The adaptation of the cjk auto-hinter module to blue stringsets in
2013-08-25 had three severe bugs. Mea culpa.
1. Contrary to the latin auto-hinter, characters for reference and
overshoot values of a blue zone are specified separately. Due to
the screwed-up change it didn't work at all.
2. A boolean comparison was erroneously replaced with a cast,
causing invalid results with the `^' operator later on. The
visual artifact caused by this problem is the topic of the bug
report.
3. Two flag values were inverted, causing incorrect assignment of
reference and overshoot values.
* src/autofit/afblue.dat: Fix CJK bluestrings, introducing a new
syntax to have both reference and overshoot characters in a single
string. This is error #1.
Add extensive comments.
* src/autofit/afblue.hin (AF_BLUE_PROPERTY_CJK_FILL): Removed, no
longer used.
(AF_BLUE_PROPERTY_CJK_TOP, AF_BLUE_PROPERTY_CJK_HORIZ): Fix values.
This is error #3.
* src/autofit/afblue.c, src/autofit/afblue.h: Regenerated.
* src/autofit/afcjk.c (af_cjk_metrics_init_blues): Correct error #1.
Use character `|' to separate characters for reference and overshoot
values.
Improve tracing messages, synchronizing them with the latin
auto-hinter.
(af_cjk_hints_compute_blue_edges): Fix value of `is_top_right_blue'.
This is error #2.
(af_cjk_align_linked_edge): Add tracing message.
* src/autofit/afcjk.h (AF_CJK_IS_FILLED_BLUE): Removed, no longer
used.
* src/autofit/hbshim.c (af_get_coverage): Merge input glyph coverage
of GSUB lookups into output coverage. Otherwise, ligatures are not
handled properly.
Don't check blue zone characters for default coverage.
In particular, local extrema without horizontal or vertical segments
are better recognized:
+ A + D
\ /
\ /
\ /
\ /
\ + C
\ /
B +/
If the distances AB and CD are large, point B wasn't previously
detected as an extremum since the `ft_corner_is_flat' function
`swallowed' BC regardless of its direction, tagging point B as weak.
The next iteration started at B and made `ft_corner_is_flat' swallow
point C, tagging it as weak also, et voilà.
To improve that, another pass gets now performed before calling
`ft_corner_is_flat' to improve the `topology' of an outline: A
sequence of non-horizontal or non-vertical vectors that point into
the same quadrant are handled as a single, large vector.
Additionally, distances of near points are now accumulated, which
makes the auto-hinter handle them as if they were prepended to the
next non-near vector.
This generally improves the auto-hinter's rendering results.
* src/autofit/afhints.c (af_glyph_hints_reload): Implement it.
* src/autofit/afhints.h (AF_FLAGS): Remove no longer used flag
`AF_FLAG_NEAR'.
Problem reported by Karsten Lücke <karsten.luecke@kltf.de>.
The new algorithm takes care of the width of stems: If the distance
between two segments is larger than the largest stem width, the
demerits quickly increase for larger distances. This improves
hinting of slanted fonts (especially if the inner parts of serifs
have non-horizontal `shoulders'), avoiding false stem links.
* src/autofit/aflatin.c (af_latin_hints_link_segments): Use largest
stem width (if available) to compute better demerits for distances
between stems.
(af_latin_hints_detect_features): Pass stem width array and array
size.
(af_latin_metrics_init_widths): Updated to use original algorithm.
(af_latin_hints_apply): Updated to use new algorithm.
* src/autofit/aflatin.h: Updated.
* src/autofit/afcjk.c: Updated.
This works around a problem with HarfBuzz (<= 0.9.26), which doesn't
validate glyph indices returned by
`hb_ot_layout_lookup_collect_glyphs'.
* src/autofit/hbshim.c (af_get_coverage): Guard `idx'.
* docs/CHANGES: Updated.
* src/cff/cf2ft.c (cf2_initLocalRegionBuffer,
cf2_initGlobalRegionBuffer): It is possible for a charstring to call
a subroutine if no subroutines exist. This is an error but should
not trigger an assert. Split the assert to account for this.
