The primary goal of this organization structure is to keep
our top level BUILD.bazel file short, with as little logic
as feasible. The logic required to control which files to
include, which third_party deps are needed, what system libraries
should be linked again, etc, should be in the BUILD.bazel
file best should be as close to the affected files as feasible.
In essence, we use filegroup() rules to bubble up the files
needed to build Skia (all as one big cc_library call) and
cc_library rules to bubble up the other components needed to build.
For example, //src/ports/SkFontHost_FreeType.cpp needs FreeType,
but only if we are compiling Skia with that type of font
support. With the new organization structure in this CL,
//src/ports/BUILD.bazel should have the logic that determines
if the cpp file should be included in the build of Skia and
if it is, that the Skia build should depend on //third_party:freetype2
Another example is //src/gpu/ganesh/BUILD.bazel, which
chooses which of the dawn, gl, vulkan, etc backend sources,
and the associated dependencies to include in the build.
It does not specify what those are, but delegates to the
BUILD.bazel files in the subdirectories housing the
backend-specific code.
The structure guidelines for BUILD.bazel files are as follows:
- Have a filegroup() called "hdrs" (for public headers) or
"srcs" (for private headers and all .cpp files) that is
visible to the parent directory. This should list the
files from the containing directory to include in the
build.
See //include/core/BUILD.bazel and //src/effects/BUILD.bazel
as examples.
- filegroup() rules can list a child directory's "hdrs"
or "srcs" in their "srcs" attributes, but should not contain
select statements pertaining to child directory files.
See //include/gpu/BUILD.bazel and //src/gpu/ganesh/BUILD.bazel
as examples.
- May have a cc_library() called "deps". This can specify
dependencies, cc_opts, and linkopts, but not srcs or hdrs. [1]
See //src/codec/BUILD.bazel as an example. These should
be visible to the parent directory.
- "hdrs", "srcs", and "deps" for the primary Skia build
(currently called "skia_core") should bubble up through
//include/BUILD.bazel and //src/BUILD.bazel, one directory
at a time.
This CL demonstrates a very basic build of Skia with many features
turned off (CPU only, no fonts, no codecs). Follow-on CLs will
add to these rules as more targets are supported. See bazel/Makefile
for the builds that work with just this CL.
Suggested Review Order:
- //BUILD.bazel to see the very small skia_core rule which
delegates all the logic down stack. Note that it has a
dependency on //bazel:defines_from_flags which will set
all the defines listed there when compiling all the
.cpp and .h files in skia_core *and* anything that depends
on skia_core, but *not* //src:deps.
- //include/BUILD.bazel and other BUILD.bazel files in the
subdirectories of that folder. Note that the filegroups in
//include/private/... are called "srcs" to be similar to
how Bazel wants "private headers" to be in the "srcs" of
cc_library, cc_binary, etc. and only public headers are
to be in "hdrs" [2].
- //src/BUILD.bazel and other BUILD.bazel files in the
subdirectories of that folder. //src/gpu/ganesh/...
will be filled in for dawn, vulkan, and GL in the next CL.
- //PRESUBMIT.py, which adds a check that runs buildifier [3]
on modified BUILD.bazel files to make sure they stay
consistently formatted.
- //bazel/... to see the new option I added to make sksl
opt-in or opt-out, so one could build Skia with sksl,
but not with a gpu backend.
- Misc .h and .cpp files, whose includes were removed if
unnecessary or #ifdef'd out to make the minimal build
work without GPU or SkSL includes.
- //bazel/Makefile to see the builds that work with this CL.
[1] Setting srcs or hdrs is error-prone at best, because those
files will be compiled with a different set of defines than
the rest of skia_core, because they wouldn't depend on
//bazel:defines_from_flags.
[2] https://bazel.build/reference/be/c-cpp#cc_library.hdrs
[3] https://github.com/bazelbuild/buildtools/releases
Change-Id: I5e0e3ae01ad42d672506d5aad1239f2512188191
Bug: skia:12541
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/543977
Reviewed-by: Leandro Lovisolo <lovisolo@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
gazelle ended up being more liability than asset for our C++ rules.
