Features/Platform/Graphite font shaping

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Status

Support the Graphite font shaping technology
Stage	Feature Inbox
Status	In progress
Release target	`
Health	OK
Status note	Patches for integration in Gecko currently under review.

{{#set:Feature name=Support the Graphite font shaping technology

|Feature stage=Feature Inbox |Feature status=In progress |Feature version=` |Feature health=OK |Feature status note=Patches for integration in Gecko currently under review. }}

Team

Product manager	Chris Blizzard
Directly Responsible Individual	`
Lead engineer	Jonathan Kew
Security lead	`
Privacy lead	`
Localization lead	`
Accessibility lead	`
QA lead	`
UX lead	`
Product marketing lead	`
Operations lead	`
Additional members	John Daggett

{{#set:Feature product manager=Chris Blizzard

|Feature feature manager=` |Feature lead engineer=Jonathan Kew |Feature security lead=` |Feature privacy lead=` |Feature localization lead=` |Feature accessibility lead=` |Feature qa lead=` |Feature ux lead=` |Feature product marketing lead=` |Feature operations lead=` |Feature additional members=John Daggett }}

Open issues/risks

The Graphite shaping library includes a small, limited-functionality virtual machine that executes shaping instructions in the fonts. This could represent a potential attack surface (via maliciously-crafted web fonts), and needs to be reviewed and tested for robustness.

Stage 1: Definition

1. Feature overview

Graphite[1] is a "smart font" technology developed by SIL International to provide support for languages/scripts with complex shaping requirements - contextual glyph changes, positioning, etc. Unlike the OpenType model used in Uniscribe, Harfbuzz, etc, it does not require script-specific behavior to be coded in per-script "shaping engines", but puts full control into the hands of the font developer.

This means that Graphite allows user communities to implement their script by creating a suitable font *without* being dependent on Microsoft to define shaping engine and OpenType feature specifications[2] for the script. This is particularly valuable for minority groups whose script may not be well standardized, and where major industry players have little interest in developing support.

[1] http://scripts.sil.org/RenderingGraphite
[2] http://www.microsoft.com/typography/SpecificationsOverview.mspx

2. Users & use cases

Graphite support is targeted primarily at minority-language user communities in South-East Asia and other areas where complex writing systems are used, and industry standards are still a long way from providing adequate support. Examples include minority groups in Myanmar (Burma) using variants of Burmese script[3] and communities in Thailand using the Lanna script.[4]

Graphite is also likely to be valuable in implementing scripts such as SignWriting[5], used by some sign-language communities.

In addition, Graphite can be used by font designers to provide improved support for complex behaviors such as calligraphic styles and placement of multiple diacritics even in "simple" scripts.

[3] http://scriptsource.org/scr/Mymr
[4] http://scriptsource.org/scr/Lana
[5] http://en.wikipedia.org/wiki/SignWriting

3. Dependencies

The Graphite2 library: http://projects.palaso.org/projects/graphitedev

4. Requirements

The presence of Graphite support must not regress behavior or performance for non-Graphite fonts.

Rendering text with a Graphite font should have equivalent performance to rendering with an OpenType font of similar complexity. (Dual-technology fonts such as Charis SIL could be used to compare.)

Non-goals

`

Stage 2: Design

5. Functional specification

When rendering text using a font that has Graphite tables, use the Graphite shaper instead of Harfbuzz to handle glyph layout. Such text should render identically to other Graphite-enabled applications such as OpenOffice or FieldWorks.

6. User experience design

`

Stage 3: Planning

7. Implementation plan

`

8. Reviews

Security review

`

Privacy review

`

Localization review

`

Accessibility

`

Quality Assurance review

`

Operations review

`

Stage 4: Development

9. Implementation

https://bugzilla.mozilla.org/show_bug.cgi?id=631479

Stage 5: Release

10. Landing criteria

` {{#set:Feature open issues and risks=The Graphite shaping library includes a small, limited-functionality virtual machine that executes shaping instructions in the fonts. This could represent a potential attack surface (via maliciously-crafted web fonts), and needs to be reviewed and tested for robustness. |Feature overview=Graphite[1] is a "smart font" technology developed by SIL International to provide support for languages/scripts with complex shaping requirements - contextual glyph changes, positioning, etc. Unlike the OpenType model used in Uniscribe, Harfbuzz, etc, it does not require script-specific behavior to be coded in per-script "shaping engines", but puts full control into the hands of the font developer.

This means that Graphite allows user communities to implement their script by creating a suitable font *without* being dependent on Microsoft to define shaping engine and OpenType feature specifications[2] for the script. This is particularly valuable for minority groups whose script may not be well standardized, and where major industry players have little interest in developing support.

[1] http://scripts.sil.org/RenderingGraphite
[2] http://www.microsoft.com/typography/SpecificationsOverview.mspx |Feature users and use cases=Graphite support is targeted primarily at minority-language user communities in South-East Asia and other areas where complex writing systems are used, and industry standards are still a long way from providing adequate support. Examples include minority groups in Myanmar (Burma) using variants of Burmese script[3] and communities in Thailand using the Lanna script.[4]

Graphite is also likely to be valuable in implementing scripts such as SignWriting[5], used by some sign-language communities.

In addition, Graphite can be used by font designers to provide improved support for complex behaviors such as calligraphic styles and placement of multiple diacritics even in "simple" scripts.

[3] http://scriptsource.org/scr/Mymr
[4] http://scriptsource.org/scr/Lana
[5] http://en.wikipedia.org/wiki/SignWriting |Feature dependencies=The Graphite2 library: http://projects.palaso.org/projects/graphitedev |Feature requirements=The presence of Graphite support must not regress behavior or performance for non-Graphite fonts.

Rendering text with a Graphite font should have equivalent performance to rendering with an OpenType font of similar complexity. (Dual-technology fonts such as Charis SIL could be used to compare.) |Feature non-goals=` |Feature functional spec=When rendering text using a font that has Graphite tables, use the Graphite shaper instead of Harfbuzz to handle glyph layout. Such text should render identically to other Graphite-enabled applications such as OpenOffice or FieldWorks. |Feature ux design=` |Feature implementation plan=` |Feature security review=` |Feature privacy review=` |Feature localization review=` |Feature accessibility review=` |Feature qa review=` |Feature operations review=` |Feature implementation notes=https://bugzilla.mozilla.org/show_bug.cgi?id=631479 |Feature landing criteria=` }}

Feature details

Priority	Unprioritized
Rank	999
Theme / Goal	`
Roadmap	`
Secondary roadmap	`
Feature list	Platform
Project	`
Engineering team	Graphics

{{#set:Feature priority=Unprioritized

|Feature rank=999 |Feature theme=` |Feature roadmap=` |Feature secondary roadmap=` |Feature list=Platform |Feature project=` |Feature engineering team=Graphics }}

Team status notes

	status	notes
Products	`	`
Engineering	`	`
Security	`	`
Privacy	`	`
Localization	`	`
Accessibility	`	`
Quality assurance	`	`
User experience	`	`
Product marketing	`	`
Operations	`	`

{{#set:Feature products status=`

|Feature products notes=` |Feature engineering status=` |Feature engineering notes=` |Feature security status=` |Feature security health=` |Feature security notes=` |Feature privacy status=` |Feature privacy notes=` |Feature localization status=` |Feature localization notes=` |Feature accessibility status=` |Feature accessibility notes=` |Feature qa status=` |Feature qa notes=` |Feature ux status=` |Feature ux notes=` |Feature product marketing status=` |Feature product marketing notes=` |Feature operations status=` |Feature operations notes=` }}