diff --git a/ANNOUNCE b/ANNOUNCE
index d1f360aa..0e13d74d 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,5 +1,5 @@
 
-Libpng 1.2.41beta07 - October 18, 2009
+Libpng 1.2.41beta07 - October 21, 2009
 
 This is not intended to be a public release.  It will be replaced
 within a few weeks by a public version or by another test version.
@@ -73,7 +73,9 @@ version 1.2.41beta06 [October 18, 2009]
   Converted all PNG_NO_* tests to PNG_*_SUPPORTED everywhere except pngconf.h
     as in libpng-1.4.0beta78 and later.
 
-version 1.2.41beta07 [October 18, 2009]
+version 1.2.41beta07 [October 21, 2009]
+  Ported some cosmetic changes from libpng-1.4.0rc01, changing
+    many "#if defined(x)" to "#ifdef x" in png.h and pngconf.h.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 
diff --git a/CHANGES b/CHANGES
index f6cfa951..3e25113f 100644
--- a/CHANGES
+++ b/CHANGES
@@ -2466,7 +2466,7 @@ version 1.2.40beta01 [August 20, 2009]
 version 1.2.40rc01 [September 2, 2009]
   Various bugfixes and improvements to CMakeLists.txt (Philip Lowman)
 
-version 1.2.40 and 1.0.49 [October 18, 2009]
+version 1.2.40 and 1.0.49 [October 21, 2009]
   No changes.
 
 version 1.0.50 [September 10, 2009]
@@ -2503,7 +2503,9 @@ version 1.2.41beta06 [October 18, 2009]
   Converted all PNG_NO_* tests to PNG_*_SUPPORTED everywhere except pngconf.h
     as in libpng-1.4.0beta78 and later.
 
-version 1.2.41beta07 [October 18, 2009]
+version 1.2.41beta07 [October 21, 2009]
+  Ported some cosmetic changes from libpng-1.4.0rc01, changing
+    many "#if defined(x)" to "#ifdef x" in png.h and pngconf.h.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/png.c b/png.c
index 3b1b034d..29f49bff 100644
--- a/png.c
+++ b/png.c
@@ -1,7 +1,7 @@
 
 /* png.c - location for general purpose libpng functions
  *
- * Last changed in libpng 1.2.41 [October 18, 2009]
+ * Last changed in libpng 1.2.41 [October 21, 2009]
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -717,7 +717,7 @@ png_charp PNGAPI
 png_get_copyright(png_structp png_ptr)
 {
    png_ptr = png_ptr;  /* Silence compiler warning about unused png_ptr */
-   return ((png_charp) "\n libpng version 1.2.41beta07 - October 18, 2009\n\
+   return ((png_charp) "\n libpng version 1.2.41beta07 - October 21, 2009\n\
    Copyright (c) 1998-2009 Glenn Randers-Pehrson\n\
    Copyright (c) 1996-1997 Andreas Dilger\n\
    Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.\n");
diff --git a/png.h b/png.h
index 13929fa9..8949f7f0 100644
--- a/png.h
+++ b/png.h
@@ -1,6 +1,6 @@
 /* png.h - header file for PNG reference library
  *
- * libpng version 1.2.41beta07 - October 18, 2009
+ * libpng version 1.2.41beta07 - October 21, 2009
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -10,7 +10,7 @@
  * Authors and maintainers:
  *  libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
  *  libpng versions 0.89c, June 1996, through 0.96, May 1997: Andreas Dilger
- *  libpng versions 0.97, January 1998, through 1.2.41beta07 - October 18, 2009: Glenn
+ *  libpng versions 0.97, January 1998, through 1.2.41beta07 - October 21, 2009: Glenn
  *  See also "Contributing Authors", below.
  *
  * Note about libpng version numbers:
@@ -277,7 +277,7 @@
  *
  * This code is released under the libpng license.
  *
- * libpng versions 1.2.6, August 15, 2004, through 1.2.41beta07, October 18, 2009, are
+ * libpng versions 1.2.6, August 15, 2004, through 1.2.41beta07, October 21, 2009, are
  * Copyright (c) 2004, 2006-2009 Glenn Randers-Pehrson, and are
  * distributed according to the same disclaimer and license as libpng-1.2.5
  * with the following individual added to the list of Contributing Authors:
@@ -389,7 +389,7 @@
  * Y2K compliance in libpng:
  * =========================
  *
- *    October 18, 2009
+ *    October 21, 2009
  *
  *    Since the PNG Development group is an ad-hoc body, we can't make
  *    an official declaration.
@@ -453,7 +453,7 @@
 /* Version information for png.h - this should match the version in png.c */
 #define PNG_LIBPNG_VER_STRING "1.2.41beta07"
 #define PNG_HEADER_VERSION_STRING \
-   " libpng version 1.2.41beta07 - October 18, 2009\n"
+   " libpng version 1.2.41beta07 - October 21, 2009\n"
 
 #define PNG_LIBPNG_VER_SONUM   0
 #define PNG_LIBPNG_VER_DLLNUM  13
@@ -514,11 +514,11 @@
  * StringFileInfo block must contain a SpecialBuild string.
  */
 
-#if defined(PNG_USER_PRIVATEBUILD)
+#ifdef PNG_USER_PRIVATEBUILD
 #  define PNG_LIBPNG_BUILD_TYPE \
           (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_PRIVATE)
 #else
-#  if defined(PNG_LIBPNG_SPECIALBUILD)
+#  ifdef PNG_LIBPNG_SPECIALBUILD
 #    define PNG_LIBPNG_BUILD_TYPE \
             (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_SPECIAL)
 #  else
@@ -825,13 +825,13 @@ typedef struct png_info_struct
    float gamma; /* gamma value of image, if (valid & PNG_INFO_gAMA) */
 #endif
 
-#if defined(PNG_sRGB_SUPPORTED)
+#ifdef PNG_sRGB_SUPPORTED
     /* GR-P, 0.96a */
     /* Data valid if (valid & PNG_INFO_sRGB) non-zero. */
    png_byte srgb_intent; /* sRGB rendering intent [0, 1, 2, or 3] */
 #endif
 
-#if defined(PNG_TEXT_SUPPORTED)
+#ifdef PNG_TEXT_SUPPORTED
    /* The tEXt, and zTXt chunks contain human-readable textual data in
     * uncompressed, compressed, and optionally compressed forms, respectively.
     * The data in "text" is an array of pointers to uncompressed,
@@ -845,14 +845,14 @@ typedef struct png_info_struct
    png_textp text; /* array of comments read/to write */
 #endif /* PNG_TEXT_SUPPORTED */
 
-#if defined(PNG_tIME_SUPPORTED)
+#ifdef PNG_tIME_SUPPORTED
    /* The tIME chunk holds the last time the displayed image data was
     * modified.  See the png_time struct for the contents of this struct.
     */
    png_time mod_time;
 #endif
 
-#if defined(PNG_sBIT_SUPPORTED)
+#ifdef PNG_sBIT_SUPPORTED
    /* The sBIT chunk specifies the number of significant high-order bits
     * in the pixel data.  Values are in the range [1, bit_depth], and are
     * only specified for the channels in the pixel data.  The contents of
@@ -887,7 +887,7 @@ defined(PNG_READ_BACKGROUND_SUPPORTED)
    png_color_16 background;
 #endif
 
-#if defined(PNG_oFFs_SUPPORTED)
+#ifdef PNG_oFFs_SUPPORTED
    /* The oFFs chunk gives the offset in "offset_unit_type" units rightwards
     * and downwards from the top-left corner of the display, page, or other
     * application-specific co-ordinate space.  See the PNG_OFFSET_ defines
@@ -898,7 +898,7 @@ defined(PNG_READ_BACKGROUND_SUPPORTED)
    png_byte offset_unit_type; /* offset units type */
 #endif
 
-#if defined(PNG_pHYs_SUPPORTED)
+#ifdef PNG_pHYs_SUPPORTED
    /* The pHYs chunk gives the physical pixel density of the image for
     * display or printing in "phys_unit_type" units (see PNG_RESOLUTION_
     * defines below).  Data is valid if (valid & PNG_INFO_pHYs) is non-zero.
@@ -908,7 +908,7 @@ defined(PNG_READ_BACKGROUND_SUPPORTED)
    png_byte phys_unit_type; /* resolution type (see PNG_RESOLUTION_ below) */
 #endif
 
-#if defined(PNG_hIST_SUPPORTED)
+#ifdef PNG_hIST_SUPPORTED
    /* The hIST chunk contains the relative frequency or importance of the
     * various palette entries, so that a viewer can intelligently select a
     * reduced-color palette, if required.  Data is an array of "num_palette"
@@ -937,7 +937,7 @@ defined(PNG_READ_BACKGROUND_SUPPORTED)
 #endif
 #endif
 
