Module third_party

Third party licenses service and types.

Rust projects depend on many crated with a variety of licenses, some of these licenses require that they must be displayed in the app binary, usually in an “about” screen. This module can be used together with the zng_tp_licenses crate to collect and bundle licenses of all used crates in your project.

The LICENSES service serves as an aggregation center for licenses of multiple sources, the OPEN_LICENSES_CMD can be implemented on_pre_event to show a custom licenses screen, or it can just be used to show the default screen provided by the default app.

Bundle Setup

Follow these steps to configure your crate and build workflow to collect and bundle crate licenses.

Install cargo about

To collect and bundle licenses in your project you must have cargo-about installed:

cargo install cargo-about

Next add file .cargo/about.toml in your crate or workspace root:

# cargo about generate -c .cargo/about.toml --format json --workspace --all-features

accepted = [
    "Apache-2.0",
    "MIT",
    "MPL-2.0",
    "Unicode-DFS-2016",
    "BSL-1.0",
    "BSD-2-Clause",
    "BSD-3-Clause",
    "ISC",
    "Zlib",
    "CC0-1.0",
]

ignore-build-dependencies = true
ignore-dev-dependencies = true
filter-noassertion = true
private = { ignore = true }

Next call the command to test and modify the accepted config:

cargo about generate -c .cargo/about.toml --format json --workspace --all-features

If the command prints a JSON dump you are done with this step.

Add zng-tp-licenses

Next, add dependency to the zng_tp_licenses your crate Cargo.toml:

[package]
resolver = "2" # recommended, to not include "build" feature in the normal dependency.

[features]
# Recommended, so you only bundle in release builds.
#
# Note that if you use a feature, don't forget to build with `--features bundle_licenses`.
bundle_licenses = ["dep:zng-tp-licenses"]

[dependencies]
zng-tp-licenses = { version = "0.2.9", features = ["bundle"], optional = true }

[build-dependencies]
zng-tp-licenses = { version = "0.2.0", features = ["build"], optional = true }

Implement Bundle

Next, in your crates build script (build.rs) add:

fn main() {
    #[cfg(feature = "bundle_licenses")]
    {
        let licenses = zng_tp_licenses::collect_cargo_about("../.cargo/about.toml");
        zng_tp_licenses::write_bundle(&licenses);
    }
}

Implement a function that includes the bundle and decodes it. Register the function it in your app init code:

#[cfg(feature = "bundle_licenses")]
fn bundled_licenses() -> Vec<zng::third_party::LicenseUsed> {
    zng_tp_licenses::include_bundle!()
}

APP.defaults().run(async {
    #[cfg(feature = "bundle_licenses")]
    zng::third_party::LICENSES.register(bundled_licenses);
});

Review Licenses

Call the OPEN_LICENSES_CMD in a test button, check if all the required licenses are present, cargo about and zng_tp_licenses are a best effort only helpers, you must ensure that the generated results meet yours or your company’s legal obligations.

use zng::prelude::*;

fn review_licenses() -> impl UiNode {
    // zng::third_party::LICENSES.include_view_process().set(false);

    Button!(zng::third_party::OPEN_LICENSES_CMD)
}

Limitations

Only crate licenses reachable thought cargo metadata are included. Static linked libraries in -sys crates may have required licenses that are not included. Other bundled resources such as fonts and images may also be licensed.

The LICENSES service accepts multiple sources, so you can implement your own custom bundle, the zng_tp_licenses crate provides helpers for manually encoding (compressing) licenses. See the zng-view build script for an example of how to include more licenses.

Full API

See zng_app::third_party and zng_tp_licenses for the full API.

Structs

• LICENSES
  Third party licenses.
• License
  Represents a license id, name and text.
• LicenseUsed
  Represents a license and dependencies that use it.
• User
  Represents a project or package that uses a license.
• UserLicense
  Represents a license user with license.

Statics

• OPEN_LICENSES_CMD
  Open or focus the third party licenses screen.