libpng を Homebrew, apk, dnf, MacPorts, Nix, pacman, zypper でインストール

プロジェクトリンク

• ホームページ
• リポジトリ
• 上流ドキュメント
• パッケージマネージャページ

コマンドとエイリアス

• libpng-config
• libpng16-config
• png-fix-itxt
• pngfix

プロジェクトの歴史

libpng began in 1995 during the early PNG effort, when the image format was designed as a patent-unencumbered replacement path for GIF-era workflows. The upstream README credits Guy Eric Schalnat as the original author and former maintainer, followed by Andreas Dilger, Glenn Randers-Pehrson, and Cosmin Truta.

The README's historical notes say libpng was in extensive use and testing from mid-1995, that 0.89 was the first official release in 1996, and that 1.0.0 was released in March 1998 after API churn had settled. Later history focused on keeping the public API stable while hiding internal structures and moving callers toward accessor functions.

採用の歴史

libpng's adoption follows PNG itself: once PNG became a web and graphics interchange staple, the reference library became a common dependency for image viewers, browsers, toolkits, converters, and build systems.

The upstream home page emphasizes that libpng supports almost all PNG features, is extensible, and has been tested for more than 30 years. That longevity is why distributions treat it as base image infrastructure rather than an optional graphics experiment.

使われ方

Developers use libpng to read, inspect, transform, and write PNG streams from C and C-compatible languages. The package also ships small tools such as `pngfix` and config helpers used by builds.

The manual, example.c, pngtest.c, and bundled test images make libpng both a production library and a reference implementation that other encoders and decoders can compare against.

パッケージ好きにとっての重要性

libpng is one of the canonical small C libraries that sits underneath a surprising amount of desktop, web, and server software. Its packaging details matter because a security fix or ABI break can affect a large image-processing dependency graph.

It is also a reference-library package in the strict sense: package maintainers are not just shipping any PNG implementation, but the implementation maintained by the PNG development community as the official reference library.

タイムライン

• 1995-03-29: The CHANGES file records libpng version 0.1.
• 1996-06-05: The CHANGES file records version 0.89, described by the README as the first official release.
• 1998-03-08: The CHANGES file records version 1.0.0.
• 2011: The 1.5 line made direct access to png_struct and png_info private, according to the README's historical notes.
• 2018: The README credits Cosmin Truta as maintainer beginning in 2018.

Related projects

• PNG is the image format that libpng implements and documents alongside the W3C, RFC, and ISO/IEC specifications.
• zlib is libpng's compression dependency for DEFLATE data inside PNG files.
• png-mng-implement is the mailing-list community referenced by upstream for implementation questions.

ソース

• https://raw.githubusercontent.com/pnggroup/libpng/libpng16/CHANGES
• https://raw.githubusercontent.com/pnggroup/libpng/libpng16/README
• https://www.libpng.org/pub/png/libpng.html
• https://www.libpng.org/pub/png/pngdocs.html
• https://www.libpng.org/pub/png/pnghist.html