skia2/bazel/common_config_settings/BUILD.bazel
Kevin Lubick 8ed49ea6e3 [infra] Add Bazel rules for codecs.
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>
2021-11-11 20:10:01 +00:00

116 lines
3.0 KiB
Python

load(":defs.bzl", "string_flag_with_values")
# @platforms is found at https://github.com/bazelbuild/platforms
package(default_visibility = ["//:__subpackages__"])
config_setting(
name = "linux_x64",
constraint_values = [
"@platforms//cpu:x86_64",
"@platforms//os:linux",
],
)
config_setting(
name = "windows_x64",
constraint_values = [
"@platforms//cpu:x86_64",
"@platforms//os:windows",
],
)
config_setting(
name = "linux_arm64",
constraint_values = [
"@platforms//cpu:arm64",
"@platforms//os:linux",
],
)
config_setting(
name = "debug_build",
values = {"compilation_mode": "dbg"},
)
config_setting(
name = "release_build",
values = {"compilation_mode": "opt"},
)
constraint_value(
name = "fuchsia",
constraint_setting = "@platforms//os:os",
)
config_setting(
name = "fuchsia_arm64",
constraint_values = [
"@platforms//cpu:arm64",
":fuchsia",
],
)
# We define this here because the emscripten toolchain calls the cpu wasm, whereas the
# bazelbuild/platforms call it wasm32. https://github.com/emscripten-core/emsdk/issues/919
config_setting(
name = "cpu_wasm",
values = {
"cpu": "wasm",
},
)
# =============================================================================
# Configurable Skia Features
# =============================================================================
# These are flags that we can specify when invoking bazel build to turn on and
# off certain features, such as GPU backend, or codec support.
# https://docs.bazel.build/versions/4.2.1/skylark/config.html#using-build-settings-on-the-command-line
# For example, to use the GL backend with the WebGL flavor, one would run
# bazel build //:skia-core --//bazel/common_config_settings:gpu_backend=gl_backend \
# --//bazel/common_config_settings:with_gl_standard=webgl_standard
# This is a bit wordy, so we define aliases in the //.bazelrc file that condense this to
# bazel build //:skia-core --gpu_backend=gl_backend --with_gl_standard=webgl_standard
#
# Developers can specify their own short-hands by making a .bazelrc file in their home
# directory. https://docs.bazel.build/versions/main/guide.html#where-are-the-bazelrc-files
#
string_flag_with_values(
flag_name = "gpu_backend",
multiple = True,
values = [
"gl_backend",
"vulkan_backend",
],
)
string_flag_with_values(
flag_name = "with_gl_standard",
values = [
"gles_standard",
"gl_standard",
"webgl_standard",
],
)
string_flag_with_values(
default = "empty_fontmgr_factory",
flag_name = "fontmgr_factory",
values = [
"empty_fontmgr_factory",
"custom_directory_fontmgr_factory",
],
)
string_flag_with_values(
flag_name = "include_codec",
multiple = True,
values = [
"gif_codec",
"jpeg_codec",
"png_codec",
"raw_codec",
"webp_codec",
],
)