This is a work-around for a feature missing in Harfbuzz that
can make a text run that contains a surrogate and a ligature
crash. This will potentially cause the ligatures to break up
if you combine them with a surrogate, causing visual changes
to the text, but the scripts that require GSUB should not be
affected by this, since they will not use surrogates. Still,
it's not a permanent fix, but will serve as a bandaid for the
crash until the underlying problem has been fixed.
Task-number: QTBUG-22275
Change-Id: I90c37fba76bc7d1f369f3afddd1bd0dc306f5750
Reviewed-by: Jiang Jiang <jiang.jiang@nokia.com>
return true;
}
+static HB_Bool containsSurrogates(HB_ShaperItem *item)
+{
+ for (hb_uint32 i=0; i<item->stringLength; ++i) {
+ HB_UChar16 ucs = item->string[i];
+ if ( HB_IsHighSurrogate(ucs) || HB_IsLowSurrogate(ucs) )
+ return true;
+ }
+
+ return false;
+}
+
HB_Bool HB_OpenTypeShape(HB_ShaperItem *item, const hb_uint32 *properties)
{
HB_GlyphAttributes *tmpAttributes;
#endif
face->glyphs_substituted = false;
- if (face->gsub) {
+ if (face->gsub && !containsSurrogates(item)) {
unsigned int error = HB_GSUB_Apply_String(face->gsub, face->buffer);
if (error && error != HB_Err_Not_Covered)
return false;