Conditionally compile png_combine_row() and png_read_finish_row()

which are only used by sequential PNG readers.  This can save some
resources in applications that only do progressive reading.

ANNOUNCE

 
-Libpng 1.2.37beta02 - May 16, 2009
+Libpng 1.2.37beta02 - May 18, 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.
@@ -51,9 +51,11 @@ version 1.2.37beta01 [May 14, 2009]
   Updated some of the makefiles in the scripts directory (merged with
     those in libpng-1.4.0beta57).
 
-version 1.2.37beta02 [May 16, 2009]
+version 1.2.37beta02 [May 18, 2009]
   Fixed typo in libpng documentation (FILTER_AVE should be FILTER_AVG)
   Relocated misplaced #endif in pngwrite.c, sCAL chunk handler.
+  Conditionally compile png_combine_row() and png_read_finish_row()
+    which are not used by progressive readers.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 

CHANGES

@@ -2376,9 +2376,11 @@ version 1.2.37beta01 [May 14, 2009]
   Updated some of the makefiles in the scripts directory (merged with
     those in libpng-1.4.0beta57).
 
-version 1.2.37beta02 [May 16, 2009]
+version 1.2.37beta02 [May 18, 2009]
   Fixed typo in libpng documentation (FILTER_AVE should be FILTER_AVG)
   Relocated misplaced #endif in pngwrite.c, sCAL chunk handler.
+  Conditionally compile png_combine_row() and png_read_finish_row()
+    which are not used by progressive readers.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

pngrutil.c

 
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.2.37 [May 15, 2009]
+ * Last changed in libpng 1.2.37 [May 18, 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)
@@ -2325,6 +2325,7 @@ png_check_chunk_name(png_structp png_ptr, png_bytep chunk_name)
    }
 }
 
+#ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
 /* Combines the row recently read in with the existing pixels in the
    row.  This routine takes care of alpha and transparency if requested.
    This routine also handles the two methods of progressive display
@@ -2536,6 +2537,7 @@ png_combine_row(png_structp png_ptr, png_bytep row, int mask)
       }
    }
 }
+#endif /* PNG_NO_SEQUENTIAL_READ_SUPPORTED */
 
 #ifdef PNG_READ_INTERLACING_SUPPORTED
 /* OLD pre-1.0.9 interface:
@@ -2887,6 +2889,7 @@ png_read_filter_row(png_structp png_ptr, png_row_infop row_info, png_bytep row,
    }
 }
 
+#ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
 void /* PRIVATE */
 png_read_finish_row(png_structp png_ptr)
 {
@@ -2917,8 +2920,6 @@ png_read_finish_row(png_structp png_ptr)
    if (png_ptr->interlaced)
    {
       png_ptr->row_number = 0;
-      png_memset_check(png_ptr, png_ptr->prev_row, 0,
-         png_ptr->rowbytes + 1);
       do
       {
          png_ptr->pass++;
@@ -3018,6 +3019,7 @@ png_read_finish_row(png_structp png_ptr)
 
    png_ptr->mode |= PNG_AFTER_IDAT;
 }
+#endif /* PNG_NO_SEQUENTIAL_READ_SUPPORTED */
 
 void /* PRIVATE */
 png_read_start_row(png_structp png_ptr)
@@ -3187,7 +3189,7 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
    if (row_bytes + 64 > png_ptr->old_big_row_buf_size)
    {
      png_free(png_ptr, png_ptr->big_row_buf);
-      png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 64);
+     png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 64);
      if (png_ptr->interlaced)
        png_memset(png_ptr->big_row_buf, 0, row_bytes + 64);
      png_ptr->row_buf = png_ptr->big_row_buf + 32;
@@ -3195,21 +3197,30 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
    }
 
 #ifdef PNG_MAX_MALLOC_64K
-   if ((png_uint_32)png_ptr->rowbytes + 1 > (png_uint_32)65536L)
+   if ((png_uint_32)row_bytes + 1 > (png_uint_32)65536L)
       png_error(png_ptr, "This image requires a row greater than 64KB");
 #endif
-   if ((png_uint_32)png_ptr->rowbytes > (png_uint_32)(PNG_SIZE_MAX - 1))
+   if ((png_uint_32)row_bytes > (png_uint_32)(PNG_SIZE_MAX - 1))
       png_error(png_ptr, "Row has too many bytes to allocate in memory.");
 
-   if (png_ptr->rowbytes+1 > png_ptr->old_prev_row_size)
+   if (row_bytes + 1 > png_ptr->old_prev_row_size)
    {
-     png_free(png_ptr, png_ptr->prev_row);
-     png_ptr->prev_row = (png_bytep)png_malloc(png_ptr, (png_uint_32)(
-        png_ptr->rowbytes + 1));
-     png_ptr->old_prev_row_size = png_ptr->rowbytes+1;
+      png_free(png_ptr, png_ptr->prev_row);
+      png_ptr->prev_row = (png_bytep)png_malloc(png_ptr, (png_uint_32)(
+        row_bytes + 1));
+      png_memset_check(png_ptr, png_ptr->prev_row, 0, row_bytes + 1);
+      png_ptr->old_prev_row_size = row_bytes + 1;
+   }
+   else
+   {
+      if (png_ptr->reset_prev_row == 1)
+      {
+         png_memset_check(png_ptr, png_ptr->prev_row, 0, row_bytes + 1);
+      }
    }
 
-   png_memset_check(png_ptr, png_ptr->prev_row, 0, png_ptr->rowbytes + 1);
+   png_ptr->reset_prev_row = 0;  
+   png_ptr->rowbytes = row_bytes;
 
    png_debug1(3, "width = %lu,", png_ptr->width);
    png_debug1(3, "height = %lu,", png_ptr->height);