Before this patch, the font fallback chain iterated all installed font
families if a variation selector was specified.

This CL narrows down the range of iteration.
To decide the font family for the variation sequence, we need to search
for both the variation sequence and its base code point.
The new range of the iteration is a union of them.

With this change, the running time of Paint.hasGlyph for the variation
sequence improves 50% and the running time of Paint.measureText for the
variation sequence improves 40% for the large text case on Nexus 6
userdebug.

Bug: 26784699
Bug: 11750374

Change-Id: Iced1349e3ca750821d8882c551551f65bb569794

It turned out that hb_font_t creation is not a lightweight operation.
Especially, Paint.hasGlyph creates hb_font_t for all existing fonts
every time. To improve the performance, cache hb_font_t instead
of hb_face_t.

Note that to calculate horizontal advance, MinikinPaint needs to be
associated with hb_font_t by calling hb_font_set_funcs. With this patch,
hb_font_set_funcs may be called multiple times for the same hb_font_t
object. However this is not an issue since MinikinPaint is unique
during layout.

Bug: 26784699

Change-Id: I516498ae9f0127d700fc9829327e9789845a1416

The motivation of this CL is enhance the font fallback score design
to support multiple language font fallback.

This CL contains following changes:
- Break language based font score into two: script-based score and
  primary-language-based score.
- The primary-language-based score is 0 if the script-based score is 0.
  If the script-based score is not 0 and the primary language is the
  as same as the requested one, the font gets an extra score of 1.
- The language score gets a higher multiplier for languages higher in
  the locale list.

Bug: 25122318
Bug: 26168983
Change-Id: Ib999997a88e6977e341f4c325e2a1b41a59db2d5

The caller of FontFamily::hasVariationSelector needs to acquire the
lock before calling it, but FontCollection::hasVariationSelector
didn't acquire the lock. This caused a race condition.
This CL fixes this race condition.

Also, it turned out that assertMinikinLocked didn't assert even on
eng or userdebug device. This CL enables assertion on eng and userdebug
device since this assertion must be treated as bug.

BUG: 26323806

Change-Id: I9c4b1e1f09c6793e387fbdb8bb654cc0a13c65d5

This is 2nd attempt of I8df992a6851021903478972601a9a5c9424b100c.

The main purpose of this CL is expanding FontLanguage to be able to
save full script tag. Previously, FontLangauge kept only limited script
tags. With this CL, FontLanguage keeps all script tags.

This CL contains the following changes:
- FontLanguage changes:
-- Moved to private directory not to be instantiated outside of Minikin.
-- Removed bool(), bits(), FontLanguage(uint32_t) methods which are no
   longer used.
-- Change the FontLanguage internal data structure.
-- Introduces script match logic.

- FontLanguages changes:
-- Moved to private directory not to be instantiated outside of Minikin.
-- This is now std::vector<FontLanguage>

- FontLanguageListCache changes:
-- Now FontLanguageListCache::getId through
   FontStyle::registerLanguageList is the only way to instantiate the
   FontLanguage.
-- Normalize input to be BCP47 compliant identifier by ICU.

Bug: 26168983
Change-Id: I431b3f361a7635497c05b85e8ecbeb48d9aef63e

This reverts commit 5e995fb8.

Change-Id: I761e0e41906742fbe3d3ac34170af3101e18042a

The main purpose of this CL is expanding FontLanguage to be able to
save full script tag. Previously, FontLangauge kept only limited script
tags. With this CL, FontLanguage keeps all script tags.

This CL contains the following changes:
- FontLanguage changes:
-- Moved to private directory not to be instantiated outside of Minikin.
-- Removed bool(), bits(), FontLanguage(uint32_t) methods which are no
   longer used.
-- Change the FontLanguage internal data structure.
-- Introduces script match logic.

