Merge pull request #41100 from bruvzg/ctl_text_server_interface

[Complex Text Layouts] Implement TextServer interface.

1 files changed, 2412 insertions, 0 deletions

diff --git a/thirdparty/harfbuzz/NEWS b/thirdparty/harfbuzz/NEWS
new file mode 100644
index 0000000000..f211a3781c
--- /dev/null
+++ b/thirdparty/harfbuzz/NEWS
@@ -0,0 +1,2412 @@
+Overview of changes leading to 2.7.2
+Saturday, August 29, 2020
+====================================
+- Fix a regression in the previous release that caused a crash with Kaithi.
+- More OOM fixes.
+
+
+Overview of changes leading to 2.7.1
+Thursday, August 13, 2020
+====================================
+- ot-funcs now handles variable empty glyphs better when hvar/vvar isn't present.
+- Reverted a GDEF processing regression.
+- A couple of fixes to handle OOM better.
+
+
+Overview of changes leading to 2.7.0
+Saturday, July 25, 2020
+====================================
+- Use an implementation for round that always rounds up, some minor fluctuations
+  are expected on var font specially when hb-ot callback is used.
+- Fix an AAT's `kerx` issue on broken rendering of Devanagari Sangam MN.
+- Remove AAT's `lcar` table support from _get_ligature_carets API, not even much
+  use on macOS installed fonts (only two files).  GDEF support is the recommended
+  one and expected to work properly after issues fixed two releases ago.
+- Minor memory fixes to handle OOM better specially in hb-ft.
+- Minor .so files versioning scheme change and remove stable/unstable scheme
+  differences, was never used in practice (always default to stable scheme).
+- We are now suggesting careful packaging of the library using meson,
+  https://github.com/harfbuzz/harfbuzz/wiki/Notes-on-migration-to-meson
+  for more information.
+- Distribution package URL is changed, either use GitHub generated tarballs,
+  `https://github.com/harfbuzz/harfbuzz/archive/$pkgver.tar.gz`
+  or, even more preferably use commit hash of the release and git checkouts like,
+  `git+https://github.com/harfbuzz/harfbuzz#commit=$commit`
+
+
+Overview of changes leading to 2.6.8
+Monday, June 22, 2020
+====================================
+- New API to fetch glyph alternates from GSUB table.
+- hb-coretext build fix for macOS < 10.10.
+- Meson build fixes, cmake port removal is postponed but please prepare for
+  it and give us feedback.
+  Autotools is still our main build system however please consider
+  experimenting with meson also for packaging the library.
+- New API:
++hb_ot_layout_lookup_get_glyph_alternates()
+
+
+Overview of changes leading to 2.6.7
+Wednesday, June 3, 2020
+====================================
+- Update to Unicode 13.0.0.
+- Fix hb_ot_layout_get_ligature_carets for fonts without lcar table, it was
+  completely broken for all the other fonts since 2.1.2.
+- As a part of our migration to meson, this release will be the last one
+  to provide cmake port files but autotools still is our main build system.
+  There is a possibility that the next version or the after be released
+  using meson.
+
+
+Overview of changes leading to 2.6.6
+Tuesday, May 12, 2020
+====================================
+- A fix in AAT kerning for Geeza Pro.
+- Better support for resource fork fonts on macOS.
+
+
+Overview of changes leading to 2.6.5
+Friday, April 17, 2020
+====================================
+- Add experimental meson build system.  Autotools is still the primary
+  and supported build system.
+- AAT is now always preferred for horizontal scripts when both AAT and OT
+  layout tables exist at the same time.
+- Subsetter improvements.
+- New API:
++hb_ft_font_lock_face()
++hb_ft_font_unlock_face()
+
+
+Overview of changes leading to 2.6.4
+Monday, October 29, 2019
+====================================
+- Small bug fix.
+- Build fixes.
+
+
+Overview of changes leading to 2.6.3
+Monday, October 28, 2019
+====================================
+- Misc small fixes, mostly to build-related issues.
+- New API:
++hb_font_get_nominal_glyphs()
+
+
+Overview of changes leading to 2.6.2
+Monday, September 30, 2019
+====================================
+- Misc small fixes, mostly to build-related issues.
+
+
+Overview of changes leading to 2.6.1
+Thursday, August 22, 2019
+====================================
+- Fix regression with hb_font_create_sub_font scaling introduced in 2.6.0.
+- Change interpretation of font PTEM size / CoreText font size handling.
+  See https://github.com/harfbuzz/harfbuzz/pull/1484
+- hb-ot-font: Prefer symbol cmap subtable if present.
+- Apply 'dist'/'abvm'/'blwm' features to all scripts.
+- Drop experimental DirectWrite API.
+
+
+Overview of changes leading to 2.6.0
+Tuesday, August 13, 2019
+====================================
+- New OpenType metrics, baseline, and metadata table access APIs.
+- New API to set font variations to a named-instance.
+- New hb-gdi.h header and API for creating hb_face_t from HFONT.
+- Amalgam: Provide a single-file harfbuzz.cc file for easier alternate building.
+- More size-reduction configurable options, enabled by HB_TINY.
+- New API:
++hb_font_set_var_named_instance()
++hb_gdi_face_create()
++hb_ot_layout_baseline_tag_t
++hb_ot_layout_get_baseline()
++hb_ot_meta_tag_t
++hb_ot_meta_get_entry_tags()
++hb_ot_meta_reference_entry()
++hb_ot_metrics_tag_t
++hb_ot_metrics_get_position()
++hb_ot_metrics_get_variation()
++hb_ot_metrics_get_x_variation()
++hb_ot_metrics_get_y_variation()
+
+
+Overview of changes leading to 2.5.3
+Wednesday, June 26, 2019
+====================================
+- Fix UCD script data for Unicode 10+ scripts.  This was broken since 2.5.0.
+- More optimizations for HB_TINY.
+
+
+Overview of changes leading to 2.5.2
+Thursday, June 20, 2019
+====================================
+- More hb-config.hh facilities to shrink library size, namely when built as
+  HB_TINY.
+- New documentation of custom configurations in CONFIG.md.
+- Fix build on gcc 4.8.  That's supported again.
+- Universal Shaping Engine improvements thanks to David Corbett.
+- API Changes: Undeprecate some horizontal-kerning API and re-enable in hb-ft,
+  such that Type1 fonts will continue kerning.
+
+
+Overview of changes leading to 2.5.1
+Friday, May 31, 2019
+====================================
+- Fix build with various versions of Visual Studio.
+- Improved documentation, thanks to Nathan Willis.
+- Bugfix in subsetting glyf table.
+- Improved scripts for cross-compiling for Windows using mingw.
+- Rename HB_MATH_GLYPH_PART_FLAG_EXTENDER to HB_OT_MATH_GLYPH_PART_FLAG_EXTENDER.
+  A deprecated macro is added for backwards-compatibility.
+
+
+Overview of changes leading to 2.5.0
+Friday, May 24, 2019
+====================================
+- This release does not include much functional changes, but includes major internal
+  code-base changes.  We now require C++11.  Support for gcc 4.8 and earlier has been
+  dropped.
+- New hb-config.hh facility for compiling smaller library for embedded and web usecases.
+- New Unicode Character Databse implementation that is half the size of previously-used
+  UCDN.
+- Subsetter improvements.
+- Improved documentation, thanks to Nathan Willis.
+- Misc shaping fixes.
+
+
+Overview of changes leading to 2.4.0
+Monday, March 25, 2019
+====================================
+- Unicode 12.
+- Misc fixes.
+- Subsetter improvements.
+- New API:
+HB_BUFFER_FLAG_DO_NOT_INSERT_DOTTED_CIRCLE
+hb_directwrite_face_create()
+
+
+Overview of changes leading to 2.3.1
+Wednesday, January 30, 2019
+====================================
+- AAT bug fixes.
+- Misc internal housekeeping cleanup.
+
+
+Overview of changes leading to 2.3.0
+Thursday, December 20, 2018
+====================================
+- Fix regression on big-endian architectures.  Ouch!
+- Misc bug and build fixes.
+- Fix subsetting of simple GSUB/GDEF.
+- Merge CFF / CFF2 support contributed by Adobe.  This mostly involves
+  the subsetter, but also get_glyph_extents on CFF fonts.
+
+New API in hb-aat.h:
++hb_aat_layout_has_substitution()
++hb_aat_layout_has_positioning()
++hb_aat_layout_has_tracking()
+
+
+Overview of changes leading to 2.2.0
+Thursday, November 29, 2018
+====================================
+- Misc shaping bug fixes.
+- Add font variations named-instance API.
+- Deprecate font variations axis enumeration API and add replacement.
+- AAT shaping improvements:
+  o Fixed 'kern' table Format 2 implementation.
+  o Implement 'feat' table API for feature detection.
+  o Blacklist 'GSUB' table of fonts from 'MUTF' foundry that also have 'morx'.
+
+New API:
++hb_aat_layout_feature_type_t
++hb_aat_layout_feature_selector_t
++hb_aat_layout_get_feature_types()
++hb_aat_layout_feature_type_get_name_id
++hb_aat_layout_feature_selector_info_t
++HB_AAT_LAYOUT_NO_SELECTOR_INDEX
++hb_aat_layout_feature_type_get_selector_infos()
++hb_ot_var_axis_flags_t
++hb_ot_var_axis_info_t
++hb_ot_var_get_axis_infos()
++hb_ot_var_find_axis_info()
++hb_ot_var_get_named_instance_count()
++hb_ot_var_named_instance_get_subfamily_name_id()
++hb_ot_var_named_instance_get_postscript_name_id()
++hb_ot_var_named_instance_get_design_coords()
+
+Deprecated API:
++HB_OT_VAR_NO_AXIS_INDEX
++hb_ot_var_axis_t
++hb_ot_var_get_axes()
++hb_ot_var_find_axis()
+
+
+Overview of changes leading to 2.1.3
+Friday, November 16, 2018
+====================================
+- Fix AAT 'mort' shaping, which was broken in 2.1.2
+
+
+Overview of changes leading to 2.1.2
+Friday, November 16, 2018
+====================================
+- Various internal changes.
+- AAT shaping improvements:
+  o Implement kern table Format 1 state-machine-based kerning.
+  o Implement cross-stream kerning (cursive positioning, etc).
+  o Ignore emptyish GSUB tables (zero scripts) if morx present.
+  o Don't apply GPOS if morx is being applied.  Matches Apple.
+
+
+-Overview of changes leading to 2.1.1
+Monday, November 5, 2018
+====================================
+- AAT improvements:
+  o Implement 'mort' table.
