Overview of changes in 1.90
===========================

This is an unstable development release leading towards
Pango 2.0, which will be major new version, and will not
be API or ABI compatible with Pango 1.x.

The API changes in this release are not final, and feedback
on the changes and features in this release is very appreciated,
so we can fix up oversights and omissions before finalizing
the 2.0 API.

This release is parallel-installable with Pango 1.50.x.

Changes
-------

Pango is now shipped as a single shared object, libpango-2.so,
which contains the high-level cross-platform code as well as
platform-specific fontmap implementations and the cairo
support (if it is enabled).

Linking both libpango-1.so and libpango-2.so into the same
process is not supported, and we try to detect and prevent
this situation.

Major new APIs
--------------

- PangoLineBreaker:

  PangoLineBreaker is the core of pango's line-breaking algorithm,
  broken out from PangoLayout. Having this available independent
  from PangoLayout will facilitate uses such as multi-column
  layout, text flow between frames and shaping paragraphs around
  images.

- PangoLines

  PangoLines is the 'formatted output' part of a PangoLayout, and
  can be used to collect the output of a PangoLineBreaker.

- PangoFontMap

  The PangoFontMap class has seen some significant changes. It is
  now possible to instantiate a PangoFontMap, and populate it manually
  with PangoFontFamily and PangoFontFace objects.

  There are platform-specific subclasses

  - PangoFcFontMap
  - PangoCoreTextFontMap
  - PangoDirectWriteFontMap

  which will use platform API to enumerate fonts and populate
  the fontmap.

- PangoGenericFamily

  PangoGenericFamily is a new object representing generic font
  families such as 'Sans' or 'Serif', which are populated with
  lots of individual font families matching these general styles.

  When a PangoFontMap returns a fontset matching a query, it will
  always include at least on PangoGenericFamily in the result, to
  ensure good charset coverage.

  In the past, this was achieved by having the fontconfig fontmap
  always return a fontset including *all* the system fonts, with
  varying order. The new approach should be more performant on
  systems with many fonts, where sorting all the fonts is expensive.

- PangoHbFace, PangoHbFont

  The Pango font classes have been replaced by this pair of classes
  which are thin wrappers around hb_face_t and hb_font_t. Since
  HarfBuzz provides these cross-platform objects for us, we don't
  need platform-specific font implementations anymore.

  As one of the advantages of the new font implementation it is
  now possible to instantiate fonts from a font file, or from font
  data in memory.

  The cairo support code has learned to generate cairo scaled
  fonts from PangoHbFont objects.

- PangoUserFont, PangoUserFace

  These are a new kind of callback-based font implementation to
  allow for entirely application-defined font handling, including
  glyph drawing.

Other API changes
-----------------

- PangoAttribute has been reimplemented

- All deprecated APIs have been dropped

- The PangoScript enumeration has been replaced by GUnicodeScript

- PangoCoverage has been replaced by pango_font_face_has_char

- PangoColor has gained an alpha field

- The PangoFontsetSimple object is unused and has been dropped

- PangoXft, PangoFT2 and other backend-specific rendering APIs
  have been dropped for now

- Most structs have been made private

- Many smaller API cleanups and reductions