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authorMatthias Clasen <mclasen@redhat.com>2021-08-27 10:29:13 -0400
committerMatthias Clasen <mclasen@redhat.com>2021-08-27 12:18:26 -0400
commitc9f3cc464c4f06cc31c2b42e5c305a7fd7ae5879 (patch)
tree231ae9d2302a22dae157d49acfe98a6ebe7bdb6a /pango/glyphstring.c
parent0fe6d50dea9ae15086d292cc8af9770606f68b21 (diff)
downloadpango-c9f3cc464c4f06cc31c2b42e5c305a7fd7ae5879.tar.gz
Try harder to find positions in clusters
Try to find a single non-mark glyph in a multi-glyph cluster to use its ligature caret information. This fixes situations in Arabic where you can have marks on top of ligatures, e.g. ﻉﻭ.
Diffstat (limited to 'pango/glyphstring.c')
-rw-r--r--pango/glyphstring.c35
1 files changed, 32 insertions, 3 deletions
diff --git a/pango/glyphstring.c b/pango/glyphstring.c
index cda4cf40..30d68220 100644
--- a/pango/glyphstring.c
+++ b/pango/glyphstring.c
@@ -520,17 +520,46 @@ pango_glyph_string_index_to_x (PangoGlyphString *glyphs,
* with an m-n situation, where LigatureCaretList is
* not going to help. Just give up and do the simple thing.
*/
- if (cluster_offset > 0 && cluster_offset < cluster_chars &&
- start_glyph_pos == end_glyph_pos)
+ if (cluster_offset > 0 && cluster_offset < cluster_chars)
{
hb_font_t *hb_font;
hb_position_t caret;
unsigned int caret_count = 1;
+ int glyph_pos;
hb_font = pango_font_get_hb_font (analysis->font);
+
+ if (start_glyph_pos == end_glyph_pos)
+ glyph_pos = start_glyph_pos;
+ else
+ {
+ hb_face_t *hb_face;
+
+ hb_face = hb_font_get_face (hb_font);
+
+ glyph_pos = -1;
+ for (i = start_glyph_pos; i <= end_glyph_pos; i++)
+ {
+ if (hb_ot_layout_get_glyph_class (hb_face, glyphs->glyphs[i].glyph) != HB_OT_LAYOUT_GLYPH_CLASS_MARK)
+ {
+ if (glyph_pos != -1)
+ {
+ /* multiple non-mark glyphs in cluster, giving up */
+ goto fallback;
+ }
+ glyph_pos = i;
+ }
+ }
+ if (glyph_pos == -1)
+ {
+ /* no non-mark glyph in a multi-glyph cluster, giving up */
+ goto fallback;
+ }
+ }
+
hb_ot_layout_get_ligature_carets (hb_font,
(analysis->level % 2) ? HB_DIRECTION_RTL : HB_DIRECTION_LTR,
- glyphs->glyphs[start_glyph_pos].glyph,
+ glyphs->glyphs[glyph_pos].glyph,
cluster_offset - 1, &caret_count, &caret);
if (caret_count > 0)
{