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

Some fonts contain a cmap segment for char 0xffff that contains an
invalid rangeOffset. This was rejected by the existing code, which
means the font is considered to have empty Unicode coverage. This patch
just discards the invalid segment (consistent with OpenType Sanitizer),
making the custom font display.

Bug: 18106256
Change-Id: Icc8616a3030f80e62db906332be64d434ae72ea2

The old logic for fake bolding results in no fake bolding for a bold
span on a light weight (300) because the target weight (600 in this
case) didn't meet the condition. This patch fine-tunes the threshold
to enable fake bolding for this.

Bug: 17587185

Change-Id: I04abd00a74240cbed79c417f81486aa2158b2806

Fractional advance widths were causing subtle problems with text
positioning when the same text was drawn with different spans in the
hwui renderer. Quantizing the coordinates on layout (as opposed to
waiting until the renderer draws the glyphs) solves the problem.

This patch also fixes a discrepancy between x position and advance
widths when letterspacing.

Bug: 17347779
Change-Id: Ia705944047408c2839d5ad078eefd6bbec446872

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

This reduces another allocation (last one?) we were doing when
fulfilling shaping requests from the cache.

Bug: 17111260
Change-Id: Ieb8ae1ccfcaacedb257e1e9263777f10623aaf98

C++ local var initialization always tricks me.  Previously, Layout
didn't have a constructor, which meant that defining it on the stack
left mAdvance uninitialized.  This was not an issue when we were doing
"new Layout()", since that invokes zero-initialization, but was an
issue for the skipCache path that was allocating layout on stack by
just "Layout l" instead of "Layout l = Layout()".  To avoid surprises,
add a constructors that clears everything.

Also adds reset() method to reset the layout for reuse.

Change-Id: I3e02f00da9dd7d360abe13f63c310f6882292d0a

Avoid copying the string for cache lookup.

Bug: 17111260
Change-Id: Ic220bfc991fc6b3dada197304aabdf72a8941bd7

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

Bug: 15246510
Change-Id: I544915d29b2be4fb9f82f1989188a3a918c50fbc

Was broken after recent CSS removal.

Change-Id: I160fbc73286b21336d6f3943ff92d7d150dff74b

We are stack-allocating MinikinPaint objects in Minikin clients, and
without a constructor adding new members to the struct cannot be done
without updating all clients (only one right now!).

Change-Id: I4170f16498bb6b07cb795495011aca58087ed0bd

All usage is ported to the new doLayout() API now.

Bug: 16651112
Change-Id: I2c959138a69853b5e30098889d771fe5f4cfaa66

New API removes CSS string and directly takes needed objects.

Bug: 16651112
Change-Id: Ie5f7c2ab05be6cbd77cae0a5fd6bb453771ada59

Replaces invalid unicode with replacement character U+FFFD and always
makes forward progress.

Bug: 15849380

Change-Id: Ic59ef6c64b0f5c4450bcae61597adcc269d6e7c5

Extract language from FontStyle during shaping.  Don't attach CSS
to LayoutContext.

Change-Id: Ie621d3415410178d0d15fa7b810eb8e412342ab6

It has been unused outside minikin.

Change-Id: Iaa2237767d81c77f90d0264e633375e601dd72f1

Bug: 15594400
Change-Id: Ied94d7674be4097b0f44c9b0770d3294dc6433c1

Bug: 15849380
Change-Id: Ib5285e57c5806bd399600fadd56e8bc809da323f

Change-Id: I50a112739847fa826088854f6d172a188ff4cfb3

Change-Id: I29a59edfe6102257c9f308aac1b4348ef7a18db7

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

Change-Id: Iffad3ef724b565d5d8fed17722630fd74cda9234

Proper Japanese layout requires sophisticated rules for spacing
punctuation, not just turning on the "palt" (proportional alternate)
feature. Until we can support the whole set, roll back palt.

Change-Id: If2359c529b70b1dd45dddc00e5f4aa1c91f8b0e9

Expose a method to purge caches used for TextLayout, useful for low
memory conditions.

Change-Id: I92f41afe987b7be4af5ca0a0c50fb51be35a2758

This patch includes an implementation of grapheme cluster breaking,
which is especially useful for repositioning the cursor for left and
right arrow key presses. The implementation is closely based on Unicode
TR29, and uses the ICU grapheme cluster break property, but is tailored
to more closely match the existing implementation and expected behavior.

Part of a fix for b/15653110 Improve behavior of arrow keys in EditText

Change-Id: I8eb742f77039c9ab7b2838285018cf8a8fc88343

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

* commit 'e68467e9':
  Tighten requirements for fake bold

* commit '15651697':
  Support for fake bold and italics

* commit 'b1eae5ea':
  Add baseFont method to FontCollection

The simple predicate for fake bold (2 or more grades darker than
requested) was applying it to thin (100 weight) when normal was
requested. This patch tightens the predicate to also require that
the requested weight be in the bold range.

Fix for bug 15588352 "sans-serif-thin doesn't work on lockscreen"

Change-Id: Id9988bd149a9c8a7c943e3b221f7fb4b37fb6ddb
(cherry picked from commit 9f9f3b1e)

The simple predicate for fake bold (2 or more grades darker than
requested) was applying it to thin (100 weight) when normal was
requested. This patch tightens the predicate to also require that
the requested weight be in the bold range.

Fix for bug 15588352 "sans-serif-thin doesn't work on lockscreen"

Change-Id: Id9988bd149a9c8a7c943e3b221f7fb4b37fb6ddb

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