- From: Dael Jackson <daelcss@gmail.com>
- Date: Wed, 23 Mar 2016 20:00:36 -0400
- To: www-style@w3.org
- Cc: public-fx@w3.org
========================================= These are the official CSSWG minutes. Unless you're correcting the minutes, Please respond by starting a new thread with an appropriate subject line. ========================================= Fill & Stroke on CSS Text ------------------------- - fantasai presented the work she and TabAtkins had done to draft how fill and stroke properties effect CSS Text. The work is currently in the text-decoration L4 spec: https://drafts.csswg.org/css-text-decor-4/ Major points include * Redefining 'fill' and 'stroke' as shorthands of other properties * Incorporating background-like image capabilities * Handling inheritance / nesting via fill-origin and stroke-origin * Need to investigate more deeply into which "boxes" serve as sizing/positioning origins for text * SVG has text-decoration fills, which need to be handled as well * Multiple strokes were requested - It was noted that stroke-align may be too difficult for this level - Wrt dashing * The dashing origin for text is not defined; therefore might not be appropriate for text to have dashed strokes. * Dashing on strokes may need to be syncronized with additional dashing capabilities for CSS borders - RESOLVED: Merge heycam's spec paint spec with this proposal and put into FX repository - RESOLVED: Add -webkit-background-clip-text to the spec stating that authors must not use it but browsers may support it. (Deprecated appendix.) ===== FULL MINUTES BELOW ====== Agenda: https://wiki.csswg.org/planning/sydney-2016 Scribe: tantek Fill & Stroke on CSS Text ========================= astearns: fill & stroke on CSS text - who put this? fantasai. [fantasai projects] <fantasai> https://drafts.csswg.org/css-text-decor-4/ fantasai: TabAtkins and I had action item from couple of years ago fantasai: to draft up fill & stroke properties from SVG fantasai: and how they apply to text. fantasai: We did that a few weeks ago. Spec Home --------- fantasai: Which spec should they go in? fantasai: We stuck them in text-decoration. fantasai: They might need to go into their own separate spec. fantasai: So that's one open question. fantasai: Where should we put these properties? heycam: I broke-out some improvements to the stroking properties which we decided to defer from SVG2 <heycam> https://svgwg.org/specs/strokes/ heycam: They have not been made a working draft yet, heycam: should be a single place for all of these heycam: rather than multiple documents. heycam: I don't particularly mind where they go. heycam: So this is just breaking out the SVG definition and then a couple of extensions to those values. fantasai: I think we can merge the two Stroke Alignment ---------------- fantasai: for stroke-alignment we shortened to stroke-align. fantasai: We considered stroke-position (analogous to text-line-position) but that would be confusing with all the image stuff that has to go in. heycam: So that's the alignment property that... fantasai: We were talking about it last time. fantasai: We had agreed to add it. fantasai: It doesn't work to stroke text with center alignment very well if you have a semi-transparent stroke. tav: I looked into implementing stroke-alignment. tav: and it was quite complicated. tav: What you do with the end caps. tav: It gets quite complicated. fantasai: I think the round cap would be a full / whole circle fantasai: the rest of it would look like you clipped out the shape itself. tav: What do you do about paths that cross each other? tav: How do you handle the fill rules? tav: I would love to have, tav: thought it would be easy, tav: turns out to be very complicated. heycam: Presumably these issues don't crop up with text. fantasai: We can put it into the draft. Tav: Would be good to work on it. <AmeliaBR> Examples of these problems in the Issues in SVG Strokes: https://svgwg.org/specs/strokes/#SpecifyingStrokeAlignment Tav: One thing that was missing, SVG now has paint-order. fantasai: We didn't think that would be needed in CSS. fantasai: You never want to put the stroke behind the paint. heycam: Conceptually yes, but in practice, outsetting the stroke heycam: and making sure you don't get seams between the outer stroke and the shape. heycam: At least if you have opaque colors. Tav: You could also do the painting and then apply the opacity to that. fantasai: You could also ... solid filled and transparent stroke. <BradK> Or always have the text knock out the stroke Shorthanding ------------ fantasai: We re-arranged the way the properties interact so we have shorthanding. fantasai: So stroke is stroke-... fantasai: same with fill. fantasai: We put in all the background properties. fantasai: Have all been put in as equivalent fill-* and stroke-* props. fantasai: wrt fragmentation fantasai: Do you glue everything back together? fantasai: Do you take bounding box? fantasai: Do you clone it separately? fantasai: Added fill-break and stroke-break to decide heycam: Shorthand for stroke, I'm concerned that SVG defines specifying stroke-width before stroke. heycam: I don't know if you done any research. fantasai: We had two options for stroke shorthand. fantasai: 1. include all stroke properties fantasai: 2. include only paint related properties, geometry separate fantasai: Could go with either option Image Fills/Strokes ------------------- AmeliaBR: Couple things I wanted to break out. AmeliaBR: