[devel] Changed some "#if defined(" to "ifdef"

and revised libpng style to mention not using the TAB character.

ANNOUNCE

 
-Libpng 1.4.0beta81 - September 20, 2009
+Libpng 1.4.0beta81 - September 23, 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.
@@ -550,11 +550,12 @@ version 1.4.0beta80 [September 17, 2009]
     (Dennis Gustafsson)
   Fixed typo introduced in beta78 in pngtest.c ("#if def " should be "#ifdef ") 
 
-version 1.4.0beta81 [September 20, 2009]
+version 1.4.0beta81 [September 23, 2009]
   Eliminated unused PNG_FLAG_FREE_* defines from pngpriv.h
   Expanded TAB characters in pngrtran.c
   Removed PNG_CONST from all "PNG_CONST PNG_CHNK" declarations to avoid
     compiler complaints about doubly declaring things "const".
+  Changed some "#if defined(" to "ifdef"
 
 version 1.4.0betaN [future]
   Build shared libraries with -lz and sometimes -lm.

CHANGES

@@ -2236,11 +2236,12 @@ version 1.4.0beta80 [September 17, 2009]
     (Dennis Gustafsson)
   Fixed typo introduced in beta78 in pngtest.c ("#if def " should be "#ifdef ") 
 
-version 1.4.0beta81 [September 20, 2009]
+version 1.4.0beta81 [September 23, 2009]
   Eliminated unused PNG_FLAG_FREE_* defines from pngpriv.h
   Expanded TAB characters in pngrtran.c
   Removed PNG_CONST from all "PNG_CONST PNG_CHNK" declarations to avoid
     compiler complaints about doubly declaring things "const".
+  Changed some "#if defined(" to "ifdef"
 
 version 1.4.0betaN [future]
   Build shared libraries with -lz and sometimes -lm.

libpng-1.4.0beta81.txt

 libpng.txt - A description on how to use and modify libpng
 
- libpng version 1.4.0beta81 - September 17, 2009
+ libpng version 1.4.0beta81 - September 23, 2009
  Updated and distributed by Glenn Randers-Pehrson
  <glennrp at users.sourceforge.net>
  Copyright (c) 1998-2009 Glenn Randers-Pehrson
@@ -11,7 +11,7 @@ libpng.txt - A description on how to use and modify libpng
 
  Based on:
 
- libpng versions 0.97, January 1998, through 1.4.0beta81 - September 17, 2009
+ libpng versions 0.97, January 1998, through 1.4.0beta81 - September 23, 2009
  Updated and distributed by Glenn Randers-Pehrson
  Copyright (c) 1998-2009 Glenn Randers-Pehrson
 
@@ -3183,17 +3183,19 @@ cast, nor do we put one between a function name and the
 left parenthesis that follows it:
 
     for (i = 2; i > 0; --i)
-       x[i] = a(x) + (int)b;
+       y[i] = a(x) + (int)b;
 
 We prefer #ifdef and #ifndef to #if defined() and if !defined()
 when there is only one macro being tested.
 
+We do not use the TAB character for indentation in the C sources.
+
 Other rules can be inferred by inspecting the libpng
 source.
 
 XIII. Y2K Compliance in libpng
 
-September 17, 2009
+September 23, 2009
 
 Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.

pngconf.h

 
 /* pngconf.h - machine configurable file for libpng
  *
- * libpng version 1.4.0beta81 - September 17, 2009
+ * libpng version 1.4.0beta81 - September 23, 2009
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -139,7 +139,7 @@
 
 /* Enabled by default in 1.2.0.  You can disable this if you don't need to
    support PNGs that are embedded in MNG datastreams */
-#if !defined(PNG_NO_MNG_FEATURES)
+#ifndef PNG_NO_MNG_FEATURES
 #  ifndef PNG_MNG_FEATURES_SUPPORTED
 #    define PNG_MNG_FEATURES_SUPPORTED
 #  endif
@@ -200,44 +200,44 @@
  *   PNG_BUILD_DLL and PNG_STATIC because those change some defaults
  *   such as CONSOLE_IO.
  */
-#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
@@ -262,7 +262,7 @@
 #  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
@@ -1029,8 +1029,8 @@
 #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
@@ -1103,8 +1103,8 @@ 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>
@@ -1137,7 +1137,7 @@ 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;
@@ -1186,7 +1186,7 @@ typedef char            FAR * FAR * FAR * png_charppp;
 #  define PNG_DLL
 #endif
 