* src/cff/cf2hints.c (cf2_hintmap_build): Return when `hintMask' is
invalid. In this case, it is not safe to use the length of
`hStemHintArray'; the exception has already been recorded in
`hintMask'.
bdflib puts data from the input stream into a buffer in chunks of
1024 bytes. The data itself gets then parsed line by line, simply
increasing the current pointer into the buffer; if the search for
the final newline character exceeds the buffer size, more data gets
read.
However, in case the current line's end is very near to the buffer
end, and the keyword to compare with is longer than the current
line's length, an out-of-bounds read might happen since `memcmp'
doesn't stop properly at the string end.
* src/bdf/bdflib.c: s/ft_memcmp/ft_strncmp/ to make comparisons
stop at string ends.
* src/autofit/afcjk.c (af_cjk_metrics_init_widths),
src/autofit/aflatin.c (af_latin_metrics_init_widths): Fix handling
of alternative standard characters.
This also fixes a compilation warning in non-debug mode.
* src/cff/cf2ft.c (cf2_checkTransform): Convert assertion into
parameter check.
(cf2_decoder_parse_charstrings): Call `cf2_checkTransform' only if
we are scaling the outline.
(cf2_getPpemY): Remove problematic assertion.
This is useful for OpenType features like `c2sc' (caps to small
caps) that don't have lowercase letters by definition, or other
features that mainly operate on numerals.
* src/autofit/afscript.h: Add more standard characters.
* src/autofit/aftypes.h: Update use of `SCRIPT' macro.
(AF_ScriptClassRec): Add members to hold two more standard
characters.
(AF_DEFINE_SCRIPT_CLASS): Updated.
* src/autofit/afglobal.c, src/autofit/afglobal.h,
* src/autofit/afpic.c, src/autofit/afranges.h, src/autofit/hbshim.c:
Update use of `SCRIPT' macro.
* src/autofit/afcjk.c (af_cjk_metrics_init_widths),
src/autofit/aflatin.c (af_latin_metrics_init_widths): Scan two more
standard characters.
* src/sfnt/ttsbit.c (tt_sbit_decoder_load_bitmap) <glyph_format==5>:
Don't check metrics, which this format doesn't have.
This is another correction to the commit from 2013-11-21.
* src/type1/t1load.c (t1_parse_font_matrix): Properly handle result
of `T1_ToFixedArray'.
* src/cid/cidload.c (cid_parse_font_matrix): Synchronize with
`t1_parse_font_matrix'.
* src/type42/t42parse.c (t42_parse_font_matrix): Synchronize with
`t1_parse_font_matrix'.
(t42_parse_encoding): Synchronize with `t1_parse_encoding'.
* src/psaux/psobjs.c (ps_parser_load_field) <T1_FIELD_TYPE_BBOX>,
<T1_FIELD_TYPE_MMOX>: Properly handle result of `ps_tofixedarray'.
Split the single, incorrect Indic entry into separate scripts so
that the covered ranges are the same: Bengali, Devanagari, Gujarati,
Gurmukhi, Kannada, Limbu, Malayalam, Oriya, Sinhala, Sundanese,
Syloti Nagri, Tamil, Telugu, and Tibetan. At the same time, remove
entries for Meetai Mayak and Sharada – the Unicode ranges were
incorrect (and nobody has complained about that), fonts are scarce
for those scripts, and the Indic auto-hinter support is rudimentary
anyways.
* src/autofit/afscript.h: Updated, using AF_CONFIG_OPTION_INDIC and
AF_CONFIG_OPTION_CJK.
* src/autofit/afstyles.h (STYLE_DEFAULT_INDIC): New auxiliary macro.
Use it, together with AF_CONFIG_OPTION_INDIC and
AF_CONFIG_OPTION_CJK, to update.
* src/autofit/afranges.c [AF_CONFIG_OPTION_INDIC]: Updated.
[!AF_CONFIG_OPTION_INDIC, !AF_CONFIG_OPTION_CJK]: Removed.
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Werner Lemberg