-#if defined(PNG_pCAL_SUPPORTED)
+#ifdef PNG_pCAL_SUPPORTED
    /* The pCAL chunk describes a transformation between the stored pixel
     * values and original physical data values used to create the image.
     * The integer range [0, 2^bit_depth - 1] maps to the floating-point
@@ -970,7 +970,7 @@ defined(PNG_READ_BACKGROUND_SUPPORTED)
    png_size_t unknown_chunks_num;
 #endif
 
-#if defined(PNG_iCCP_SUPPORTED)
+#ifdef PNG_iCCP_SUPPORTED
    /* iCCP chunk data. */
    png_charp iccp_name;     /* profile name */
    png_charp iccp_profile;  /* International Color Consortium profile data */
@@ -979,13 +979,13 @@ defined(PNG_READ_BACKGROUND_SUPPORTED)
    png_byte iccp_compression; /* Always zero */
 #endif
 
-#if defined(PNG_sPLT_SUPPORTED)
+#ifdef PNG_sPLT_SUPPORTED
    /* Data on sPLT chunks (there may be more than one). */
    png_sPLT_tp splt_palettes;
    png_uint_32 splt_palettes_num;
 #endif
 
-#if defined(PNG_sCAL_SUPPORTED)
+#ifdef PNG_sCAL_SUPPORTED
    /* The sCAL chunk describes the actual physical dimensions of the
     * subject matter of the graphic.  The chunk contains a unit specification
     * a byte value, and two ASCII strings representing floating-point
@@ -1004,7 +1004,7 @@ defined(PNG_READ_BACKGROUND_SUPPORTED)
 #endif
 #endif
 
-#if defined(PNG_INFO_IMAGE_SUPPORTED)
+#ifdef PNG_INFO_IMAGE_SUPPORTED
    /* Memory has been allocated if (valid & PNG_ALLOCATED_INFO_ROWS) non-zero */
    /* Data valid if (valid & PNG_INFO_IDAT) non-zero */
    png_bytepp row_pointers;        /* the image bits */
@@ -1175,10 +1175,10 @@ typedef void (PNGAPI *png_user_transform_ptr) PNGARG((png_structp,
     png_row_infop, png_bytep));
 #endif
 
-#if defined(PNG_USER_CHUNKS_SUPPORTED)
+#ifdef PNG_USER_CHUNKS_SUPPORTED
 typedef int (PNGAPI *png_user_chunk_ptr) PNGARG((png_structp, png_unknown_chunkp));
 #endif
-#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
+#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
 typedef void (PNGAPI *png_unknown_chunk_ptr) PNGARG((png_structp));
 #endif
 
@@ -1227,16 +1227,16 @@ struct png_struct_def
    png_rw_ptr read_data_fn;   /* function for reading input data */
    png_voidp io_ptr;          /* ptr to application struct for I/O functions */
 
-#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
+#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
    png_user_transform_ptr read_user_transform_fn; /* user read transform */
 #endif
 
-#if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
+#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
    png_user_transform_ptr write_user_transform_fn; /* user write transform */
 #endif
 
 /* These were added in libpng-1.0.2 */
-#if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
+#ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
     defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
    png_voidp user_transform_ptr; /* user supplied struct for user transform */
@@ -1303,18 +1303,18 @@ struct png_struct_def
 #endif
 #endif
 
-#if defined(PNG_bKGD_SUPPORTED)
+#ifdef PNG_bKGD_SUPPORTED
    png_byte background_gamma_type;
 #  ifdef PNG_FLOATING_POINT_SUPPORTED
    float background_gamma;
 #  endif
    png_color_16 background;   /* background color in screen gamma space */
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
    png_color_16 background_1; /* background normalized to gamma 1.0 */
 #endif
 #endif /* PNG_bKGD_SUPPORTED */
 
-#if defined(PNG_WRITE_FLUSH_SUPPORTED)
+#ifdef PNG_WRITE_FLUSH_SUPPORTED
    png_flush_ptr output_flush_fn; /* Function for flushing output */
    png_uint_32 flush_dist;    /* how many rows apart to flush, 0 - no flush */
    png_uint_32 flush_rows;    /* number of rows written since last flush */
@@ -1370,7 +1370,7 @@ struct png_struct_def
    int process_mode;                 /* what push library is currently doing */
    int cur_palette;                  /* current push library palette index */
 
-#  if defined(PNG_TEXT_SUPPORTED)
+#  ifdef PNG_TEXT_SUPPORTED
      png_size_t current_text_size;   /* current size of text input data */
      png_size_t current_text_left;   /* how much text left to read in input */
      png_charp current_text;         /* current text chunk buffer */
@@ -1387,7 +1387,7 @@ struct png_struct_def
    png_uint_16 offset_table_count_free;
 #endif
 
-#if defined(PNG_READ_DITHER_SUPPORTED)
+#ifdef PNG_READ_DITHER_SUPPORTED
    png_bytep palette_lookup;         /* lookup table for dithering */
    png_bytep dither_index;           /* index translation for palette files */
 #endif
@@ -1396,7 +1396,7 @@ struct png_struct_def
    png_uint_16p hist;                /* histogram */
 #endif
 
-#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
    png_byte heuristic_method;        /* heuristic for row filter selection */
    png_byte num_prev_filters;        /* number of weights for previous rows */
    png_bytep prev_filters;           /* filter type(s) of previous row(s) */
@@ -1406,7 +1406,7 @@ struct png_struct_def
    png_uint_16p inv_filter_costs;    /* 1/relative filter calculation cost */
 #endif
 
-#if defined(PNG_TIME_RFC1123_SUPPORTED)
+#ifdef PNG_TIME_RFC1123_SUPPORTED
    png_charp time_buffer;            /* String to hold RFC 1123 time text */
 #endif
 
@@ -1416,7 +1416,7 @@ struct png_struct_def
    png_uint_32 free_me;   /* flags items libpng is responsible for freeing */
 #endif
 
-#if defined(PNG_USER_CHUNKS_SUPPORTED)
+#ifdef PNG_USER_CHUNKS_SUPPORTED
    png_voidp user_chunk_ptr;
    png_user_chunk_ptr read_user_chunk_fn; /* user read chunk handler */
 #endif
@@ -1427,7 +1427,7 @@ struct png_struct_def
 #endif
 
 /* New members added in libpng-1.0.3 */
-#if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
    png_byte rgb_to_gray_status;
    /* These were changed from png_byte in libpng-1.0.6 */
    png_uint_16 rgb_to_gray_red_coeff;
@@ -1453,19 +1453,19 @@ struct png_struct_def
 #endif
 
 /* New member added in libpng-1.0.9, ifdef'ed out in 1.0.12, enabled in 1.2.0 */
-#if defined(PNG_MNG_FEATURES_SUPPORTED)
+#ifdef PNG_MNG_FEATURES_SUPPORTED
    png_byte filter_type;
 #endif
 
-#if defined(PNG_1_0_X)
+#ifdef PNG_1_0_X
 /* New member added in libpng-1.0.10, ifdef'ed out in 1.2.0 */
    png_uint_32 row_buf_size;
 #endif
 
 /* New members added in libpng-1.2.0 */
-#if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
-#  if !defined(PNG_1_0_X)
-#    if defined(PNG_MMX_CODE_SUPPORTED)
+#ifdef PNG_ASSEMBLER_CODE_SUPPORTED
+#  ifndef PNG_1_0_X
+#    ifdef PNG_MMX_CODE_SUPPORTED
    png_byte     mmx_bitdepth_threshold;
    png_uint_32  mmx_rowbytes_threshold;
 #    endif
@@ -1483,7 +1483,7 @@ struct png_struct_def
 /* New member added in libpng-1.0.13 and 1.2.0 */
    png_bytep big_row_buf;        /* buffer to save current (unfiltered) row */
 
-#if defined(PNG_READ_DITHER_SUPPORTED)
+#ifdef PNG_READ_DITHER_SUPPORTED
 /* The following three members were added at version 1.0.14 and 1.2.4 */
    png_bytep dither_sort;        /* working sort array */
    png_bytep index_to_palette;   /* where the original index currently is */
@@ -1501,7 +1501,7 @@ struct png_struct_def
 #endif
 
 /* New member added in libpng-1.0.25 and 1.2.17 */
-#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
+#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
    /* Storage for unknown chunk that the library doesn't recognize. */
    png_unknown_chunk unknown_chunk;
 #endif
@@ -1621,20 +1621,20 @@ extern PNG_EXPORT(void,png_write_info_before_PLTE) PNGARG((png_structp png_ptr,
 extern PNG_EXPORT(void,png_write_info) PNGARG((png_structp png_ptr,
    png_infop info_ptr));
 
