spec text justify auto

Summary

Documents with "text-align: justify" are not interoperable today, so any specs involves some costs. We need to make a choice which costs to take and which not to.

Following criteria are out of scope of this discussion:

• text-align is not justify. The choice does not make any differences in this case.
• has lang attribute. The spec says UA may tailor by the content language.
• text-jusitfy: inter-word. The spec defines behavior in this case.

Options

Expand CJ: Expand ideograph (i.e., between ideograph and any), but not Hangul Solid CJK: Not expand ideograph nor Hangul Compromise: A compromised algorithm, spacing varies by the content of line Reintroduce inter-ideograph: Add text-justify: inter-ideograph back

Current Behavior

Table of expansions:

Test	Gecko Expands	Trident	Webkit	Blink
				Mac	Win/Android/Opera
untagged default (screenshots)	None	None	+Han +Kana -Hangul		None
Japanese default (screenshots)	+Han +Kana -Hangul
Korean default (screenshots)	None
untagged inter-ideographic (screenshots)	None	+Han +Kana +Hangul

• All cases in single HTML file (screenshots)
• List of all test files and screenshots (or in Dropbox if unstable)

Future Possibilities

Document Type	Expand CJ not K	Solid CJK	Compromise
text-justify: inter-ideograph (for IE5+)	A	D*	B*
Chinese/Japanese (100%)	A	D	B
Korean (Hangul only, 70-80%)	A	A	B
Korean (Hangul+Han, 20-30%)	C	A	B
Korean (Han only, 1-10%)	A	D	B

Letters represent quality of results

• Adding inter-ideograph can make this A.

Regressions

Document Type	Engine	Expand CJ not K	Solid CJK	Compromise
text-justify: inter-ideograph (for IE5+)	Webkit	o	-*	-*
	Trident	o	-*	-*
	Blink	o/+	-*/o	-*/+
	Gecko	+	o	+
Chinese/Japanese (100%)	Webkit	o	-	-
	Trident	+	o	+
	Blink	o/+	-/o	-/+
	Gecko	+	o	+
Korean (Hangul only, 70-80%)	Webkit	o	o	-
	Trident	o	o	-
	Blink	o	o	-
	Gecko	o	o	-
Korean (Hangul+Han, 20-30%)	Webkit	o	+	+ and -
	Trident	-	o	-
	Blink	o/-	+/o	+ and -/-
	Gecko	-	o	-
Korean (Han only, 1-10%)	Webkit	o	-	-
	Trident	+	o	+
	Blink	o/+	-/o	-/+
	Gecko	+	o	+

• + indicates better
• - indicates worse
• o indicates same