On 9/19/24 4:58 PM, Chromestatus wrote:
Contact emails
msten...@chromium.org
Explainer
https://github.com/mstensho/page-margin-boxes
Specification
https://drafts.csswg.org/css-page-3/#margin-boxes
Summary
Add support for page margin boxes, when printing a web document, or
exporting it as PDF. @page margin boxes allows an author to define the
contents in the margin area of a page, for instance to provide custom
headers and footers, rather than using the built-in headers and
footers generated by the browser. A margin box is defined via an
at-rule inside a CSS @page rule. There are 16 rules defined, one for
each page margin box. There's one margin box for each of the 4 corners
on the page, and three (start, middle, end) for each of the 4 sides.
The appearance and the contents of a margin box are specified with CSS
properties inside the at-rule, including the "content" property.
Counters are also to be supported, for page numbering. The
specification defines two special counter names: "page" for the
current page number, and "pages" for the total number of pages.
Blink component
Blink>Layout>Printing
<https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink>Layout>Printing>
TAG review
https://github.com/w3ctag/design-reviews/issues/918
TAG review status
Issues addressed
Risks
Interoperability and Compatibility
The spec defines the CSS counter names 'page' and 'pages'. Both are
accessible by the document's contents, so that any element may use the
counters to tell the current page number, or the total number of
pages. Documents that use these counter names without being aware of
this feature may be in for a surprise. Most browsers offer to generate
some default headers and footers, and they are usually enabled by
default. If the document has margin at-rules, they may come in
conflict. We need some way of making sure that we either use the
browser-default headers and footers, or the author-defined @page margins.
Can you clarify what you mean by "in for a surprise"? I don't think I
understand the compat implications of @page+ margin boxes here.
Also, do you have a plan for default header/footer conflicts w/
developer-provided ones?
/Gecko/: No signal
(https://github.com/mozilla/standards-positions/issues/921)
/WebKit/: No signal
(https://github.com/WebKit/standards-positions/issues/275)
/Web developers/: Positive
https://bugs.chromium.org/p/chromium/issues/detail?id=320370 currently
has 98 stars.
/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?
None
Debuggability
None
I think it's possible to emulate the print media via DevTools. Maybe
there are other possible debug modes to visually represent these named
margin boxes (as follow up work)?
Will this feature be supported on all six Blink platforms
(Windows, Mac, Linux, ChromeOS, 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>?
No
WPT tests will be written and submitted while working on this feature.
Flag name on chrome://flags
None
Finch feature name
PageMarginBoxes
Requires code in //chrome?
False
Tracking bug
https://bugs.chromium.org/p/chromium/issues/detail?id=320370
Estimated milestones
Shipping on desktop 131
Shipping on Android 131
Shipping on WebView 131
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).
None
Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5195769732923392?gate=6322213557108736
Links to previous Intent discussions
Intent to Prototype:
https://groups.google.com/a/chromium.org/g/blink-dev/c/ZCPkcu_dSF8
This intent message was generated by Chrome Platform Status
<https://chromestatus.com>.
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