+# ifdef PNG_READ_INTERLACING_SUPPORTED
+ int passes = png_set_interlace_handling(png_ptr);
+# else /* !READ_INTERLACING */
+ int passes = png_get_interlace_type(png_ptr, info_ptr) ==
+ PNG_INTERLACE_ADAM7 ? PNG_INTERLACE_ADAM7_PASSES : 1;
+# endif /* !READ_INTERLACING */