Justification Priority Table

A Justification Priority (JstfPriority) table defines justification suggestions for a single priority level. Each priority level specifies whether to enable or disable GSUB and GPOS lookups or apply text justification lookups to shrink and extend lines of text.

JstfPriority has offsets to four tables with line shrinkage data: two are JstfGSUBModList tables for enabling and disabling glyph substitution lookups, and two are JstfGPOSModList tables for enabling and disabling glyph positioning lookups. Offsets to JstfGSUBModList and JstfGPOSModList tables also are defined for line extension.

Example 3 at the end of this chapter demonstrates two JstfPriority tables for two justification suggestions.

JstfPriority table

Type

Name

Description

Offset

ShrinkageEnableGSUB

Offset to Shrinkage Enable JstfGSUBModList table

  

—from beginning of JstfPriority table

  

—may be NULL

Offset

ShrinkageDisableGSUB

Offset to Shrinkage Disable JstfGSUBModList table

  

—from beginning of JstfPriority table

  

—may be NULL

Offset

ShrinkageEnableGPOS

Offset to Shrinkage Enable JstfGPOSModList table

  

—from beginning of JstfPriority table

  

—may be NULL

Offset

ShrinkageDisableGPOS

Offset to Shrinkage Disable JstfGPOSModList table

  

—from beginning of JstfPriority table

  

—may be NULL

Offset

ShrinkageJstfMax

Offset to Shrinkage JstfMax table

  

—from beginning of JstfPriority table

  

—may be NULL

Offset

ExtensionEnableGSUB

Offset to Extension Enable JstfGSUBModList table

  

—may be NULL

Offset

ExtensionDisableGSUB

Offset to Extension Disable JstfGSUBModList table

  

—from beginning of JstfPriority table

  

—may be NULL

Offset

ExtensionEnableGPOS

Offset to Extension Enable JstfGSUBModList table

  

—may be NULL

Offset

ExtensionDisableGPOS

Offset to Extension Disable JstfGSUBModList table

  

—from beginning of JstfPriority table

  

—may be NULL

Offset

ExtensionJstfMax

Offset to Extension JstfMax table

  

—from beginning of JstfPriority table

  

—may be NULL