- FontLanguages changes:
-- Moved to private directory not to be instantiated outside of Minikin.
-- This is now std::vector<FontLanguage>

- FontLanguageListCache changes:
-- Now FontLanguageListCache::getId through
   FontStyle::registerLanguageList is the only way to instantiate the
   FontLanguage.
-- Normalize input to be BCP47 compliant identifier by ICU.

Bug: 26168983
Change-Id: I8df992a6851021903478972601a9a5c9424b100c

Removing the extra score of 2 for the script matching from the font
fallback score calculation.  If the two langauges have different
scripts, we should treat them as different languages.

Change-Id: Ie0d6f27bd1086248895935a7bd01b5d404044ad0

FontLanguageListCache is an intentionally leaky singleton and its
internal cache won't be purged.

BUG: 25122318

Change-Id: I272097e979fe44b83fd86822235350e12eda8f51

If U+FE0E is appended to the emoji code point, the glyph should have a
text presentation.
On the other hand, if U+FE0F is appended to the emoji code point, the
glyph should have an emoji presentation.

Bug: 11256006
Change-Id: I5187d44500b13a138e7ffbcf2c72e2da06374c8c

To optimize the font family search, mRanges is used for narrowing down
the search range. However, mRanges is constructed from format 4 or
format 12 entries. So, if the font supports a variation sequence but doesn't
support the base character of the sequence, the font may not be listed in
mRanges.

The proper way to fix this issue is using format 14 subtable information
for mRanges construction. However, this is not a trivial work since currently
we rely on HarfBuzz for variation sequence lookup and it doesn't provide any
API for retrieving coverage information.

Thus, as the quick fix, iterate all font families in font fallback chain if
the variation sequence is specified.

Change-Id: I278da84be8fb8f553590e2e42ed450b7e4a34eca

To implement Paint.hasGlyph(), we need a new method to ask the
FontCollection if it has a glyph for the code point and variation
selector pair.

Bug: 11256006
Change-Id: Ie4185c91bcaa4d01aee6beb97784b1f9d2a88f12

This patch basically ignores variation selectors for the purpose of
itemization into font runs. This allows GSUB to be applied when input
sequences contain variation selectors.

Bug: 25368653
Change-Id: I9c1d325ae0cd322c21b7e850d0ec4d73551b2372

This issue was introduced by I22ce0e9eadc941f84e3a9b23462f194e51dd7180.
Need to decrement the two utf16 chars in KEYCAP handling.

To add unit tests, this CL also addresses the Bug: 24184208 by
introducing self built fonts since there is no good example in system
installed fonts.

Bug: 24184208
Change-Id: I23fa008adbaced78a3cb96442a6bc8892ab84ce8

This patch basically ignores variation selectors for the purpose of
itemization into font runs. This allows GSUB to be applied when input
sequences contain variation selectors.

Bug: 25368653
Change-Id: I9c1d325ae0cd322c21b7e850d0ec4d73551b2372

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

This CL contains the following changes:
- Add a variation selector argument into getFamilyForChar to be able to
  select fonts which support variation selector.
- In case no fonts support the codepoint and variation selector pair,
  add a fallback rule which selects font family with ignoring variation
  selector.
- Change FontCollection::itemize to not change the font family
  immediately preceding a variation selector.
- Introduce unit tests for variation selectors.

With this CL, TextView can render the variation selectors correctly.

Bug: 11256006
Change-Id: I22ce0e9eadc941f84e3a9b23462f194e51dd7180

This CL introduces new method hasVariationSelector into FontFamily but it
is not used in production code. So no behavior changes are expected.

This CL contains the following changes:
- Introduce hasVariationSelector which returns true if the corresponding
  font has a glyph for a code point and variation selector pair.
- Introduce purgeHbFontCache since hb_face_t won't be released by
  keeping hb_font_t.
- Introduce unit tests with self-built font.

Change-Id: I659a6d03d9ec446b409e1fba2758452abb9f44fa

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

For build-system CFLAGS clean-up, fix unused variables.

Reorder initializer list to initialize in the order of member
declarations.

