- From: Amelia Bellamy-Royds via GitHub <sysbot+gh@w3.org>
- Date: Thu, 26 Jul 2018 18:59:45 +0000
- To: public-css-archive@w3.org

To summarize: There are two algorithms that are imprecise: - How to expand a shape by a given margin. For definitions, you may want to look at the SVG stroke-shape algorithms, but beware that this is an "outside" stroke which isn't yet explicitly defined in SVG (although it's an outside stroke on an always-closed shape, so that helps). See https://svgwg.org/specs/strokes/ That said, shape-outside also needs to apply to shapes generated by the opacity threshold on an image, so the definition needs to work even if you don't have a crisp mathematical definition of the shape. - Given a final shape (with margin included), how do you trim line boxes to fit up against it? E.g., in the diagram in [Example 7 in the spec](https://drafts.csswg.org/css-shapes/#shapes-from-image), it looks like the corners of the 1em-high basic line boxes are fitted tight against the final float shape, but expansions of the line box from line leading is ignored. Now, that's probably just a matter of making a nice diagram rather than a conscious choice. But when writing the code, you need to know whether you need to leave space for the half-leading on either side of the line of text. And as Tab points out, then there's the question of how to find the intersection point of a rectangle and an arbitrary shape (which may not have a mathematical definition) in an algorithmically efficient way. Especially when you factor in that each rectangle has a minimum content width associated with it, and that you may need to slide the rectangle down until you find a place where it can fit. Given that neither of these calculations have crisp, clear algorithms for finding the optimal solution, I'd be hesitant about baking a full algorithm into the spec. But I do agree that there should probably be some clarifications. -- GitHub Notification of comment by AmeliaBR Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/2949#issuecomment-408200818 using your GitHub account

Received on Thursday, 26 July 2018 18:59:53 UTC