+  o Implement 'kern' subtables Format 1 and Format 3.
+
+
+Overview of changes leading to 2.1.0
+Tuesday, October 30, 2018
+====================================
+- AAT shaping improvements:
+  o Allow user controlling AAT features, for whole buffer only currently.
+  o Several 'morx' fixes.
+  o Implement tuple-kerns in 'kerx'; Fixes kerning with Apple default
+    San Francisco fonts.
+- Support for color fonts:
+  o COLR/CPAL API to fetch color layers.
+  o SVG table to fetch SVG documents.
+  o CBDT/sbix API to fetch PNG images.
+- New 'name' table API.
+- hb-ot-font now uses 'VORG' table to correctly position CFF glyphs
+  in vertical layout.
+- Various fuzzer-found bug fixes.
+
+Changed API:
+
+A type and a macro added in 2.0.0 were renamed:
+
+hb_name_id_t -> hb_ot_name_id_t
+HB_NAME_ID_INVALID -> HB_OT_NAME_ID_INVALID
+
+New API:
+
++hb_color_t
++HB_COLOR
++hb_color_get_alpha()
++hb_color_get_red()
++hb_color_get_green()
++hb_color_get_blue()
++hb_ot_color_has_palettes()
++hb_ot_color_palette_get_count()
++hb_ot_color_palette_get_name_id()
++hb_ot_color_palette_color_get_name_id()
++hb_ot_color_palette_flags_t
++hb_ot_color_palette_get_flags()
++hb_ot_color_palette_get_colors()
++hb_ot_color_has_layers()
++hb_ot_color_layer_t
++hb_ot_color_glyph_get_layers()
++hb_ot_color_has_svg()
++hb_ot_color_glyph_reference_svg()
++hb_ot_color_has_png()
++hb_ot_color_glyph_reference_png()
+
++hb_ot_name_id_t
++HB_OT_NAME_ID_INVALID
++HB_OT_NAME_ID_COPYRIGHT
++HB_OT_NAME_ID_FONT_FAMILY
++HB_OT_NAME_ID_FONT_SUBFAMILY
++HB_OT_NAME_ID_UNIQUE_ID
++HB_OT_NAME_ID_FULL_NAME
++HB_OT_NAME_ID_VERSION_STRING
++HB_OT_NAME_ID_POSTSCRIPT_NAME
++HB_OT_NAME_ID_TRADEMARK
++HB_OT_NAME_ID_MANUFACTURER
++HB_OT_NAME_ID_DESIGNER
++HB_OT_NAME_ID_DESCRIPTION
++HB_OT_NAME_ID_VENDOR_URL
++HB_OT_NAME_ID_DESIGNER_URL
++HB_OT_NAME_ID_LICENSE
++HB_OT_NAME_ID_LICENSE_URL
++HB_OT_NAME_ID_TYPOGRAPHIC_FAMILY
++HB_OT_NAME_ID_TYPOGRAPHIC_SUBFAMILY
++HB_OT_NAME_ID_MAC_FULL_NAME
++HB_OT_NAME_ID_SAMPLE_TEXT
++HB_OT_NAME_ID_CID_FINDFONT_NAME
++HB_OT_NAME_ID_WWS_FAMILY
++HB_OT_NAME_ID_WWS_SUBFAMILY
++HB_OT_NAME_ID_LIGHT_BACKGROUND
++HB_OT_NAME_ID_DARK_BACKGROUND
++HB_OT_NAME_ID_VARIATIONS_PS_PREFIX
++hb_ot_name_entry_t
++hb_ot_name_list_names()
++hb_ot_name_get_utf8()
++hb_ot_name_get_utf16()
++hb_ot_name_get_utf32()
+
+
+Overview of changes leading to 2.0.2
+Saturday, October 20, 2018
+====================================
+- Fix two minor memory access issues in AAT tables.
+
+
+Overview of changes leading to 2.0.1
+Friday, October 19, 2018
+====================================
+- Fix hb-version.h reported release version that went wrong (1.8.0)
+  with previous release.
+- Fix extrapolation in 'trak' table.
+- Fix hb-font infinite-recursion issue with some font funcs and
+  subclassed fonts.
+- Implement variation-kerning format in kerx table, although without
+  variation.
+- Fix return value of hb_map_is_empty().
+
+
+Overview of changes leading to 2.0.0
+Thursday, October 18, 2018
+====================================
+- Added AAT shaping support (morx/kerx/trak).
+  Automatically used if GSUB/GPOS are not available respectively.
+  Set HB_OPTIONS=aat env var to have morx/kerx preferred over
+  GSUB/GPOS.
+- Apply TrueType kern table internally, instead of relying on
+  hb_font_t callbacks.
+- Khmer shaper significantly rewritten to better match Uniscribe.
+- Indic3 tags ('dev3', etc) are passed to USE shaper.
+- .dfont Mac font containers implemented.
+- Script- and language-mapping revamped to better use BCP 47.
+- Misc USE and Indic fixes.
+- Misc everything fixes.
+- Too many things to list.  Biggest release since 0.9.1, with
+  over 500 commits in just over 5 weeks!  Didn't intend it to
+  be a big release.  Just happened to become.
+- hb-ft now locks underlying FT_Face during use.
+
+API changes:
+
+- Newly-created hb_font_t's now have our internal "hb-ot-font"
+  callbacks set on them, so they should work out of the box
+  without any callbacks set.  If callbacks are set, everything
+  is back to what it was before, the fallback callbacks are
+  null.  If you to get the internal implementation modified,
+  sub_font it.
+
+- New hb_font_funcs_set_nominal_glyphs_func() allows speeding
+  up character to glyph mapping.
+
+New API:
++HB_FEATURE_GLOBAL_START
++HB_FEATURE_GLOBAL_END
++hb_buffer_set_invisible_glyph()
++hb_buffer_get_invisible_glyph()
++hb_font_funcs_set_nominal_glyphs_func()
++hb_ot_layout_table_select_script()
++hb_ot_layout_script_select_language()
++hb_ot_layout_feature_get_name_ids()
++hb_ot_layout_feature_get_characters()
++hb_name_id_t
++HB_NAME_ID_INVALID
++HB_OT_MAX_TAGS_PER_SCRIPT
++hb_ot_tags_from_script_and_language()
++hb_ot_tags_to_script_and_language()
+
+Deprecated API:
+-hb_font_funcs_set_glyph_func()
+-hb_unicode_eastasian_width_func_t
+-hb_unicode_funcs_set_eastasian_width_func()
+-hb_unicode_eastasian_width()
+-hb_unicode_decompose_compatibility_func_t
+-HB_UNICODE_MAX_DECOMPOSITION_LEN
+-hb_unicode_funcs_set_decompose_compatibility_func()
+-hb_unicode_decompose_compatibility()
+-hb_font_funcs_set_glyph_h_kerning_func()
+-hb_font_funcs_set_glyph_v_kerning_func()
+-hb_font_get_glyph_h_kerning()
+-hb_font_get_glyph_v_kerning()
+-hb_font_get_glyph_kerning_for_direction()
+-hb_ot_layout_table_choose_script()
+-hb_ot_layout_script_find_language()
+-hb_ot_tags_from_script()
+-hb_ot_tag_from_language()
+
+
+Overview of changes leading to 1.9.0
+Monday, September 10, 2018
+====================================
+- Added 'cmap' API to hb_face_t.
+- Face-builder API.
+- hb-ot-font re-creation should be much leaner now, as the
+  font tables it uses are cached on hb_face_t now.
+- Internal source header file name changes:
+  hb-*-private.hh is renamed to hb-*.hh.
+
+New API:
++HB_UNICODE_MAX
++hb_face_collect_unicodes()
++hb_face_collect_variation_selectors()
++hb_face_collect_variation_unicodes()
++hb_face_builder_create()
++hb_face_builder_add_table()
+
+
+Overview of changes leading to 1.8.8
+Tuesday, August 14, 2018
+====================================
+- Fix hb-icu crash on architectures where compare_exchange_weak() can
+  fail falsely.  This bug was introduced in 1.8.4.
+  https://bugs.chromium.org/p/chromium/issues/detail?id=873568
+- More internal refactoring of atomic operations and singletons.
+- API changes:
+  The following functions do NOT reference their return value before
+  returning:
+  * hb_unicode_funcs_get_default()
+  * hb_glib_get_unicode_funcs()
+  * hb_icu_get_unicode_funcs()
+  This is consistent with their naming ("get", instead of "reference")
+  as well as how they are used in the wild (ie. no one calls destroy()
+  on their return value.)
+
+
+Overview of changes leading to 1.8.7
+Wednesday, August 8, 2018
+====================================
+- Fix assertion failure with GDEF-blacklisted fonts.
+
+
+Overview of changes leading to 1.8.6
+Tuesday, August 7, 2018
+====================================
+- Internal code shuffling.
+- New API to speed up getting advance widths for implementations
+  that have heavy overhead in get_h_advance callback:
++hb_font_funcs_set_glyph_h_advances_func
++hb_font_funcs_set_glyph_v_advances_func
++hb_font_get_glyph_advances_for_direction
++hb_font_get_glyph_h_advances
++hb_font_get_glyph_h_advances_func_t
++hb_font_get_glyph_v_advances
++hb_font_get_glyph_v_advances_func_t
+
+
+Overview of changes leading to 1.8.5
+Wednesday, August 1, 2018
+====================================
+- Major Khmer shaper improvements to better match Microsoft.
+- Indic bug fixes.
+- Internal improvements to atomic operations.
+
+
+Overview of changes leading to 1.8.4
+Tuesday, July 17, 2018
+====================================
+- Fix build on non-C++11.
+- Use C++-style GCC atomics and C++11 atomics.
+
+
+Overview of changes leading to 1.8.3
+Wednesday, July 11, 2018
+====================================
+- A couple of Indic / USE bug fixes.
+- Disable vectorization, as it was causing unaligned access bus error on
+  certain 32bit architectures.
+
+
+Overview of changes leading to 1.8.2
+Tuesday, July 3, 2018
+====================================
+- Fix infinite loop in Khmer shaper.
+- Improve hb_blob_create_from_file() for streams.
+
+
+Overview of changes leading to 1.8.1
+Tuesday, June 12, 2018
+====================================
+- Fix hb-version.h file generation; last two releases went out with wrong ones.
+- Add correctness bug in hb_set_t operations, introduced in 1.7.7.
+- Remove HB_SUBSET_BUILTIN build option.  Not necessary.
+
+
+Overview of changes leading to 1.8.0
+Tuesday, June 5, 2018
+====================================
+- Update to Unicode 11.0.0.