-#ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 /* Read the information before the actual image data. */
 extern PNG_EXPORT(void,png_read_info) PNGARG((png_structp png_ptr,
    png_infop info_ptr));
 #endif
 
-#if defined(PNG_TIME_RFC1123_SUPPORTED)
+#ifdef PNG_TIME_RFC1123_SUPPORTED
 extern PNG_EXPORT(png_charp,png_convert_to_rfc1123)
    PNGARG((png_structp png_ptr, png_timep ptime));
 #endif
 
-#if !defined(_WIN32_WCE)
+#ifndef _WIN32_WCE
 /* "time.h" functions are not supported on WindowsCE */
-#if defined(PNG_WRITE_tIME_SUPPORTED)
+#ifdef PNG_WRITE_tIME_SUPPORTED
 /* Convert from a struct tm to png_time */
 extern PNG_EXPORT(void,png_convert_from_struct_tm) PNGARG((png_timep ptime,
    struct tm FAR * ttime));
@@ -1645,10 +1645,10 @@ extern PNG_EXPORT(void,png_convert_from_time_t) PNGARG((png_timep ptime,
 #endif /* PNG_WRITE_tIME_SUPPORTED */
 #endif /* _WIN32_WCE */
 
-#if defined(PNG_READ_EXPAND_SUPPORTED)
+#ifdef PNG_READ_EXPAND_SUPPORTED
 /* Expand data to 24-bit RGB, or 8-bit grayscale, with alpha if available. */
 extern PNG_EXPORT(void,png_set_expand) PNGARG((png_structp png_ptr));
-#if !defined(PNG_1_0_X)
+#ifndef PNG_1_0_X
 extern PNG_EXPORT(void,png_set_expand_gray_1_2_4_to_8) PNGARG((png_structp
   png_ptr));
 #endif
@@ -1665,12 +1665,12 @@ extern PNG_EXPORT(void,png_set_gray_1_2_4_to_8) PNGARG((png_structp png_ptr));
 extern PNG_EXPORT(void,png_set_bgr) PNGARG((png_structp png_ptr));
 #endif
 
-#if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
 /* Expand the grayscale to 24-bit RGB if necessary. */
 extern PNG_EXPORT(void,png_set_gray_to_rgb) PNGARG((png_structp png_ptr));
 #endif
 
-#if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
 /* Reduce RGB to grayscale. */
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(void,png_set_rgb_to_gray) PNGARG((png_structp png_ptr,
@@ -1685,7 +1685,7 @@ extern PNG_EXPORT(png_byte,png_get_rgb_to_gray_status) PNGARG((png_structp
 extern PNG_EXPORT(void,png_build_grayscale_palette) PNGARG((int bit_depth,
    png_colorp palette));
 
-#if defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
+#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
 extern PNG_EXPORT(void,png_set_strip_alpha) PNGARG((png_structp png_ptr));
 #endif
 
@@ -1707,7 +1707,7 @@ extern PNG_EXPORT(void,png_set_filler) PNGARG((png_structp png_ptr,
 #define PNG_FILLER_BEFORE 0
 #define PNG_FILLER_AFTER 1
 /* Add an alpha byte to 8-bit Gray or 24-bit RGB images. */
-#if !defined(PNG_1_0_X)
+#ifndef PNG_1_0_X
 extern PNG_EXPORT(void,png_set_add_alpha) PNGARG((png_structp png_ptr,
    png_uint_32 filler, int flags));
 #endif
@@ -1745,7 +1745,7 @@ extern PNG_EXPORT(int,png_set_interlace_handling) PNGARG((png_structp png_ptr));
 extern PNG_EXPORT(void,png_set_invert_mono) PNGARG((png_structp png_ptr));
 #endif
 
-#if defined(PNG_READ_BACKGROUND_SUPPORTED)
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
 /* Handle alpha and tRNS by replacing with a background color. */
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(void,png_set_background) PNGARG((png_structp png_ptr,
@@ -1758,19 +1758,19 @@ extern PNG_EXPORT(void,png_set_background) PNGARG((png_structp png_ptr,
 #define PNG_BACKGROUND_GAMMA_UNIQUE  3
 #endif
 
-#if defined(PNG_READ_16_TO_8_SUPPORTED)
+#ifdef PNG_READ_16_TO_8_SUPPORTED
 /* Strip the second byte of information from a 16-bit depth file. */
 extern PNG_EXPORT(void,png_set_strip_16) PNGARG((png_structp png_ptr));
 #endif
 
-#if defined(PNG_READ_DITHER_SUPPORTED)
+#ifdef PNG_READ_DITHER_SUPPORTED
 /* Turn on dithering, and reduce the palette to the number of colors available. */
 extern PNG_EXPORT(void,png_set_dither) PNGARG((png_structp png_ptr,
    png_colorp palette, int num_palette, int maximum_colors,
    png_uint_16p histogram, int full_dither));
 #endif
 
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
 /* Handle gamma correction. Screen_gamma=(display_exponent) */
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(void,png_set_gamma) PNGARG((png_structp png_ptr,
@@ -1788,7 +1788,7 @@ extern PNG_EXPORT(void,png_permit_empty_plte) PNGARG((png_structp png_ptr,
 #endif
 #endif
 
-#if defined(PNG_WRITE_FLUSH_SUPPORTED)
+#ifdef PNG_WRITE_FLUSH_SUPPORTED
 /* Set how many lines between output flushes - 0 for no flushing */
 extern PNG_EXPORT(void,png_set_flush) PNGARG((png_structp png_ptr, int nrows));
 /* Flush the current PNG output buffer */
@@ -1995,7 +1995,7 @@ extern PNG_EXPORT(void,png_set_compression_method) PNGARG((png_structp png_ptr,
  * more information.
  */
 
-#if !defined(PNG_NO_STDIO)
+#ifdef PNG_STDIO_SUPPORTED
 /* Initialize the input/output for the PNG file to the default functions. */
 extern PNG_EXPORT(void,png_init_io) PNGARG((png_structp png_ptr, png_FILE_p fp));
 #endif
@@ -2105,7 +2105,7 @@ extern PNG_EXPORT(void,png_progressive_combine_row) PNGARG((png_structp png_ptr,
 extern PNG_EXPORT(png_voidp,png_malloc) PNGARG((png_structp png_ptr,
    png_uint_32 size));
 
-#if defined(PNG_1_0_X)
+#ifdef PNG_1_0_X
 #  define png_malloc_warn png_malloc
 #else
 /* Added at libpng version 1.2.4 */
@@ -2116,7 +2116,7 @@ extern PNG_EXPORT(png_voidp,png_malloc_warn) PNGARG((png_structp png_ptr,
 /* Frees a pointer allocated by png_malloc() */
 extern PNG_EXPORT(void,png_free) PNGARG((png_structp png_ptr, png_voidp ptr));
 
-#if defined(PNG_1_0_X)
+#ifdef PNG_1_0_X
 /* Function to allocate memory for zlib. */
 extern PNG_EXPORT(voidpf,png_zalloc) PNGARG((voidpf png_ptr, uInt items,
    uInt size));
@@ -2217,7 +2217,7 @@ png_infop info_ptr, png_uint_32 flag));
 extern PNG_EXPORT(png_uint_32,png_get_rowbytes) PNGARG((png_structp png_ptr,
 png_infop info_ptr));
 
-#if defined(PNG_INFO_IMAGE_SUPPORTED)
+#ifdef PNG_INFO_IMAGE_SUPPORTED
 /* Returns row_pointers, which is an array of pointers to scanlines that was
  * returned from png_read_png().
  */
@@ -2293,17 +2293,17 @@ png_ptr, png_infop info_ptr));
 extern PNG_EXPORT(png_bytep,png_get_signature) PNGARG((png_structp png_ptr,
 png_infop info_ptr));
 
-#if defined(PNG_bKGD_SUPPORTED)
+#ifdef PNG_bKGD_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_bKGD) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_color_16p *background));
 #endif
 
-#if defined(PNG_bKGD_SUPPORTED)
+#ifdef PNG_bKGD_SUPPORTED
 extern PNG_EXPORT(void,png_set_bKGD) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_color_16p background));
 #endif
 
-#if defined(PNG_cHRM_SUPPORTED)
+#ifdef PNG_cHRM_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_cHRM) PNGARG((png_structp png_ptr,
    png_infop info_ptr, double *white_x, double *white_y, double *red_x,
@@ -2319,7 +2319,7 @@ extern PNG_EXPORT(png_uint_32,png_get_cHRM_fixed) PNGARG((png_structp png_ptr,
 #endif
 #endif
 