So far SVG has talked about breaking out stroke and fill point into many different sub-properties AmeliaBR: to match the CSS background, AmeliaBR: That seems to be what they have done here, AmeliaBR: would love to get that into SVG2. AmeliaBR: That puts a lot of timing on getting all the issues cleaned up. AmeliaBR: When I looked at it previously the main issues come around how do you work the CSS background properties with SVG paint servers, things like object bounding boxes. fantasai: We handled this with the fill- and stroke-origin properties. fantasai: On the background where it is transparent, the text is painted by itself. fantasai: You need to know what element is setting the stroke. fantasai: If I am an element and parent has a fill, need to not just use same image but also same origin. fantasai: We decided to make the image properties inherit fantasai: And use a 'match-parent' value on the -origin properties fantasai: to mean "use the same fill positioning area as my parent" fantasai: so that if you set a bunch of image fills on the paragraph, those properties will inherit to the links and anything inside it. fantasai: But you would use the positioning area defined by the paragraph fantasai: so that it looks like all part of the same image fill. fantasai: Everything has got the same positioning pattern. fantasai: You can even do some of the text with a different color pattern, while keeping the fill pattern aligned across the entire element. fantasai: When you set the stroke or the fill, you choose which box to use as origin: content-box, stroke-box, fill-box fantasai: But in the shorthand, instead of setting fill-origin to initial value 'match-parent' fantasai: When you use the shorthand you set your fill, it will automatically make that element the origin for that element's fill and for its descendants. AmeliaBR: That makes sense, AmeliaBR: does enable matching up with existing SVG behavior AmeliaBR: which is that TSPANS and other child elements match the bounding box of the parent text element for painting and scaling the paint content. AmeliaBR: There are a couple of other confusions with paint servers, because the paint server itself has these two different options AmeliaBR: for objectBoundingBox vs. userSpaceOnUse. AmeliaBR: Those are issues we have seen come up with filters and masks and clip paths. AmeliaBR: We don't know how those translate for non-SVG content. Synchronizing with SVG ---------------------- AmeliaBR: Overall this is a great draft. AmeliaBR: I'd like to see all these options and controls in SVG2 AmeliaBR: or whatever part of SVG start supporting multiple layered fill & stroke. AmeliaBR: Right now all we have in the spec is single complicated shorthand property. AmeliaBR: At the very least we have to make sure that the syntax we are using for the fill and shorthand properties AmeliaBR: are consistent with all the options you are adding. AmeliaBR: There is a timing issue about what spec should have all these in it. fantasai: If we are applying these to CSS, these should not be in the SVG spec fantasai: we need these either in a CSS module or an FXTF module. Origins for Glyphs ------------------ fantasai: There's a couple of issues fantasai: 1 was SVG paint server issue that was mentioned fantasai: 2 there was the question of default fill origin. if you don't set, should it default to the content box or the fill box? fantasai: So content-box, padding-box, border-box are defined as CSS for SVG shapes. We tried to be consistent with Masking. fantasai: box ... box ... box... fantasai: If it's an inline element, the intention was the glyphs themselves, not the box. fantasai: If you have Zapfino and want to fill it so that it goes from super dark at the top to super light at the bottom fantasai: it needs to include all of the glyph bounds, including any ascenders and descenders outside the em box. heycam: For text the fill bounding box is the one that gives you the union of the glyph cells. heycam: A different name like ink-box may make sense. fantasai: What about the stroke-box? heycam: Yes stroking box. fantasai: What does the stroke box mean for SVG? is the fill box sometimes smaller? fantasai: What do you do when you have those kinds of glyphs? heycam: Maybe it's an internal naming term in the spec that conflicts. heycam: Mention fill-box in the SVG spec heycam: and then change the glyph cells to something else? <AmeliaBR> That's probably an issue in the SVG spec currently (multiple bounding boxes not well defined for text) [fantasai goes to draw a picture] Layering -------- AmeliaBR: One thing, have you looked at it yet, I've seen it come up in SVG: AmeliaBR: Painting order for fill and stroke, it's a question of when glyphs overlap, or stroke from one overlaps another, or text-shadows, whether you draw one glyph at a time (most SVG implementations), or one element at a time. AmeliaBR: Not sure if that is spec'd. AmeliaBR: It's something that results in unpleasantly ugly options. AmeliaBR: I want it as an option in the spec eventually. fantasai: In CSS the text for shadows, the shadows are supposed to be just below the text. fantasai: The shadows are required to all be underneath all the text for a given element. fantasai: But we also encourage the user agents to paint the shadows behind all of the text in a run together insofar as possible. heycam: ... strokes underneath the other glyphs... fantasai: ... because if you have negative letter-spacing you have glyphs that end