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This chapter discusses how to to use fonts.
The interface for working with fonts in EGT is the egt::Font class. This class handles properties related to working with fonts, but there are still some other libraries in play. Underneath, the egt::Font class uses Fontconfig and Freetype for finding and rendering fonts.
Creating and assigning an egt::Font to a specific widget involves using the egt::v1::Widget::font() member function.
Fontconfig is a library for configuring and customizing font access. This is the library EGT uses to discover fonts installed on the system automatically.
Selecting fonts from within EGT ultimately uses Fontconfig. The Fontconfig documentation should be the ultimate source of how to make the best use of and how to configure Fontconfig. However, to help introduce how to debug using Fontconfig, several things are worth noting.
To see what fonts will be returned given a specific name, you can use the fc-match utility, not to be confused with the fc-query utility.
To see what installed fonts contain a certain code point, you can use the fc-list utility and specify one or more code points in hex.
When running an EGT application, or any application that uses Fontconfig, you can define the environment variable FC_DEBUG that will cause Fontconfig to issue some useful information.
The value of the FC_DEBUG variable, depending on what you want printed, is defined in the Fontconfig documentation.
Installing fonts is a system level operation outside of EGT itself. In most cases the font can be copied to /usr/share/fonts, fc-cache can be run, and it will be automatically found by EGT.
A useful tool to load a font and inspect it can be found here.
While there are hundreds if not thousands of fonts available from all different sources under various licenses, both free and non-free, Google provides some relatively complete and free fonts called Google Noto Fonts.
When text is rendered by a computer, sometimes characters are displayed as “tofu”. They are little boxes to indicate your device doesn’t have a font to display the text.
Google has been developing a font family called Noto, which aims to support all languages with a harmonious look and feel. Noto is Google’s answer to tofu. The name noto is to convey the idea that Google’s goal is to see “no more tofu”. Noto has multiple styles and weights, and is freely available to all. The comprehensive set of fonts and tools used in our development is available in our GitHub repositories.
These Google Noto Fonts also include specific support for many languages requiring Unicode support.
Noto Sans CJK and Noto Serif CJK comprehensively cover Simplified Chinese, Traditional Chinese, Japanese, and Korean in a unified font family. This includes the full coverage of CJK Ideographs with variation support for 4 regions, Kangxi radicals, Japanese Kana, Korean Hangul, and other CJK symbols and letters in the Basic Multilingual Plane of Unicode. It also provides limited coverage of CJK Ideographs in Plane 2 of Unicode as necessary to support standards from China and Japan.
FreeType is used by EGT to render any font that is available and installed in the system.
FreeType is a software font engine that is designed to be small, efficient, highly customizable, and portable while capable of producing high-quality output (glyph images). It can be used in graphics libraries, display servers, font conversion tools, text image generation tools, and many other products as well.
Both Fontconfig and FreeType support international fonts in many various languages and EGT takes advantage of this and in turn provides complete internationalization support for rendered text.
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