[master] Revise pngconf.h (iTXt handling)

and avoid reference to time.h "tm" structure in png.h and pngwrite.c

png.h

@@ -1646,18 +1646,18 @@ extern PNG_EXPORT(png_charp,png_convert_to_rfc1123)
    PNGARG((png_structp png_ptr, png_timep ptime));
 #endif
 
-#ifndef _WIN32_WCE
-/* "time.h" functions are not supported on WindowsCE */
 #ifdef PNG_WRITE_tIME_SUPPORTED
 /* Convert from a struct tm to png_time */
+#  ifndef _WIN32_WCE
+/* "tm" structure is not supported on WindowsCE */
 extern PNG_EXPORT(void,png_convert_from_struct_tm) PNGARG((png_timep ptime,
    struct tm FAR * ttime));
 
 /* Convert from time_t to png_time.  Uses gmtime() */
 extern PNG_EXPORT(void,png_convert_from_time_t) PNGARG((png_timep ptime,
    time_t ttime));
+#  endif /* _WIN32_WCE */
 #endif /* PNG_WRITE_tIME_SUPPORTED */
-#endif /* _WIN32_WCE */
 
 #ifdef PNG_READ_EXPAND_SUPPORTED
 /* Expand data to 24-bit RGB, or 8-bit grayscale, with alpha if available. */

pngconf.h

@@ -523,43 +523,22 @@
  * iTXt support was added.  iTXt support was turned off by default through
  * libpng-1.2.x, to support old apps that malloc the png_text structure
  * instead of calling png_set_text() and letting libpng malloc it.  It
- * will be turned on by default in libpng-1.4.0.
+ * was turned on by default in libpng-1.2.41.
  */
 
-/* If you have previously been defining PNG_iTXt_SUPPORTED, please
+#if 0
- * continue to do so in libpng-1.2.41 and later, until you switch to
+#ifndef PNG_NO_iTXt
- * libpng-1.4.0, even though it is not necessary now to gain iTXt support.
- * Your PNG_iTXt_SUPPORTED definition will be interpreted in png_set_text()
- * as a signal that you have defined it in your builds of previous libpng
- * versions that did not support iTXt by default.
- */
-#if !defined(PNG_iTXt_SUPPORTED) && !defined(PNG_READ_iTXt_SUPPORTED) && \
-    !defined(PNG_WRITE_iTXt_SUPPORTED)
-#  define PNG_iTXt_NOT_PREVIOUSLY_SUPPORTED
-#endif
-
-#if defined(PNG_1_0_X) || defined (PNG_1_2_X)
 #  ifndef PNG_iTXt_SUPPORTED
-#    ifndef PNG_NO_iTXt_SUPPORTED
+#    define PNG_iTXt_SUPPORTED
-#      define PNG_NO_iTXt_SUPPORTED
 #  endif
-#    ifndef PNG_NO_READ_iTXt
-#      define PNG_NO_READ_iTXt
-#    endif
-#    ifndef PNG_NO_WRITE_iTXt
-#      define PNG_NO_WRITE_iTXt
-#    endif
-#  endif
-#endif
-
-#ifndef PNG_NO_iTXt_SUPPORTED
 #  if !defined(PNG_READ_iTXt_SUPPORTED) && !defined(PNG_NO_READ_iTXt)
-#    define PNG_READ_iTXt
+#    define PNG_READ_iTXt_SUPPORTED
 #  endif
 #  if !defined(PNG_WRITE_iTXt_SUPPORTED) && !defined(PNG_NO_WRITE_iTXt)
-#    define PNG_WRITE_iTXt
+#    define PNG_WRITE_iTXt_SUPPORTED
 #  endif
 #endif
+#endif
 
 /* The following support, added after version 1.0.0, can be turned off here en
  * masse by defining PNG_LEGACY_SUPPORTED in case you need binary compatibility

pngwrite.c

@@ -425,7 +425,7 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
 
 #ifdef PNG_WRITE_tIME_SUPPORTED
 #ifndef _WIN32_WCE
-/* "time.h" functions are not supported on WindowsCE */
+/* "tm" structure is not supported on WindowsCE */
 void PNGAPI
 png_convert_from_struct_tm(png_timep ptime, struct tm FAR * ttime)
 {
@@ -452,7 +452,6 @@ png_convert_from_time_t(png_timep ptime, time_t ttime)
 #endif
 #endif
 
-
 /* Initialize png_ptr structure, and allocate any memory needed */
 png_structp PNGAPI
 png_create_write_struct(png_const_charp user_png_ver, png_voidp error_ptr,