libpng: Optimize RGBA png_do_expand_palette

third_party/libpng/pngstruct.h

 
 /* pngstruct.h - header file for PNG reference library
  *
  * Last changed in libpng 1.6.18 [July 23, 2015]
  * Copyright (c) 1998-2002,2004,2006-2015 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.)
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
@@ skipping 210 matching lines @@
    png_bytep prev_row;        /* buffer to save previous (unfiltered) row.
                                * While reading this is a pointer into
                                * big_prev_row; while writing it is separately
                                * allocated if needed.
                                */
    png_bytep row_buf;         /* buffer to save current (unfiltered) row.
                                * While reading, this is a pointer into
                                * big_row_buf; while writing it is separately
                                * allocated.
                                */
+#ifdef PNG_READ_EXPAND_SUPPORTED
+   png_bytep row_tmp_palette; /* Buffer to accelerate palette transformations. */
+#endif
 #ifdef PNG_WRITE_FILTER_SUPPORTED
    png_bytep try_row;    /* buffer to save trial row when filtering */
    png_bytep tst_row;    /* buffer to save best trial row when filtering */
 #endif
    png_size_t info_rowbytes;  /* Added in 1.5.4: cache of updated row bytes */
 
    png_uint_32 idat_size;     /* current IDAT size for read */
    png_uint_32 crc;           /* current chunk CRC value */
    png_colorp palette;        /* palette from the input file */
    png_uint_16 num_palette;   /* number of color entries in palette */
@@ skipping 233 matching lines @@
    void (*read_filter[PNG_FILTER_VALUE_LAST-1])(png_row_infop row_info,
       png_bytep row, png_const_bytep prev_row);
 
 #ifdef PNG_READ_SUPPORTED
 #if defined(PNG_COLORSPACE_SUPPORTED) || defined(PNG_GAMMA_SUPPORTED)
    png_colorspace   colorspace;
 #endif
 #endif
 };
 #endif /* PNGSTRUCT_H */