Commit 6f09011fe61638392cdc982af97447e579a7a69d
2015-10-24T10:10:22
[sfnt] Sanitize bitmap strike glyph height. Problem reported by Nikolay Sivov <bunglehead@gmail.com>. * src/sfnt/ttsbit.c (tt_face_load_strike_metrics): Avoid zero value for `metrics->height' by applying some heuristics.
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diff --git a/ChangeLog b/ChangeLog
index 228211b..81c2332 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2015-10-24 Werner Lemberg <wl@gnu.org>
+
+ [sfnt] Sanitize bitmap strike glyph height.
+
+ Problem reported by Nikolay Sivov <bunglehead@gmail.com>.
+
+ * src/sfnt/ttsbit.c (tt_face_load_strike_metrics): Avoid zero value
+ for `metrics->height' by applying some heuristics.
+
2015-10-22 Werner Lemberg <wl@gnu.org>
[sfnt, type42] Fix clang compiler warnings.
diff --git a/src/sfnt/ttsbit.c b/src/sfnt/ttsbit.c
index 8235255..4272d93 100644
--- 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 */