
 #include "png.h"
-#if defined(PNG_READ_SUPPORTED)
+#ifdef PNG_READ_SUPPORTED
 
 /* Set the action on getting a CRC error for an ancillary or critical chunk. */
@@ -26 +27 @@
 {
    png_debug(1, "in png_set_crc_action");
-   /* Tell libpng how we react to CRC errors in critical chunks */
+ 
    if (png_ptr == NULL)
       return;
+
+   /* Tell libpng how we react to CRC errors in critical chunks */
    switch (crit_action)
    {
@@ -56 +59 @@
    }
 
+   /* Tell libpng how we react to CRC errors in ancillary chunks */
    switch (ancil_action)
    {
@@ -95 +99 @@
 {
    png_debug(1, "in png_set_background");
+ 
    if (png_ptr == NULL)
       return;
@@ -112 +117 @@
 #endif
 
-#if defined(PNG_READ_16_TO_8_SUPPORTED)
+#ifdef PNG_READ_16_TO_8_SUPPORTED
 /* Strip 16 bit depth files to 8 bit depth */
 void PNGAPI
@@ -118 +123 @@
 {
    png_debug(1, "in png_set_strip_16");
+
    if (png_ptr == NULL)
       return;
@@ -124 +130 @@
 #endif
 
-#if defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
+#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
 void PNGAPI
 png_set_strip_alpha(png_structp png_ptr)
 {
    png_debug(1, "in png_set_strip_alpha");
+
    if (png_ptr == NULL)
       return;
@@ -135 +142 @@
 #endif
 
-#if defined(PNG_READ_DITHER_SUPPORTED)
+#ifdef PNG_READ_DITHER_SUPPORTED
 /* Dither file to 8 bit.  Supply a palette, the current number
  * of elements in the palette, the maximum number of elements
@@ -160 +167 @@
 {
    png_debug(1, "in png_set_dither");
+
    if (png_ptr == NULL)
       return;
@@ -329 +337 @@
          }
 
-         hash = (png_dsortpp)png_malloc(png_ptr, (png_uint_32)(769 *
+         hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 *
             png_sizeof(png_dsortp)));
-         png_memset(hash, 0, 769 * png_sizeof(png_dsortp));
 
          num_new_palette = num_palette;
@@ -477 +484 @@
       int num_blue = (1 << PNG_DITHER_BLUE_BITS);
       png_size_t num_entries = ((png_size_t)1 << total_bits);
-      png_ptr->palette_lookup = (png_bytep )png_malloc(png_ptr,
+
+      png_ptr->palette_lookup = (png_bytep )png_calloc(png_ptr,
          (png_uint_32)(num_entries * png_sizeof(png_byte)));
-      png_memset(png_ptr->palette_lookup, 0, num_entries *
-         png_sizeof(png_byte));
 
       distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries *
          png_sizeof(png_byte)));
-
       png_memset(distance, 0xff, num_entries * png_sizeof(png_byte));
 
@@ -545 +550 @@
 {
    png_debug(1, "in png_set_gamma");
+
    if (png_ptr == NULL)
       return;
+
    if ((fabs(scrn_gamma * file_gamma - 1.0) > PNG_GAMMA_THRESHOLD) ||
        (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) ||
@@ -556 +563 @@
 #endif
 
-#if defined(PNG_READ_EXPAND_SUPPORTED)
+#ifdef PNG_READ_EXPAND_SUPPORTED
 /* Expand paletted images to RGB, expand grayscale images of
  * less than 8-bit depth to 8-bit depth, and expand tRNS chunks
@@ -565 +572 @@
 {
    png_debug(1, "in png_set_expand");
+
    if (png_ptr == NULL)
       return;
+
    png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
    png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
@@ -584 +593 @@
  *  doing, whereas "expand" can (and does) mean any number of things.
  *
- *  GRP 20060307: In libpng-1.4.0, png_set_gray_1_2_4_to_8() was modified
- *  to expand only the sample depth but not to expand the tRNS to alpha.
+ *  GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified
+ *  to expand only the sample depth but not to expand the tRNS to alpha
+ *  and its name was changed to png_set_expand_gray_1_2_4_to_8().
  */
 
