skera

skera is a Rust library and binary for subsetting a font file according to provided input.

Installation

Library

To use skera in your Rust project, add it via cargo:

cargo add skera

CLI

To install the skera command-line tool, use cargo install with the cli feature enabled:

cargo install skera --features cli

Usage

CLI

To subset a font using the command-line tool:

skera --path <INPUT_PATH> --unicodes <UNICODES> --output-file <OUTPUT_PATH>

For a full list of available options and flags, run:

skera --help

Profiling

How-To: Profile a Skera Binary using Samply

Prerequisites

Install samply using Cargo:

cargo install samply

Step 1: Enable Debug Symbols in Release Profiles

Add the following configuration to your root Cargo.toml:

[profile.release]
debug = true

Step 2: Compile your crate using the release profile with the cli feature:

cargo build --release -p skera --features="cli"

Step 3: Record and Profile the Binary

Run the generated release executable using samply record. Replace with your compiled binary's name and <args...> with any execution arguments:

samply record target/release/skera <args...>

example:

samply record target/release/skera font-file --unicodes=* --output-file=out

Step 4: Analyze the Results

Once your binary finishes execution, samply automatically starts a local web server and prints a URL to the console:

Server listening on http://127.0.0.1:3000
Press Ctrl+C to stop.

Open the provided link in your web browser. The browser will open the Firefox Profiler interface, populated with your recorded run's call tree, flame graph, and timeline views.

Alternative Profiling Tools

If samply is not suitable for your target environment, you may consider these alternative options:

cargo-flamegraph: A tool that utilizes perf (on Linux) or dtrace (on macOS) to generate a static vector-graphic .svg flame graph.

cargo install cargo-flamegraph
cargo flamegraph -p skera --features="cli"

perf (Linux-only): The standard system profiler on Linux, useful for command-line profiling and capturing kernel-level events.

perf record -g -- target/release/skera
perf report