It required devs to manually run the command frequently (and was
easy to forget until the CQ failed). The fact that we still had to
edit the source files (e.g. the "srcs" cc_libraries) meant that
the mixture between generated and hand-written caused some
tension (see include/third_party/vulkan for a good example).
The combination of gazelle and our IWYU enforcement added several
bits of churn without any real benefit. The generated rules
also didn't help identify cases where we were not keeping tight
boundaries (e.g. non-gpu code and gpu code).
Identifying third_party deps automatically ended up being trickier
than anticipated (see the deleted //third_party/file_map_for_bazel.json)
Using the "maximum set of dependencies" worked ok, but ended up
increasing build time unnecessarily. For example, compiling
CanvasKit for WebGL always needed to compile Dawn because
SkSLCompiler.cpp sometimes needs to include tint/tint.h.
Follow-up CLs will rebuild the BUILD.bazel rules without gazelle.
Note to Reviewers:
- The only file worth manually reviewing here is bazel/Makefile.
Change-Id: I36d6fc3747487fabaf699690780c95f1f6765770
Bug: skia:12541
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/543976
Reviewed-by: Leandro Lovisolo <lovisolo@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
G3 prefers license() first.
This was done mechanically with a big find/replace
Change-Id: I8c33c7bc10a6bec42e966cad81c259954e841811
Bug: skia:13211
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/535898
Reviewed-by: Ben Wagner <bungeman@google.com>
Ran the following commands:
find -name "BUILD.bazel" -exec sed -i -e '1iload("//bazel:macros.bzl", "cc_library", "exports_files_legacy")\nexports_files_legacy()' {} +
buildifier --lint=fix --mode=fix -r .
This had the effect of making sure we can export all of our
files in G3 (until we no longer have legacy targets) and
making all of our cc_libraries shim-able.
bazel/macros.bzl has the human-contributed changes, the rest
were mechanical.
Change-Id: I8e24e30e74b038cfd072cdbe4078bfd1d213dd46
Bug: skia:13211
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/535359
Reviewed-by: Ben Wagner <bungeman@google.com>
It's time to better organize //third_party/BUILD.bazel
This CL starts by moving the "third party" stuff we closely own.
Change-Id: I3e0be0044b790794e94f34af6202860ce0a7b7aa
Bug: skia:12541
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/531999
Reviewed-by: Ben Wagner <bungeman@google.com>
For importing into G3, this will simplify the regex needed
and allow us to stub out things not supported (e.g. gazelle)
Change-Id: I770f5dee6f29e555356742dae36212ad6cfb713a
Bug: skia:12541
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/529836
Reviewed-by: Ben Wagner <bungeman@google.com>
Change-Id: I238d29ba0250224fa593845ae65192653f58faff
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/528156
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
sk_app has existing support for Dawn on top of Vulkan, and
this adds support to build //example:hello_world_dawn and
get this to run on Linux.
Dawn depends on Tint and abseil-cpp. Tint further depends on
spirv_tools and spirv_headers (for writing to the SPIR-V format).
Dawn and Tint only have GN and CMake support, so we need to make
our Bazel rules for them (see //third_party/BUILD.bazel).
abseil-cpp and the SPIR-V libraries have Bazel support, so we
can just include them (see //WORKSPACE.bazel). It is important
that @spirv_headers be called that exactly because @spirv_tools
depends on it by that name.
The hand-crafted cc_library rules for Dawn and Tint were produced
by reading the appropriate GN files and using the parts necessary
for a supporting Vulkan+Linux. If we use Dawn for other backends
(e.g. WebGPU), we will need to expand the Bazel rules. One day,
we might contribute the Bazel rules to Dawn and Tint so they
can support them and avoid breaking us if new files are added.
