LGTM2 On Wed, Oct 5, 2022 at 5:48 PM Philip Jägenstedt <foo...@chromium.org> wrote:
> LGTM1 with some strings attached. > > We discussed this in the API owners meeting (present: Chris, Yoav, Mike, > Daniel, me) > > Since this matches other implementations and is somewhat deliberate > unspec'd, shipping this sounds good. Very nice to see highly starred > interop issues being fixed :) > > Great that tests will be added, presumably those will be tentative > <https://web-platform-tests.org/writing-tests/file-names.html?highlight=tentative> > due to a lack of a spec. > > Traian, Philip, since this will be interoperable, can you propose a spec > change that would define it? Or if that runs into some roadblock, can you > loop back to this thread? (This does not block shipping.) > > On Thu, Sep 29, 2022 at 11:55 PM 'Philip Rogers' via blink-dev < > blink-dev@chromium.org> wrote: > >> >> >> On Thursday, September 29, 2022 at 12:17:10 PM UTC-7 Chris Harrelson >> wrote: >> >>> On Thu, Sep 29, 2022 at 12:15 PM Mike Taylor <mike...@chromium.org> >>> wrote: >>> >>>> On 9/28/22 3:01 PM, Traian Captan wrote: >>>> >>>> Contact emails >>>> >>>> tca...@chromium.org >>>> >>>> Explainer >>>> >>>> Though not a formal explainer, Emilio has an excellent writeup of this >>>> issue at https://crisal.io/words/2020/06/13/rounding-borders.html. >>>> >>>> Spec >>>> >>>> With this change to blink, all implementations will agree, and this can >>>> be specified (see: https://github.com/w3c/csswg-drafts/issues/5210). >>>> >>>> Is there any current blocker to specifying this (besides someone doing >>>> the work)? >>>> >>> >>> Currently, the specs intentionally avoid specifying pixel-snapping >>> behavior, and instead leave it up to engines to decide how they want to do >>> it. Changing that would be a significant effort. >>> >> >> Once this change lands, won't it be straightforward to specify this >> specific aspect of snapping? This change is visible in the computed style. >> >>> >>>> Summary >>>> >>>> Snap border, outline and column-rule widths before layout to avoid gaps >>>> between backgrounds and borders caused by paint-time snapping. With this >>>> change, Blink will match Gecko and WebKit. >>>> >>>> Blink component >>>> >>>> Blink >>>> <https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink> >>>> >>>> Motivation >>>> >>>> Currently Blink snaps the border widths at paint time. This can cause a >>>> visible 1px gap between a parent element's border and a child's background >>>> when the border is rounded down during paint since the snapping floors the >>>> value but the layout rounded it up to calculate the child’s s position (eg >>>> border-width is set to 10.75 pixels, rounded to 10px at paint time, but 11 >>>> at layout time). By making this change Blink will also behave like Gecko >>>> and WebKit and increase interoperability. >>>> >>>> Search tags >>>> >>>> border-width <https://chromestatus.com/features#tags:border-width>, >>>> outline-width <https://chromestatus.com/features#tags:outline-width>, >>>> column-rule-width >>>> <https://chromestatus.com/features#tags:column-rule-width> >>>> >>>> TAG review >>>> >>>> Skipping because this is a straightforward interop fix. >>>> >>>> TAG review status >>>> >>>> N/A >>>> >>>> Risks Interoperability and Compatibility >>>> >>>> Gecko and WebKit already snap borders before layout. >>>> >>>> This change would make Blink behave the same and increase >>>> interoperability and compatibility. >>>> >>>> The explainer section has a link to a blog post describing the >>>> differences in more detail. >>>> >>>> This issue and the proposed fix have been discussed in: Issue 1201762: >>>> [Task] Investigate border snapping before layout >>>> <https://crbug.com/1201762>, which is currently blocking 10 issues. >>>> >>>> >>>> >>>> This issue was also discussed on: >>>> >>>> https://github.com/w3c/csswg-drafts/issues/2114 >>>> >>>> https://github.com/w3c/csswg-drafts/issues/5210 >>>> >>>> >>>> >>>> Gecko: Shipped/Shipping >>>> >>>> WebKit: Shipped/Shipping >>>> >>>> Web developers: Strongly positive - This has been reported in at least >>>> 10 separate bugs with a cumulative star count of 75. >>>> >>>> Other signals: >>>> >>>> WebView application risks >>>> >>>> Does this intent deprecate or change behavior of existing APIs, such >>>> that it has potentially high risk for Android WebView-based applications? >>>> >>>> No >>>> >>>> >>>> Debuggability >>>> >>>> N/A >>>> >>>> >>>> Will this feature be supported on all six Blink platforms (Windows, >>>> Mac, Linux, Chrome OS, Android, and Android WebView)? >>>> >>>> Yes >>>> >>>> Is this feature fully tested by web-platform-tests >>>> <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md> >>>> ? >>>> >>>> New test will be added with the patch. >>>> >>>> Flag name Requires code in //chrome? >>>> >>>> False >>>> >>>> >>>> Tracking bug >>>> >>>> https://crbug.com/1201762 >>>> >>>> >>>> Launch bug >>>> >>>> https://crbug.com/1120347 >>>> Estimated milestones >>>> >>>> M108 >>>> Anticipated spec changes >>>> >>>> Open questions about a feature may be a source of future web compat or >>>> interop issues. Please list open issues (e.g. links to known github issues >>>> in the project for the feature specification) whose resolution may >>>> introduce web compat/interop risk (e.g., changing to naming or structure of >>>> the API in a non-backward-compatible way). >>>> >>>> https://github.com/w3c/csswg-drafts/issues/5210 >>>> Link to entry on the Chrome Platform Status >>>> >>>> https://chromestatus.com/feature/4651561863610368 >>>> >>>> This intent message was generated by Chrome Platform Status >>>> <https://chromestatus.com/>. >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "blink-dev" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to blink-dev+...@chromium.org. >>>> To view this discussion on the web visit >>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAFxahvsyqk3h2TZwDVJzb1KVgLjqmWDWMs3V9-1sZRA7pXkyOQ%40mail.gmail.com >>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAFxahvsyqk3h2TZwDVJzb1KVgLjqmWDWMs3V9-1sZRA7pXkyOQ%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "blink-dev" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to blink-dev+...@chromium.org. >>>> >>> To view this discussion on the web visit >>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/addc5bee-3957-b9f7-9f41-a0a2a7802618%40chromium.org >>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/addc5bee-3957-b9f7-9f41-a0a2a7802618%40chromium.org?utm_medium=email&utm_source=footer> >>>> . >>>> >>> -- >> You received this message because you are subscribed to the Google Groups >> "blink-dev" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to blink-dev+unsubscr...@chromium.org. >> To view this discussion on the web visit >> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/40644a65-1656-497d-a19d-caad46855c64n%40chromium.org >> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/40644a65-1656-497d-a19d-caad46855c64n%40chromium.org?utm_medium=email&utm_source=footer> >> . >> > -- > You received this message because you are subscribed to the Google Groups > "blink-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to blink-dev+unsubscr...@chromium.org. > To view this discussion on the web visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAARdPYeWLsmb0pvEmqOdvhEzaeFuUn-0vva2ofFH5Hn89zjV1g%40mail.gmail.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAARdPYeWLsmb0pvEmqOdvhEzaeFuUn-0vva2ofFH5Hn89zjV1g%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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