-#if defined(PNG_cHRM_SUPPORTED)
+#ifdef PNG_cHRM_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(void,png_set_cHRM) PNGARG((png_structp png_ptr,
    png_infop info_ptr, double white_x, double white_y, double red_x,
@@ -2334,7 +2334,7 @@ extern PNG_EXPORT(void,png_set_cHRM_fixed) PNGARG((png_structp png_ptr,
 #endif
 #endif
 
-#if defined(PNG_gAMA_SUPPORTED)
+#ifdef PNG_gAMA_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_gAMA) PNGARG((png_structp png_ptr,
    png_infop info_ptr, double *file_gamma));
@@ -2343,7 +2343,7 @@ extern PNG_EXPORT(png_uint_32,png_get_gAMA_fixed) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_fixed_point *int_file_gamma));
 #endif
 
-#if defined(PNG_gAMA_SUPPORTED)
+#ifdef PNG_gAMA_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(void,png_set_gAMA) PNGARG((png_structp png_ptr,
    png_infop info_ptr, double file_gamma));
@@ -2352,12 +2352,12 @@ extern PNG_EXPORT(void,png_set_gAMA_fixed) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_fixed_point int_file_gamma));
 #endif
 
-#if defined(PNG_hIST_SUPPORTED)
+#ifdef PNG_hIST_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_hIST) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_16p *hist));
 #endif
 
-#if defined(PNG_hIST_SUPPORTED)
+#ifdef PNG_hIST_SUPPORTED
 extern PNG_EXPORT(void,png_set_hIST) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_16p hist));
 #endif
@@ -2372,36 +2372,36 @@ extern PNG_EXPORT(void,png_set_IHDR) PNGARG((png_structp png_ptr,
    int color_type, int interlace_method, int compression_method,
    int filter_method));
 
-#if defined(PNG_oFFs_SUPPORTED)
+#ifdef PNG_oFFs_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_oFFs) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_int_32 *offset_x, png_int_32 *offset_y,
    int *unit_type));
 #endif
 
-#if defined(PNG_oFFs_SUPPORTED)
+#ifdef PNG_oFFs_SUPPORTED
 extern PNG_EXPORT(void,png_set_oFFs) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_int_32 offset_x, png_int_32 offset_y,
    int unit_type));
 #endif
 
-#if defined(PNG_pCAL_SUPPORTED)
+#ifdef PNG_pCAL_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_pCAL) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_charp *purpose, png_int_32 *X0, png_int_32 *X1,
    int *type, int *nparams, png_charp *units, png_charpp *params));
 #endif
 
-#if defined(PNG_pCAL_SUPPORTED)
+#ifdef PNG_pCAL_SUPPORTED
 extern PNG_EXPORT(void,png_set_pCAL) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_charp purpose, png_int_32 X0, png_int_32 X1,
    int type, int nparams, png_charp units, png_charpp params));
 #endif
 
-#if defined(PNG_pHYs_SUPPORTED)
+#ifdef PNG_pHYs_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_pHYs) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_32 *res_x, png_uint_32 *res_y, int *unit_type));
 #endif
 
-#if defined(PNG_pHYs_SUPPORTED)
+#ifdef PNG_pHYs_SUPPORTED
 extern PNG_EXPORT(void,png_set_pHYs) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_32 res_x, png_uint_32 res_y, int unit_type));
 #endif
@@ -2412,53 +2412,53 @@ extern PNG_EXPORT(png_uint_32,png_get_PLTE) PNGARG((png_structp png_ptr,
 extern PNG_EXPORT(void,png_set_PLTE) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_colorp palette, int num_palette));
 
-#if defined(PNG_sBIT_SUPPORTED)
+#ifdef PNG_sBIT_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_sBIT) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_color_8p *sig_bit));
 #endif
 
-#if defined(PNG_sBIT_SUPPORTED)
+#ifdef PNG_sBIT_SUPPORTED
 extern PNG_EXPORT(void,png_set_sBIT) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_color_8p sig_bit));
 #endif
 
-#if defined(PNG_sRGB_SUPPORTED)
+#ifdef PNG_sRGB_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_sRGB) PNGARG((png_structp png_ptr,
    png_infop info_ptr, int *intent));
 #endif
 
-#if defined(PNG_sRGB_SUPPORTED)
+#ifdef PNG_sRGB_SUPPORTED
 extern PNG_EXPORT(void,png_set_sRGB) PNGARG((png_structp png_ptr,
    png_infop info_ptr, int intent));
 extern PNG_EXPORT(void,png_set_sRGB_gAMA_and_cHRM) PNGARG((png_structp png_ptr,
    png_infop info_ptr, int intent));
 #endif
 
-#if defined(PNG_iCCP_SUPPORTED)
+#ifdef PNG_iCCP_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_iCCP) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_charpp name, int *compression_type,
    png_charpp profile, png_uint_32 *proflen));
    /* Note to maintainer: profile should be png_bytepp */
 #endif
 
-#if defined(PNG_iCCP_SUPPORTED)
+#ifdef PNG_iCCP_SUPPORTED
 extern PNG_EXPORT(void,png_set_iCCP) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_charp name, int compression_type,
    png_charp profile, png_uint_32 proflen));
    /* Note to maintainer: profile should be png_bytep */
 #endif
 
-#if defined(PNG_sPLT_SUPPORTED)
+#ifdef PNG_sPLT_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_sPLT) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_sPLT_tpp entries));
 #endif
 
-#if defined(PNG_sPLT_SUPPORTED)
+#ifdef PNG_sPLT_SUPPORTED
 extern PNG_EXPORT(void,png_set_sPLT) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_sPLT_tp entries, int nentries));
 #endif
 
-#if defined(PNG_TEXT_SUPPORTED)
+#ifdef PNG_TEXT_SUPPORTED
 /* png_get_text also returns the number of text chunks in *num_text */
 extern PNG_EXPORT(png_uint_32,png_get_text) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_textp *text_ptr, int *num_text));
@@ -2472,37 +2472,37 @@ extern PNG_EXPORT(png_uint_32,png_get_text) PNGARG((png_structp png_ptr,
  *  they will never be NULL pointers.
  */
 
-#if defined(PNG_TEXT_SUPPORTED)
+#ifdef PNG_TEXT_SUPPORTED
 extern PNG_EXPORT(void,png_set_text) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_textp text_ptr, int num_text));
 #endif
 
-#if defined(PNG_tIME_SUPPORTED)
+#ifdef PNG_tIME_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_tIME) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_timep *mod_time));
 #endif
 
-#if defined(PNG_tIME_SUPPORTED)
+#ifdef PNG_tIME_SUPPORTED
 extern PNG_EXPORT(void,png_set_tIME) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_timep mod_time));
 #endif
 
-#if defined(PNG_tRNS_SUPPORTED)
+#ifdef PNG_tRNS_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_tRNS) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_bytep *trans, int *num_trans,
    png_color_16p *trans_values));
 #endif
 
-#if defined(PNG_tRNS_SUPPORTED)
+#ifdef PNG_tRNS_SUPPORTED
 extern PNG_EXPORT(void,png_set_tRNS) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_bytep trans, int num_trans,
    png_color_16p trans_values));
 #endif
 
-#if defined(PNG_tRNS_SUPPORTED)
+#ifdef PNG_tRNS_SUPPORTED
 #endif
 
-#if defined(PNG_sCAL_SUPPORTED)
+#ifdef PNG_sCAL_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_sCAL) PNGARG((png_structp png_ptr,
    png_infop info_ptr, int *unit, double *width, double *height));
@@ -2514,7 +2514,7 @@ extern PNG_EXPORT(png_uint_32,png_get_sCAL_s) PNGARG((png_structp png_ptr,
 #endif
 #endif /* PNG_sCAL_SUPPORTED */
 
-#if defined(PNG_sCAL_SUPPORTED)
+#ifdef PNG_sCAL_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(void,png_set_sCAL) PNGARG((png_structp png_ptr,
    png_infop info_ptr, int unit, double width, double height));
@@ -2541,7 +2541,7 @@ extern PNG_EXPORT(void, png_set_keep_unknown_chunks) PNGARG((png_structp
 PNG_EXPORT(int,png_handle_as_unknown) PNGARG((png_structp png_ptr, png_bytep
    chunk_name));
 #endif
-#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
+#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
 extern PNG_EXPORT(void, png_set_unknown_chunks) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_unknown_chunkp unknowns, int num_unknowns));
 extern PNG_EXPORT(void, png_set_unknown_chunk_location)
@@ -2557,7 +2557,7 @@ extern PNG_EXPORT(png_uint_32,png_get_unknown_chunks) PNGARG((png_structp
 extern PNG_EXPORT(void, png_set_invalid) PNGARG((png_structp png_ptr,
    png_infop info_ptr, int mask));
 
