Gecko (software)


Gecko is a browser engine developed by Mozilla. It is used in the Firefox browser, the Thunderbird email client, and many other projects.
Gecko is designed to support open Internet standards, and is used by different applications to display web pages and, in some cases, an application's user interface itself. Gecko offers a rich programming API that makes it suitable for a wide variety of roles in Internet-enabled applications, such as web browsers, content presentation, and client/server.
Gecko is written in C++ and JavaScript, and, since 2016, additionally in Rust. It is free and open-source software subject to the terms of the Mozilla Public License version 2. Mozilla officially supports its use on Android, Linux, macOS, and Windows.

History

Development of the layout engine now known as Gecko began at Netscape in 1997, following the company's purchase of DigitalStyle. The existing Netscape rendering engine, originally written for Netscape Navigator 1.0 and upgraded through the years, was slow, did not comply well with W3C standards, had limited support for dynamic HTML and lacked features such as incremental reflow. The new layout engine was developed in parallel with the old, with the intention being to integrate it into Netscape Communicator when it was mature and stable. At least one more major revision of Netscape was expected to be released with the old layout engine before the switch.
After the launch of the Mozilla project in early 1998, the new layout engine code was released under an open-source license. Originally unveiled as Raptor, the name had to be changed to NGLayout due to trademark problems. Netscape later rebranded NGLayout as Gecko. While Mozilla Organization initially continued to use the NGLayout name, eventually the Gecko branding won out.
In October 1998, Netscape announced that its next browser would use Gecko rather than the old layout engine, requiring large parts of the application to be rewritten. While this decision was popular with web standards advocates, it was largely unpopular with Netscape developers, who were unhappy with the six months given for the rewrite. It also meant that most of the work done for Netscape Communicator 5.0 had to be abandoned. Netscape 6, the first Netscape release to incorporate Gecko, was released in November 2000.
As Gecko development continued, other applications and embedders began to make use of it. America Online, by this time Netscape's parent company, eventually adopted it for use in CompuServe 7.0 and AOL for Mac OS X. However, with the exception of a few betas, Gecko was never used in the main Microsoft Windows AOL client.
On July 15, 2003, AOL laid off the remaining Gecko developers and the Mozilla Foundation became the main steward of Gecko development. Today, Gecko is developed by employees of the Mozilla Corporation, employees of companies that contribute to the Mozilla project, and volunteers.
In October 2016, Mozilla announced [|Quantum], an ongoing project encompassing several software development efforts to "build the next-generation web engine for Firefox users". It includes numerous improvements to Gecko, taken from the experimental Servo project. Firefox 57, also known as "Firefox Quantum", first shipping in November 2017, is the initial version with major components from the Quantum/Servo projects enabled. These include increased performance in the CSS and GPU rendering components. Additional components will be merged from Servo to Gecko incrementally in future versions.
In September 2018, Mozilla announced GeckoView, the foundation of Mozilla's next generation of mobile products based on a software library that makes Gecko reusable for Android, encompassing newer software development efforts to "decouple the engine itself from its user interface, and made it easy to embed in other applications". Firefox Focus 7.0, shipped in the same month, is the initial version introduced GeckoView, with increased performance in median page loading. Firefox Reality was also built with GeckoView. In June 2019, Mozilla announced Firefox Preview as an ongoing project that focuses on building Android web browser with GeckoView.

Standards support

From the outset, Gecko was designed to support open Internet standards. Some of the standards Gecko supports include:
Gecko also partially supports SVG 1.1. The SVG font, color profile, animation, view, and cursor modules are yet to be implemented and the filter and text modules are only partially implemented. The extensibility module is also implemented but is currently disabled.
In order to support web pages designed for legacy versions of Netscape and Internet Explorer, Gecko supports DOCTYPE switching. Documents with a modern DOCTYPE are rendered in standards compliance mode, which follows the W3C standards strictly. Documents that have no DOCTYPE or an older DOCTYPE are rendered in quirks mode, which emulates some of the non-standard oddities of Netscape Communicator 4.x; however, some of the 4.x features are not supported.
Gecko also has limited support for some non-standard Internet Explorer features, such as the marquee element and the document.all property.

Usage

Gecko is primarily used in web browsers, the earliest being Netscape 6 and Mozilla Suite. It is also used in other Mozilla web browser derivatives such as Firefox and Firefox for mobile and the implementation of the Internet Explorer-clone that is part of Wine. Mozilla also uses it in their Thunderbird email-client.
Other web browsers using Gecko include GNU IceCat, Waterfox, K-Meleon, Lunascape, Portable Firefox, Conkeror, Classilla, TenFourFox.
Other products using Gecko include Nightingale, Instantbird and Google's picture-organization software Picasa.
Gecko is also used by Sugar for the OLPC XO-1 computer. Gecko is used as a complete implementation of the XUL. Gecko currently defines the XUL specification.

Past users

Products that have historically used Gecko include Pale Moon, Songbird, Epiphany and GNOME DevHelp both have replaced Gecko with WebKitGTK, Sunbird, and other web browsers including Swiftfox, Flock, Galeon, Camino, Minimo, Beonex Communicator, Kazehakase, and MicroB.

Proprietary dependency

On Windows and other platforms, Gecko depends on proprietary compilers. Thus, FOSS distributions of Linux can not include the Gecko package used in the Windows compatibility layer Wine.
After Gecko 2.0, the version number was bumped to 5.0 to match Firefox 5, and from then on has been kept in sync with the major version number for both Firefox and Thunderbird, to reflect the fact that it is no longer a separate component.

Bloat

In the Netscape era, a combination of poor technical and management decisions resulted in Gecko software bloat. Thus in 2001 Apple chose to fork KHTML, not Gecko, to create the WebKit engine for its Safari browser. However, by 2008 Mozilla had addressed some of the bloat problems, resulting in big performance improvements for Gecko.

Quantum

Quantum is a Mozilla project encompassing several software development efforts to "build the next-generation web engine for Firefox users". It includes numerous improvements to Gecko, largely incorporated from the experimental Servo project. Quantum also includes refinements to the user interface and interactions.
Firefox 57, released in November 2017, is the initial version with a Servo component enabled. Mozilla dubs this and several planned future releases "Firefox Quantum".

Background

In 2013, Mozilla began the experimental Servo project, which is an engine designed from scratch with the goals of improving concurrency and parallelism while also reducing memory safety vulnerabilities. An important factor is writing Servo in the Rust programming language, also created by Mozilla, which is designed to generate compiled code with better memory safety, concurrency, and parallelism than compiled C++ code.
As of April 2016, Servo needed at least several years of development to become a full-featured browser engine. Thus the decision to start the Quantum project to bring stable portions of Servo into Firefox.

Component

The Quantum project is composed of several sub-projects.
The Mozilla Azure project is a stateless low-level graphics abstraction API used in Firefox. The project has several objectives including more accurate Direct2D compatibility, optimized state interoperability, and improved control over performance characteristics and bugs. Azure will provide 2D hardware acceleration on top of 3D graphics backends. Firefox began using Azure instead of Cairo in 2012. It is written in C++ and used by Servo. The Azure name is an ode to the early Netscape founder James H. Clark and his earlier work at SGI. Jim Clark invented Geometry Engine at Stanford University in 1979 which was the first GPU. Silicon Graphics were also the original inventors of OpenGL.