From: https://github.com/pld-linux/autotrace/blob/master/autotrace-libpng.patch

--- autotrace-0.31.1/input-png.c.orig	2002-10-10 22:44:14.000000000 +0200
+++ autotrace-0.31.1/input-png.c	2013-03-22 20:20:49.835238916 +0100
@@ -42,17 +42,17 @@
 
 static void handle_warning(png_structp png, const at_string message) {
         LOG1("PNG warning: %s", message);
-	at_exception_warning((at_exception_type *)png->error_ptr,
+	at_exception_warning((at_exception_type *)png_get_error_ptr(png),
 			     message);
-	/* at_exception_fatal((at_exception_type *)at_png->error_ptr,
+	/* at_exception_fatal((at_exception_type *)png_get_error_ptr(at_png),
 	   "PNG warning"); */
 }
 
 static void handle_error(png_structp png, const at_string message) {
 	LOG1("PNG error: %s", message);
-	at_exception_fatal((at_exception_type *)png->error_ptr,
+	at_exception_fatal((at_exception_type *)png_get_error_ptr(png),
 			   message);
-	/* at_exception_fatal((at_exception_type *)at_png->error_ptr,
+	/* at_exception_fatal((at_exception_type *)png_get_error_ptr(at_png),
 	   "PNG error"); */
 	
 }
@@ -157,8 +157,8 @@
 
 	png_set_strip_16(png_ptr);
 	png_set_packing(png_ptr);
-	if ((png_ptr->bit_depth < 8) ||
-	    (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ||
+	if ((png_get_bit_depth(png_ptr, info_ptr) < 8) ||
+	    (png_get_color_type(png_ptr, info_ptr) == PNG_COLOR_TYPE_PALETTE) ||
 	    (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)))
 		png_set_expand(png_ptr);
 
@@ -184,17 +184,16 @@
 	png_read_update_info(png_ptr, info_ptr);
 
 
-	info_ptr->row_pointers = (png_bytepp)png_malloc(png_ptr,
-							info_ptr->height * sizeof(png_bytep));
+	png_set_rows(png_ptr, info_ptr, (png_bytepp)png_malloc(png_ptr,
+							png_get_image_height(png_ptr, info_ptr) * sizeof(png_bytep)));
 #ifdef PNG_FREE_ME_SUPPORTED
 	info_ptr->free_me |= PNG_FREE_ROWS;
 #endif
-	for (row = 0; row < (int)info_ptr->height; row++)
-		info_ptr->row_pointers[row] = (png_bytep)png_malloc(png_ptr,
+	for (row = 0; row < (int)png_get_image_height(png_ptr, info_ptr); row++)
+		png_get_rows(png_ptr, info_ptr)[row] = (png_bytep)png_malloc(png_ptr,
 								    png_get_rowbytes(png_ptr, info_ptr));
 	
-	png_read_image(png_ptr, info_ptr->row_pointers);
-	info_ptr->valid |= PNG_INFO_IDAT;
+	png_read_image(png_ptr, png_get_rows(png_ptr, info_ptr));
 	png_read_end(png_ptr, info_ptr);
 	return png_get_rows(png_ptr, info_ptr);
 }