-#if defined(PNG_INFO_IMAGE_SUPPORTED)
+#ifdef PNG_INFO_IMAGE_SUPPORTED
 /* The "params" pointer is currently not used and is for future expansion. */
 extern PNG_EXPORT(void, png_read_png) PNGARG((png_structp png_ptr,
                         png_infop info_ptr,
@@ -2693,8 +2693,8 @@ extern PNG_EXPORT(png_uint_32,png_permit_mng_features) PNGARG((png_structp
 #define PNG_HANDLE_CHUNK_ALWAYS       3
 
 /* Added to version 1.2.0 */
-#if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
-#if defined(PNG_MMX_CODE_SUPPORTED)
+#ifdef PNG_ASSEMBLER_CODE_SUPPORTED
+#ifdef PNG_MMX_CODE_SUPPORTED
 #define PNG_ASM_FLAG_MMX_SUPPORT_COMPILED  0x01  /* not user-settable */
 #define PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU    0x02  /* not user-settable */
 #define PNG_ASM_FLAG_MMX_READ_COMBINE_ROW  0x04
@@ -2722,7 +2722,7 @@ extern PNG_EXPORT(png_uint_32,png_permit_mng_features) PNGARG((png_structp
 #define PNG_SELECT_WRITE  2
 #endif /* PNG_MMX_CODE_SUPPORTED */
 
-#if !defined(PNG_1_0_X)
+#ifndef PNG_1_0_X
 /* pngget.c */
 extern PNG_EXPORT(png_uint_32,png_get_mmx_flagmask)
    PNGARG((int flag_select, int *compilerID));
@@ -2754,7 +2754,7 @@ extern PNG_EXPORT(void,png_set_mmx_thresholds)
 
 #endif /* PNG_1_0_X */
 
-#if !defined(PNG_1_0_X)
+#ifndef PNG_1_0_X
 /* png.c, pnggccrd.c, or pngvcrd.c */
 extern PNG_EXPORT(int,png_mmx_support) PNGARG((void));
 #endif /* PNG_1_0_X */
@@ -2832,7 +2832,7 @@ extern PNG_EXPORT(png_uint_32,png_get_user_height_max) PNGARG((png_structp
  * routine also assumes we are using two's complement format for negative
  * values, which is almost certainly true.
  */
-#if defined(PNG_READ_BIG_ENDIAN_SUPPORTED)
+#ifdef PNG_READ_BIG_ENDIAN_SUPPORTED
 #  define png_get_uint_32(buf) ( *((png_uint_32p) (buf)))
 #  define png_get_uint_16(buf) ( *((png_uint_16p) (buf)))
 #  define png_get_int_32(buf)  ( *((png_int_32p)  (buf)))
@@ -2878,7 +2878,7 @@ extern PNG_EXPORT(void,png_save_uint_16)
 #define PNG_AFTER_IDAT              0x08 /* Have complete zlib datastream */
 #define PNG_HAVE_IEND               0x10
 
-#if defined(PNG_INTERNAL)
+#ifdef PNG_INTERNAL
 
 /* More modes of operation.  Note that after an init, mode is set to
  * zero automatically when the structure is created.
@@ -3134,8 +3134,8 @@ PNG_EXTERN void PNGAPI png_push_fill_buffer PNGARG((png_structp png_ptr,
 PNG_EXTERN void PNGAPI png_default_write_data PNGARG((png_structp png_ptr,
    png_bytep data, png_size_t length));
 
-#if defined(PNG_WRITE_FLUSH_SUPPORTED)
-#if !defined(PNG_NO_STDIO)
+#ifdef PNG_WRITE_FLUSH_SUPPORTED
+#ifdef PNG_STDIO_SUPPORTED
 PNG_EXTERN void PNGAPI png_default_flush PNGARG((png_structp png_ptr));
 #endif
 #endif
@@ -3182,7 +3182,7 @@ PNG_EXTERN int png_crc_error PNGARG((png_structp png_ptr));
 PNG_EXTERN void png_calculate_crc PNGARG((png_structp png_ptr, png_bytep ptr,
    png_size_t length));
 
-#if defined(PNG_WRITE_FLUSH_SUPPORTED)
+#ifdef PNG_WRITE_FLUSH_SUPPORTED
 PNG_EXTERN void png_flush PNGARG((png_structp png_ptr));
 #endif
 
@@ -3207,7 +3207,7 @@ PNG_EXTERN void png_write_IDAT PNGARG((png_structp png_ptr, png_bytep data,
 
 PNG_EXTERN void png_write_IEND PNGARG((png_structp png_ptr));
 
-#if defined(PNG_WRITE_gAMA_SUPPORTED)
+#ifdef PNG_WRITE_gAMA_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 PNG_EXTERN void png_write_gAMA PNGARG((png_structp png_ptr, double file_gamma));
 #endif
@@ -3217,12 +3217,12 @@ PNG_EXTERN void png_write_gAMA_fixed PNGARG((png_structp png_ptr, png_fixed_poin
 #endif
 #endif
 
-#if defined(PNG_WRITE_sBIT_SUPPORTED)
+#ifdef PNG_WRITE_sBIT_SUPPORTED
 PNG_EXTERN void png_write_sBIT PNGARG((png_structp png_ptr, png_color_8p sbit,
    int color_type));
 #endif
 
-#if defined(PNG_WRITE_cHRM_SUPPORTED)
+#ifdef PNG_WRITE_cHRM_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 PNG_EXTERN void png_write_cHRM PNGARG((png_structp png_ptr,
    double white_x, double white_y,
@@ -3238,34 +3238,34 @@ PNG_EXTERN void png_write_cHRM_fixed PNGARG((png_structp png_ptr,
 #endif
 #endif
 
-#if defined(PNG_WRITE_sRGB_SUPPORTED)
+#ifdef PNG_WRITE_sRGB_SUPPORTED
 PNG_EXTERN void png_write_sRGB PNGARG((png_structp png_ptr,
    int intent));
 #endif
 
-#if defined(PNG_WRITE_iCCP_SUPPORTED)
+#ifdef PNG_WRITE_iCCP_SUPPORTED
 PNG_EXTERN void png_write_iCCP PNGARG((png_structp png_ptr,
    png_charp name, int compression_type,
    png_charp profile, int proflen));
    /* Note to maintainer: profile should be png_bytep */
 #endif
 
-#if defined(PNG_WRITE_sPLT_SUPPORTED)
+#ifdef PNG_WRITE_sPLT_SUPPORTED
 PNG_EXTERN void png_write_sPLT PNGARG((png_structp png_ptr,
    png_sPLT_tp palette));
 #endif
 
-#if defined(PNG_WRITE_tRNS_SUPPORTED)
+#ifdef PNG_WRITE_tRNS_SUPPORTED
 PNG_EXTERN void png_write_tRNS PNGARG((png_structp png_ptr, png_bytep trans,
    png_color_16p values, int number, int color_type));
 #endif
 
-#if defined(PNG_WRITE_bKGD_SUPPORTED)
+#ifdef PNG_WRITE_bKGD_SUPPORTED
 PNG_EXTERN void png_write_bKGD PNGARG((png_structp png_ptr,
    png_color_16p values, int color_type));
 #endif
 
-#if defined(PNG_WRITE_hIST_SUPPORTED)
+#ifdef PNG_WRITE_hIST_SUPPORTED
 PNG_EXTERN void png_write_hIST PNGARG((png_structp png_ptr, png_uint_16p hist,
    int num_hist));
 #endif
@@ -3276,50 +3276,50 @@ PNG_EXTERN png_size_t png_check_keyword PNGARG((png_structp png_ptr,
    png_charp key, png_charpp new_key));
 #endif
 
-#if defined(PNG_WRITE_tEXt_SUPPORTED)
+#ifdef PNG_WRITE_tEXt_SUPPORTED
 PNG_EXTERN void png_write_tEXt PNGARG((png_structp png_ptr, png_charp key,
    png_charp text, png_size_t text_len));
 #endif
 
-#if defined(PNG_WRITE_zTXt_SUPPORTED)
+#ifdef PNG_WRITE_zTXt_SUPPORTED
 PNG_EXTERN void png_write_zTXt PNGARG((png_structp png_ptr, png_charp key,
    png_charp text, png_size_t text_len, int compression));
 #endif
 