Suggested Review Order
- bazel/common_config_settings/BUILD.bazel to see introduction
of new select-able option "has_gpu_backend" which cleans up
some of our code that is enabled for any GPU backend.
- src/*/BUILD.bazel to see has_gpu_backend rolled out.
- WORKSPACE.bazel to see DEPS declared there (using the files
in third_party/externals, which are brought in via
tools/git-sync-deps).
- third_party/BUILD.bazel which adds Dawn and Tint rules.
It may be helpful to look in third_party/externals for
the Dawn [1] and Tint [2] GN files. Especially interesting
are the Python scripts [3] Dawn uses to generate some
header and source files.
- All other files.
[1] https://dawn.googlesource.com/dawn/+/d9f22ce0346b222759d5510be3d1cd93caa5ab86/src/dawn/native/BUILD.gn#183
[2] https://dawn.googlesource.com/tint/+/453d5ae84ec30ab51ac592c13d472412ae8b5fc9/src/tint/BUILD.gn#174
[3] https://dawn.googlesource.com/dawn/+/d9f22ce0346b222759d5510be3d1cd93caa5ab86/generator/dawn_json_generator.py#774
Change-Id: Ied5b162045d8e841b9666457f0158457e2b078d4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/516996
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
PS 1 is re-generating existing BUILD.bazel files
PS 2 is generating BUILD.bazel files for tests/gms
PS 3+ makes modifications to build all of the gms and tests.
It is recommended to view this CL with just a diff between
PS 2 and the end, due to the large amount of generated changes
in PS 1 and 2.
We make a filegroup for the gms and tests because they need
to be compiled as one large blob in order for the registries
to work. Maybe in the future we will break these up, but at least
for WASM/JS, the overhead of starting a browser for each new
test would likely grind things to a halt, so we just group them
all together for now. It's also the most similar to what we
currently do.
In gm/BUILD.bazel and tests/BUILD.bazel, we add a cc_library
that encapsulates all of the deps of the tests, so we can
easily include that the build. These were discovered via
trial and error, not anything automatic or systematic.
The is_skia_dev_build config_setting is very similar to the
GN equivalent from which it was based.
The list of gms and tests to skip (e.g. which are incompatible
with WASM) was determined by building the wasm bundle:
modules/canvaskit$ make bazel_gms_release
tools/run-wasm-gm-tests$ make run_local_debug
# Don't forget to click the button on the screen after the
# browser loads
This way of invoking the tests will be replace soon with
`bazel test <something>`. As such, I didn't bother fully
documenting the current way.
Suggested review order:
- modules/canvaskit/BUILD.bazel taking note that we always
use profiling-funcs to make the stacktraces human readable.
- gm/BUILD.bazel and tests/BUILD.bazel to see the lists of
gms/tests. Notice the tests are roughly partitioned because
we don't support things like vulkan/PDF in the wasm build
and we will want a way to not build certain tests for
certain configurations
- tools/* noting some of the cc_libraries added to make
dependencies easier to add when needed.
- All other files.
Change-Id: I43059cd93c28af1c4c12b93d6ebd9c46a12d381f
Bug: skia:12541
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/506256
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
- Use latest emscripten toolchain (3.1.0)
- Autogenerate the atoms and manually fix some of the file lists.
- Add a known_good_builds target to bazel/Makefile to help
check the things we expect to work with Bazel.
Change-Id: Ia5f51e7b9eb5c108386820ad59180c8f862f5a70
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/491438
Reviewed-by: Ben Wagner <bungeman@google.com>
To make the atomic rules a bit easier to work with, in many
of the folders, this adds in cc_library rules to group
together the sources from that folder (and subfolders
where prudent). We only needs sources because those atoms
should have their headers as deps.
One issue that was pointed out is that there is currently
no way to restrict the inclusion of certain packages,
a la, `gn check`. For example, there is no mechanism from
stopping a dev from adding
#include "modules/canvaskit/WasmCommon.h"
to something in //src/core (except circular dependencies).