+
+
+Overview of changes leading to 1.7.7
+Tuesday, June 5, 2018
+====================================
+- Lots of internal changes, but not yet exposed externally.
+- All HarfBuzz objects are significantly smaller in size now.
+- Sinhala: Position repha on top of post-consonant, not base.
+  This better matches Windows 10 behavior, which was changed
+  from previous Windows versions.
+- New build options:
+  o New cpp macro HB_NO_ATEXIT
+  o New cpp macro HB_SUBSET_BUILTIN
+- Significant libharfbuzz-subset changes. API subject to change.
+- New API in libharfbuzz:
+
++hb_blob_create_from_file()
++hb_face_count()
+
+A hashmap implementation:
++hb-map.h
++HB_MAP_VALUE_INVALID
++hb_map_t
++hb_map_create()
++hb_map_get_empty()
++hb_map_reference()
++hb_map_destroy()
++hb_map_set_user_data()
++hb_map_get_user_data()
++hb_map_allocation_successful()
++hb_map_clear()
++hb_map_is_empty()
++hb_map_get_population()
++hb_map_set()
++hb_map_get()
++hb_map_del()
++hb_map_has()
+
+
+Overview of changes leading to 1.7.6
+Wednesday, March 7, 2018
+====================================
+
+- Fix to hb_set_t binary operations. Ouch.
+- New experimental harfbuzz-subset library. All of hb-subset.h
+  is experimental right now and API WILL change.
+
+- New API:
+hb_blob_copy_writable_or_fail()
+HB_OT_TAG_BASE
+hb_set_previous()
+hb_set_previous_range()
+
+
+Overview of changes leading to 1.7.5
+Tuesday, January 30, 2018
+====================================
+
+- Separate Khmer shaper from Indic.
+- First stab at AAT morx. Not hooked up.
+- Misc bug fixes.
+
+
+Overview of changes leading to 1.7.4
+Wednesday, December 20, 2017
+====================================
+
+- Fix collect_glyphs() regression caused by hb_set_t changes.
+
+
+Overview of changes leading to 1.7.3
+Monday, December 18, 2017
+====================================
+
+- hb_set_t performance tuning and optimizations.
+- Speed up collect_glyphs() and reject garbage data.
+- In hb_coretext_font_create() set font point-size (ptem).
+- Misc fixes.
+
+
+Overview of changes leading to 1.7.2
+Monday, December 4, 2017
+====================================
+
+- Optimize hb_set_add_range().
+- Misc fixes.
+- New API:
+hb_coretext_font_create()
+
+
+Overview of changes leading to 1.7.1
+Tuesday, November 14, 2017
+====================================
+
+- Fix atexit object destruction regression.
+- Fix minor integer-overflow.
+
+
+Overview of changes leading to 1.7.0
+Monday, November 13, 2017
+====================================
+
+- Minor Indic fixes.
+- Implement kerning and glyph names in hb-ot-font.
+- Various DSO optimization re .data and .bss sizes.
+- Make C++11 optional; build fixes.
+- Mark all other backends "unsafe-to-break".
+- Graphite fix.
+
+
+Overview of changes leading to 1.6.3
+Thursday, October 26th, 2017
+====================================
+
+- Fix hb_set_t some more.  Should be solid now.
+- Implement get_glyph_name() for hb-ot-font.
+- Misc fixes.
+
+
+Overview of changes leading to 1.6.2
+Monday, October 23nd, 2017
+====================================
+
+- Yesterday's release had a bad crasher; don't use it.  That's what
+  happens when one works on Sunday...
+  https://github.com/harfbuzz/harfbuzz/issues/578
+- Build fixes for FreeBSD and Chrome Android.
+
+
+Overview of changes leading to 1.6.1
+Sunday, October 22nd, 2017
+====================================
+
+- Don't skip over COMBINING GRAPHEME JOINER when ligating, etc.
+  To be refined: https://github.com/harfbuzz/harfbuzz/issues/554
+- Faster hb_set_t implementation.
+- Don't use deprecated ICU API.
+- Fix undefined-behavior in Myanmar shaper, introduced in 1.6.0
+- Deprecated API:
+  hb_set_invert()
+
+
+Overview of changes leading to 1.6.0
+Friday, October the 13th, 2017
+====================================
+
+- Update to Unicode 10.
+
+- Various Indic and Universal Shaping Engine fixes as a result of
+  HarfBuzz Hackfest with Jonathan Kew at Web Engines Hackfest at
+  the Igalia offices in A Coruña, Spain.  Thanks Igalia for having
+  us!
+
+- Implement Unicode Arabic Mark Ordering Algorithm UTR#53.
+
+- Implement optical sizing / tracking in CoreText backend, using
+  new API hb_font_set_ptem().
+
+- Allow notifying hb_font_t that underlying FT_Face changed sizing,
+  using new API hb_ft_font_changed().
+
+- More Graphite backend RTL fixes.
+
+- Fix caching of variable font shaping plans.
+
+- hb-view / hb-shape now accept following new arguments:
+
+  o --unicodes: takes a list of hex numbers that represent Unicode
+    codepoints.
+
+New API:
++hb_face_get_table_tags()
++hb_font_set_ptem()
++hb_font_get_ptem()
++hb_ft_font_changed()
+
+
+Overview of changes leading to 1.5.1
+Tuesday, September 5, 2017
+====================================
+
+- Fix "unsafe-to-break" in fallback shaping and other corner cases.
+  All our tests pass with --verify now, meaning unsafe-to-break API
+  works as expected.
+- Add --unicodes to hb-view / hb-shape.
+- [indic] Treat Consonant_With_Stacker as consonant.  This will need
+  further tweaking.
+- hb_buffer_diff() tweaks.
+
+
+Overview of changes leading to 1.5.0
+Wednesday, August 23, 2017
+====================================
+
+- Misc new API, for appending a buffer to another, and for comparing
+  contents of two buffers for types of differences.
+
+- New "unsafe-to-break" API.  Can be used to speed up reshaping
+  in line-breaking situations.  Essentially, after shaping, it returns
+  positions in the input string (some of the cluster boundaries) that
+  are "safe to break" in that if the text is segmented at that position
+  and two sides reshaped and concatenated, the shaping result is
+  exactly the same as shaping the text in one piece.
+
+  hb-view and hb-shape and hb-shape now take --verify, which verifies
+  the above property.
+
+  Some corner cases of the implementation are still not quite working.
+  Those will be fixed in subsequent releases.
+
+- New API:
+
+hb_buffer_append()
+
+hb_glyph_flags_t
+HB_GLYPH_FLAG_UNSAFE_TO_BREAK
+HB_GLYPH_FLAG_DEFINED
+hb_glyph_info_get_glyph_flags()
+
+HB_BUFFER_SERIALIZE_FLAG_GLYPH_FLAGS
+
+hb_buffer_diff_flags_t
+HB_BUFFER_DIFF_FLAG_EQUAL
+HB_BUFFER_DIFF_FLAG_CONTENT_TYPE_MISMATCH
+HB_BUFFER_DIFF_FLAG_LENGTH_MISMATCH
+HB_BUFFER_DIFF_FLAG_NOTDEF_PRESENT
+HB_BUFFER_DIFF_FLAG_DOTTED_CIRCLE_PRESENT
+HB_BUFFER_DIFF_FLAG_CODEPOINT_MISMATCH
+HB_BUFFER_DIFF_FLAG_CLUSTER_MISMATCH
+HB_BUFFER_DIFF_FLAG_GLYPH_FLAGS_MISMATCH
+HB_BUFFER_DIFF_FLAG_POSITION_MISMATCH
+hb_buffer_diff
+
+
+Overview of changes leading to 1.4.8
+Tuesday, August 8, 2017
+====================================
+
+- Major fix to avar table handling.
+- Rename hb-shape --show-message to --trace.
+- Build fixes.
+
+
+Overview of changes leading to 1.4.7
+Tuesday, July 18, 2017
+====================================
+
+- Multiple Indic, Tibetan, and Cham fixes.
+- CoreText: Allow disabling kerning.
+- Adjust Arabic feature order again.
+- Misc build fixes.
+
+
+Overview of changes leading to 1.4.6
+Sunday, April 23, 2017
+====================================
+
+- Graphite2: Fix RTL positioning issue.
+- Backlist GDEF of more versions of Padauk and Tahoma.
+- New, experimental, cmake alternative build system.
+
+
+Overview of changes leading to 1.4.5
+Friday, March 10, 2017
+====================================
+
+- Revert "Fix Context lookup application when moving back after a glyph..."
+  This introduced memory access problems.  To be fixed properly soon.
+
+
+Overview of changes leading to 1.4.4
+Sunday, March 5, 2017
+====================================
+
+- Fix Context lookup application when moving back after a glyph deletion.
+- Fix buffer-overrun in Bengali.
+
+
+Overview of changes leading to 1.4.3
+Saturday, February 25, 2017
+====================================
+
+- Route Adlam script to Arabic shaper.
+- Misc fixes.
+- New API:
+  hb_font_set_face()
+- Deprecate API:
+  hb_graphite2_font_get_gr_font()
+
+
+Overview of changes leading to 1.4.2
+Monday, January 23, 2017
+====================================
+
+- Implement OpenType Font Variation tables avar/fvar/HVAR/VVAR.
+- hb-shape and hb-view now accept --variations.
+- New API:
+
+hb_variation_t
+hb_variation_from_string()
+hb_variation_to_string()
+
+hb_font_set_variations()
+hb_font_set_var_coords_design()
+hb_font_get_var_coords_normalized()
+
+hb-ot-var.h:
+hb_ot_var_axis_t
+hb_ot_var_has_data()
+hb_ot_var_get_axis_count()
+hb_ot_var_get_axes()
+hb_ot_var_find_axis()
+hb_ot_var_normalize_variations()
+hb_ot_var_normalize_coords()
+
+- MVAR to be implemented later.  Access to named instances to be
+  implemented later as well.
+
+- Misc fixes.
+
+
+Overview of changes leading to 1.4.1
+Thursday, January 5, 2017
+====================================
+
+- Always build and use UCDN for Unicode data by default.
+  Reduces dependence on version of Unicode data in glib,
+  specially in the Windows bundles we are shipping, which
+  have very old glib.
