• Unicode 14.0 support (David Corbett).

• The hb-subset API and the harfbuzz-subset library's ABI are now declared stable. The harfbuzz-subset library would not have been possible without the work of Garret Rieger and Qunxin Liu from Google Fonts, and the earlier work of Michiharu Ariza from Adobe.

• The hb-style API is now stable and no longer experimental.

• New API:
  +hb_style_tag_t
  +hb_style_get_value()
  +hb_subset_input_t
  +hb_subset_flags_t
  +hb_subset_sets_t
  +hb_subset_input_create_or_fail()
  +hb_subset_input_reference()
  +hb_subset_input_destroy()
  +hb_subset_input_set_user_data()
  +hb_subset_input_get_user_data()
  +hb_subset_input_unicode_set()
  +hb_subset_input_glyph_set()
  +hb_subset_input_set()
  +hb_subset_input_get_flags()
  +hb_subset_input_set_flags()
  +hb_subset_or_fail()

• Removed old unstable harfbuzz-subset API:
  -hb_subset_input_nameid_set()
  -hb_subset_input_namelangid_set()
  -hb_subset_input_layout_features_set()
  -hb_subset_input_no_subset_tables_set()
  -hb_subset_input_drop_tables_set()
  -hb_subset_input_set_drop_hints()
  -hb_subset_input_get_drop_hints()
  -hb_subset_input_set_desubroutinize()
  -hb_subset_input_get_desubroutinize()
  -hb_subset_input_set_retain_gids()
  -hb_subset_input_get_retain_gids()
  -hb_subset_input_set_name_legacy()
  -hb_subset_input_get_name_legacy()
  -hb_subset_input_set_overlaps_flag()
  -hb_subset_input_get_overlaps_flag()
  -hb_subset_input_set_notdef_outline()
  -hb_subset_input_get_notdef_outline()
  -hb_subset_input_set_no_prune_unicode_ranges()
  -hb_subset_input_get_no_prune_unicode_ranges()
  -hb_subset()

• Final subset API is in place and if no issues are discovered, it will be the stable subset API of HarfBuzz 3.0.0. Old API is kept to ease transition, but will be removed in 3.0.0.
• Various fuzzer-found bug fixes.
• hb_buffer_append() now handles the pre- and post-context which previously were left unchanged in the destination buffer.
• hb-view / hb-shape now accept following new arguments:
  • --unicodes-before/after: takes a list of hex numbers that represent Unicode
    codepoints.
• Undeprecated API:
  hb_set_invert()

• Subsetter API is being stabilized, with the first stable API to happen in
  3.0.0 release (https://github.com/harfbuzz/harfbuzz/issues/3078).
• Support multiple variation axes with same tag, aka HOI.
• The “coretext” testing shaper now passes font variations to CoreText.
• hb-shape/hb-view does not break line at new lines unless text is read from
  file.
• hb-view and hb-subset has a --batch now, similar to hb-shape.
• The --batch mode now uses ; as argument separator instead of : used previously.
• The --batch in hb-shape does not expect 0th argument anymore. That is, the
  lines read are interpreted as argv[1:], instead of argv[0:].
• The --batch option has been undocumented. We are ready to document it; send
  feedback if you find it useful.
• hb-subset got arguments revamps. Added much-requested --gids-file, --glyphs,
  --glyphs-file, --unicodes-file, supporting ranges in --unicodes.
• Various bug fixes.

• Shaping LTR digits for RTL scripts now makes the native direction of the
  digits LTR, applying shaping and positioning rules on the same glyph order as
  Uniscribe. (Jonathan Kew, Khaled Hosny).
• Subsetting COLR v1 and CPAL tables is now supported. (Garret Rieger, Qunxin Liu)
• Various fixes and improvements to the subsetter. (Garret Rieger, Qunxin Liu, Behdad)
• When applying morx table, mark glyph widths should not be zeroed. (Jonathan Kew)
• GPOS is preferred over kerx, if GSUB was applied. (Behdad)
• Regional_Indicator pairs are grouped together when clustering. (Behdad)
• New APIs:
  +hb_blob_create_or_fail()
  +hb_blob_create_from_file_or_fail()
  +hb_set_copy()

• Subsetter now fully supports GSUB/GPOS/GDEF tables (including variations); as
  such, layout tables are retained by subsetter by default. (Garret Rieger, Qunxin Liu)
• Build scripts no longer check for FontConfig as HarfBuzz does not use it.
• hb-view supports iTerm2 and kitty inline image protocols (Khaled Hosny),
  it can also use Chafa for terminal graphics if available (Hans Petter Jansson).

• Shape joining scripts other than Arabic/Syriac using the Universal Shaping Engine.
  Previously these were shaped using the generalized Arabic shaper. (David Corbett)
• Fix regression in shaping of U+0B55 ORIYA SIGN OVERLINE. (David Corbett)
• Update language tags. (David Corbett)
• Variations: reduce error: do not round each interpolated delta. (Just van Rossum)
• Documentation improvements. (Khaled Hosny, Nathan Willis)
• Subsetter improvements: subsets most, if not all, lookup types now. (Garret Rieger, Qunxin Liu)
• Fuzzer-found fixes and other improvements when memory failures happen. (Behdad)
• Removed most atomic implementations now that we have C++11 atomic impl. (Behdad)
• General codebase upkeep; using more C++11 features: constexpr constructors, etc. (Behdad)

• Fix missing --enable-introspection configure option from previous release tarball.
• Documentation updates.

• Update USE shaper to 2020-08-13 specification, and other improvements.
• Don’t disable liga feature in myanmar shaper, to match Uniscribe.
• Improvements to language and script tags handling.
• Update language system tag registry to OpenType 1.8.4
• Support for serializing and deserializing Unicode buffers. Serialized buffers
  are now delimited with <> or [] based on whether it is a Unicode or
  glyphs buffer.
• Increase buffer work limits to handle fonts with many complex lookups.
• Handle more shaping operations in trace output.
• Memory access fixes.
• More OOM fixes.
• Improved documentation.
• Build system improvements.
• New API:
  +hb_buffer_has_positions()
  +hb_buffer_serialize()
  +hb_buffer_serialize_unicode()
  +hb_buffer_deserialize_unicode()

• 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, Aug 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()