@@ -593 +603 @@
 {
    png_debug(1, "in png_set_palette_to_rgb");
+
    if (png_ptr == NULL)
       return;
+
    png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
    png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
 }
 
-#if !defined(PNG_1_0_X)
+#ifndef PNG_1_0_X
 /* Expand grayscale images of less than 8-bit depth to 8 bits. */
 void PNGAPI
@@ -605 +617 @@
 {
    png_debug(1, "in png_set_expand_gray_1_2_4_to_8");
+
    if (png_ptr == NULL)
       return;
+
    png_ptr->transformations |= PNG_EXPAND;
    png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
@@ -619 +633 @@
 {
    png_debug(1, "in png_set_gray_1_2_4_to_8");
+
    if (png_ptr == NULL)
       return;
+
    png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
 }
@@ -631 +647 @@
 {
    png_debug(1, "in png_set_tRNS_to_alpha");
+
    png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
    png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
@@ -636 +653 @@
 #endif /* defined(PNG_READ_EXPAND_SUPPORTED) */
 
-#if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
 void PNGAPI
 png_set_gray_to_rgb(png_structp png_ptr)
 {
    png_debug(1, "in png_set_gray_to_rgb");
+
    png_ptr->transformations |= PNG_GRAY_TO_RGB;
    png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
@@ -646 +664 @@
 #endif
 
-#if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
-#if defined(PNG_FLOATING_POINT_SUPPORTED)
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+#ifdef PNG_FLOATING_POINT_SUPPORTED
 /* Convert a RGB image to a grayscale of the same width.  This allows us,
  * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image.
@@ -669 +687 @@
 {
    png_debug(1, "in png_set_rgb_to_gray");
+
    if (png_ptr == NULL)
       return;
+
    switch(error_action)
    {
@@ -682 +702 @@
    }
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
-#if defined(PNG_READ_EXPAND_SUPPORTED)
+#ifdef PNG_READ_EXPAND_SUPPORTED
       png_ptr->transformations |= PNG_EXPAND;
 #else
@@ -725 +745 @@
 {
    png_debug(1, "in png_set_read_user_transform_fn");
+
    if (png_ptr == NULL)
       return;
-#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
+
+#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
    png_ptr->transformations |= PNG_USER_TRANSFORM;
    png_ptr->read_user_transform_fn = read_user_transform_fn;
@@ -746 +768 @@
 {
    png_debug(1, "in png_init_read_transformations");
-#if defined(PNG_USELESS_TESTS_SUPPORTED)
-   if (png_ptr != NULL)
+
+#ifdef PNG_USELESS_TESTS_SUPPORTED
+  if (png_ptr != NULL)
 #endif
   {
@@ -757 +780 @@
 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
 
-#if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
    /* Detect gray background and attempt to enable optimization
     * for gray --> RGB case
@@ -844 +867 @@
             png_ptr->palette[png_ptr->background.index].blue;
 
-#if defined(PNG_READ_INVERT_ALPHA_SUPPORTED)
+#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
         if (png_ptr->transformations & PNG_INVERT_ALPHA)
         {
-#if defined(PNG_READ_EXPAND_SUPPORTED)
+#ifdef PNG_READ_EXPAND_SUPPORTED
            if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
 #endif
@@ -890 +913 @@
    {
       png_build_gamma_table(png_ptr);
-#if defined(PNG_READ_BACKGROUND_SUPPORTED)
+
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
       if (png_ptr->transformations & PNG_BACKGROUND)
       {
@@ -991 +1015 @@
                }
             }
-            /* Prevent the transformations being done again, and make sure
-             * that the now spurious alpha channel is stripped - the code
-             * has just reduced background composition and gamma correction
-             * to a simple alpha channel strip.
-             */
-            png_ptr->transformations &= ~PNG_BACKGROUND;
-            png_ptr->transformations &= ~PNG_GAMMA;
-            png_ptr->transformations |= PNG_STRIP_ALPHA;
+            /* Prevent the transformations being done again, and make sure
+             * that the now spurious alpha channel is stripped - the code
+             * has just reduced background composition and gamma correction
+             * to a simple alpha channel strip.
+             */
+            png_ptr->transformations &= ~PNG_BACKGROUND;
+            png_ptr->transformations &= ~PNG_GAMMA;
+            png_ptr->transformations |= PNG_STRIP_ALPHA;
          }
          /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
@@ -1076 +1100 @@
          }
 