+
+
+Overview of changes leading to 1.4.0
+Thursday, January 5, 2017
+====================================
+
+- Merged "OpenType GX" branch which adds core of support for
+  OpenType 1.8 Font Variations.  To that extent, the relevant
+  new API is:
+
+New API:
+hb_font_set_var_coords_normalized()
+
+  with supporting API:
+
+New API:
+HB_OT_LAYOUT_NO_VARIATIONS_INDEX
+hb_ot_layout_table_find_feature_variations()
+hb_ot_layout_feature_with_variations_get_lookups()
+hb_shape_plan_create2()
+hb_shape_plan_create_cached2()
+
+  Currently variations in GSUB/GPOS/GDEF are fully supported,
+  and no other tables are supported.  In particular, fvar/avar
+  are NOT supported, hence the hb_font_set_var_coords_normalized()
+  taking normalized coordinates.  API to take design coordinates
+  will be added in the future.
+
+  HVAR/VVAR/MVAR support will also be added to hb-ot-font in the
+  future.
+
+- Fix regression in GDEF glyph class processing.
+- Add decompositions for Chakma, Limbu, and Balinese in USE shaper.
+- Misc fixes.
+
+
+Overview of changes leading to 1.3.4
+Monday, December 5, 2016
+====================================
+
+- Fix vertical glyph origin in hb-ot-font.
+- Implement CBDT/CBLC color font glyph extents in hb-ot-font.
+
+
+Overview of changes leading to 1.3.3
+Wednesday, September 28, 2016
+====================================
+
+- Implement parsing of OpenType MATH table.
+New API:
+HB_OT_TAG_MATH
+HB_OT_MATH_SCRIPT
+hb_ot_math_constant_t
+hb_ot_math_kern_t
+hb_ot_math_glyph_variant_t
+hb_ot_math_glyph_part_flags_t
+hb_ot_math_glyph_part_t
+hb_ot_math_has_data
+hb_ot_math_get_constant
+hb_ot_math_get_glyph_italics_correction
+hb_ot_math_get_glyph_top_accent_attachment
+hb_ot_math_get_glyph_kerning
+hb_ot_math_is_glyph_extended_shape
+hb_ot_math_get_glyph_variants
+hb_ot_math_get_min_connector_overlap
+hb_ot_math_get_glyph_assembly
+
+
+Overview of changes leading to 1.3.2
+Wednesday, September 27, 2016
+====================================
+
+- Fix build of hb-coretext on older OS X versions.
+
+
+Overview of changes leading to 1.3.1
+Wednesday, September 7, 2016
+====================================
+
+- Blacklist bad GDEF of more fonts (Padauk).
+- More CoreText backend crash fixes with OS X 10.9.5.
+- Misc fixes.
+
+
+Overview of changes leading to 1.3.0
+Thursday, July 21, 2016
+====================================
+
+- Update to Unicode 9.0.0
+- Move Javanese from Indic shaper to Universal Shaping Engine.
+- Allow MultipleSubst to delete a glyph (matching Windows engine).
+- Update Universal Shaping Engine to latest draft from Microsoft.
+- DirectWrite backend improvements.  Note: this backend is for testing ONLY.
+- CoreText backend improvements with unreachable fonts.
+- Implement symbol fonts (cmap 3.0.0) in hb-ft and hb-ot-font.
+- Blacklist bad GDEF of more fonts (Tahoma & others).
+- Misc fixes.
+
+
+Overview of changes leading to 1.2.7
+Monday, May 2, 2016
+====================================
+
+- Blacklist another version of Times New Roman (Bold) Italic from Windows 7.
+- Fix Mongolian Free Variation Selectors shaping with certain fonts.
+- Fix Tibetan shorthand contractions shaping.
+- Improved list of language tag mappings.
+- Unbreak build on Windows CE.
+- Make 'glyf' table loading lazy in hb-ot-font.
+
+
+Overview of changes leading to 1.2.6
+Friday, April 8, 2016
+====================================
+
+- Blacklist GDEF table of another set of Times New Roman (Bold) Italic.
+- DirectWrite backend improvements.  Note: DirectWrite backend is
+  exclusively for our internal testing and should NOT be used in any
+  production system whatsoever.
+
+
+Overview of changes leading to 1.2.5
+Monday, April 4, 2016
+====================================
+
+- Fix GDEF mark-filtering-set, which was broken in 1.2.3.
+
+
+Overview of changes leading to 1.2.4
+Thursday, March 17, 2016
+====================================
+
+- Synthesize GDEF glyph class for any glyph that does not have one in GDEF.
+  I really hope we don't discover broken fonts that shape badly with this
+  change.
+- Misc build and other minor fixes.
+- API changes:
+  - Added HB_NDEBUG.  It's fine for production systems to define this to
+    disable high-overhead debugging checks.  However, I also reduced the
+    overhead of those checks, so it's a non-issue right now.  You can
+    forget it.  Just not defining anything at all is fine.
+
+
+Overview of changes leading to 1.2.3
+Thursday, February 25, 2016
+====================================
+
+- Blacklist GDEF table of certain versions of Times New Roman (Bold) Italic,
+  due to bug in glyph class of ASCII double-quote character.  This should
+  address "regression" introduced in 1.2.0 when we switched mark zeroing
+  in most shapers from BY_UNICODE_LATE to BY_GDEF_LATE.
+  This fourth release in a week should finally stablize things...
+
+- hb-ot-font's get_glyph() implementation saw some optimizations.  Though,
+  might be really hard to measure in real-world situations.
+
+- Also, two rather small API changes:
+
+We now disable some time-consuming internal bookkeeping if built with NDEBUG
+defined.  This is a first time that we use NDEBUG to disable debug code.  If
+there exist production systems that do NOT want to enable NDEBUG, please let
+me know and I'll add HB_NDEBUG.
+
+Added get_nominal_glyph() and get_variation_glyph() instead of get_glyph()
+
+New API:
+- hb_font_get_nominal_glyph_func_t
+- hb_font_get_variation_glyph_func_t
+- hb_font_funcs_set_nominal_glyph_func()
+- hb_font_funcs_set_variation_glyph_func()
+- hb_font_get_nominal_glyph()
+- hb_font_get_variation_glyph()
+
+Deprecated API:
+- hb_font_get_glyph_func_t
+- hb_font_funcs_set_glyph_func()
+
+Clients that implement their own font-funcs are encouraged to replace
+their get_glyph() implementation with a get_nominal_glyph() and
+get_variation_glyph() pair.  The variation version can assume that
+variation_selector argument is not zero.  Old (deprecated) functions
+will continue working indefinitely using internal gymnastics; it is
+just more efficient to use the new functions.
+
+
+Overview of changes leading to 1.2.2
+Wednesday, February 24, 2016
+====================================
+
+- Fix regression with mark positioning with fonts that have
+  non-zero mark advances.  This was introduced in 1.2.0 while
+  trying to make mark and cursive attachments to work together.
+  I have partially reverted that, so this version is much more
+  like what we had before.  All clients who updated to 1.2.0
+  should update to this version.
+
+
+Overview of changes leading to 1.2.1
+Tuesday, February 23, 2016
+====================================
+
+- CoreText: Fix bug with wrong scale if font scale was changed later.
+  https://github.com/libass/libass/issues/212
+- CoreText: Drastically speed up font initialization.
+- CoreText: Fix tiny leak.
+- Group ZWJ/ZWNJ with previous syllable under cluster-level=0.
+  https://github.com/harfbuzz/harfbuzz/issues/217
+- Add test/shaping/README.md about how to add tests to the suite.
+
+
+Overview of changes leading to 1.2.0
+Friday, February 19, 2016
+====================================
+
+- Fix various issues (hangs mostly) in case of memory allocation failure.
+- Change mark zeroing types of most shapers from BY_UNICODE_LATE to
+  BY_GDEF_LATE.  This seems to be what Uniscribe does.
+- Change mark zeroing of USE shaper from NONE to BY_GDEF_EARLY.  That's
+  what Windows does.
+- Allow GPOS cursive connection on marks, and fix the interaction with
+  mark attachment.  This work resulted in some changes to how mark
+  attachments work.  See:
+  https://github.com/harfbuzz/harfbuzz/issues/211
+  https://github.com/harfbuzz/harfbuzz/commit/86c68c7a2c971efe8e35b1f1bd99401dc8b688d2
+- Graphite2 shaper: improved negative advance handling (eg. Nastaliq).
+- Add nmake-based build system for Windows.
+- Minor speedup.
+- Misc. improvements.
+
+
+Overview of changes leading to 1.1.3
+Monday, January 11, 2016
+====================================
+
+- Ported Indic shaper to Unicode 8.0 data.
+- Universal Shaping Engine fixes.
+- Speed up CoreText shaper when font fallback happens in CoreText.
+- Documentation improvements, thanks to Khaled Hosny.
+- Very rough directwrite shaper for testing, thanks to Ebrahim Byagowi.
+- Misc bug fixes.
+- New API:
+
+  * Font extents:
+      hb_font_extents_t
+      hb_font_get_font_extents_func_t
+      hb_font_get_font_h_extents_func_t
+      hb_font_get_font_v_extents_func_t
+      hb_font_funcs_set_font_h_extents_func
+      hb_font_funcs_set_font_v_extents_func
+      hb_font_get_h_extents
+      hb_font_get_v_extents
+      hb_font_get_extents_for_direction
+
+  * Buffer message (aka debug):
+      hb_buffer_message_func_t
+      hb_buffer_set_message_func()
+    Actual message protocol to be fleshed out later.
+
+
+Overview of changes leading to 1.1.2
+Wednesday, November 26, 2015
+====================================
+
+- Fix badly-broken fallback shaper that affected terminology.
+  https://github.com/harfbuzz/harfbuzz/issues/187
+- Fix y_scaling in Graphite shaper.
+- API changes:
+  * An unset glyph_h_origin() function in font-funcs now (sensibly)
+    implies horizontal origin at 0,0.  Ie, the nil callback returns
+    true instead of false.  As such, implementations that have a
+    glyph_h_origin() that simply returns true, can remove that function
+    with HarfBuzz >= 1.1.2.  This results in a tiny speedup.
+
+
+Overview of changes leading to 1.1.1
+Wednesday, November 24, 2015
+====================================
+
+- Build fixes, specially for hb-coretext.
+
+
+Overview of changes leading to 1.1.0
+Wednesday, November 18, 2015
+====================================
+
+- Implement 'stch' stretch feature for Syriac Abbreviation Mark.
+  https://github.com/harfbuzz/harfbuzz/issues/141
+- Disable use of decompose_compatibility() callback.
+- Implement "shaping" of various Unicode space characters, even
+  if the font does not support them.
+  https://github.com/harfbuzz/harfbuzz/issues/153
+- If font does not support U+2011 NO-BREAK HYPHEN, fallback to
+  U+2010 HYPHEN.
+- Changes resulting from libFuzzer continuous fuzzing:
+  * Reject font tables that need more than 8 edits,
+  * Bound buffer growth during shaping to 32x,
+  * Fix assertions and other issues at OOM / buffer max-growth.