We can probably address that using Bazel's visibility
rules as needed:
https://docs.bazel.build/versions/main/visibility.htmlhttps://docs.bazel.build/versions/main/be/functions.html#package_group
It is recommended to look at this CL patchset by patchset.
PS1: Update gazelle command to generate rules in more folders.
PS2: A few changes to make generation work better.
PS3: The result of running make generate in //bazel
PS4: Adding the rules to build sksllex, the simplest binary I
could find in the Skia repo.
PS5: Adding the rules to build skdiff, a more complex binary.
I tried a few approaches, but ended up gravitating back
towards the layout where we have each folder/package
group up the sources. I imagine at some point, we'll have
skdiff depend on skia_core or something, which will
have things like //src/core, //src/codecs, //src/pathops
all bundled together.
PS7: Added in the groupings of sources, similar to what we had
earlier. I liked these for readability. These helped fix
up the //:skia_core build, and by extension, the CanvasKit
build.
Change-Id: I3faa7c4e821c876b243617aacf0246efa524cbde
Bug: skia:12541
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/476219
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Leandro Lovisolo <lovisolo@google.com>
This adds a simple go program to test the installed go
toolchain, and a Make rule to codify the arguments to
our gazelle binary, built with extensions.
I could not figure out how to get the .json file to work
with the gazelle() Bazel rule, but this works ok for now.
Bug: skia:12541
Change-Id: I5067b15c7518951aeb69559d3871799d3b5745f4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/475716
Reviewed-by: Leandro Lovisolo <lovisolo@google.com>
Importantly, this adds options for encoding using
certain codecs, not just decoding.
Change-Id: I4a610ebf985b67d4545c71b3f3eed4c7807e6a26
Bug: skia:12541
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/472277
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Leandro Lovisolo <lovisolo@google.com>
This re-works src/ports/BUILD.bazel to work like our other
BUILD files, i.e. one rule "srcs" that brings in the necessary
private filegroups.
To work around an abort with LLVM [1], we have to go back to an
earlier version of emscripten (temporarily?).
Future work should look at using transitions [2] to allow various
executables (e.g. CanvasKit, DM) to set their own set of Bazel
flags, w/o the build invokers having to specify them.
These transitions might be able to handle more complex cases
that we currently use if statements in GN to deal with.
The Freetype build rule was created by taking the BUILD.gn
rule, adding in all the sources listed there and then playing
compile-whack-a-mole to add in all the headers and included
.c files.
Suggested Review Order:
- third_party/BUILD.bazel to see freetype build rules
- bazel/common_config_settings/ to see treatment of fontmgr
like codecs (many possible) and fontmgr_factory (only one).
- src/ports/BUILD.bazel
- BUILD.bazel
- modules/canvaskit/BUILD.bazel. Take note of the gen_rule that
calls tools/embed_resources.py to produce the .cpp file
containing the embedded font data.
- Everything else.
[1] https://github.com/emscripten-core/emscripten/issues/15528
[2] https://github.com/bazelbuild/examples/tree/main/rules/starlark_configurations/cc_binary_selectable_copts
Bug: skia:12541
Change-Id: I08dab82a901d80507007b354ca20cbfad2c2388f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/471636
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Leandro Lovisolo <lovisolo@google.com>
Many things are not enabled currently (e.g. Skottie, Paragraph),
but we can render many APIs using WebGL.
To turn on Paragraph, etc, we'll need to tackle fonts, which
is a separate effort.
This also changes where the build artifacts go. ./build/ is
easier to deal with than the old way of sticking them in
./npm_build/bin
Change-Id: Ia377360af580a887d03630670438fea2e3157e90
Bug: skia:12541
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/470682
Reviewed-by: Leandro Lovisolo <lovisolo@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
This ports the third_party BUILD.gn files related to codecs
(with a best-effort on arm/SIMD stuff). This includes:
- libpng
- libjpeg-turbo
- libwebp
- wuffs (gif)
- libgifcodec
- dng_sdk and piex (raw codec)
This expands the string_flag_with_values macro to allow
multiple values to be set at once. This was added in Bazel 5.0.0,
however the latest pre-release version of that has a bug [1]
which slows down compilation dramatically. This was fixed at
ToT, but not released. As a result, I started using the Bazel
6 pre-release (via bazelisk).