-#if defined(PNG_WRITE_iTXt_SUPPORTED)
+#ifdef PNG_WRITE_iTXt_SUPPORTED
 PNG_EXTERN void png_write_iTXt PNGARG((png_structp png_ptr,
    int compression, png_charp key, png_charp lang, png_charp lang_key,
    png_charp text));
 #endif
 
-#if defined(PNG_TEXT_SUPPORTED)  /* Added at version 1.0.14 and 1.2.4 */
+#ifdef PNG_TEXT_SUPPORTED  /* Added at version 1.0.14 and 1.2.4 */
 PNG_EXTERN int png_set_text_2 PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_textp text_ptr, int num_text));
 #endif
 
-#if defined(PNG_WRITE_oFFs_SUPPORTED)
+#ifdef PNG_WRITE_oFFs_SUPPORTED
 PNG_EXTERN void png_write_oFFs PNGARG((png_structp png_ptr,
    png_int_32 x_offset, png_int_32 y_offset, int unit_type));
 #endif
 
-#if defined(PNG_WRITE_pCAL_SUPPORTED)
+#ifdef PNG_WRITE_pCAL_SUPPORTED
 PNG_EXTERN void png_write_pCAL PNGARG((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));
 #endif
 
-#if defined(PNG_WRITE_pHYs_SUPPORTED)
+#ifdef PNG_WRITE_pHYs_SUPPORTED
 PNG_EXTERN void png_write_pHYs PNGARG((png_structp png_ptr,
    png_uint_32 x_pixels_per_unit, png_uint_32 y_pixels_per_unit,
    int unit_type));
 #endif
 
-#if defined(PNG_WRITE_tIME_SUPPORTED)
+#ifdef PNG_WRITE_tIME_SUPPORTED
 PNG_EXTERN void png_write_tIME PNGARG((png_structp png_ptr,
    png_timep mod_time));
 #endif
 
-#if defined(PNG_WRITE_sCAL_SUPPORTED)
+#ifdef PNG_WRITE_sCAL_SUPPORTED
 #if defined(PNG_FLOATING_POINT_SUPPORTED) && !defined(PNG_NO_STDIO)
 PNG_EXTERN void png_write_sCAL PNGARG((png_structp png_ptr,
    int unit, double width, double height));
@@ -3337,7 +3337,7 @@ PNG_EXTERN void png_write_finish_row PNGARG((png_structp png_ptr));
 /* Internal use only.   Called before first row of data */
 PNG_EXTERN void png_write_start_row PNGARG((png_structp png_ptr));
 
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
 PNG_EXTERN void png_build_gamma_table PNGARG((png_structp png_ptr));
 #endif
 
@@ -3345,7 +3345,7 @@ PNG_EXTERN void png_build_gamma_table PNGARG((png_structp png_ptr));
 PNG_EXTERN void png_combine_row PNGARG((png_structp png_ptr, png_bytep row,
    int mask));
 
-#if defined(PNG_READ_INTERLACING_SUPPORTED)
+#ifdef PNG_READ_INTERLACING_SUPPORTED
 /* Expand an interlaced row */
 /* OLD pre-1.0.9 interface:
 PNG_EXTERN void png_do_read_interlace PNGARG((png_row_infop row_info,
@@ -3356,7 +3356,7 @@ PNG_EXTERN void png_do_read_interlace PNGARG((png_structp png_ptr));
 
 /* GRR TO DO (2.0 or whenever):  simplify other internal calling interfaces */
 
-#if defined(PNG_WRITE_INTERLACING_SUPPORTED)
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
 /* Grab pixels out of a row for an interlaced pass */
 PNG_EXTERN void png_do_write_interlace PNGARG((png_row_infop row_info,
    png_bytep row, int pass));
@@ -3383,27 +3383,27 @@ PNG_EXTERN void png_read_transform_info PNGARG((png_structp png_ptr,
    png_infop info_ptr));
 
 /* These are the functions that do the transformations */
-#if defined(PNG_READ_FILLER_SUPPORTED)
+#ifdef PNG_READ_FILLER_SUPPORTED
 PNG_EXTERN void png_do_read_filler PNGARG((png_row_infop row_info,
    png_bytep row, png_uint_32 filler, png_uint_32 flags));
 #endif
 
-#if defined(PNG_READ_SWAP_ALPHA_SUPPORTED)
+#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
 PNG_EXTERN void png_do_read_swap_alpha PNGARG((png_row_infop row_info,
    png_bytep row));
 #endif
 
-#if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
+#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
 PNG_EXTERN void png_do_write_swap_alpha PNGARG((png_row_infop row_info,
    png_bytep row));
 #endif
 
-#if defined(PNG_READ_INVERT_ALPHA_SUPPORTED)
+#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
 PNG_EXTERN void png_do_read_invert_alpha PNGARG((png_row_infop row_info,
    png_bytep row));
 #endif
 
-#if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
+#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
 PNG_EXTERN void png_do_write_invert_alpha PNGARG((png_row_infop row_info,
    png_bytep row));
 #endif
@@ -3422,21 +3422,21 @@ PNG_EXTERN void png_do_swap PNGARG((png_row_infop row_info, png_bytep row));
 PNG_EXTERN void png_do_packswap PNGARG((png_row_infop row_info, png_bytep row));
 #endif
 
-#if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
 PNG_EXTERN int png_do_rgb_to_gray PNGARG((png_structp png_ptr, png_row_infop
    row_info, png_bytep row));
 #endif
 
-#if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
 PNG_EXTERN void png_do_gray_to_rgb PNGARG((png_row_infop row_info,
    png_bytep row));
 #endif
 
-#if defined(PNG_READ_PACK_SUPPORTED)
+#ifdef PNG_READ_PACK_SUPPORTED
 PNG_EXTERN void png_do_unpack PNGARG((png_row_infop row_info, png_bytep row));
 #endif
 
-#if defined(PNG_READ_SHIFT_SUPPORTED)
+#ifdef PNG_READ_SHIFT_SUPPORTED
 PNG_EXTERN void png_do_unshift PNGARG((png_row_infop row_info, png_bytep row,
    png_color_8p sig_bits));
 #endif
@@ -3445,15 +3445,15 @@ PNG_EXTERN void png_do_unshift PNGARG((png_row_infop row_info, png_bytep row,
 PNG_EXTERN void png_do_invert PNGARG((png_row_infop row_info, png_bytep row));
 #endif
 
-#if defined(PNG_READ_16_TO_8_SUPPORTED)
+#ifdef PNG_READ_16_TO_8_SUPPORTED
 PNG_EXTERN void png_do_chop PNGARG((png_row_infop row_info, png_bytep row));
 #endif
 
-#if defined(PNG_READ_DITHER_SUPPORTED)
+#ifdef PNG_READ_DITHER_SUPPORTED
 PNG_EXTERN void png_do_dither PNGARG((png_row_infop row_info,
    png_bytep row, png_bytep palette_lookup, png_bytep dither_lookup));
 
-#  if defined(PNG_CORRECT_PALETTE_SUPPORTED)
+#  ifdef PNG_CORRECT_PALETTE_SUPPORTED
 PNG_EXTERN void png_correct_palette PNGARG((png_structp png_ptr,
    png_colorp palette, int num_palette));
 #  endif
@@ -3463,18 +3463,18 @@ PNG_EXTERN void png_correct_palette PNGARG((png_structp png_ptr,
 PNG_EXTERN void png_do_bgr PNGARG((png_row_infop row_info, png_bytep row));
 #endif
 
-#if defined(PNG_WRITE_PACK_SUPPORTED)
+#ifdef PNG_WRITE_PACK_SUPPORTED
 PNG_EXTERN void png_do_pack PNGARG((png_row_infop row_info,
    png_bytep row, png_uint_32 bit_depth));
 #endif
 
-#if defined(PNG_WRITE_SHIFT_SUPPORTED)
+#ifdef PNG_WRITE_SHIFT_SUPPORTED
 PNG_EXTERN void png_do_shift PNGARG((png_row_infop row_info, png_bytep row,
    png_color_8p bit_depth));
 #endif
 
-#if defined(PNG_READ_BACKGROUND_SUPPORTED)
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
+#ifdef PNG_READ_GAMMA_SUPPORTED
 PNG_EXTERN void png_do_background PNGARG((png_row_infop row_info, png_bytep row,
    png_color_16p trans_values, png_color_16p background,
    png_color_16p background_1,
@@ -3487,13 +3487,13 @@ PNG_EXTERN void png_do_background PNGARG((png_row_infop row_info, png_bytep row,
 #endif
 #endif
 
