When the Android runtime starts, the system preloads a series of assets
in the Zygote process. These assets are shared across all processes.
Unfortunately, each one of these assets is later uploaded in its own
OpenGL texture, once per process. This wastes memory and generates
unnecessary OpenGL state changes.
This CL introduces an asset server that provides an atlas to all processes.
Note: bitmaps used by skia shaders are *not* sampled from the atlas.
It's an uncommon use case and would require extra texture transforms
in the GL shaders.
WHAT IS THE ASSETS ATLAS
The "assets atlas" is a single, shareable graphic buffer that contains
all the system's preloaded bitmap drawables (this includes 9-patches.)
The atlas is made of two distinct objects: the graphic buffer that
contains the actual pixels and the map which indicates where each
preloaded bitmap can be found in the atlas (essentially a pair of
x and y coordinates.)
HOW IS THE ASSETS ATLAS GENERATED
Because we need to support a wide variety of devices and because it
is easy to change the list of preloaded drawables, the atlas is
generated at runtime, during the startup phase of the system process.
There are several steps that lead to the atlas generation:
1. If the device is booting for the first time, or if the device was
updated, we need to find the best atlas configuration. To do so,
the atlas service tries a number of width, height and algorithm
variations that allows us to pack as many assets as possible while
using as little memory as possible. Once a best configuration is found,
it gets written to disk in /data/system/framework_atlas
2. Given a best configuration (algorithm variant, dimensions and
number of bitmaps that can be packed in the atlas), the atlas service
packs all the preloaded bitmaps into a single graphic buffer object.
3. The packing is done using Skia in a temporary native bitmap. The
Skia bitmap is then copied into the graphic buffer using OpenGL ES
to benefit from texture swizzling.
HOW PROCESSES USE THE ATLAS
Whenever a process' hardware renderer initializes its EGL context,
it queries the atlas service for the graphic buffer and the map.
It is important to remember that both the context and the map will
be valid for the lifetime of the hardware renderer (if the system
process goes down, all apps get killed as well.)
Every time the hardware renderer needs to render a bitmap, it first
checks whether the bitmap can be found in the assets atlas. When
the bitmap is part of the atlas, texture coordinates are remapped
appropriately before rendering.
Change-Id: I8eaecf53e7f6a33d90da3d0047c5ceec89ea3af0
Continuing to flesh out storage backends by adding an external
storage document backend. Still rough, but it can traverse files
and directories.
Early pass at OPEN/CREATE_DOC picker UI, which offers to traverse
any known storage backends. Supports opening subdirectories and
returning a picked file.
Change-Id: Idc3554036b3816a93d9b465ee8a620746859d2ae
Introduces new DocumentsContract which storage backends must
implement. Backends surface a simple directory-like organizational
structure that enables a document to appear at multiple locations in
that hierarchy. Querying a document or the contents of a directory
will return a Cursor populated with DocumentColumns, which includes
simple metadata.
Adds new OPEN_DOC and CREATE_DOC Intents, and permission to protect
storage backends.
Change-Id: Ib4984bc980182b2cedbe552908e5be94604ef085
I.e. don't bother trying to send a BOOT_COMPLETED broadcast to the
newly-installed/enabled system app when its host user isn't live.
Also use the static isSystemApp()-type helpers instead of duplicating
those tests locally.
Bug 8594153
Change-Id: I4bd0b86351d67f72c44eae8d1afce6a98f034d31
Before, we'd have something like 2006 4月12. After, we have 2006 4 12.
The alternative would require using custom NumberPicker.Formatter instances
for the year and day fields in these locales, and that seems significantly
more disruptive.
Bug: 8766552
Change-Id: I568578aae2f80f2acfc53cd277ef3beae6743472
