ref: 6f09011fe61638392cdc982af97447e579a7a69d
parent: e93d326c8ba52ae12589844bad5badeace4c7943
author: Werner Lemberg <[email protected]>
date: Sat Oct 24 06:10:22 EDT 2015
[sfnt] Sanitize bitmap strike glyph height. Problem reported by Nikolay Sivov <[email protected]>. * src/sfnt/ttsbit.c (tt_face_load_strike_metrics): Avoid zero value for `metrics->height' by applying some heuristics.
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2015-10-24 Werner Lemberg <[email protected]>
+
+ [sfnt] Sanitize bitmap strike glyph height.
+
+ Problem reported by Nikolay Sivov <[email protected]>.
+
+ * src/sfnt/ttsbit.c (tt_face_load_strike_metrics): Avoid zero value
+ for `metrics->height' by applying some heuristics.
+
2015-10-22 Werner Lemberg <[email protected]>
[sfnt, type42] Fix clang compiler warnings.
--- a/src/sfnt/ttsbit.c
+++ b/src/sfnt/ttsbit.c
@@ -247,6 +247,8 @@
case TT_SBIT_TABLE_TYPE_CBLC:
{FT_Byte* strike;
+ FT_Char max_before_bl;
+ FT_Char min_after_bl;
strike = face->sbit_table + 8 + strike_index * 48;
@@ -256,7 +258,63 @@
metrics->ascender = (FT_Char)strike[16] * 64; /* hori.ascender */
metrics->descender = (FT_Char)strike[17] * 64; /* hori.descender */
- metrics->height = metrics->ascender - metrics->descender;
+
+ /* Due to fuzzy wording in the EBLC documentation, we find both */
+ /* positive and negative values for `descender'. Additionally, */
+ /* many fonts have both `ascender' and `descender' set to zero */
+ /* (which is definitely wrong). MS Windows simply ignores all */
+ /* those values... For these reasons we apply some heuristics */
+ /* to get a reasonable, non-zero value for the height. */
+
+ max_before_bl = (FT_Char)strike[24];
+ min_after_bl = (FT_Char)strike[25];
+
+ if ( metrics->descender > 0 )
+ {+ /* compare sign of descender with `min_after_bl' */
+ if ( min_after_bl < 0 )
+ metrics->descender = -metrics->descender;
+ }
+
+ else if ( metrics->descender == 0 )
+ {+ if ( metrics->ascender == 0 )
+ {+ FT_TRACE2(( "tt_face_load_strike_metrics:"
+ " sanitizing invalid ascender and descender\n"
+ " "
+ " values for strike (%d, %d)\n",
+ metrics->x_ppem, metrics->y_ppem ));
+
+ /* sanitize buggy ascender and descender values */
+ if ( max_before_bl || min_after_bl )
+ {+ metrics->ascender = max_before_bl;
+ metrics->descender = min_after_bl;
+ }
+ else
+ {+ metrics->ascender = metrics->y_ppem;
+ metrics->descender = 0;
+ }
+ }
+ }
+
+#if 0
+ else
+ ; /* if we have a negative descender, simply use it */
+#endif
+
+ metrics->height = metrics->ascender - metrics->descender;
+ if ( metrics->height == 0 )
+ {+ FT_TRACE2(( "tt_face_load_strike_metrics:"
+ " sanitizing invalid height value\n"
+ " "
+ " for strike (%d, %d)\n",
+ metrics->x_ppem, metrics->y_ppem ));
+ metrics->height = metrics->y_ppem;
+ }
/* Is this correct? */
metrics->max_advance = ( (FT_Char)strike[22] + /* min_origin_SB */