-#if defined(PNG_READ_GAMMA_SUPPORTED)
+#ifdef PNG_READ_GAMMA_SUPPORTED
 PNG_EXTERN void png_do_gamma PNGARG((png_row_infop row_info, png_bytep row,
    png_bytep gamma_table, png_uint_16pp gamma_16_table,
    int gamma_shift));
 #endif
 
-#if defined(PNG_READ_EXPAND_SUPPORTED)
+#ifdef PNG_READ_EXPAND_SUPPORTED
 PNG_EXTERN void png_do_expand_palette PNGARG((png_row_infop row_info,
    png_bytep row, png_colorp palette, png_bytep trans, int num_trans));
 PNG_EXTERN void png_do_expand PNGARG((png_row_infop row_info,
@@ -3512,87 +3512,87 @@ PNG_EXTERN void png_handle_PLTE PNGARG((png_structp png_ptr, png_infop info_ptr,
 PNG_EXTERN void png_handle_IEND PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 
-#if defined(PNG_READ_bKGD_SUPPORTED)
+#ifdef PNG_READ_bKGD_SUPPORTED
 PNG_EXTERN void png_handle_bKGD PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif
 
-#if defined(PNG_READ_cHRM_SUPPORTED)
+#ifdef PNG_READ_cHRM_SUPPORTED
 PNG_EXTERN void png_handle_cHRM PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif
 
-#if defined(PNG_READ_gAMA_SUPPORTED)
+#ifdef PNG_READ_gAMA_SUPPORTED
 PNG_EXTERN void png_handle_gAMA PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif
 
-#if defined(PNG_READ_hIST_SUPPORTED)
+#ifdef PNG_READ_hIST_SUPPORTED
 PNG_EXTERN void png_handle_hIST PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif
 
-#if defined(PNG_READ_iCCP_SUPPORTED)
+#ifdef PNG_READ_iCCP_SUPPORTED
 extern void png_handle_iCCP PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif /* PNG_READ_iCCP_SUPPORTED */
 
-#if defined(PNG_READ_iTXt_SUPPORTED)
+#ifdef PNG_READ_iTXt_SUPPORTED
 PNG_EXTERN void png_handle_iTXt PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif
 
-#if defined(PNG_READ_oFFs_SUPPORTED)
+#ifdef PNG_READ_oFFs_SUPPORTED
 PNG_EXTERN void png_handle_oFFs PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif
 
-#if defined(PNG_READ_pCAL_SUPPORTED)
+#ifdef PNG_READ_pCAL_SUPPORTED
 PNG_EXTERN void png_handle_pCAL PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif
 
-#if defined(PNG_READ_pHYs_SUPPORTED)
+#ifdef PNG_READ_pHYs_SUPPORTED
 PNG_EXTERN void png_handle_pHYs PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif
 
-#if defined(PNG_READ_sBIT_SUPPORTED)
+#ifdef PNG_READ_sBIT_SUPPORTED
 PNG_EXTERN void png_handle_sBIT PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif
 
-#if defined(PNG_READ_sCAL_SUPPORTED)
+#ifdef PNG_READ_sCAL_SUPPORTED
 PNG_EXTERN void png_handle_sCAL PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif
 
-#if defined(PNG_READ_sPLT_SUPPORTED)
+#ifdef PNG_READ_sPLT_SUPPORTED
 extern void png_handle_sPLT PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif /* PNG_READ_sPLT_SUPPORTED */
 
-#if defined(PNG_READ_sRGB_SUPPORTED)
+#ifdef PNG_READ_sRGB_SUPPORTED
 PNG_EXTERN void png_handle_sRGB PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif
 
-#if defined(PNG_READ_tEXt_SUPPORTED)
+#ifdef PNG_READ_tEXt_SUPPORTED
 PNG_EXTERN void png_handle_tEXt PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif
 
-#if defined(PNG_READ_tIME_SUPPORTED)
+#ifdef PNG_READ_tIME_SUPPORTED
 PNG_EXTERN void png_handle_tIME PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif
 
-#if defined(PNG_READ_tRNS_SUPPORTED)
+#ifdef PNG_READ_tRNS_SUPPORTED
 PNG_EXTERN void png_handle_tRNS PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif
 
-#if defined(PNG_READ_zTXt_SUPPORTED)
+#ifdef PNG_READ_zTXt_SUPPORTED
 PNG_EXTERN void png_handle_zTXt PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif
@@ -3637,19 +3637,19 @@ PNG_EXTERN void png_push_read_end PNGARG((png_structp png_ptr,
 PNG_EXTERN void png_process_some_data PNGARG((png_structp png_ptr,
    png_infop info_ptr));
 PNG_EXTERN void png_read_push_finish_row PNGARG((png_structp png_ptr));
-#if defined(PNG_READ_tEXt_SUPPORTED)
+#ifdef PNG_READ_tEXt_SUPPORTED
 PNG_EXTERN void png_push_handle_tEXt PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_32 length));
 PNG_EXTERN void png_push_read_tEXt PNGARG((png_structp png_ptr,
    png_infop info_ptr));
 #endif
-#if defined(PNG_READ_zTXt_SUPPORTED)
+#ifdef PNG_READ_zTXt_SUPPORTED
 PNG_EXTERN void png_push_handle_zTXt PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_32 length));
 PNG_EXTERN void png_push_read_zTXt PNGARG((png_structp png_ptr,
    png_infop info_ptr));
 #endif
-#if defined(PNG_READ_iTXt_SUPPORTED)
+#ifdef PNG_READ_iTXt_SUPPORTED
 PNG_EXTERN void png_push_handle_iTXt PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_32 length));
 PNG_EXTERN void png_push_read_iTXt PNGARG((png_structp png_ptr,
@@ -3665,8 +3665,8 @@ PNG_EXTERN void png_do_write_intrapixel PNGARG((png_row_infop row_info,
    png_bytep row));
 #endif
 
-#if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
-#if defined(PNG_MMX_CODE_SUPPORTED)
+#ifdef PNG_ASSEMBLER_CODE_SUPPORTED
+#ifdef PNG_MMX_CODE_SUPPORTED
 /* png.c */ /* PRIVATE */
 PNG_EXTERN void png_init_mmx_flags PNGARG((png_structp png_ptr));
 #endif
@@ -3688,7 +3688,7 @@ png_infop info_ptr));
 PNG_EXTERN float png_get_y_offset_inches PNGARG((png_structp png_ptr,
 png_infop info_ptr));
 
-#if defined(PNG_pHYs_SUPPORTED)
+#ifdef PNG_pHYs_SUPPORTED
 PNG_EXTERN png_uint_32 png_get_pHYs_dpi PNGARG((png_structp png_ptr,
 png_infop info_ptr, png_uint_32 *res_x, png_uint_32 *res_y, int *unit_type));
 #endif /* PNG_pHYs_SUPPORTED */
@@ -3698,7 +3698,7 @@ png_infop info_ptr, png_uint_32 *res_x, png_uint_32 *res_y, int *unit_type));
 PNG_EXTERN png_uint_32 png_read_chunk_header PNGARG((png_structp png_ptr));
 
 /* Added at libpng version 1.2.34 */
-#if defined(PNG_cHRM_SUPPORTED)
+#ifdef PNG_cHRM_SUPPORTED
 PNG_EXTERN int png_check_cHRM_fixed PNGARG((png_structp png_ptr,
    png_fixed_point int_white_x, png_fixed_point int_white_y,
    png_fixed_point int_red_x, png_fixed_point int_red_y, png_fixed_point
@@ -3706,8 +3706,8 @@ PNG_EXTERN int png_check_cHRM_fixed PNGARG((png_structp png_ptr,
    png_fixed_point int_blue_y));
 #endif
 
-#if defined(PNG_cHRM_SUPPORTED)
-#if !defined(PNG_NO_CHECK_cHRM)
+#ifdef PNG_cHRM_SUPPORTED
+#ifdef PNG_CHECK_cHRM_SUPPORTED
 /* Added at libpng version 1.2.34 */
 PNG_EXTERN void png_64bit_product PNGARG((long v1, long v2,
    unsigned long *hi_product, unsigned long *lo_product));
diff --git a/pngconf.h b/pngconf.h
index 5bfc84bb..0fb39c05 100644
--- a/pngconf.h
+++ b/pngconf.h
@@ -1,7 +1,7 @@
 
