Due to the way emoji ZWJ sequences are defined, the ICU line breaking
algorithm determines that there are valid line breaks inside the
sequence. This patch suppresses these line breaks.

Bug: 25433289
Change-Id: I225ebebc0f4186e4b8f48fee399c4a62b3f0218a

Due to the way emoji ZWJ sequences are defined, the ICU line breaking
algorithm determines that there are valid line breaks inside the
sequence. This patch suppresses these line breaks.

Bug: 25433289
Change-Id: I225ebebc0f4186e4b8f48fee399c4a62b3f0218a

This is 2nd trial of I30a0914a4633bd93eb60957cdf378770f04d8428

- To suppress noisy unused parameter warnings, comment out unused
  arguments.
- Add -Werror for suppressing further warning.
- Add -Wall -Wextra for safety.
- Use "z" prefix for format string of size_t.

Verified that compile succeeded on all arm,arm64,mips,x86,x86_64.

Change-Id: I7ad208464486b8a35da53929cb1cfe541ed0052f

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

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

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

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

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

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

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

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