-         /* Done the gamma correction. */
-         png_ptr->transformations &= ~PNG_GAMMA;
+         /* Done the gamma correction. */
+         png_ptr->transformations &= ~PNG_GAMMA;
       }
    }
-#if defined(PNG_READ_BACKGROUND_SUPPORTED)
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
    else
 #endif
 #endif /* PNG_READ_GAMMA_SUPPORTED && PNG_FLOATING_POINT_SUPPORTED */
-#if defined(PNG_READ_BACKGROUND_SUPPORTED)
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
    /* No GAMMA transformation */
    if ((png_ptr->transformations & PNG_BACKGROUND) &&
@@ -1122 +1146 @@
 #endif /* PNG_READ_BACKGROUND_SUPPORTED */
 
-#if defined(PNG_READ_SHIFT_SUPPORTED)
+#ifdef PNG_READ_SHIFT_SUPPORTED
    if ((png_ptr->transformations & PNG_SHIFT) &&
       (color_type == PNG_COLOR_TYPE_PALETTE))
@@ -1162 +1186 @@
 {
    png_debug(1, "in png_read_transform_info");
-#if defined(PNG_READ_EXPAND_SUPPORTED)
+
+#ifdef PNG_READ_EXPAND_SUPPORTED
    if (png_ptr->transformations & PNG_EXPAND)
    {
@@ -1189 +1214 @@
 #endif
 
-#if defined(PNG_READ_BACKGROUND_SUPPORTED)
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
    if (png_ptr->transformations & PNG_BACKGROUND)
    {
@@ -1198 +1223 @@
 #endif
 
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
    if (png_ptr->transformations & PNG_GAMMA)
    {
@@ -1210 +1235 @@
 #endif
 
-#if defined(PNG_READ_16_TO_8_SUPPORTED)
+#ifdef PNG_READ_16_TO_8_SUPPORTED
    if ((png_ptr->transformations & PNG_16_TO_8) && (info_ptr->bit_depth == 16))
       info_ptr->bit_depth = 8;
 #endif
 
-#if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
    if (png_ptr->transformations & PNG_GRAY_TO_RGB)
       info_ptr->color_type |= PNG_COLOR_MASK_COLOR;
 #endif
 
-#if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
    if (png_ptr->transformations & PNG_RGB_TO_GRAY)
       info_ptr->color_type &= ~PNG_COLOR_MASK_COLOR;
 #endif
 
-#if defined(PNG_READ_DITHER_SUPPORTED)
+#ifdef PNG_READ_DITHER_SUPPORTED
    if (png_ptr->transformations & PNG_DITHER)
    {
@@ -1237 +1262 @@
 #endif
 
-#if defined(PNG_READ_PACK_SUPPORTED)
+#ifdef PNG_READ_PACK_SUPPORTED
    if ((png_ptr->transformations & PNG_PACK) && (info_ptr->bit_depth < 8))
       info_ptr->bit_depth = 8;
@@ -1249 +1274 @@
       info_ptr->channels = 1;
 
-#if defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
+#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
    if (png_ptr->flags & PNG_FLAG_STRIP_ALPHA)
       info_ptr->color_type &= ~PNG_COLOR_MASK_ALPHA;
@@ -1257 +1282 @@
       info_ptr->channels++;
 