-#if defined(__CYGWIN__)
+#ifdef __CYGWIN__
 #  undef PNGAPI
 #  define PNGAPI __cdecl
 #  undef PNG_IMPEXP
@@ -1229,7 +1229,7 @@ typedef char            FAR * FAR * FAR * png_charppp;
 #     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
@@ -1240,7 +1240,7 @@ typedef char            FAR * FAR * FAR * png_charppp;
 #           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
@@ -1250,8 +1250,8 @@ typedef char            FAR * FAR * FAR * png_charppp;
 #        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)
@@ -1306,7 +1306,7 @@ typedef char            FAR * FAR * FAR * png_charppp;
 #  endif
 #endif
 
-#if defined(USE_FAR_KEYWORD)
+#ifdef USE_FAR_KEYWORD
 /* use this to make far-to-near assignments */
 #  define CHECK   1
 #  define NOCHECK 0
@@ -1320,7 +1320,7 @@ typedef char            FAR * FAR * FAR * png_charppp;
 #  define png_memset  _fmemset
 #  define png_sprintf sprintf
 #else
-#  if defined(_WINDOWS_)  /* favor Windows over C runtime fns */
+#  ifdef _WINDOWS_  /* favor Windows over C runtime fns */
 #    define CVT_PTR(ptr)         (ptr)
 #    define CVT_PTR_NOCHECK(ptr) (ptr)
 #    define png_strcpy  lstrcpyA

pngpriv.h

 
 /* pngpriv.h - private declarations for use inside libpng
  *
- * libpng version 1.4.0beta81 - September 20, 2009
+ * libpng version 1.4.0beta81 - September 23, 2009
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -41,8 +41,8 @@
  * 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.
@@ -76,7 +76,7 @@
     defined(_WIN32) || defined(__WIN32__)
 #  include <windows.h>  /* defines _WINDOWS_ macro */
 /* I have no idea why is this necessary... */
-#  if defined(_MSC_VER)
+#  ifdef _MSC_VER
 #    include <malloc.h>
 #  endif
 #endif
@@ -325,7 +325,7 @@ 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
 
@@ -347,7 +347,7 @@ 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
@@ -357,12 +357,12 @@ 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,
@@ -376,34 +376,34 @@ PNG_EXTERN void png_write_cHRM_fixed PNGARG((png_structp png_ptr,
    png_fixed_point int_blue_y));
 #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
@@ -414,50 +414,50 @@ 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_STDIO_SUPPORTED)
 PNG_EXTERN void png_write_sCAL PNGARG((png_structp png_ptr,
    int unit, double width, double height));
@@ -475,7 +475,7 @@ 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
 
@@ -483,7 +483,7 @@ 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,
@@ -494,7 +494,7 @@ 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));
@@ -521,27 +521,27 @@ 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
@@ -552,7 +552,7 @@ PNG_EXTERN void png_do_strip_filler PNGARG((png_row_infop row_info,
    png_bytep row, png_uint_32 flags));
 #endif
 
-#if defined(PNG_READ_PREMULTIPLY_ALPHA_SUPPORTED)
+#ifdef PNG_READ_PREMULTIPLY_ALPHA_SUPPORTED
 PNG_EXTERN void png_do_read_premultiply_alpha
    PNGARG((png_row_infop row_info, png_bytep row));
 #endif
@@ -565,21 +565,21 @@ 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
@@ -588,15 +588,15 @@ 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
@@ -606,18 +606,18 @@ 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_color, png_color_16p background,
    png_color_16p background_1,
@@ -630,13 +630,13 @@ 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,
@@ -655,87 +655,87 @@ 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
@@ -780,19 +780,19 @@ 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,
@@ -809,7 +809,7 @@ PNG_EXTERN void png_do_write_intrapixel PNGARG((png_row_infop row_info,
 #endif
 
 /* Added at libpng version 1.4.0 */
-#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