+- Misc fixes and optimizations.
+- API changes:
+  * All fonts created with hb_font_create() now inherit from
+    (ie. have parent) hb_font_get_empty().
+
+
+Overview of changes leading to 1.0.6
+Thursday, October 15, 2015
+====================================
+
+- Reduce max nesting level in OT lookups from 8 to 6.
+  Should not affect any real font as far as I know.
+- Fix memory access issue in ot-font.
+- Revert default load-flags of fonts created using hb_ft_font_create()
+  back to FT_LOAD_DEFAULT|FT_LOAD_NO_HINTING.  This was changed in
+  last release (1.0.5), but caused major issues, so revert.
+  https://github.com/harfbuzz/harfbuzz/issues/143
+
+
+Overview of changes leading to 1.0.5
+Tuesday, October 13, 2015
+====================================
+
+- Fix multiple memory access bugs discovered using libFuzzer.
+  https://github.com/harfbuzz/harfbuzz/issues/139
+  Everyone should upgrade to this version as soon as possible.
+  We now have continuous fuzzing set up, to avoid issues like
+  these creeping in again.
+- Misc fixes.
+
+- New API:
+  * hb_font_set_parent().
+  * hb_ft_font_[sg]et_load_flags()
+    The default flags for fonts created using hb_ft_font_create()
+    has changed to default to FT_LOAD_DEFAULT now.  Previously it
+    was defaulting to FT_LOAD_DFEAULT|FT_LOAD_NO_HINTING.
+
+- API changes:
+  * Fonts now default to units-per-EM as their scale, instead of 0.
+  * hb_font_create_sub_font() does NOT make parent font immutable
+    anymore.  hb_font_make_immutable() does.
+
+
+Overview of changes leading to 1.0.4
+Wednesday, September 30, 2015
+====================================
+
+- Fix minor out-of-bounds read error.
+
+
+Overview of changes leading to 1.0.3
+Tuesday, September 1, 2015
+====================================
+
+- Start of user documentation, from Simon Cozens!
+- Implement glyph_extents() for TrueType fonts in hb-ot-font.
+- Improve GPOS cursive attachments with conflicting lookups.
+- More fixes for cluster-level = 1.
+- Uniscribe positioning fix.
+
+
+Overview of changes leading to 1.0.2
+Wednesday, August 19, 2015
+====================================
+
+- Fix shaping with cluster-level > 0.
+- Fix Uniscribe backend font-size scaling.
+- Declare dependencies in harfbuzz.pc.
+  FreeType is not declared though, to avoid bugs in pkg-config
+  0.26 with recursive dependencies.
+- Slightly improved debug infrastructure.  More to come later.
+- Misc build fixes.
+
+
+Overview of changes leading to 1.0.1
+Monday, July 27, 2015
+====================================
+
+- Fix out-of-bounds access in USE shaper.
+
+
+Overview of changes leading to 1.0.0
+Sunday, July 26, 2015
+====================================
+
+- Implement Universal Shaping Engine:
+  https://www.microsoft.com/typography/OpenTypeDev/USE/intro.htm
+  http://blogs.windows.com/bloggingwindows/2015/02/23/windows-shapes-the-worlds-languages/
+- Bump version to 1.0.0.  The soname was NOT bumped.
+
+
+Overview of changes leading to 0.9.42
+Thursday, July 26, 2015
+=====================================
+
+- New API to allow for retrieving finer-grained cluster
+  mappings if the client desires to handle them.  Default
+  behavior is unchanged.
+- Fix cluster merging when removing default-ignorables.
+- Update to Unicode 8.0
+- hb-graphite2 fixes.
+- Misc fixes.
+- Removed HB_NO_MERGE_CLUSTERS hack.
+- New API:
+  hb_buffer_cluster_level_t enum
+  hb_buffer_get_cluster_level()
+  hb_buffer_set_cluster_level()
+  hb-shape / hb-view --cluster-level
+
+
+Overview of changes leading to 0.9.41
+Thursday, June 18, 2015
+=====================================
+
+- Fix hb-coretext with trailing whitespace in right-to-left.
+- New API: hb_buffer_reverse_range().
+- Allow implementing atomic ops in config.h.
+- Fix hb_language_t in language bindings.
+- Misc fixes.
+
+
+Overview of changes leading to 0.9.40
+Friday, March 20, 2015
+=====================================
+
+- Another hb-coretext crasher fix.  Ouch!
+- Happy Norouz!
+
+
+Overview of changes leading to 0.9.39
+Wednesday, March 4, 2015
+=====================================
+
+- Critical hb-coretext fixes.
+- Optimizations and refactoring; no functional change
+  expected.
+- Misc build fixes.
+
+
+Overview of changes leading to 0.9.38
+Friday, January 23, 2015
+=====================================
+
+- Fix minor out-of-bounds access in Indic shaper.
+- Change New Tai Lue shaping engine from South-East Asian to default,
+  reflecting change in Unicode encoding model.
+- Add hb-shape --font-size.  Can take up to two numbers for separate
+  x / y size.
+- Fix CoreText and FreeType scale issues with negative scales.
+- Reject blobs larger than 2GB.  This might break some icu-le-hb clients
+  that need security fixes.  See:
+  http://www.icu-project.org/trac/ticket/11450
+- Avoid accessing font tables during face destruction, in casce rogue
+  clients released face data already.
+- Fix up gobject-introspection a bit.  Python bindings kinda working.
+  See README.python.
+- Misc fixes.
+- API additions:
+  hb_ft_face_create_referenced()
+  hb_ft_font_create_referenced()
+
+
+Overview of changes leading to 0.9.37
+Wednesday, December 17, 2014
+=====================================
+
+- Fix out-of-bounds access in Context lookup format 3.
+- Indic: Allow ZWJ/ZWNJ before syllable modifiers.
+
+
+Overview of changes leading to 0.9.36
+Thursday, November 20, 2014
+=====================================
+
+- First time that three months went by without a release since
+  0.9.2 was released on August 10, 2012!
+- Fix performance bug in hb_ot_collect_glyphs():
+  https://bugzilla.mozilla.org/show_bug.cgi?id=1090869
+- Add basic vertical-text support to hb-ot-font.
+- Misc build fixes.
+
+
+Overview of changes leading to 0.9.35
+Saturday, August 13, 2014
+=====================================
+
+- Fix major shape-plan caching bug when more than one shaper were
+  provided to hb_shape_full() (as exercised by XeTeX).
+  http://www.mail-archive.com/debian-bugs-dist@lists.debian.org/msg1246370.html
+- Fix Arabic fallback shaping regression.  This was broken in 0.9.32.
+- Major hb-coretext fixes.  That backend is complete now, including
+  respecing buffer direction and language, down to vertical writing.
+- Build fixes for Windows CE.  Should build fine now.
+- Misc fixes:
+  Use atexit() only if it's safe to call from shared library
+  https://bugs.freedesktop.org/show_bug.cgi?id=82246
+  Mandaic had errors in its Unicode Joining_Type
+  https://bugs.freedesktop.org/show_bug.cgi?id=82306
+- API changes:
+
+  * hb_buffer_clear_contents() does not reset buffer flags now.
+
+    After 763e5466c0a03a7c27020e1e2598e488612529a7, one doesn't
+    need to set flags for different pieces of text.  The flags now
+    are something the client sets up once, depending on how it
+    actually uses the buffer.  As such, don't clear it in
+    clear_contents().
+
+    I don't expect any changes to be needed to any existing client.
+
+
+Overview of changes leading to 0.9.34
+Saturday, August 2, 2014
+=====================================
+
+- hb_feature_from_string() now accepts CSS font-feature-settings format.
+- As a result, hb-shape / hb-view --features also accept CSS-style strings.
+  Eg, "'liga' off" is accepted now.
+- Add old-spec Myanmar shaper:
+  https://bugs.freedesktop.org/show_bug.cgi?id=81775
+- Don't apply 'calt' in Hangul shaper.
+- Fix mark advance zeroing for Hebrew shaper:
+  https://bugs.freedesktop.org/show_bug.cgi?id=76767
+- Implement Windows-1256 custom Arabic shaping.  Only built on Windows,
+  and requires help from get_glyph().  Used by Firefox.
+  https://bugzilla.mozilla.org/show_bug.cgi?id=1045139
+- Disable 'liga' in vertical text.
+- Build fixes.
+- API changes:
+
+  * Make HB_BUFFER_FLAG_BOT/EOT easier to use.
+
+    Previously, we expected users to provide BOT/EOT flags when the
+    text *segment* was at paragraph boundaries.  This meant that for
+    clients that provide full paragraph to HarfBuzz (eg. Pango), they
+    had code like this:
+
+      hb_buffer_set_flags (hb_buffer,
+                           (item_offset == 0 ? HB_BUFFER_FLAG_BOT : 0) |
+                           (item_offset + item_length == paragraph_length ?
+                            HB_BUFFER_FLAG_EOT : 0));
+
+      hb_buffer_add_utf8 (hb_buffer,
+                          paragraph_text, paragraph_length,
+                          item_offset, item_length);
+
+    After this change such clients can simply say:
+
+      hb_buffer_set_flags (hb_buffer,
+                           HB_BUFFER_FLAG_BOT | HB_BUFFER_FLAG_EOT);
+
+      hb_buffer_add_utf8 (hb_buffer,
+                          paragraph_text, paragraph_length,
+                          item_offset, item_length);
+
+    Ie, HarfBuzz itself checks whether the segment is at the beginning/end
+    of the paragraph.  Clients that only pass item-at-a-time to HarfBuzz
+    continue not setting any flags whatsoever.
+
+    Another way to put it is: if there's pre-context text in the buffer,
+    HarfBuzz ignores the BOT flag.  If there's post-context, it ignores
+    EOT flag.
+
+
+Overview of changes leading to 0.9.33
+Tuesday, July 22, 2014
+=====================================
+
+- Turn off ARabic 'cswh' feature that was accidentally turned on.
+- Add HB_TAG_MAX_SIGNED.
+- Make hb_face_make_immutable() really make face immutable!
+- Windows build fixes.
+
+
+Overview of changes leading to 0.9.32
+Thursday, July 17, 2014
+=====================================
+
+- Apply Arabic shaping features in spec order exactly.
+- Another fix for Mongolian free variation selectors.
+- For non-Arabic scripts in Arabic shaper apply 'rlig' and 'calt'
+  together.
+- Minor adjustment to U+FFFD logic.
+- Fix hb-coretext build.
+
+
+Overview of changes leading to 0.9.31
+Wednesday, July 16, 2014
+=====================================
+
+- Only accept valid UTF-8/16/32; we missed many cases before.
