Pango
Library for text rendering
Pango (stylized as Παν語) is a text (i.e. glyph) layout engine library which works with the HarfBuzz shaping engine for displaying multi-language text.
Full-function rendering of text and cross-platform support is achieved when Pango is used with platform APIs or third-party libraries, such as Uniscribe and FreeType, as text rendering backends. Pango-processed text will appear similar under different operating systems.
Pango is a special-purpose library for text and not a general-purpose graphics rendering library such as Cairo, with which Pango can be used. The Cairo documentation recommends Pango be used to "render" text rather than Cairo for all but the simplest text "rendering".
01History and naming
The name pango comes from Greek pan (παν, 'all') and Japanese go (語, 'language').
In January 2000, the merger of the GScript and GnomeText projects was named Pango.
Pango version 1.0.0 was released 11 March 2002.
02Support for OpenType features
Pango 1.17 and newer support the 'locl' feature tag that allows localized glyphs to be used for the same Unicode code point. Assuming you have Verdana version 5.01 installed, which supports the 'locl' feature for the latn/ROM (Romanian) script, a quick demonstration (on Linux) is:
for lang in en ro do pango-view \ --font="Verdana 64" \ --text "şţ vs. șț in $lang" \ --language=$lang doneFor an explanation of the substitutions rules for Romanian, see this discussion.
Setting the locale via the POSIX environment variable, e.g. LANG=ro_RO.UTF-8 will also cause Pango to use 'locl' font feature. Finally, you can change the language on the fly in the same text using Pango markup, e.g.:
pango-view \ --font="Verdana 24" \ --markup \ --text 'In the same text: şţ(en) and <span lang="ro">şţ(ro).</span>'Since 1.37.1, Pango added more attributes to provide complete support for processing OpenType feature.
03Major users
Pango has been integrated into most Linux distributions. The GTK UI toolkit uses Pango for all of its text rendering. The Linux versions of the Mozilla Firefox web browser and Mozilla Thunderbird mail client use Pango for text rendering.
Sources and credits
This article is adapted from the Wikipedia article “Pango”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- Pango-name.svg by Tsaitgaist, Great Brightstar, Public domain
- Pango locl demo.png by Vasile Gaburici, Public domain
- GTK+ software architecture.svg by ScotXW, CC BY-SA 4.0
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