-#if defined(PNG_READ_FILLER_SUPPORTED)
+#ifdef PNG_READ_FILLER_SUPPORTED
    /* STRIP_ALPHA and FILLER allowed:  MASK_ALPHA bit stripped above */
    if ((png_ptr->transformations & PNG_FILLER) &&
@@ -1265 +1290 @@
       info_ptr->channels++;
       /* If adding a true alpha channel not just filler */
-#if !defined(PNG_1_0_X)
+#ifndef PNG_1_0_X
       if (png_ptr->transformations & PNG_ADD_ALPHA)
         info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
@@ -1288 +1313 @@
    info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width);
 
-#if !defined(PNG_READ_EXPAND_SUPPORTED)
+#ifndef PNG_READ_EXPAND_SUPPORTED
    if (png_ptr)
       return;
@@ -1302 +1327 @@
 {
    png_debug(1, "in png_do_read_transformations");
+
    if (png_ptr->row_buf == NULL)
    {
-#if !defined(PNG_NO_STDIO) && !defined(_WIN32_WCE)
+#if defined(PNG_STDIO_SUPPORTED) && !defined(_WIN32_WCE)
       char msg[50];
 
@@ -1328 +1354 @@
 #endif
 
-#if defined(PNG_READ_EXPAND_SUPPORTED)
+#ifdef PNG_READ_EXPAND_SUPPORTED
    if (png_ptr->transformations & PNG_EXPAND)
    {
@@ -1349 +1375 @@
 #endif
 
-#if defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
+#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
    if (png_ptr->flags & PNG_FLAG_STRIP_ALPHA)
       png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
@@ -1355 +1381 @@
 #endif
 
-#if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
    if (png_ptr->transformations & PNG_RGB_TO_GRAY)
    {
@@ -1404 +1430 @@
  */
 
-#if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
    /* If gray -> RGB, do so now only if background is non-gray; else do later
     * for performance reasons
@@ -1413 +1439 @@
 #endif
 
-#if defined(PNG_READ_BACKGROUND_SUPPORTED)
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
    if ((png_ptr->transformations & PNG_BACKGROUND) &&
       ((png_ptr->num_trans != 0 ) ||
@@ -1419 +1445 @@
       png_do_background(&(png_ptr->row_info), png_ptr->row_buf + 1,
          &(png_ptr->trans_values), &(png_ptr->background)
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
          , &(png_ptr->background_1),
          png_ptr->gamma_table, png_ptr->gamma_from_1,
@@ -1429 +1455 @@
 #endif
 
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
    if ((png_ptr->transformations & PNG_GAMMA) &&
-#if defined(PNG_READ_BACKGROUND_SUPPORTED)
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
        !((png_ptr->transformations & PNG_BACKGROUND) &&
        ((png_ptr->num_trans != 0) ||
@@ -1442 +1468 @@
 #endif
 
-#if defined(PNG_READ_16_TO_8_SUPPORTED)
+#ifdef PNG_READ_16_TO_8_SUPPORTED
    if (png_ptr->transformations & PNG_16_TO_8)
       png_do_chop(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
 
-#if defined(PNG_READ_DITHER_SUPPORTED)
+#ifdef PNG_READ_DITHER_SUPPORTED
    if (png_ptr->transformations & PNG_DITHER)
    {
@@ -1457 +1483 @@
 #endif
 
-#if defined(PNG_READ_INVERT_SUPPORTED)
+#ifdef PNG_READ_INVERT_SUPPORTED
    if (png_ptr->transformations & PNG_INVERT_MONO)
       png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
 
-#if defined(PNG_READ_SHIFT_SUPPORTED)
+#ifdef PNG_READ_SHIFT_SUPPORTED
    if (png_ptr->transformations & PNG_SHIFT)
       png_do_unshift(&(png_ptr->row_info), png_ptr->row_buf + 1,
@@ -1468 +1494 @@
 #endif
 