+- Better shaping of invalid UTF-8/16/32.  Falls back to
+  U+FFFD REPLACEMENT CHARACTER now.
+- With all changes in this release, the buffer will contain fully
+  valid Unicode after hb_buffer_add_utf8/16/32 no matter how
+  broken the input is.  This can be overridden though.  See below.
+- Fix Mongolian Variation Selectors for fonts without GDEF.
+- Fix minor invalid buffer access.
+- Accept zh-Hant and zh-Hans language tags.  hb_ot_tag_to_language()
+  now uses these instead of private tags.
+- Build fixes.
+- New API:
+  * hb_buffer_add_codepoints().  This does what hb_buffer_add_utf32()
+    used to do, ie. no validity check on the input at all.  add_utf32
+    now replaces invalid Unicode codepoints with the replacement
+    character (see below).
+  * hb_buffer_set_replacement_codepoint()
+  * hb_buffer_get_replacement_codepoint()
+    Previously, in hb_buffer_add_utf8 and hb_buffer_add_utf16, when
+    we detected broken input, we replaced that with (hb_codepoint_t)-1.
+    This has changed to use U+FFFD now, but can be changed using these
+    new API.
+
+
+Overview of changes leading to 0.9.30
+Wednesday, July 9, 2014
+=====================================
+
+- Update to Unicode 7.0.0:
+  * New scripts Manichaean and Psalter Pahlavi are shaped using
+    Arabic shaper.
+  * All the other new scripts to through the generic shaper for
+    now.
+- Minor Indic improvements.
+- Fix graphite2 backend cluster mapping [crasher!]
+- API changes:
+  * New HB_SCRIPT_* values for Unicode 7.0 scripts.
+  * New function hb_ot_layout_language_get_required_feature().
+- Build fixes.
+
+
+Overview of changes leading to 0.9.29
+Thursday, May 29, 2014
+=====================================
+
+- Implement cmap in hb-ot-font.h.  No variation-selectors yet.
+- Myanmar: Allow MedialYa+Asat.
+- Various Indic fixes:
+  * Support most characters in Extended Devanagary and Vedic
+    Unicode blocks.
+  * Allow digits and a some punctuation as consonant placeholders.
+- Build fixes.
+
+
+Overview of changes leading to 0.9.28
+Monday, April 28, 2014
+=====================================
+
+- Unbreak old-spec Indic shaping. (bug 76705)
+- Fix shaping of U+17DD and U+0FC6.
+- Add HB_NO_MERGE_CLUSTERS build option.  NOT to be enabled by default
+  for shipping libraries.  It's an option for further experimentation
+  right now.  When we are sure how to do it properly, we will add
+  public run-time API for the functionality.
+- Build fixes.
+
+
+Overview of changes leading to 0.9.27
+Tuesday, March 18, 2014
+=====================================
+
+- Don't use "register" storage class specifier
+- Wrap definition of free_langs() with HAVE_ATEXIT
+- Add coretext_aat shaper and hb_coretext_face_create() constructor
+- If HAVE_ICU_BUILTIN is defined, use hb-icu Unicode callbacks
+- Add Myanmar test case from OpenType Myanmar spec
+- Only do fallback Hebrew composition if no GPOS 'mark' available
+- Allow bootstrapping without gtk-doc
+- Use AM_MISSING_PROG for ragel and git
+- Typo in ucdn's Makefile.am
+- Improve MemoryBarrier() implementation
+
+
+Overview of changes leading to 0.9.26
+Thursday, January 30, 2014
+=====================================
+
+- Misc fixes.
+- Fix application of 'rtlm' feature.
+- Automatically apply frac/numr/dnom around U+2044 FRACTION SLASH.
+- New header: hb-ot-shape.h
+- Uniscribe: fix scratch-buffer accounting.
+- Reorder Tai Tham SAKOT to after tone-marks.
+- Add Hangul shaper.
+- New files:
+  hb-ot-shape-complex-hangul.cc
+  hb-ot-shape-complex-hebrew.cc
+  hb-ot-shape-complex-tibetan.cc
+- Disable 'cswh' feature in Arabic shaper.
+- Coretext: better handle surrogate pairs.
+- Add HB_TAG_MAX and _HB_SCRIPT_MAX_VALUE.
+
+
+Overview of changes leading to 0.9.25
+Wednesday, December 4, 2013
+=====================================
+
+- Myanmar shaper improvements.
+- Avoid font fallback in CoreText backend.
+- Additional OpenType language tag mappiongs.
+- More aggressive shape-plan caching.
+- Build with / require automake 1.13.
+- Build with libtool 2.4.2.418 alpha to support ppc64le.
+
+
+Overview of changes leading to 0.9.24
+Tuesday, November 13, 2013
+=====================================
+
+- Misc compiler warning fixes with clang.
+- No functional changes.
+
+
+Overview of changes leading to 0.9.23
+Monday, October 28, 2013
+=====================================
+
+- "Udupi HarfBuzz Hackfest", Paris, October 14..18 2013.
+- Fix (Chain)Context recursion with non-monotone lookup positions.
+- Misc Indic bug fixes.
+- New Javanese / Buginese shaping, similar to Windows 8.1.
+
+
+Overview of changes leading to 0.9.22
+Thursday, October 3, 2013
+=====================================
+
+- Fix use-after-end-of-scope in hb_language_from_string().
+- Fix hiding of default_ignorables if font doesn't have space glyph.
+- Protect against out-of-range lookup indices.
+
+- API Changes:
+
+  * Added hb_ot_layout_table_get_lookup_count()
+
+
+Overview of changes leading to 0.9.21
+Monday, September 16, 2013
+=====================================
+
+- Rename gobject-introspection library name from harfbuzz to HarfBuzz.
+- Remove (long disabled) hb-old and hb-icu-le test shapers.
+- Misc gtk-doc and gobject-introspection annotations.
+- Misc fixes.
+- API changes:
+
+  * Add HB_SET_VALUE_INVALID
+
+Overview of changes leading to 0.9.20
+Thursday, August 29, 2013
+=====================================
+
+General:
+- Misc substitute_closure() fixes.
+- Build fixes.
+
+Documentation:
+- gtk-doc boilerplate integrated.  Docs are built now, but
+  contain no contents.  By next release hopefully we have
+  some content in.  Enable using --enable-gtk-doc.
+
+GObject and Introspection:
+- Added harfbuzz-gobject library (hb-gobject.h) that has type
+  bindings for all HarfBuzz objects and enums.  Enable using
+  --with-gobject.
+- Added gobject-introspection boilerplate.  Nothing useful
+  right now.  Work in progress.  Gets enabled automatically if
+  --with-gobject is used.  Override with --disable-introspection.
+
+OpenType shaper:
+- Apply 'mark' in Myanmar shaper.
+- Don't apply 'dlig' by default.
+
+Uniscribe shaper:
+- Support user features.
+- Fix loading of fonts that are also installed on the system.
+- Fix shaping of Arabic Presentation Forms.
+- Fix build with wide chars.
+
+CoreText shaper:
+- Support user features.
+
+Source changes:
+- hb_face_t code moved to hb-face.h / hb-face.cc.
+- Added hb-deprecated.h.
+
+API changes:
+- Added HB_DISABLE_DEPRECATED.
+- Deprecated HB_SCRIPT_CANADIAN_ABORIGINAL; replaced by
+  HB_SCRIPT_CANADIAN_SYLLABICS.
+- Deprecated HB_BUFFER_FLAGS_DEFAULT; replaced by
+  HB_BUFFER_FLAG_DEFAULT.
+- Deprecated HB_BUFFER_SERIALIZE_FLAGS_DEFAULT; replaced by
+  HB_BUFFER_SERIALIZE_FLAG_DEFAULT.
+
+
+Overview of changes leading to 0.9.19
+Tuesday, July 16, 2013
+=====================================
+
+- Build fixes.
+- Better handling of multiple variation selectors in a row.
+- Pass on variation selector to GSUB if not consumed by cmap.
+- Fix undefined memory access.
+- Add Javanese config to Indic shaper.
+- Misc bug fixes.
+
+Overview of changes leading to 0.9.18
+Tuesday, May 28, 2013
+=====================================
+
+New build system:
+
+- All unneeded code is all disabled by default,
+
+- Uniscribe and CoreText shapers can be enabled with their --with options,
+
+- icu_le and old shapers cannot be enabled for now,
+
+- glib, freetype, and cairo will be detected automatically.
+  They can be force on/off'ed with their --with options,
+
+- icu and graphite2 are default off, can be enabled with their --with
+  options,
+
+Moreover, ICU support is now build into a separate library:
+libharfbuzz-icu.so, and a new harfbuzz-icu.pc is shipped for it.
+Distros can enable ICU now without every application on earth
+getting linked to via libharfbuzz.so.
+
+For distros I recommend that they make sure they are building --with-glib
+--with-freetype --with-cairo, --with-icu, and optionally --with-graphite2;
+And package harfbuzz and harfbuzz-icu separately.
+
+
+Overview of changes leading to 0.9.17
+Monday, May 20, 2013
+=====================================
+
+- Build fixes.
+- Fix bug in hb_set_get_min().
+- Fix regression with Arabic mark positioning / width-zeroing.
+
+Overview of changes leading to 0.9.16
+Friday, April 19, 2013
+=====================================
+
+- Major speedup in OpenType lookup processing.  With the Amiri
+  Arabic font, this release is over 3x faster than previous
+  release.  All scripts / languages should see this speedup.
+
+- New --num-iterations option for hb-shape / hb-view; useful for
+  profiling.
+
+Overview of changes leading to 0.9.15
+Friday, April 05, 2013
+=====================================
+
+- Build fixes.
+- Fix crasher in graphite2 shaper.
+- Fix Arabic mark width zeroing regression.
+- Don't compose Hangul jamo into Unicode syllables.
+
+
+Overview of changes leading to 0.9.14
+Thursday, March 21, 2013
+=====================================
+
+- Build fixes.
+- Fix time-consuming sanitize with malicious fonts.
+- Implement hb_buffer_deserialize_glyphs() for both json and text.
+- Do not ignore Hangul filler characters.
+- Indic fixes:
+  * Fix Malayalam pre-base reordering interaction with post-forms.
+  * Further adjust ZWJ handling.  Should fix known regressions from
+    0.9.13.
+
+
+Overview of changes leading to 0.9.13
+Thursday, February 25, 2013
+=====================================
+
+- Build fixes.
