Re: [csswg-drafts] [css-text-3] Note unclear in bidi & line boxes (#5759)

**To be clear, this objection isn't about alignment.  The alignment rules all make sense.  It's about the ordering of inline-level content within a line**.

Let me make some alternative suggestions then, as inline comments on your text.

> The start and end sides of a line box are determined by the inline base direction of the line box. Although they usually match, the inline base direction of a line box is distinct from the inline base direction of the containing block or the bidi paragraph. The line box’s inline base direction affects text-align-all, text-align-last, text-indent, and hanging-punctuation—i.e. the position and alignment of its contents with respect to its edges. It does not affect the formatting or ordering of inline content (which is controlled by the Unicode bidirectional algorithm as applied by [CSS-WRITING-MODES-3]).

The text in brackets at the end makes it sound as if each line box should arrange the ordering of inline content independently, by applying the UBA.  That's not the case for the 2nd line box in my example – it takes its directionality from the overall paragraph direction, which includes the strong characters in the previous line.  Do you need that parenthetical text there, given that you then go on to specify how things work in the following text?

> In most cases, a line box’s inline base direction is given by its containing block's computed direction. However if its containing block has unicode-bidi: plaintext [CSS-WRITING-MODES-3]: 

> • If the bidi paragraph to which the line box belongs (that is, the bidi paragraph for which the line box holds content) has strong directionality, the line box’s inline base direction is that direction. 

Ok. (That aligns with what i was saying previously.)

> • If the line box is empty (i.e. contains no atomic inlines or characters other than the newline character, if any) or otherwise has no strong directionality (contains only weak or neutral characters), its inline base direction is taken from the preceding line box (if any), or, if this is the first line box in the containing block, from the direction property of the containing block. (This can result in an RTL line box whose contents have an LTR base direction.) 

It seems to me that this paragraph should begin with 'Otherwise, ', because it doesn't apply to the 2nd line box in my example – that is covered by the first bullet.

I think the text in parens at the end is too vague.  I think you mean that the inline base direction of the line box (RTL) would cause the line box content to be aligned RTL, but the ordering of inline-level content within the line is LTR because it is  'controlled by the Unicode bidirectional algorithm as applied by [CSS-WRITING-MODES-3]'.


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Received on Thursday, 10 December 2020 11:01:41 UTC