This doesn't change current behavior. It's a preparation
for the following CLs.

Bug: 22408712
Change-Id: Ic018422254aa3904655f499194caad74f0c0fc5d

Currently codepoint to glyph ID resolution is done through MinikinFont
interface. To support variation selector, use HarfBuzz API instead of
calling this interface since one of its implementation Skia doesn't
support variation selector.

On the other hand, we don't want to get glyph horizontal advance values
by HarfBuzz since HarfBuzz doesn't return correct values when the hinting
is active.

Thus, use ot_font as a parent font and override
glyph_h_advance/glyph_h_origin functions as is.

With this change, MinikinFont::GetGlyph is no longer necessary but not
removing in this CL for easy reverting since removing interface requires
multi-repository commit.

This is a base work of b/11256006 and this patch doesn't provide any
user visible changes.

Bug: 11256006
Change-Id: I061172c0b674bb649ce8bc013ffecf38708bdc41

This CL does:
1. Move the getNextWordBreak/getPrevWordBreak function to a separate source file.
2. Adding "ForCache" suffix for function name for making clear these function is
   for layout cache.
3. Introduce unit tests for them.

Bug: 11256006
Change-Id: I4138751a4570915f1a0d6c8921f89700f8ec7f35

Initial unit tests for Minikin functionality. Also fixes an incorrect
Hangul case (uncovered in testing), and improves handling of broken
UTF-16.

Change-Id: I69b441d8e3b19ed06abcc56f13271abadf3d1010

Reported externally at https://code.google.com/p/android/issues/detail?id=167715.
Bug: 21498085

Change-Id: I73f22de03b0151ce31a6b3070d051a2a701b33d2

Also handle the case of weird language code that we don't understand
properly better, by treating them not equal to each other.

Change-Id: Iaccb251fa38d700932f6eadac254d3d1fa09b3ea

This tailors Unicode's Grapheme_Cluster_Break property to better
classify characters currently with the Control property value.

Also adds support for rule GB9b of UAX #29, needed since there are
now characters we are tailoring to be Prepend. The rule was
previously ommited in our implementation because there was no
characters in the Prepend class.

Bug: 15653110
Change-Id: If10da88df0980f7d676c8c0b950eda5fb8dbe741

In computing scores for which fallback font to choose, a match of a
variant given explicitly in the xml config file scores higher than a
family with no explicit variant. One consequence is that U+2010
HYPHEN is chosen from the Naskh Arabic font in the fallback case.

This patch scores families with no variants as a match (effectively
the same as if the xml file specified both variants). Thus, it will
choose the first matching font (Roboto), which is a better choice.

This patch also revises the list of "sticky" characters to include
various hyphens, so Arabic (and potentially other scripts) text that
includes hyphens can access the script-specific variants matched to
the underlying text.

Bug: 22824219
Change-Id: I6ec1043037f89cad50ca99ac24c473395546bcdf

This reverts commit 3e0fc64d.

Bug: 22589743
Bug: 22121742
Change-Id: I7b482ffb8a0ee174ddc804aa890de45bdbd758e3

It's essential not to apply a break opportunity within a replacement
span, otherwise things can happen such as displaying the span twice.
The old code tested this case based on zero-width characters.
However, this test was both imprecise, and also in some cases read
uninitialized values from the mCharWidths array, which in turn led
to inconsistent line breaking of the same text.

This patch applies all line break opportunities (as identified by
ICU) within text (as opposed to replacement spans), and also applies
break opportunities at the beginning and end of replacement spans,
but avoids breaks within a replacement span.

Bug: 20138621
Change-Id: I36baeb44d6808356649e1bb69ca57f093fc8c723

Previously, the standard C tolower() function was used, which
didn't support any characters beyond the basic ASCII letters.

Bug: 22506121
Change-Id: Ibb81121caa29be44fbb59aa98891e9faafc57592

This adds various hyphen-like characters missed in the previous
patch, that should disallow automatic hyphenation of words containing
them.