Change-Id: I64358b2dcf0e39d0f4e18fdc3473de867f84fcba

This will significantly reduce memory usage and also speed the creation
of new font families. In particular, the coverage bitmaps for the fonts
in the fallback stack will be computed once in the Zygote, rather than
separately in each app process.

Bug: 17756900
Change-Id: I66f5706bddd4658d78fe5b709f7251ca9d2ff4f8

This will significantly reduce memory usage and also speed the creation
of new font families. In particular, the coverage bitmaps for the fonts
in the fallback stack will be computed once in the Zygote, rather than
separately in each app process.

Bug: 17756900
Change-Id: I66f5706bddd4658d78fe5b709f7251ca9d2ff4f8

This patch finds an appropriate fallback font in the case where no font
directly maps the requested character, but a font does exist for the
character's canonical decomposition. This yields correct rendering of
compatibility characters such as U+FA70.

Bug: 15816880
Bug: 16856221
Change-Id: Idff8ed6b942fec992a0815a32028b95af091d0ee

The U+20E3 COMBINING KEYCAP is used in our fonts to generate an emoji
rendering of ASCII numbers and letters through GSUB.  For that to work
we need to choose the same (Emoji) font for the character coming
*before* the COMBINING KEYCAP character.

This is a special-case of a broader need to choose fonts per grapheme
cluster as opposed to per character, but for now, special-case U+20E3.

Bug: 7557244
Change-Id: I958e5a01068df8495bbb9bc3b9ed871cea1838b6

When a run has no cmap coverage in any font, use the base font. Most of
the time, this will cause rendering of the .notdef glyph, which is
preferable to displaying nothing. In some cases, Harfbuzz may be able to
decompose the characters (not in the cmap) to ones that are, in which
case we'll render those, as long as they're in the base font.

Bug: 6629748
Bug: 15816880
Change-Id: Ibb1b9242c83626e0c7db363ad65ce44a967a005e

Fixes b/15734816 In the text "Wi-Fi", "-Fi" appears bolder than "Wi"

The problem was caused by "stickiness" in choosing fonts, where layout
would prefer using a font used for preceding characters as long as it
mapped the following characters in a run, in favor of the "best match"
rules. This patch adds a whitelist for making the stickiness more
conservative, only applying it for characters necessary for correct
shaping (ZWJ and ZWNJ in particular) and basic punctuation, where it is
desirable to match the style of the preceding text.

Change-Id: I1cf116879f074a5a71c351846707bfdd07b0d320

Fix for bug 15570313 "Missing text on nonexistent font file"

This patch makes sure that the lastChar and mInstances arrays are in
sync with each other even when a FontFamily being added has no valid
fonts in it. Previously, when they got out of sync, unicode coverage
calculation would be wrong, resulting in missing text.

Change-Id: I69c727ef69e2c61e2b2d6b81d5a28c806327f865

This patch adds support for computing when fake bold and fake italics
are needed (because the styles are requested but not provided by the
matching FontFamily), and providing them as part of the layout result.

Part of the fix for bug 15436379 Fake bold doesn't fully work (Minikin)

Change-Id: I180c034b559837943673b5c272c8e890178dff0d

This patch adds a method to retrieve the base font from a
FontCollection, which is useful when querying global font metrics.

Part of the fix for bug 15467288 "Inconsistent line heights on
Minikin builds"

Change-Id: I268ae5128d0852a020d746bc22af81fc1a623228

This patch adds support for computing when fake bold and fake italics
are needed (because the styles are requested but not provided by the
matching FontFamily), and providing them as part of the layout result.

Part of the fix for bug 15436379 Fake bold doesn't fully work (Minikin)

Change-Id: I180c034b559837943673b5c272c8e890178dff0d

This patch adds a method to retrieve the base font from a
FontCollection, which is useful when querying global font metrics.