 /* pngconf.h - machine configurable file for libpng
  *
- * libpng version 1.2.41beta07 - October 18, 2009
+ * libpng version 1.2.41beta07 - October 21, 2009
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -188,44 +188,44 @@
  *   PNG_BUILD_DLL and PNG_STATIC because those change some defaults
  *   such as CONSOLE_IO and whether GLOBAL_ARRAYS are allowed.
  */
-#if defined(__CYGWIN__)
-#  if defined(ALL_STATIC)
-#    if defined(PNG_BUILD_DLL)
+#ifdef __CYGWIN__
+#  ifdef ALL_STATIC
+#    ifdef PNG_BUILD_DLL
 #      undef PNG_BUILD_DLL
 #    endif
-#    if defined(PNG_USE_DLL)
+#    ifdef PNG_USE_DLL
 #      undef PNG_USE_DLL
 #    endif
-#    if defined(PNG_DLL)
+#    ifdef PNG_DLL
 #      undef PNG_DLL
 #    endif
-#    if !defined(PNG_STATIC)
+#    ifndef PNG_STATIC
 #      define PNG_STATIC
 #    endif
 #  else
-#    if defined (PNG_BUILD_DLL)
-#      if defined(PNG_STATIC)
+#    ifdef PNG_BUILD_DLL
+#      ifdef PNG_STATIC
 #        undef PNG_STATIC
 #      endif
-#      if defined(PNG_USE_DLL)
+#      ifdef PNG_USE_DLL
 #        undef PNG_USE_DLL
 #      endif
-#      if !defined(PNG_DLL)
+#      ifndef PNG_DLL
 #        define PNG_DLL
 #      endif
 #    else
-#      if defined(PNG_STATIC)
-#        if defined(PNG_USE_DLL)
+#      ifdef PNG_STATIC
+#        ifdef PNG_USE_DLL
 #          undef PNG_USE_DLL
 #        endif
-#        if defined(PNG_DLL)
+#        ifdef PNG_DLL
 #          undef PNG_DLL
 #        endif
 #      else
-#        if !defined(PNG_USE_DLL)
+#        ifndef PNG_USE_DLL
 #          define PNG_USE_DLL
 #        endif
-#        if !defined(PNG_DLL)
+#        ifndef PNG_DLL
 #          define PNG_DLL
 #        endif
 #      endif
@@ -250,7 +250,7 @@
 #  define PNG_STDIO_SUPPORTED
 #endif
 
-#if defined(_WIN32_WCE)
+#ifdef _WIN32_WCE
 #  include <windows.h>
    /* Console I/O functions are not supported on WindowsCE */
 #  define PNG_NO_CONSOLE_IO
@@ -279,7 +279,7 @@
 #      endif
 #    endif
 #  else
-#    if !defined(_WIN32_WCE)
+#    ifndef _WIN32_WCE
 /* "stdio.h" functions are not supported on WindowsCE */
 #      include <stdio.h>
 #    endif
@@ -400,8 +400,8 @@
  * them inside an appropriate ifdef/endif pair for portability.
  */
 
-#if defined(PNG_FLOATING_POINT_SUPPORTED)
-#  if defined(MACOS)
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+#  ifdef MACOS
      /* We need to check that <math.h> hasn't already been included earlier
       * as it seems it doesn't agree with <fp.h>, yet we should really use
       * <fp.h> if possible.
@@ -529,7 +529,7 @@
 #  endif
 #endif
 
-#if !defined(PNG_NO_iTXt_SUPPORTED)
+#ifndef PNG_NO_iTXt_SUPPORTED
 #  if !defined(PNG_READ_iTXt_SUPPORTED) && !defined(PNG_NO_READ_iTXt)
 #    define PNG_READ_iTXt
 #  endif
@@ -802,7 +802,7 @@
 #    endif
 #  endif
 
-#  if defined(__APPLE__)
+#  ifdef __APPLE__
 #    if !defined(PNG_MMX_CODE_SUPPORTED) && !defined(PNG_NO_MMX_CODE)
 #      define PNG_NO_MMX_CODE
 #    endif
@@ -822,7 +822,7 @@
 /* end of obsolete code to be removed from libpng-1.4.0 */
 
 /* Added at libpng-1.2.0 */
-#if !defined(PNG_1_0_X)
+#ifndef PNG_1_0_X
 #if !defined(PNG_NO_USER_MEM) && !defined(PNG_USER_MEM_SUPPORTED)
 #  define PNG_USER_MEM_SUPPORTED
 #endif
@@ -1168,8 +1168,8 @@
 #endif
 
 /* need the time information for reading tIME chunks */
-#if defined(PNG_tIME_SUPPORTED)
-#  if !defined(_WIN32_WCE)
+#ifdef PNG_tIME_SUPPORTED
+#  ifndef _WIN32_WCE
      /* "time.h" functions are not supported on WindowsCE */
 #    include <time.h>
 #  endif
@@ -1241,8 +1241,8 @@ typedef unsigned char png_byte;
  */
 
 /* MSC Medium model */
-#if defined(FAR)
-#  if defined(M_I86MM)
+#ifdef FAR
+#  ifdef M_I86MM
 #    define USE_FAR_KEYWORD
 #    define FARDATA FAR
 #    include <dos.h>
@@ -1275,7 +1275,7 @@ typedef char            FAR * png_charp;
 typedef png_fixed_point FAR * png_fixed_point_p;
 
 #ifndef PNG_NO_STDIO
-#if defined(_WIN32_WCE)
+#ifdef _WIN32_WCE
 typedef HANDLE                png_FILE_p;
 #else
 typedef FILE                * png_FILE_p;
@@ -1339,17 +1339,17 @@ typedef z_stream FAR *  png_zstreamp;
  * When building a static lib, default to no GLOBAL ARRAYS, but allow
  * command-line override
  */
-#if defined(__CYGWIN__)
-#  if !defined(PNG_STATIC)
-#    if defined(PNG_USE_GLOBAL_ARRAYS)
+#ifdef __CYGWIN__
+#  ifndef PNG_STATIC
+#    ifdef PNG_USE_GLOBAL_ARRAYS
 #      undef PNG_USE_GLOBAL_ARRAYS
 #    endif
-#    if !defined(PNG_USE_LOCAL_ARRAYS)
+#    ifndef PNG_USE_LOCAL_ARRAYS
 #      define PNG_USE_LOCAL_ARRAYS
 #    endif
 #  else
 #    if defined(PNG_USE_LOCAL_ARRAYS) || defined(PNG_NO_GLOBAL_ARRAYS)
-#      if defined(PNG_USE_GLOBAL_ARRAYS)
+#      ifdef PNG_USE_GLOBAL_ARRAYS
 #        undef PNG_USE_GLOBAL_ARRAYS
 #      endif
 #    endif
@@ -1372,7 +1372,7 @@ typedef z_stream FAR *  png_zstreamp;
 #  endif
 #endif
 
-#if defined(__CYGWIN__)
+#ifdef __CYGWIN__
 #  undef PNGAPI
 #  define PNGAPI __cdecl
 #  undef PNG_IMPEXP
@@ -1413,7 +1413,7 @@ typedef z_stream FAR *  png_zstreamp;
 #     define PNG_IMPEXP
 #  endif
 
-#  if !defined(PNG_IMPEXP)
+#  ifndef PNG_IMPEXP
 
 #     define PNG_EXPORT_TYPE1(type,symbol)  PNG_IMPEXP type PNGAPI symbol
 #     define PNG_EXPORT_TYPE2(type,symbol)  type PNG_IMPEXP PNGAPI symbol
@@ -1424,7 +1424,7 @@ typedef z_stream FAR *  png_zstreamp;
 #           define PNG_EXPORT PNG_EXPORT_TYPE1
 #        else
 #           define PNG_EXPORT PNG_EXPORT_TYPE2
-#           if defined(PNG_BUILD_DLL)
+#           ifdef PNG_BUILD_DLL
 #              define PNG_IMPEXP __export
 #           else
 #              define PNG_IMPEXP /*__import */ /* doesn't exist AFAIK in
@@ -1434,8 +1434,8 @@ typedef z_stream FAR *  png_zstreamp;
 #        endif
 #     endif
 
-#     if !defined(PNG_IMPEXP)
-#        if defined(PNG_BUILD_DLL)
+#     ifndef PNG_IMPEXP
+#        ifdef PNG_BUILD_DLL
 #           define PNG_IMPEXP __declspec(dllexport)
 #        else
 #           define PNG_IMPEXP __declspec(dllimport)
@@ -1496,7 +1496,7 @@ typedef z_stream FAR *  png_zstreamp;
    (LIBPNG_WAS_COMPILED_WITH__PNG_SETJMP_NOT_SUPPORTED)
 #endif
 
-#if defined(USE_FAR_KEYWORD)  /* memory model independent fns */
+#ifdef USE_FAR_KEYWORD  /* memory model independent fns */
 /* use this to make far-to-near assignments */
 #  define CHECK   1
 #  define NOCHECK 0