+- Ngapi HarfBuzz Hackfest in London (February 2013):
+  * Fixed all known Indic bugs,
+  * New Win8-style Myanmar shaper,
+  * New South-East Asian shaper for Tai Tham, Cham, and New Tai Lue,
+  * Smartly ignore Default_Ignorable characters (joiners, etc) wheb
+    matching GSUB/GPOS lookups,
+  * Fix 'Phags-Pa U+A872 shaping,
+  * Fix partial disabling of default-on features,
+  * Allow disabling of TrueType kerning.
+- Fix possible crasher with broken fonts with overlapping tables.
+- Removed generated files from git again.  So, one needs ragel to
+  bootstrap from the git tree.
+
+API changes:
+- hb_shape() and related APIs now abort if buffer direction is
+  HB_DIRECTION_INVALID.  Previously, hb_shape() was calling
+  hb_buffer_guess_segment_properties() on the buffer before
+  shaping.  The heuristics in that function are fragile.  If the
+  user really wants the old behvaior, they can call that function
+  right before calling hb_shape() to get the old behavior.
+- hb_blob_create_sub_blob() always creates sub-blob with
+  HB_MEMORY_MODE_READONLY.  See comments for the reason.
+
+
+Overview of changes leading to 0.9.12
+Thursday, January 18, 2013
+=====================================
+
+- Build fixes for Sun compiler.
+- Minor bug fix.
+
+Overview of changes leading to 0.9.11
+Thursday, January 10, 2013
+=====================================
+
+- Build fixes.
+- Fix GPOS mark attachment with null Anchor offsets.
+- [Indic] Fix old-spec reordering of viramas if sequence ends in one.
+- Fix multi-threaded shaper data creation crash.
+- Add atomic ops for Solaris.
+
+API changes:
+- Rename hb_buffer_clear() to hb_buffer_clear_contents().
+
+
+Overview of changes leading to 0.9.10
+Thursday, January 3, 2013
+=====================================
+
+- [Indic] Fixed rendering of Malayalam dot-reph
+- Updated OT language tags.
+- Updated graphite2 backend.
+- Improved hb_ot_layout_get_size_params() logic.
+- Improve hb-shape/hb-view help output.
+- Fixed hb-set.h implementation to not crash.
+- Fixed various issues with hb_ot_layout_collect_lookups().
+- Various build fixes.
+
+New API:
+
+hb_graphite2_face_get_gr_face()
+hb_graphite2_font_get_gr_font()
+hb_coretext_face_get_cg_font()
+
+Modified API:
+
+hb_ot_layout_get_size_params()
+
+
+Overview of changes leading to 0.9.9
+Wednesday, December 5, 2012
+====================================
+
+- Fix build on Windows.
+- Minor improvements.
+
+
+Overview of changes leading to 0.9.8
+Tuesday, December 4, 2012
+====================================
+
+
+- Actually implement hb_shape_plan_get_shaper ().
+- Make UCDB data tables const.
+- Lots of internal refactoring in OTLayout tables.
+- Flesh out hb_ot_layout_lookup_collect_glyphs().
+
+New API:
+
+hb_ot_layout_collect_lookups()
+hb_ot_layout_get_size_params()
+
+
+Overview of changes leading to 0.9.7
+Sunday, November 21, 2012
+====================================
+
+
+HarfBuzz "All-You-Can-Eat-Sushi" (aka Vancouver) Hackfest and follow-on fixes.
+
+- Fix Arabic contextual joining using pre-context text.
+- Fix Sinhala "split matra" mess.
+- Fix Khmer shaping with broken fonts.
+- Implement Thai "PUA" shaping for old fonts.
+- Do NOT route Kharoshthi script through the Indic shaper.
+- Disable fallback positioning for Indic and Thai shapers.
+- Misc fixes.
+
+
+hb-shape / hb-view changes:
+
+- Add --text-before and --text-after
+- Add --bot / --eot / --preserve-default-ignorables
+- hb-shape --output-format=json
+
+
+New API:
+
+hb_buffer_clear()
+
+hb_buffer_flags_t
+
+HB_BUFFER_FLAGS_DEFAULT
+HB_BUFFER_FLAG_BOT
+HB_BUFFER_FLAG_EOT
+HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES
+
+hb_buffer_set_flags()
+hb_buffer_get_flags()
+
+HB_BUFFER_SERIALIZE_FLAGS
+hb_buffer_serialize_glyphs()
+hb_buffer_deserialize_glyphs()
+hb_buffer_serialize_list_formats()
+
+hb_set_add_range()
+hb_set_del_range()
+hb_set_get_population()
+hb_set_next_range()
+
+hb_face_[sg]et_glyph_count()
+
+hb_segment_properties_t
+HB_SEGMENT_PROPERTIES_DEFAULT
+hb_segment_properties_equal()
+hb_segment_properties_hash()
+
+hb_buffer_set_segment_properties()
+hb_buffer_get_segment_properties()
+
+hb_ot_layout_glyph_class_t
+hb_ot_layout_get_glyph_class()
+hb_ot_layout_get_glyphs_in_class()
+
+hb_shape_plan_t
+hb_shape_plan_create()
+hb_shape_plan_create_cached()
+hb_shape_plan_get_empty()
+hb_shape_plan_reference()
+hb_shape_plan_destroy()
+hb_shape_plan_set_user_data()
+hb_shape_plan_get_user_data()
+hb_shape_plan_execute()
+hb_shape_plan_get_shaper()
+
+hb_ot_shape_plan_collect_lookups()
+
+
+API changes:
+
+- Remove "mask" parameter from hb_buffer_add().
+- Rename hb_ot_layout_would_substitute_lookup() and hb_ot_layout_substitute_closure_lookup().
+- hb-set.h API const correction.
+- Renamed hb_set_min/max() to hb_set_get_min/max().
+- Rename hb_ot_layout_feature_get_lookup_indexes() to hb_ot_layout_feature_get_lookups().
+- Rename hb_buffer_guess_properties() to hb_buffer_guess_segment_properties().
+
+
+
+Overview of changes leading to 0.9.6
+Sunday, November 13, 2012
+====================================
+
+- Don't clear pre-context text if no new context is provided.
+- Fix ReverseChainingSubstLookup, which was totally borked.
+- Adjust output format of hb-shape a bit.
+- Include config.h.in in-tree.  Makes it easier for alternate build systems.
+- Fix hb_buffer_set_length(buffer, 0) invalid memory allocation.
+- Use ICU LayoutEngine's C API instead of C++.  Avoids much headache.
+- Drop glyphs for all of Unicode Default_Ignorable characters.
+- Misc build fixes.
+
+Arabic shaper:
+- Enable 'dlig' and 'mset' features in Arabic shaper.
+- Implement 'Phags-pa shaping, improve Mongolian.
+
+Indic shaper:
+- Decompose Sinhala split matras the way old HarfBuzz / Pango did.
+- Initial support for Consonant Medials.
+- Start adding new-style Myanmar shaping.
+- Make reph and 'pref' logic introspect the font.
+- Route Meetei-Mayek through the Indic shaper.
+- Don't apply 'liga' in Indic shaper.
+- Improve Malayalam pre-base reordering Ra interaction with Chillus.
+
+
+
+Overview of changes leading to 0.9.5
+Sunday, October 14, 2012
+====================================
+
+- Synthetic-GSUB Arabic fallback shaping.
+
+- Misc Indic improvements.
+
+- Add build system support for pthread.
+
+- Imported UCDN for in-tree Unicode callbacks implementation.
+
+- Context-aware Arabic joining.
+
+- Misc other fixes.
+
+- New API:
+
+  hb_feature_to/from-string()
+  hb_buffer_[sg]et_content_type()
+
+
+
+Overview of changes leading to 0.9.4
+Tuesday, Sep 03, 2012
+====================================
+
+- Indic improvements with old-spec Malayalam.
+
+- Better fallback glyph positioning, specially with Thai / Lao marks.
+
+- Implement dotted-circle insertion.
+
+- Better Arabic fallback shaping / ligation.
+
+- Added ICU LayoutEngine backend for testing.  Call it by the 'icu_le' name.
+
+- Misc fixes.
+
+
+
+Overview of changes leading to 0.9.3
+Friday, Aug 18, 2012
+====================================
+
+- Fixed fallback mark positioning for left-to-right text.
+
+- Improve mark positioning for the remaining combining classes.
+
+- Unbreak Thai and fallback Arabic shaping.
+
+- Port Arabic shaper to shape-plan caching.
+
+- Use new ICU normalizer functions.
+
+
+
+Overview of changes leading to 0.9.2
+Friday, Aug 10, 2012
+====================================
+
+- Over a thousand commits!  This is the first major release of HarfBuzz.
+
+- HarfBuzz is feature-complete now!  It should be in par, or better, than
+  both Pango's shapers and old HarfBuzz / Qt shapers.
+
+- New Indic shaper, supporting main Indic scripts, Sinhala, and Khmer.
+
+- Improved Arabic shaper, with fallback Arabic shaping, supporting Arabic,
+  Sinhala, N'ko, Mongolian, and Mandaic.
+
+- New Thai / Lao shaper.
+
+- Tibetan / Hangul support in the generic shaper.
+
+- Synthetic GDEF support for fonts without a GDEF table.
+
+- Fallback mark positioning for fonts without a GPOS table.
+
+- Unicode normalization shaping heuristic during glyph mapping.
+
+- New experimental Graphite2 backend.
+
+- New Uniscribe backend (primarily for testing).
+
+- New CoreText backend (primarily for testing).
+
+- Major optimization and speedup.
+
+- Test suites and testing infrastructure (work in progress).
+
+- Greatly improved hb-view cmdline tool.
+
+- hb-shape cmdline tool.
+
+- Unicode 6.1 support.
+
+Summary of API changes:
+
+o Changed API:
+
+  - Users are expected to only include main header files now (ie. hb.h,
+    hb-glib.h, hb-ft.h, ...)
+
+  - All struct tag names had their initial underscore removed.
+    Ie. "struct _hb_buffer_t" is "struct hb_buffer_t" now.
+
+  - All set_user_data() functions now take a "replace" boolean parameter.
+
+  - hb_buffer_create() takes zero arguments now.
+    Use hb_buffer_pre_allocate() to pre-allocate.
+
+  - hb_buffer_add_utf*() now accept -1 for length parameteres,
+    meaning "nul-terminated".
+
+  - hb_direction_t enum values changed.
+
+  - All *_from_string() APIs now take a length parameter to allow for
+    non-nul-terminated strings. A -1 length means "nul-terminated".
+
+  - Typedef for hb_language_t changed.
+
+  - hb_get_table_func_t renamed to hb_reference_table_func_t.