The macro select_multi makes writing select() where multiple
elements could be on possible/easier.
One can try compiling certain codecs by running:
bazel build :skia-core --config clang --include_codec=raw_codec --include_codec=png_codec
Suggested Review Order:
- bazel/macros.bzl
- bazel/common_config_settings/defs.bzl and its BUILD.bazel
to see how the codec options are defined.
- BUILD.bazel to see how the codec settings are used.
- src/codec/BUILD.bazel to see the inclusion of Skia files to
deal with specific codecs.
- third_party/BUILD.bazel (while referencing the corresponding
BUILD.gn files, such as third_party/libwebp/BUILD.gn)
- Everything else.
Change-Id: I797375a35fa345d9835e7b2a2ab23371c45953c3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/469456
Reviewed-by: Leandro Lovisolo <lovisolo@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
These rules can be used to build our GMs on WASM+WebGL and
libskia.a with just the CPU backend (and most other features
turned off).
This can be done with the following commands:
- bazel build //modules/canvaskit:gm-bindings-wasm --gpu_backend=gl_backend --with_gl_standard=webgl_standard
- bazel build :skia-core --config clang
This pivots slightly from http://review.skia.org/463517
by using config_settings [1] instead of platforms for
the optional features that we control. This pivot was
suggested in [2]
We have BUILD.bazel files in many of the subdirectories
that specify filegroups for the appropriate files. In
an effort to make //BUILD.bazel more readable, it is
the responsibility of these subfolders to deal with
conditionally including certain .h or .cpp files.
This is done using select statements and config_settings
or platform constraints as necessary.
For example, src/gpu/BUILD.bazel will different private
filegroups for each of the supported gpu backends [3]
and a more-visible filegroup called "srcs" that has
the right selection of the private files to be used
for compilation.
An effort has been made to avoid using glob() in our
BUILD.bazel files. These file lists were made by using
`ls -1` and some regex to add in quotes. We might want
to make a helper script to assist with that, if necessary.
To specify which options we have, the settings in
//bazel/common_config_settings/BUILD.bazel have been
redesigned. They make use of a macro `string_flag_with_values`
that removes the boilerplate. Patchset 36 shows what the
file looks like w/o the macro.
The top level BUILD.bazel file will still need to use
some logic to handle defines, because local_defines is
a list of strings, not a list of labels [4].
Suggested Review Order:
- WORKSPACE.bazel to see the new dependencies on the
emsdk toolchain and bazel_skylib
- bazel/common_config_settings/* to see the few settings
defined (we have more to define, see BUILD.gn and
//gn/skia.gni for ideas)
- BUILD.bazel to see the "skia-core" cc_library rule.
See also "gms" and "tests"
- modules/canvaskit/BUILD.bazel to see the use of
the emscripten "wasm_cc_binary" rule, which depends
on the "skia-core", "gms", and "tests" rule. Note that
it only builds some of the gms as a proof of concept.
- The other BUILD.bazel files. Some of these are not
platform or feature dependent (e.g. pathops). Others
are (e.g. gpu).
- All other files.
[1] https://docs.bazel.build/versions/4.2.1/skylark/config.html#user-defined-build-settings
[2] https://github.com/emscripten-core/emsdk/pull/920
[3] In this CL, that's just the webgl one.
[4] https://docs.bazel.build/versions/main/be/c-cpp.html#cc_library.local_defines
Change-Id: Ieecf9c106d5e3a6ae97d13d66be06b4b3c207089
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/458637
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Leandro Lovisolo <lovisolo@google.com>
Owners-Override: Kevin Lubick <kjlubick@google.com>
This makes use of Bazel's pre-defined platforms
https://github.com/bazelbuild/platforms
and some of our own defined values (see
//bazel/common_config_settings/BUILD.bazel) to customize
the build rules.
