1 files changed, 19 insertions, 18 deletions

diff --git a/libskrift_get_cluster_glyph.c b/libskrift_get_cluster_glyph.c
index e8d5724..fbc3a18 100644
--- a/libskrift_get_cluster_glyph.c
+++ b/libskrift_get_cluster_glyph.c
@@ -4,8 +4,8 @@
 /* TODO try normalisation if not found, then try fallback fonts */
 
 ssize_t
-libskrift_get_cluster_glyph(LIBSKRIFT_CONTEXT *ctx, const char *text, struct libskrift_saved_grapheme *saved,
-                            double x, double y, struct libskrift_glyph **glyphp)
+libskrift_get_cluster_glyph(LIBSKRIFT_CONTEXT *ctx, const char *text, size_t text_length,
+                            struct libskrift_saved_grapheme *saved, double x, double y, struct libskrift_glyph **glyphp)
 {
 	struct libskrift_glyph *glyph0, *glyph1, *glyph2;
 	uint32_t cp0, cp1;
@@ -14,36 +14,31 @@ libskrift_get_cluster_glyph(LIBSKRIFT_CONTEXT *ctx, const char *text, struct lib
 
 	*glyphp = NULL;
 
-	if (saved && saved->cp) {
+	if (!text_length) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	if (saved && saved->have_saved) {
 		cp0 = saved->cp;
 		len = saved->len;
 	} else {
-		len = grapheme_decode(text, &cp0);
-		if (!len) {
-			errno = EINVAL;
-			return -1;
-		}
+		len = grapheme_cp_decode(&cp0, (const void *)text, text_length);
 	}
 
 	if (libskrift_get_grapheme_glyph(ctx, cp0, x, y, &glyph0))
 		return -1;
 
 	x += glyph0->advance;
-	for (; cp0; cp0 = cp1, len += r) {
-		r = grapheme_decode(&text[len], &cp1);
-		if (!r) {
-			if (saved) {
-				saved->cp = 0;
-				saved->len = 0;
-			}
-			break;
-		}
+	for (; len < text_length; cp0 = cp1, len += r) {
+		r = grapheme_cp_decode(&cp1, (const void *)&text[len], text_length - len);
 		if (grapheme_boundary(cp0, cp1, &state)) {
 			if (saved) {
+				saved->have_saved = 1;
 				saved->cp = cp1;
 				saved->len = r;
 			}
-			break;
+			goto out;
 		}
 
 		if (libskrift_get_grapheme_glyph(ctx, cp1, x, y, &glyph1)) {
@@ -62,7 +57,13 @@ libskrift_get_cluster_glyph(LIBSKRIFT_CONTEXT *ctx, const char *text, struct lib
 		free(glyph1);
 		glyph0 = glyph2;
 	}
+	if (saved) {
+		saved->have_saved = 0;
+		saved->cp = 0;
+		saved->len = 0;
+	}
 
+out:
 	*glyphp = glyph0;
 
 	return (ssize_t)len;