-#if defined(PNG_READ_PACK_SUPPORTED)
+#ifdef PNG_READ_PACK_SUPPORTED
    if (png_ptr->transformations & PNG_PACK)
       png_do_unpack(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
 
-#if defined(PNG_READ_BGR_SUPPORTED)
+#ifdef PNG_READ_BGR_SUPPORTED
    if (png_ptr->transformations & PNG_BGR)
       png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
 
-#if defined(PNG_READ_PACKSWAP_SUPPORTED)
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
    if (png_ptr->transformations & PNG_PACKSWAP)
       png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
 
-#if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
    /* If gray -> RGB, do so now only if we did not do so above */
    if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
@@ -1490 +1516 @@
 #endif
 
-#if defined(PNG_READ_FILLER_SUPPORTED)
+#ifdef PNG_READ_FILLER_SUPPORTED
    if (png_ptr->transformations & PNG_FILLER)
       png_do_read_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
@@ -1496 +1522 @@
 #endif
 
-#if defined(PNG_READ_INVERT_ALPHA_SUPPORTED)
+#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
    if (png_ptr->transformations & PNG_INVERT_ALPHA)
       png_do_read_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
 
-#if defined(PNG_READ_SWAP_ALPHA_SUPPORTED)
+#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
    if (png_ptr->transformations & PNG_SWAP_ALPHA)
       png_do_read_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
 
-#if defined(PNG_READ_SWAP_SUPPORTED)
+#ifdef PNG_READ_SWAP_SUPPORTED
    if (png_ptr->transformations & PNG_SWAP_BYTES)
       png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
 
-#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
+#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
    if (png_ptr->transformations & PNG_USER_TRANSFORM)
     {
@@ -1525 +1551 @@
                /*  png_byte pixel_depth;    bits per pixel (depth*channels) */
                png_ptr->row_buf + 1);    /* start of pixel data for row */
-#if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
+#ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
       if (png_ptr->user_transform_depth)
          png_ptr->row_info.bit_depth = png_ptr->user_transform_depth;
@@ -1540 +1566 @@
 }
 
-#if defined(PNG_READ_PACK_SUPPORTED)
+#ifdef PNG_READ_PACK_SUPPORTED
 /* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
  * without changing the actual values.  Thus, if you had a row with
@@ -1551 +1577 @@
 {
    png_debug(1, "in png_do_unpack");
-#if defined(PNG_USELESS_TESTS_SUPPORTED)
+
+#ifdef PNG_USELESS_TESTS_SUPPORTED
    if (row != NULL && row_info != NULL && row_info->bit_depth < 8)
 #else
@@ -1633 +1660 @@
 #endif
 
-#if defined(PNG_READ_SHIFT_SUPPORTED)
+#ifdef PNG_READ_SHIFT_SUPPORTED
 /* Reverse the effects of png_do_shift.  This routine merely shifts the
  * pixels back to their significant bits values.  Thus, if you have
@@ -1643 +1670 @@
 {
    png_debug(1, "in png_do_unshift");
+
    if (
-#if defined(PNG_USELESS_TESTS_SUPPORTED)
+#ifdef PNG_USELESS_TESTS_SUPPORTED
        row != NULL && row_info != NULL && sig_bits != NULL &&
 #endif
@@ -1746 +1774 @@
 #endif
 
-#if defined(PNG_READ_16_TO_8_SUPPORTED)
+#ifdef PNG_READ_16_TO_8_SUPPORTED
 /* Chop rows of bit depth 16 down to 8 */
 void /* PRIVATE */
@@ -1752 +1780 @@
 {
    png_debug(1, "in png_do_chop");
-#if defined(PNG_USELESS_TESTS_SUPPORTED)
+
+#ifdef PNG_USELESS_TESTS_SUPPORTED
    if (row != NULL && row_info != NULL && row_info->bit_depth == 16)
 #else
@@ -1765 +1794 @@
       for (i = 0; i<istop; i++, sp += 2, dp++)
       {
-#if defined(PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED)
+#ifdef PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
       /* This does a more accurate scaling of the 16-bit color
        * value, rather than a simple low-byte truncation.
@@ -1804 +1833 @@
 #endif
 