up on top of each other ACTION fantasai: investigate the paint order of the glyphs with respect to shadow and stroke and fill <trackbot> Created ACTION-755 AmeliaBR: It's also ugly when you have glyphs showing boundaries between glyphs when they're supposed to look continuous, e.g. in cursive fonts/scripts fantasai: Excellent point and why we should bias towards not doing that. Paint Servers ------------- heycam: Before you were talking about issues with SVG paint servers heycam: is that with the URL syntax? heycam: Wame issue as in masking spec? fantasai: We didn't really go too much into the paint servers and how they should work. fantasai: We wrote it up as if paint servers didn't exist (laughter) fantasai: haven't really incorporated that aspect into the spec. heycam: In general this looks good. Naming ------ fantasai: One other thing we came up with: fantasai: bikeshedding issue. fantasai: Getting pissed off at how inconsistent SVG names things fantasai: I made a table of this is the syntax, this is the syntax we wished we had. heycam: To change it? fantasai: We don't know fantasai: we just want to ask SVG WG what they think <AmeliaBR> is there a link? <astearns> https://drafts.csswg.org/css-text-decor-4/#perfect-world heycam: Many things are possible if you're willing to put up with aliases to your code paths. heycam: We can try heycam: we tend not to introduce aliases to fix things like this. Dashing ------- fantasai: The dash-adjust property? heycam: Nobody implements that yet. fantasai: We made some slight modifications to the syntax. heycam: tav just asked is that really useful for text? heycam: I have a concern about dashing on text in general. heycam: It exposes things like where is the implementation considering the start of the glyph, heycam: I almost want to disallow dashing on text completely. <AmeliaBR> We (SVG WG) has already decided that text does not have a canonical origin for dash-offset fantasai: I don't have a strong opinion on that. fantasai: We were talking about it because of borders and wanting to be consistent. <BradK> +1 for borders <BradK> +1 for adding dashes between words Text Decoration --------------- fantasai: Anyone that wants to dig more into anything... fantasai: the shorthanding issue is something we need a good understanding. fantasai: should stroke be just painting. fantasai: there's one that deals with geometry. fantasai: ... paint stuff. Tav: SVG also has text-decoration where you can put different stroke and fill. fantasai: How? Tav: part of SVG 1.1 fantasai: I haven't read it. AmeliaBR: In SVG2 there are two new properties that are replacing text-decoration-color AmeliaBR: with text-decoration-fill and text-decoration-stroke AmeliaBR: and so they would naturally fit with these schema. <AmeliaBR> https://svgwg.org/svg2-draft/text.html#TextDecorationFillStroke fantasai: I don't think you can replace text-decoration-color because we already have that in CSS. We have to define the relationship. Tav: I think that's what we do. AmeliaBR: ... you have fill-color having an initial value of current-color AmeliaBR: Can do with default style sheets ... it's just an extra complication. fantasai: I'm a little confused. fantasai: You want the fill-color not to default to currentColor? AmeliaBR: In SVG you have to set fill to currentColor. AmeliaBR: If you want the color property to have an effect. fantasai: So the default is... AmeliaBR: Fill defaults to transparent black. fantasai: That could be handled by a user agent style sheet. Next Steps ---------- heycam: Next steps? fantasai: You have to tell us if you want this in a separate "paint" spec fantasai: and we need to incorporate your spec. heycam: I'll take a look at the two specs. AmeliaBR: I would vote for having a "paint" spec that could be used by both SVG and CSS AmeliaBR: that section in SVG2 is not very defined now, but is something people want for the multiple layered fill & stroke stuff. AmeliaBR: Would be good to get that cleaned up AmeliaBR: even if implementations for SVG text were slower to happen. Multiple Strokes ---------------- Tav: Does this allow for having multiple strokes? with different stroke widths? fantasai: We didn't add that to the spec. Tav: Sometimes you build up complicated paths like a road, center of the road red, dashed lines on shoulders. fantasai: That's going to be tricky because we're already using commas in the stroke-image fantasai: so we can't use comma-separate syntax fantasai: unless you're ok with using image fills for everything. Tav: How would an image fill work per path? AmeliaBR: I don't think it would be a complication AmeliaBR: it is matter of the stroke geometry properties also being list properties. fantasai: Then you would be able to define geometry, but how do you define what color they are? heycam: If you really had to you could have CSS image values you would "salt"(?) with colors. fantasai: Those layer. You want to have things side by side. Different kind of list. fantasai: So you have a two color stroke, one red, one blue. fantasai: If you have two colors, you will get red and blue stacked on top of each other in z-order. fantasai: We don't have a syntax for having multiple fills fantasai: because the fills are already a list of z-ordered images fantasai: and you're asking for laterally stacked fills. AmeliaBR: The idea is that each stroke would be a different stroke layer AmeliaBR: the only place it would get confusing, is AmeliaBR: that the CSS background