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()