-#if defined(PNG_READ_SWAP_ALPHA_SUPPORTED)
+#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
 void /* PRIVATE */
 png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
 {
    png_debug(1, "in png_do_read_swap_alpha");
-#if defined(PNG_USELESS_TESTS_SUPPORTED)
+
+#ifdef PNG_USELESS_TESTS_SUPPORTED
    if (row != NULL && row_info != NULL)
 #endif
@@ -1896 +1926 @@
 #endif
 
-#if defined(PNG_READ_INVERT_ALPHA_SUPPORTED)
+#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
 void /* PRIVATE */
 png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
 {
    png_debug(1, "in png_do_read_invert_alpha");
-#if defined(PNG_USELESS_TESTS_SUPPORTED)
+
+#ifdef PNG_USELESS_TESTS_SUPPORTED
    if (row != NULL && row_info != NULL)
 #endif
@@ -1994 +2025 @@
 #endif
 
-#if defined(PNG_READ_FILLER_SUPPORTED)
+#ifdef PNG_READ_FILLER_SUPPORTED
 /* Add filler channel if we have RGB color */
 void /* PRIVATE */
@@ -2007 +2038 @@
 
    png_debug(1, "in png_do_read_filler");
+
    if (
-#if defined(PNG_USELESS_TESTS_SUPPORTED)
+#ifdef PNG_USELESS_TESTS_SUPPORTED
        row != NULL  && row_info != NULL &&
 #endif
@@ -2170 +2202 @@
 #endif
 
-#if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
 /* Expand grayscale files to RGB, with or without alpha */
 void /* PRIVATE */
@@ -2179 +2211 @@
 
    png_debug(1, "in png_do_gray_to_rgb");
+
    if (row_info->bit_depth >= 8 &&
-#if defined(PNG_USELESS_TESTS_SUPPORTED)
+#ifdef PNG_USELESS_TESTS_SUPPORTED
        row != NULL && row_info != NULL &&
 #endif
@@ -2253 +2286 @@
 #endif
 
-#if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
 /* Reduce RGB files to grayscale, with or without alpha
  * using the equation given in Poynton's ColorFAQ at
@@ -2285 +2318 @@
 
    png_debug(1, "in png_do_rgb_to_gray");
+
    if (
-#if defined(PNG_USELESS_TESTS_SUPPORTED)
+#ifdef PNG_USELESS_TESTS_SUPPORTED
        row != NULL && row_info != NULL &&
 #endif
@@ -2523 +2557 @@
 
    png_debug(1, "in png_do_build_grayscale_palette");
+
    if (palette == NULL)
       return;
@@ -2569 +2604 @@
 {
    png_debug(1, "in png_correct_palette");
+
 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
     defined(PNG_READ_GAMMA_SUPPORTED) && defined(PNG_FLOATING_POINT_SUPPORTED)
@@ -2679 +2715 @@
    else
 #endif
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
    if (png_ptr->transformations & PNG_GAMMA)
    {
@@ -2691 +2727 @@
       }
    }
-#if defined(PNG_READ_BACKGROUND_SUPPORTED)
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
    else
 #endif
 #endif
-#if defined(PNG_READ_BACKGROUND_SUPPORTED)
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
    if (png_ptr->transformations & PNG_BACKGROUND)
    {
@@ -2744 +2780 @@
 #endif
 
