change clustering behavior

fontland/fontland/unsafe/harfbuzz-helper.rkt

@@ -12,6 +12,11 @@
                          HB_DIRECTION_TTB = 6
                          HB_DIRECTION_BTT = 7))
 
+(define hb-cluster-levels
+  '(HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES = 0
+                                               HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS	= 1
+                                               HB_BUFFER_CLUSTER_LEVEL_CHARACTERS		= 2))
+
 (define (->tag bstr)
   (integer-bytes->integer bstr #f #;(= unsigned) 'big-endian))
 

fontland/fontland/unsafe/harfbuzz.rkt

@@ -33,6 +33,7 @@
 (define (default-buffer-setup buf)
   (hb_buffer_set_direction buf 'HB_DIRECTION_LTR)
   (hb_buffer_set_script buf 'HB_SCRIPT_LATIN)
+  (hb_buffer_set_cluster_level buf 'HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS)
   (hb_buffer_set_language buf (hb_language_from_string #"en"))
   buf)
 
@@ -55,6 +56,10 @@
                                                 (_int = text-length)
                                                 -> _void))
 
+(define _hb_cluster_t (_enum hb-cluster-levels))
+(define-harfbuzz hb_buffer_set_cluster_level (_fun _hb_buffer_t _hb_cluster_t -> _void))
+(define-harfbuzz hb_buffer_get_cluster_level (_fun _hb_buffer_t -> _hb_cluster_t))
+
 (define _hb_direction_t (_enum hb-direction-values))
 (define-harfbuzz hb_buffer_set_direction (_fun _hb_buffer_t _hb_direction_t -> _void))
 (define-harfbuzz hb_buffer_get_direction (_fun _hb_buffer_t -> _hb_direction_t))