[[ Bug 19094 ]] Ensure single codepoint grapheme clusters are checked

livecodeali · livecodeali · commit f3fe91a23f7c · 2018-06-01T11:19:34.000+01:00
Previously single-codepoint grapheme clusters were not checked for
font support, so they were skipping the fallback mechanism and just
displaying a missing character.
diff --git a/docs/notes/bugfix-19094.md b/docs/notes/bugfix-19094.md
@@ -1 +1 @@
-# Certain unicode characters render incorrectly on Android 7
+# Ensure single-codepoint grapheme clusters are checked for font support
diff --git a/libgraphics/src/harfbuzztext.cpp b/libgraphics/src/harfbuzztext.cpp
@@ -241,7 +241,7 @@ static bool cluster_is_supported(hb_glyph_info_t* p_info, uindex_t p_index, uind
 {
     bool t_supported = true;
     uindex_t t_cluster = p_info[p_index] . cluster;
-    while (++p_index < p_count &&
+    while (p_index < p_count &&
            p_info[p_index] . cluster == t_cluster)
     {
         if (p_info[p_index] . codepoint == 0)
@@ -250,6 +250,7 @@ static bool cluster_is_supported(hb_glyph_info_t* p_info, uindex_t p_index, uind
             // whole cluster is unsupported
             t_supported = false;
         }
+        p_index++;
     }
     
     r_cluster_end = p_index;

Original file line number	Diff line number	Diff line change
`@@ -1 +1 @@`
`1`		`-# Certain unicode characters render incorrectly on Android 7`
	`1`	`+# Ensure single-codepoint grapheme clusters are checked for font support`
Original file line number	Diff line number	Diff line change
`@@ -241,7 +241,7 @@ static bool cluster_is_supported(hb_glyph_info_t* p_info, uindex_t p_index, uind`
`241`	`241`	`{`
`242`	`242`	`bool t_supported = true;`
`243`	`243`	`uindex_t t_cluster = p_info[p_index] . cluster;`
`244`		`- while (++p_index < p_count &&`
	`244`	`+ while (p_index < p_count &&`
`245`	`245`	`p_info[p_index] . cluster == t_cluster)`
`246`	`246`	`{`
`247`	`247`	`if (p_info[p_index] . codepoint == 0)`
`@@ -250,6 +250,7 @@ static bool cluster_is_supported(hb_glyph_info_t* p_info, uindex_t p_index, uind`
`250`	`250`	`// whole cluster is unsupported`
`251`	`251`	`t_supported = false;`
`252`	`252`	`}`
	`253`	`+ p_index++;`
`253`	`254`	`}`
`254`	`255`
`255`	`256`	`r_cluster_end = p_index;`