Bug: 22484266
Change-Id: Ie972cb50384dbe0aa1ab5ec50286b75f9877953a

Previously, automatic hyphenation blindly took almost every line
breaking opportunity as a word break, so words like "low-budget" were
treated as two separate words, "low-", and "budget", each
automatically hyphenated.

This patch makes sure the subwords in already-hyphenated phrases are
not passed to the automatic hyphenator, while keeping the possibility
of a potential line break where a hyphen already exists.

Bug: 22484266
Bug: 22287425
Change-Id: Ie46dbdd70e993d64a9b9cf44b4ae93b21459dbc2

We bypass the word layout cache for "complex" cases, which includes
things like OpenType features. We were counting a hyphen edit as such
a case, but the problem is that we measure a _lot_ of these when
doing layout with hyphenation.

This patch adds plumbing for hyphen edits to the layout cache, so
that word fragments with hyphens can be cached as well.

Bug: 22378829

Change-Id: Idba4df4faa14f48a5faccc8a7a7955a36c19ef27

The logic in getRunAdvance() assumed that any zero-width character was
part of the preceding cluster, which is valid most of the time. However,
characters such as ZWNBSP (U+FEFF) renders as a zero width glyph
and is also a grapheme cluster boundary. This patch adds a clause to
handle that case.

Bug: 22121742
Change-Id: Iad79a7d988bded1ef05f0fd7905d20669ea22051

An incorrect cluster offset calculation was causing a lot of log
messages to appear. Separately, a confusion between #if and #ifdef was
causing unintended logging of line breaks. This patch fixes both.

Bug: 22178333
Change-Id: I2b3673ed66c784f5082fd127a8dc10bd3df6ed79

The appearance of letterspacing with scripts with cursive connections
is poor, so we simply disable letterspacing for those scripts. There
may be some cases where some form of letterspacing is desirable, but
this gives the highest likelihood that the final result will be good
without requiring additional work from clients.

Bug: 21935803
Change-Id: Ie25266249ac3a2605aa89ef5132e8edbe3a06d35

A recent change added a penalty for a hyphen at the last line break,
which is visually undesirable. However, the penalty was assessed to
"widthScore", which broke the assumption (used for another
optimization) that widthScore increases monotonically. This patch
separates the penalty into a different parameter, restoring the
validity of the monotonicity assumption.

Bug: 22066119
Change-Id: I6a47a350ef3ceee2f00ee430d6954d0c307227f0

Previously, we just assumed the font in use had a U+2010 HYPHEN
character, resulting in a tofu (or an empty space) being shown when
U+2010 was not supported in the font used to render the hyphenated
word.

Now we try to fallback to U+002D HYPHEN-MINUS, which has a very good
chance of being available in at least any Latin font.

We still show a tofu when neither character is supported, to
intentionally alert that something is missing.

Bug: 20497913
Bug: 21088552
Bug: 21570828
Change-Id: Iff69bbc38836c03495e9124502b5207c39270da2

searchStart was passed to getRunAdvance, but it can be
different from the start that has been used to initialize
Layout object. As a result, wrong index could be used in
getRunAdvance.

Bug: 21744454
Change-Id: Ibe83cc50ed6f0da2a1532318bc224502be350699

Tuning for hyphenation parameters. We discourage hyphenation on the
last line, but offset this penalty by also applying a penalty for
each line, which optimizes for minimizing the number of lines. Thus,
when hyphenation can reduce the number of lines, it increases the
chance they're used.

There's probably more tuning and refinement that can be done, but
testing suggests that the tunable parameters are appropriate.

Bug: 20883322

Change-Id: Ida7eaf8aced109e426694f5a386924a842d29c4b

We were not taking context start into account when deciding whether
to split a ligature, which was causing inconsistent behavior. This
patch consistently references the widths array relative to the start
of the context.