-#if defined(PNG_READ_BACKGROUND_SUPPORTED)
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
 /* Replace any alpha or transparency with the supplied background color.
  * "background" is already in the screen gamma, while "background_1" is
@@ -2752 +2788 @@
 png_do_background(png_row_infop row_info, png_bytep row,
    png_color_16p trans_values, png_color_16p background
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
    , png_color_16p background_1,
    png_bytep gamma_table, png_bytep gamma_from_1, png_bytep gamma_to_1,
@@ -2766 +2802 @@
 
    png_debug(1, "in png_do_background");
+
    if (background != NULL &&
-#if defined(PNG_USELESS_TESTS_SUPPORTED)
+#ifdef PNG_USELESS_TESTS_SUPPORTED
        row != NULL && row_info != NULL &&
 #endif
@@ -2804 +2841 @@
                case 2:
                {
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
                   if (gamma_table != NULL)
                   {
@@ -2861 +2898 @@
                case 4:
                {
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
                   if (gamma_table != NULL)
                   {
@@ -2918 +2955 @@
                case 8:
                {
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
                   if (gamma_table != NULL)
                   {
@@ -2951 +2988 @@
                case 16:
                {
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
                   if (gamma_16 != NULL)
                   {
@@ -3000 +3037 @@
             if (row_info->bit_depth == 8)
             {
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
                if (gamma_table != NULL)
                {
@@ -3041 +3078 @@
             else /* if (row_info->bit_depth == 16) */
             {
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
                if (gamma_16 != NULL)
                {
@@ -3105 +3142 @@
             if (row_info->bit_depth == 8)
             {
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
                if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
                    gamma_table != NULL)
@@ -3147 +3184 @@
                         *dp = *sp;
                      }
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
                      else if (a == 0)
                      {
@@ -3164 +3201 @@
             else /* if (png_ptr->bit_depth == 16) */
             {
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
                if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
                    gamma_16_to_1 != NULL)
@@ -3182 +3219 @@
                         *(dp + 1) = (png_byte)(v & 0xff);
                      }
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
                      else if (a == 0)
 #else
@@ -3192 +3229 @@
                         *(dp + 1) = (png_byte)(background->gray & 0xff);
                      }
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
                      else
                      {
@@ -3218 +3255 @@
                         png_memcpy(dp, sp, 2);
                      }
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
                      else if (a == 0)
 #else
@@ -3227 +3264 @@
                         *(dp + 1) = (png_byte)(background->gray & 0xff);
                      }
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
                      else
                      {
@@ -3248 +3285 @@
             if (row_info->bit_depth == 8)
             {
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
                if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
                    gamma_table != NULL)
@@ -3321 +3358 @@
             else /* if (row_info->bit_depth == 16) */
             {
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
                if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
                    gamma_16_to_1 != NULL)
@@ -3438 +3475 @@
 #endif
 
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
 /* Gamma correct the image, avoiding the alpha channel.  Make sure
  * you do this after you deal with the transparency issue on grayscale
@@ -3455 +3492 @@
 
    png_debug(1, "in png_do_gamma");
+
    if (
-#if defined(PNG_USELESS_TESTS_SUPPORTED)
+#ifdef PNG_USELESS_TESTS_SUPPORTED
        row != NULL && row_info != NULL &&
 #endif
@@ -3629 +3667 @@
 #endif
 
-#if defined(PNG_READ_EXPAND_SUPPORTED)
+#ifdef PNG_READ_EXPAND_SUPPORTED
 /* Expands a palette row to an RGB or RGBA row depending
  * upon whether you supply trans and num_trans.
@@ -3643 +3681 @@
 
    png_debug(1, "in png_do_expand_palette");
+
    if (
-#if defined(PNG_USELESS_TESTS_SUPPORTED)
+#ifdef PNG_USELESS_TESTS_SUPPORTED
        row != NULL && row_info != NULL &&
 #endif
@@ -3789 +3828 @@
 
    png_debug(1, "in png_do_expand");
-#if defined(PNG_USELESS_TESTS_SUPPORTED)
+
+#ifdef PNG_USELESS_TESTS_SUPPORTED
    if (row != NULL && row_info != NULL)
 #endif
@@ -3990 +4030 @@
 #endif
 
