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Packaging

The generated JSON file from the previous section must be bundled together with the Fuchsia program so that it can be found at program runtime. See: Provide data files to components.

We have established some conventions for packaging resources (i.e. localized assets). The schema is intended to be extensible to other asset types, and also to be able to support combinations of asset types, which are sometimes useful to have when expressing more complex relationships between device and locale (a Hebrew icon version for a 200dpi display). All paths below are relative to the package's data directory and are found under /pkg/data on a running system.

Path Description
assets/ Stores all assets. This is similar to how the meta/ directory contains package manifests and other metadata. In the future, this directory could contain conventional indices.
assets/locales Stores data specifically for locales
assets/locales/fr-fr Stores data for particular locales. The locale names are individual directories in BCP47 format. Each program contributes a single JSON file to this directory, named program.json, where the program part of the name is chosen by the author. We will, at some point, probably need to ensure that package and library names for files here do not collide. Also, due to Fuchsia's packaging strategy, it may pay to have many smaller files storing translations instead of one large one, for ease of update.

The integrity of the path structure and proper packaging of localized resources still needs to be done manually.

Packaging localized resources

Packaging localized resources is best illustrated with an example. Let us start with the BUILD.gn file and we can focus on particular sections later.

# Copyright 2020 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import("//build/components.gni")

import("//build/intl/intl_strings.gni")


group("example") {
  testonly = true
  deps = [ ":pkg" ]
}


executable("src_intl_example_bin") {
  sources = [ "main.cc" ]
  output_name = "src_intl_example"

  deps = [
    "//sdk/lib/syslog/cpp",
    "//src/lib/intl/lookup/cpp:lib",
    "//third_party/googletest:gtest_prod",

    # This is the underlying generated FIDL code, must be included so that
    # its settings make it to the -I flag for compiler invocation.
    # Generate all needed intermediate resources.
    ":fuchsia.intl.l10n",
    ":l10n",
  ]

}


fuchsia_unittest_package("pkg") {
  package_name = "src-intl-example"
  component_name = package_name
  manifest = "meta/src-intl-example.cmx"

  deps = [
    # The binary to bundle in the package
    ":src_intl_example_bin",
  ]

  deps += [
    # These declaration works, but need to be maintained manually.  Work is
    # underway to make the "package" target collect and apply the locale files
    # automatically.
    ":en-strings",
    ":es-strings",
    ":fr-strings",

    # Contains the necessary ICU data.
    "//src/intl:icudtl",
  ]

}

resource("en-strings") {
  data_deps = [ ":l10n" ]
  sources = [ "$target_gen_dir/en/l10n.json" ]
  outputs = [ "data/assets/locales/en/l10n.json" ]
}

resource("fr-strings") {
  data_deps = [ ":l10n" ]
  sources = [ "$target_gen_dir/fr/l10n.json" ]
  outputs = [ "data/assets/locales/fr/l10n.json" ]
}

resource("es-strings") {
  data_deps = [ ":l10n" ]
  sources = [ "$target_gen_dir/es/l10n.json" ]
  outputs = [ "data/assets/locales/es/l10n.json" ]
}


intl_strings("l10n") {
  source = "strings.xml"
  source_locale = "en"
  output_locales = [
    "en",
    "fr",
    "es",
  ]
  library = "fuchsia.intl.l10n"
}

Build rule to generate the localized resources

Localized resources are based on the files on the filesystem. An example program at //src/lib/intl/example shows how you can build and deploy a Fuchsia program that contains localized messages.

intl_strings("l10n") {
  source = "strings.xml"
  source_locale = "en"
  output_locales = [
    "en",
    "fr",
    "es",
  ]
  library = "fuchsia.intl.l10n"
}

The build rule intl_strings instructs the build system to process the XML files containing strings. Refer to the section on message translation to learn more about the translation workflow. The translated messages are available in the default build output directory for this rule. The line source = "strings.xml" points to the file containing the message sources. Since these messages are always written using a spoken language, and since no particular language is more relevant than others, you also need to let the system know the language that the default strings.xml is written in.

To set the default language to English, in your BUILD.gn add source_locale = "en". The declaration of output locales allow you to specify the exact list of locale resources that you want generated. This is what output_locales is used for. This explicit declaration is for several reasons:

  • You want to have an explicitly declared list of locales you require for your program to be available at runtime.

  • The build system requires that the input and output files be declared explicitly for build correctness reasons. Since the input and output file names are generated based on the locales, the locale declaration is enough to handle this issue.

For example, if the original file name is strings.xml and the locale fr is listed in the output_locales, the build system expects a file named strings_fr.xml. These resources will need to be packaged with the binary into a Fuchsia package.

deps += [
  # These declaration works, but need to be maintained manually.  Work is
  # underway to make the "package" target collect and apply the locale files
  # automatically.
  ":en-strings",
  ":es-strings",
  ":fr-strings",

  # Contains the necessary ICU data.
  "//src/intl:icudtl",
]

Make sure to package the JSON resource into the correct directory. For translated messages, the correct directory path would be assets/locales/fr/l10n.json for the translated messages for French. It is also required to package the ICU data, is defined in the icudtl.dat section.