Bug: 21549197
Change-Id: I7c71e10c1af84354fefe782fc0b87120016e6555

Very long words cause O(n^2) behavior. These are unlikely to happen in
real text, but do happen with synthetic strings, so in those cases we
just disable hyphenation.

Bug: 20790394
Change-Id: Idf957dd40b24efe1476f619f17093a48b5bc56f7

Three hyphenation frequencies are now supported:

kHyphenationFrequency_None, which turns off both automatic
hyphenation and soft hyphens.

kHyphenationFrequency_Normal, which has aconservative amount of
hyphenation useful as a conservative default.

kHyphenationFrequency_Full, which has a typographic-quality amount of
hyphenation useful for running text and tight screens.

Bug: 21038249
Change-Id: I2800f718c887c9389a1a059d7ec07d7fa2ca1dee

namespace naming collision. Move minikin's
Bitmap out of android:: and into minikin::

Change-Id: I5ae3925f81b848dc79576429ab55243b96f7fed2

In a paragraph with a trailing newline, the width of the newline
character was included in the line width for breaking purposes,
basically as if it were a non-breaking space. This caused a
discrepancy, where Layout.getDesiredWidth() suggested that the text
would fit in a single line, but StaticLayout would break it because of
the added width of the newline character.

The proposed fix is simply to consider newline to be a space that
disappears at the end of a line.

Bug: 20152308
Change-Id: I539574c5b8ea892c8ed6aca6c59e90ccdf74a680

New functions for computing the correspondence between cursor
position and advance, respecting grapheme boundaries.

Change-Id: I620378d5f64cd74300cd43db522adeb555825dff

The name "margin" conflicts with another meaning, so we're making the
name in the public api "idents" and the code consistent in naming.

Change-Id: I9170116b4d972e4b25f0f319e78376310288eb41

In order to support layout in non-rectangular regions, the LineWidths
object needs to accept an arbitrary array of margins. This is
implemented in addition to the existing firstWidthLineCount/restWidth
mechanism for convenience, though using only arrays would have the
same expressive power.

Bug: 20182243
Change-Id: Iea96bca1a92012314ac27e617c67f306c1f1b2f2

This reverts commit 0b25d5ac.

This reverts commit daf6a6bd.

Change-Id: I3fed65046274d3aeb748f0730585ab89927f5741

This patch adds hyphenation using the Liang hyphenation algorithm,
similar to TeX. It also improves the optimized line breaker so that
it works correctly and efficiently even when the line width is not
constant (there is a specialization for constant width, which is
probably worthwhile, but performance TODOs remain).

Still to be done:

* hyphenator has many shortcuts, only tested with English

* interaction between punctuation and hyphenation is problematic

Change-Id: I2d94a1668ebc536398b7c43fcf486333eeb7c6aa

This patch adds a LineBreaker class to Minikin, which will be used for
computing line breaks in StaticLayout. The version in this patch
contains basically the same functionality that existed before, but
hopefully better performance and an interface that's suitable for more
sophisticated paragraph layout.

Note that this version contains a high quality strategy, which mostly
works but doesn't respect varying line width.

Change-Id: I02485d58b1e52856296a72cdd4efd963bc572933

Adds a "HyphenEdit" field to the Minikin Paint object, which represents
an edit to the text to add a hyphen (and, in the future, other edits to
support nonstandard hyphenation).

Change-Id: Ib4ee690b0fe2137e1d1e2c9251e5526b274ec3a7

Previously, HarfBuzz's default fallback to compatibility
decompositions resulted in Mathematical Alphanumeric Symbols getting
rendered as normal letters and digits when there was no font
available to render them. This patch disables that fallback, to
ensure they are displayed as tofus.

Based on a patch by Behdad Esfahbod.

Bug: 19202569
Change-Id: I357f172302448d4ab0b24efc86119f1977b5996b

* commit '79298c34':
  Remove hardcoded ICU include paths.