+
+  - hb_ot_layout_table_choose_script()
+
+  - Various renames in hb-unicode.h.
+
+o New API:
+
+  - hb_buffer_guess_properties()
+    Automatically called by hb_shape().
+
+  - hb_buffer_normalize_glyphs()
+
+  - hb_tag_from_string()
+
+  - hb-coretext.h
+
+  - hb-uniscribe.h
+
+  - hb_face_reference_blob()
+  - hb_face_[sg]et_index()
+  - hb_face_set_upem()
+
+  - hb_font_get_glyph_name_func_t
+    hb_font_get_glyph_from_name_func_t
+    hb_font_funcs_set_glyph_name_func()
+    hb_font_funcs_set_glyph_from_name_func()
+    hb_font_get_glyph_name()
+    hb_font_get_glyph_from_name()
+    hb_font_glyph_to_string()
+    hb_font_glyph_from_string()
+
+  - hb_font_set_funcs_data()
+
+  - hb_ft_font_set_funcs()
+  - hb_ft_font_get_face()
+
+  - hb-gobject.h (work in progress)
+
+  - hb_ot_shape_glyphs_closure()
+    hb_ot_layout_substitute_closure_lookup()
+
+  - hb-set.h
+
+  - hb_shape_full()
+
+  - hb_unicode_combining_class_t
+
+  - hb_unicode_compose_func_t
+    hb_unicode_decompose_func_t
+    hb_unicode_decompose_compatibility_func_t
+    hb_unicode_funcs_set_compose_func()
+    hb_unicode_funcs_set_decompose_func()
+    hb_unicode_funcs_set_decompose_compatibility_func()
+    hb_unicode_compose()
+    hb_unicode_decompose()
+    hb_unicode_decompose_compatibility()
+
+o Removed API:
+
+  - hb_ft_get_font_funcs()
+
+  - hb_ot_layout_substitute_start()
+    hb_ot_layout_substitute_lookup()
+    hb_ot_layout_substitute_finish()
+    hb_ot_layout_position_start()
+    hb_ot_layout_position_lookup()
+    hb_ot_layout_position_finish()
+
+
+
+Overview of changes leading to 0.6.0
+Friday, May 27, 2011
+====================================
+
+- Vertical text support in GPOS
+- Almost all API entries have unit tests now, under test/
+- All thread-safety issues are fixed
+
+Summary of API changes follows.
+
+
+* Simple Types API:
+
+  o New API:
+    HB_LANGUAGE_INVALID
+    hb_language_get_default()
+    hb_direction_to_string()
+    hb_direction_from_string()
+    hb_script_get_horizontal_direction()
+    HB_UNTAG()
+
+  o Renamed API:
+    hb_category_t renamed to hb_unicode_general_category_t
+
+  o Changed API:
+    hb_language_t is a typed pointers now
+
+  o Removed API:
+    HB_TAG_STR()
+
+
+* Use ISO 15924 tags for hb_script_t:
+
+  o New API:
+    hb_script_from_iso15924_tag()
+    hb_script_to_iso15924_tag()
+    hb_script_from_string()
+
+  o Changed API:
+    HB_SCRIPT_* enum members changed value.
+
+
+* Buffer API streamlined:
+
+  o New API:
+    hb_buffer_reset()
+    hb_buffer_set_length()
+    hb_buffer_allocation_successful()
+
+  o Renamed API:
+    hb_buffer_ensure() renamed to hb_buffer_pre_allocate()
+    hb_buffer_add_glyph() renamed to hb_buffer_add()
+
+  o Removed API:
+    hb_buffer_clear()
+    hb_buffer_clear_positions()
+
+  o Changed API:
+    hb_buffer_get_glyph_infos() takes an out length parameter now
+    hb_buffer_get_glyph_positions() takes an out length parameter now
+
+
+* Blob API streamlined:
+
+  o New API:
+    hb_blob_get_data()
+    hb_blob_get_data_writable()
+
+  o Renamed API:
+    hb_blob_create_empty() renamed to hb_blob_get_empty()
+
+  o Removed API:
+    hb_blob_lock()
+    hb_blob_unlock()
+    hb_blob_is_writable()
+    hb_blob_try_writable()
+
+  o Changed API:
+    hb_blob_create() takes user_data before destroy now
+
+
+* Unicode functions API:
+
+  o Unicode function vectors can subclass other unicode function vectors now.
+    Unimplemented callbacks in the subclass automatically chainup to the parent.
+
+  o All hb_unicode_funcs_t callbacks take a user_data now.  Their setters
+    take a user_data and its respective destroy callback.
+
+  o New API:
+    hb_unicode_funcs_get_empty()
+    hb_unicode_funcs_get_default()
+    hb_unicode_funcs_get_parent()
+
+  o Changed API:
+    hb_unicode_funcs_create() now takes a parent_funcs.
+
+  o Removed func getter functions:
+    hb_unicode_funcs_get_mirroring_func()
+    hb_unicode_funcs_get_general_category_func()
+    hb_unicode_funcs_get_script_func()
+    hb_unicode_funcs_get_combining_class_func()
+    hb_unicode_funcs_get_eastasian_width_func()
+
+
+* Face API:
+
+  o Renamed API:
+    hb_face_get_table() renamed to hb_face_reference_table()
+    hb_face_create_for_data() renamed to hb_face_create()
+
+  o Changed API:
+    hb_face_create_for_tables() takes user_data before destroy now
+    hb_face_reference_table() returns empty blob instead of NULL
+    hb_get_table_func_t accepts the face as first parameter now
+
+* Font API:
+
+  o Fonts can subclass other fonts now.  Unimplemented callbacks in the
+    subclass automatically chainup to the parent.  When chaining up,
+    scale is adjusted if the parent font has a different scale.
+
+  o All hb_font_funcs_t callbacks take a user_data now.  Their setters
+    take a user_data and its respective destroy callback.
+
+  o New API:
+    hb_font_get_parent()
+    hb_font_funcs_get_empty()
+    hb_font_create_sub_font()
+
+  o Removed API:
+    hb_font_funcs_copy()
+    hb_font_unset_funcs()
+
+  o Removed func getter functions:
+    hb_font_funcs_get_glyph_func()
+    hb_font_funcs_get_glyph_advance_func()
+    hb_font_funcs_get_glyph_extents_func()
+    hb_font_funcs_get_contour_point_func()
+    hb_font_funcs_get_kerning_func()
+
+  o Changed API:
+    hb_font_create() takes a face and references it now
+    hb_font_set_funcs() takes user_data before destroy now
+    hb_font_set_scale() accepts signed integers now
+    hb_font_get_contour_point_func_t now takes glyph first, then point_index
+    hb_font_get_glyph_func_t returns a success boolean now
+
+
+* Changed object model:
+
+  o All object types have a _get_empty() now:
+    hb_blob_get_empty()
+    hb_buffer_get_empty()
+    hb_face_get_empty()
+    hb_font_get_empty()
+    hb_font_funcs_get_empty()
+    hb_unicode_funcs_get_empty()
+
+  o Added _set_user_data() and _get_user_data() for all object types:
+    hb_blob_get_user_data()
+    hb_blob_set_user_data()
+    hb_buffer_get_user_data()
+    hb_buffer_set_user_data()
+    hb_face_get_user_data()
+    hb_face_set_user_data()
+    hb_font_funcs_get_user_data()
+    hb_font_funcs_set_user_data()
+    hb_font_get_user_data()
+    hb_font_set_user_data()
+    hb_unicode_funcs_get_user_data()
+    hb_unicode_funcs_set_user_data()
+
+  o Removed the _get_reference_count() from all object types:
+    hb_blob_get_reference_count()
+    hb_buffer_get_reference_count()
+    hb_face_get_reference_count()
+    hb_font_funcs_get_reference_count()
+    hb_font_get_reference_count()
+    hb_unicode_funcs_get_reference_count()
+
+  o Added _make_immutable() and _is_immutable() for all object types except for buffer:
+    hb_blob_make_immutable()
+    hb_blob_is_immutable()
+    hb_face_make_immutable()
+    hb_face_is_immutable()
+
+
+* Changed API for vertical text support
+
+  o The following callbacks where removed:
+    hb_font_get_glyph_advance_func_t
+    hb_font_get_kerning_func_t
+
+  o The following new callbacks added instead:
+    hb_font_get_glyph_h_advance_func_t
+    hb_font_get_glyph_v_advance_func_t
+    hb_font_get_glyph_h_origin_func_t
+    hb_font_get_glyph_v_origin_func_t
+    hb_font_get_glyph_h_kerning_func_t
+    hb_font_get_glyph_v_kerning_func_t
+
+  o The following API removed as such:
+    hb_font_funcs_set_glyph_advance_func()
+    hb_font_funcs_set_kerning_func()
+    hb_font_get_glyph_advance()
+    hb_font_get_kerning()
+
+  o New API added instead:
+    hb_font_funcs_set_glyph_h_advance_func()
+    hb_font_funcs_set_glyph_v_advance_func()
+    hb_font_funcs_set_glyph_h_origin_func()
+    hb_font_funcs_set_glyph_v_origin_func()
+    hb_font_funcs_set_glyph_h_kerning_func()
+    hb_font_funcs_set_glyph_v_kerning_func()
+    hb_font_get_glyph_h_advance()
+    hb_font_get_glyph_v_advance()
+    hb_font_get_glyph_h_origin()
+    hb_font_get_glyph_v_origin()
+    hb_font_get_glyph_h_kerning()
+    hb_font_get_glyph_v_kerning()
+
+  o The following higher-leve API added for convenience:
+    hb_font_get_glyph_advance_for_direction()
+    hb_font_get_glyph_origin_for_direction()
+    hb_font_add_glyph_origin_for_direction()
+    hb_font_subtract_glyph_origin_for_direction()
+    hb_font_get_glyph_kerning_for_direction()
+    hb_font_get_glyph_extents_for_origin()
+    hb_font_get_glyph_contour_point_for_origin()
+
+
+* OpenType Layout API:
+
+  o New API:
+    hb_ot_layout_position_start()
+    hb_ot_layout_substitute_start()
+    hb_ot_layout_substitute_finish()
+
+
+* Glue code:
+
+  o New API:
+    hb_glib_script_to_script()
+    hb_glib_script_from_script()
+    hb_icu_script_to_script()
+    hb_icu_script_from_script()
+
+
+* Version API added:
+
+  o New API:
+    HB_VERSION_MAJOR
+    HB_VERSION_MINOR
+    HB_VERSION_MICRO
+    HB_VERSION_STRING
+    HB_VERSION_CHECK()
+    hb_version()
+    hb_version_string()
+    hb_version_check()
+
+