-#if defined(PNG_READ_DITHER_SUPPORTED)
+#ifdef PNG_READ_DITHER_SUPPORTED
 void /* PRIVATE */
 png_do_dither(png_row_infop row_info, png_bytep row,
@@ -4000 +4040 @@
 
    png_debug(1, "in png_do_dither");
-#if defined(PNG_USELESS_TESTS_SUPPORTED)
+
+#ifdef PNG_USELESS_TESTS_SUPPORTED
    if (row != NULL && row_info != NULL)
 #endif
@@ -4082 +4123 @@
 
 #ifdef PNG_FLOATING_POINT_SUPPORTED
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
 static PNG_CONST int png_gamma_shift[] =
    {0x10, 0x21, 0x42, 0x84, 0x110, 0x248, 0x550, 0xff0, 0x00};
@@ -4090 +4131 @@
  * the future.  Note also how the gamma_16 tables are segmented so that
  * we don't need to allocate > 64K chunks for a full 16-bit table.
+ *
+ * See the PNG extensions document for an integer algorithm for creating
+ * the gamma tables.  Maybe we will implement that here someday.
+ *
+ * We should only reach this point if
+ *
+ *      the file_gamma is known (i.e., the gAMA or sRGB chunk is present,
+ *      or the application has provided a file_gamma)
+ *
+ *   AND
+ *      {
+ *         the screen_gamma is known
+ *      OR
+ *
+ *         RGB_to_gray transformation is being performed
+ *      }
+ *
+ *   AND
+ *      {
+ *         the screen_gamma is different from the reciprocal of the
+ *         file_gamma by more than the specified threshold
+ *
+ *      OR
+ *
+ *         a background color has been specified and the file_gamma
+ *         and screen_gamma are not 1.0, within the specified threshold.
+ *      }
  */
+
 void /* PRIVATE */
 png_build_gamma_table(png_structp png_ptr)
@@ -4200 +4269 @@
         g = 1.0;
 
-     png_ptr->gamma_16_table = (png_uint_16pp)png_malloc(png_ptr,
+     png_ptr->gamma_16_table = (png_uint_16pp)png_calloc(png_ptr,
         (png_uint_32)(num * png_sizeof(png_uint_16p)));
-     png_memset(png_ptr->gamma_16_table, 0, num * png_sizeof(png_uint_16p));
 
      if (png_ptr->transformations & (PNG_16_TO_8 | PNG_BACKGROUND))
@@ -4262 +4330 @@
         g = 1.0 / (png_ptr->gamma);
 
-        png_ptr->gamma_16_to_1 = (png_uint_16pp)png_malloc(png_ptr,
+        png_ptr->gamma_16_to_1 = (png_uint_16pp)png_calloc(png_ptr,
            (png_uint_32)(num * png_sizeof(png_uint_16p )));
-        png_memset(png_ptr->gamma_16_to_1, 0, num * png_sizeof(png_uint_16p));
 
         for (i = 0; i < num; i++)
@@ -4287 +4354 @@
            g = png_ptr->gamma;   /* Probably doing rgb_to_gray */
 
-        png_ptr->gamma_16_from_1 = (png_uint_16pp)png_malloc(png_ptr,
+        png_ptr->gamma_16_from_1 = (png_uint_16pp)png_calloc(png_ptr,
            (png_uint_32)(num * png_sizeof(png_uint_16p)));
-        png_memset(png_ptr->gamma_16_from_1, 0,
-           num * png_sizeof(png_uint_16p));
 
         for (i = 0; i < num; i++)
@@ -4315 +4380 @@
 #endif
 
-#if defined(PNG_MNG_FEATURES_SUPPORTED)
+#ifdef PNG_MNG_FEATURES_SUPPORTED
 /* Undoes intrapixel differencing  */
 void /* PRIVATE */
@@ -4321 +4386 @@
 {
    png_debug(1, "in png_do_read_intrapixel");
+
    if (
-#if defined(PNG_USELESS_TESTS_SUPPORTED)
+#ifdef PNG_USELESS_TESTS_SUPPORTED
        row != NULL && row_info != NULL &&
 #endif