Part of the fix for bug 15467288 "Inconsistent line heights on
Minikin builds"

Change-Id: I268ae5128d0852a020d746bc22af81fc1a623228

This is a fix for bug 15185229 ZWJ not working in Sinhala and Kannada.

Indic fonts (unlike Arabic) require the entire string, including ZWJ,
to be passed to Harfbuzz; it's not enough for the ZWJ to be present in
the context. The solution is to be "sticky" in font itemization,
continuing to use the same font as long as it has Unicode coverage.

Change-Id: I7673bc56fbda09f1e1a4582e8d88342343b706f1

This patch adds a "lang" pseudo-CSS property and uses it both to select
an appropriate font and control the "locl" OpenType feature to get the
most appropriate rendering for the langauge and script.  In addition,
the "-minikin-variant" property selects between "compact" and "elegant"
variants of a font, as the former is needed for vertically cramped
spaces.

This is part of the fix for bug 15179652 "Japanese font isn't shown on
LMP".

Change-Id: I7fab23c12d4c797a6d339a16e497b79a3afe9df1

This patch adds caching for both layouts and for HarfBuzz face objects.
The granularity of the cache for layouts is words, so it splits the
input string at word boundaries (using a heuristic). There are is also
some refactoring to reduce the amount of allocation and copying, and
movement towards properly supporting contexts.

The size of the caches is a fixed number of entries; thus, it is
possible to consume a large amount of memory by filling the cache with
lots of large strings. This should be refined towards a scheme that
bounds the total memory used by the cache.

This patch fixes bug 15237293 "Regression: Measure performance is
significantly slower with minikin".

Change-Id: Ie8176857e2d78656ce5479a7c04969819ef2718d

This is a fix for bug 15171911 Timely crashes (native crash in
libminikin) when I go to add a new alarm

This patch fixes an off-by-one error that caused typefaces with only one
page of Unicode coverage (ASCII or Latin-1) to have nPages = 0 instead
of the correct value of 1 in the corresponding FontCollection.

Change-Id: Id8be0c9e5713b8af22d863992921ee6382416a34

This patch adds caching for both layouts and for HarfBuzz face objects.
The granularity of the cache for layouts is words, so it splits the
input string at word boundaries (using a heuristic). There are is also
some refactoring to reduce the amount of allocation and copying, and
movement towards properly supporting contexts.

The size of the caches is a fixed number of entries; thus, it is
possible to consume a large amount of memory by filling the cache with
lots of large strings. This should be refined towards a scheme that
bounds the total memory used by the cache.

Change-Id: Ie8176857e2d78656ce5479a7c04969819ef2718d

These changes were supposed to be committed in the previous patch
"Better refcounting and locking" but seem to have gotten lost in a
rebase. It fixes a memory leak and some possible race conditions.

Change-Id: I54ca1e37500ec49756fe317cc6d6d03da9911501

These changes were supposed to be committed in the previous patch
"Better refcounting and locking" but seem to have gotten lost in a
rebase. It fixes a memory leak and some possible race conditions.

Change-Id: I54ca1e37500ec49756fe317cc6d6d03da9911501

All major externally accessible objects (especially FontFamily and
FontCollection) are now reference counted. In addition, there is a
global lock intended to make operations thread-safe.

WIP notice: in this version of the patch, not all external API entry
points are protected by the lock. That should be fixed.

Change-Id: I14106196e99eb101e8bf1bcb4b81359759d2086c

This patch improves script run itemization and also exposes metrics
and bounds for layouts. In addition, there is a fair amount of internal
cleanup, including ref counting, and making the MinikinFont abstraction
strong enough to support both FreeType and Skia implementations. There
is also a sample implementation using Skia, in the sample directory.

As part of its functionality, his patch measures the bounds of the
layout and gives access through Layout::GetBounds().  The corresponding
method is not implemented in the FreeType-only implementation of
MinikinFont, so that will probably have to be fixed.

Change-Id: Ib1a3fe9d7c90519ac651fb4aa957848e4bb758ec