I verified this by building bazel_test locally for
linux x64 as well as using the third_party deps for
a WASM build (using build files not seen in this CL).
Suggested Review Order:
- https://docs.bazel.build/versions/main/platforms.html if not
already familiar with Bazel Platforms
- third_party/BUILD.bazel to see that 1) all globs have
been removed and 2) select() targets various
platform constants or groups of constants to control
sources, headers, and local_defines.
- common_config_settings/ to see the groups of constraints
created, as well as new constraint_settings defined
(skdebug_impl)
- supported_combinations/ to see how we can define supported
sets of the constraint values (aka Bazel platforms).
I imagine expanding this more, so we might have platforms
named "linux_x64_emptyfontmgr_vulkan" or such.
- //BUILD.bazel and bazel_test.cpp to see use of SkDebugf.
- Everything else.
Change-Id: I49e4abdbcf7b76f0674efdbb1f53dc8823d110ee
Bug: skia:12541
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/463517
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Leandro Lovisolo <lovisolo@google.com>
Owners-Override: Kevin Lubick <kjlubick@google.com>
This can successfully build a C library:
bazel build --config=clang //third_party:libpng
This can build and run a statically-linked executable:
bazel test --config=clang //:bazel_test
For more verbose compile and linking output, add the
`--features diagnostic`
flag to a Bazel command (see _make_diagnostic_flags() in
toolchain/clang_toolchain_config.bzl. Similarly, a
`--features print_search_dirs` can be used to show where
clang is looking for libraries etc to link against.
These features are made available for easier debugging.
Suggested review order:
- Read https://docs.bazel.build/versions/4.2.1/tutorial/cc-toolchain-config.html
if unfamiliar with setting up C++ toolchains in Bazel
- .bazelrc and WORKSPACE.bazel that configure use and download
of the toolchain (Clang 13, musl 1.2.2)
- toolchain/build_toolchain.bzl which downloads and assembles
the toolchain (w/o installing anything on the host machine)
- toolchain/BUILD.bazel and toolchain/*trampoline.sh to see
the setup of the toolchain rules.
- toolchain/clang_toolchain_config.bzl to see the configuration
of the toolchain. Pay special attention to the various
command line flags that are set.
- See that tools/bazel_test.cc has made a new home in
experimental/bazel_test/bazel_test.cpp, with a companion
BUILD.bazel. Note the addition of some function calls
that test use of the C++ standard library.
The number being used to test the PNG library is the latest
and greatest that verifies we are compiling the one brought
in via DEPS (and not a local one).
- third_party/* to see how png (and its dependent zlib) have
been built. Pay special attention to the musl_compat hack
to fix static linking (any idea what the real cause is?)
- //BUILD.bazel to see definition of the bazel_test executable.
Change-Id: I7b0922d0d45cb9be8df2fd5fa5a1f48492654d5f
Bug: skia:12541
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/461178
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Leandro Lovisolo <lovisolo@google.com>
A few first steps toward a Bazel build.
To try it out, I think just
$ bazel test ...
I added third_party to .bazelignore to prevent Bazel from looking there.
It can handle external dependencies itself, so no need to poke into what
we sync from DEPS. Some of those have Bazel configs and we don't want
to be building them yet.
I've started by with libpng using new_git_repository(), mostly because
it's small, with a mildly complex build, and needs dependencies of its
own, zlib. Mysteriously zlib is built-in to Bazel, so that was easy.
Next up is probably a dependency that does support Bazel, using
git_repository(). That should make sure we can handle the full mix.
Change-Id: I5775a1b254d341b9a90630aa1cc433a24167f2fd
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/316636
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Joe Gregorio <jcgregorio@google.com>
