Industry Specifications

Product advantages alone give OEMs and platform developers compelling reasons to implement scalable type, such as the ability to support several typefaces and languages. For many years, mobile application developers were restricted in their ability to control the appearance and layout of text using fonts of their own choice. Fonts were also typically limited to only those provided by OEMs.

Today, support for scalable fonts on mobile devices allows developers to package or download custom fonts with their applications. OEMs and developers have another reason—to comply with industry specifications that call for support of scalable fonts for mobile applications and rich media content, such as:

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  Java Specification Request (JSR) 271, which defines the Mobile Information Device Profile (MIDP) v3.0 for the Java Micro Edition (Java ME) platform
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  The Rich-Media Environment (RME) Enabler defined by the Open Mobile Alliance
• 
  3rd Generation Partnership Project (3GPP) Dynamic and Interactive Multimedia Scene (DIMS)

The goal of the MIDP 3 specification is to create an open and platform-independent application environment for Java-based deployments to mobile devices. The standard states, “All implementations must support OpenType fonts with TrueType outlines [the industry’s font scaling standards]. Implementations SHOULD support TrueType hinting and MAY support advanced typographic functions.”

The RME specification “defines a framework that enables RME content to be distributed to and displayed on mobile devices. RME content consists of scenes of visual objects, such as video, images, animation and text.” As with MIDP 3, the RME specification states that devices “shall support downloadable OpenType fonts with TrueType outlines. TrueType hinting shall be supported for improved text readability, and advanced typographic features may be supported.”

Dynamic Font Linking

A font engine should also support dynamic font linking, which enables downloaded fonts to be linked with existing embedded fonts, allowing for dynamic extensions to character sets (Fig. 5). As an example, an Asian font may be downloaded and linked to a Latin-based font such as an English language font that exists on a mobile phone, allowing the user to access Asian characters that are not part of the English font. Other uses provide more personalized experiences—a special font style, for instance, could be linked to the existing font to provide more style or to match a particular theme.

New Architecture And Features

As mobile phones increasingly support downloaded fonts, opportunities will arise that will usher in richer content and application development, and fonts will be central to this trend. The ability to download fonts provides increased flexibility for application and content developers in a number of areas, such as gaining control over text layout and appearance, as well as extending multilingual capabilities of the device.

At the same time, developers may become vulnerable to other developers accessing fonts not licensed to them. Additionally, mobile phones may become susceptible to downloaded fonts that are corrupted or do not conform to font technology standards. Font engines address these issues through new font management and discovery features. Capabilities also enable application execution environments to validate font files prior to installing them, find fonts when applications call for them, and discover which fonts are available for use at any given time, either by font name or by various font properties.

Font engines additionally need to include font management and discovery capabilities that support multiple concurrent execution environments. New architecture enables the development of platforms and applications that provide services based on rich media environments, such as a 3GPP specification entitled Dynamic and Interactive Multimedia Scenes, the Rich Media Environment Enabler from the Open Mobile Alliance, or the MIDP 3.0 specification from the Java Community Process. A font engine should also support hardware-accelerated text rendering, which is compatible with the Khronos OpenVG application programming interface (API) for hardware acceleration.

Intelligent Text Layout

Integral to the font engine is its ability to support text layout capabilities, whether to meet local, regional, or international requirements. The layout engine should feature small code size, selectable build options, portability, a modular architecture, support for required languages, and compatibility with OpenType and Unicode standards.

Also, the layout engine should support various layout intricacies, such as bidirectional text flow, ligatures, contextual character substitution, line breaking, and cursor positioning and paragraph alignment. It should be able to wrap text around graphic objects and irregular shapes, as well as support special effects such as drop shadows, edge effects, outlines, underlines, and strike-through effects and colored text. Furthermore, the layout engine should support user-defined substitution dictionaries for displaying emoticons and graphic icons.

Layout engines work in tandem with the font engine and OpenType fonts to perform these various layout requirements. Major languages of the world should be supported, including the languages based on Latin- and Cyrillic-based scripts, in addition to Japanese, Korean, Chinese, Arabic, Greek, Hebrew, Thai, Vietnamese (Latin + diacritics), and the major written languages of Africa, India, Pakistan, Bangladesh, Sri Lanka, and Nepal.