syntax has multiple images but only one color at the bottom. AmeliaBR: It would be nice to be able to have multiple colors especially for stroke AmeliaBR: one way would be to use the image function to have a solid color. fantasai: I think I understand what you're saying now fantasai: Thought it was similar with people asking for multiple borders; they want those strokes side-by-side, not stacked. BradK: For decorate borders BradK: my experience BradK: make each one wider than the one above it, and then knock out the text shapes. -webkit-text-fill ----------------- Jet: Question about fill: Jet: It's great that these specs are coming around. Jet: We (Mozilla) are currently being lobbied to implement the circa 2006 -webkit-text-fill-color Jet: My question is about the delta between the fill color stuff we are working on here Jet: and the implementation details of -webkit-text-fill-color Jet: and if there is a delta Jet: then for the same reasons we have to implement the -webkit-... Jet: then webkit and blink can't change either. Jet: Is that something we can align on Jet: to cover existing content? fantasai: Those should ideally map to what we are doing here. fantasai: It should just work that you drop the -webkit-text- prefix and just get the stroke-color BogdanBrinza: If you implement ... BogdanBrinza: What we've seen on some websites is fill but not stroke, it makes things worse. fantasai: We decided to reuse the SVG properties because they do the same things already. AmeliaBR: They match up pretty well. AmeliaBR: They should match up pretty well. AmeliaBR: The other one that should match up is background-clip AmeliaBR: because that's where I most often see text-fill to transparent in order to just show the background fill to text. astearns: And that's the next topic. hober: Question: hober: The stroke-align property hober: could we add an issue? hober: CG doesn't really provide this capacity hober: so I'd rather not have it. hober: Maybe too early to mark at-risk? fantasai: We can mark it at risk. <astearns> (or add a note that we're not sure it's implementable) hober: Basically we can do center. fantasai: Which is the initial value. fantasai: goal of this spec is to replace the SVG properties ... fantasai: not sure of the web compat impact astearns: let's close this topic background-clip-text -------------------- Scribe: alancutter & nainar <jet> https://webkit.org/blog/164/background-clip-text/ jet: Another request from core web compat team circa 2006/2012 jet: background-clip-text. jet: Desire to specify a way forward in a universal way "correct way" jet: implement -webkit- syntax in FF jet: See if we can write spec text around that behavior. jet: First thing - see documentation that can be normative text jet: around the existing behavior. jet: Did edge team implement this -webkit- one? <hober> https://webkit.org/blog/164/background-clip-text/ gregwhitworth: I don't think so - filed multiple times gregwhitworth: Do want to implement haven't gotten around to it. <BogdanBrinza> Edge didn't implement background-text-clip but it's known issue on our backlog. jet: Interest in specifying it. jet: Webkit behavior appear as normative behavior. jet: Is it desirable for it to appear as normative text or should it be a compat spec entry? fantasai: Should be a compat spec entry. fantasai: Should be a background level 4 module entry. fantasai: If it needs to exist for engines to implement for web compat, fantasai: spec the prefixed thing - unprefixed thing. jet: I'll take an action to write jet: the actual defacto spec for the webkit property and run it by people who don't have implementation. fantasai: Do we resolve to add to background level 4? plinss: I really reaalllly dislike the idea of having a prefixed and canonical spec. plinss: We have quirks spec for stuff that isn't CSS do for web compat. fantasai: It's harder to write spec - standards mode thing. AmeliaBR: If the longterm goal is to use the new fill properties does it make sense to have it in the same spec as the fill properties. fantasai: No because the value is for the background-clip property. fantasai: Could put in here not, not as a fill/stroke value fantasai: thats fine. astearns: I like having it in the same spec as what is actually CSS so people find it. astearns: Are you okay with putting it in an appendix? Florian: It is normative - authors must not use this - browsers may/should support this. fantasai: I think "may" is fine Florian: Normative - must not use for users, in same spec - yes ugly name - others names due to legacy that aren't branded. plinss: I'm okay with it being in the ? spec as long as it's clearly defined. fantasai: You're a bad person if you use this. plinss: Your website is bad and you should feel bad if you use this. astearns: Proposed resolution is to add this to the spec with caveats proposed. astearns: Objections? <tantek> W3C specs (e.g. HTML) have put things directly into deprecation that were never in any previous W3C spec <tantek> deprecation does mean that implementation should (or must) support it but authors should not use it RESOLVED: Add -webkit-background-clip-text to the spec stating that authors must not use it but browsers may support it. RESOLVED: Merge heycam's spec text with paint fx repository <fantasai> Note to fantasai: switch default value to fill-box, map it to padding-box, define more clearly that it's glyph ink bounds on inlines. Or something
Received on Thursday, 24 March 2016 00:01:34 UTC