Write about layout

Author: delan

_posts/2025-11-02-this-month-in-servo.md

@@ -28,6 +28,17 @@ Servo now supports `new KeyboardEvent({keyCode})` and `({charCode})` (@atbrakhi,
 
 **ImageData** can now be sent over **postMessage()** and **structuredClone()** (@Gae24, #40084).
 
+## Layout engine
+
+Our layout engine can now render text in **synthetic bold** (@minghuaw, @mrobinson, #39519, #39681, #39633, #39691, #39713), and now selects more appropriate fallback fonts for **Kanji** in **Japanese text** (@arayaryoma, #39608).
+
+**‘initial-scale’** now does the right thing in **<meta name=viewport>** (@atbrakhi, @shubhamg13, @mrobinson, #40055).
+
+We’ve improved the way we handle **‘border-radius’** (@Loirooriol, #39571) and **margin collapsing** (@Loirooriol, #36322).
+While they’re fairly unassuming fixes on the surface, both of them allowed us to **find interop issues** in the big incumbent engines (@Loirooriol, [#39540](https://github.com/servo/servo/issues/39540), [#36321](https://github.com/servo/servo/issues/36321)) and **help improve web standards** (@noamr, @Loirooriol, [csswg-drafts#12961](https://github.com/w3c/csswg-drafts/issues/12961), [csswg-drafts#12218](https://github.com/w3c/csswg-drafts/issues/12218)).
+
+In other words, Servo is good for the web, even if you’re not using it yet!
+
 ## Embedding and ecosystem
 
 Our HTML-compatible **XPath** implementation now lives in its [own](https://github.com/servo/servo/tree/cd4c032908211fa2c26df550f6766080d1d28969/components/xpath) [crate](https://doc.servo.org/xpath/), and it’s no longer limited to the Servo DOM (@simonwuelker, #39546).

outline.txt

@@ -102,27 +102,27 @@
     - https://github.com/servo/servo/pull/40108	(@mrobinson, @atbrakhi, #40108)	script: Have the renderer process root viewport handle keyboard scrolling (#40108)
       input
 - layout
-    - https://github.com/servo/servo/pull/36322	(@Loirooriol, #36322)	layout: Let min/max constraints avoid collapsing bottom margins (#36322)
+    - DONE https://github.com/servo/servo/pull/36322	(@Loirooriol, #36322)	layout: Let min/max constraints avoid collapsing bottom margins (#36322)
       layout
-    - https://github.com/servo/servo/pull/39571	(@Loirooriol, #39571)	layout: Avoid negative corner radii values for border-radius (#39571)
+    - DONE https://github.com/servo/servo/pull/39571	(@Loirooriol, #39571)	layout: Avoid negative corner radii values for border-radius (#39571)
       layout
-    - https://github.com/servo/servo/pull/39519	(@minghuaw, #39519)	fonts: Initial draft of synthetic bold face for FreeType (#39519)
+    - DONE https://github.com/servo/servo/pull/39519	(@minghuaw, #39519)	fonts: Initial draft of synthetic bold face for FreeType (#39519)
       layout
     - https://github.com/servo/servo/pull/39591	(@mrobinson, @Loirooriol, #39591)	layout: Clone static position rectangles when caching in `IndependentFormattingContext` (#39591)
       layout; incremental
-    - https://github.com/servo/servo/pull/39681	(@minghuaw, @mrobinson, #39681)	fonts: Use OS/2 table to determine if font face is already bold when synthesizing bold face for FreeType platform (#39681)
+    - DONE https://github.com/servo/servo/pull/39681	(@minghuaw, @mrobinson, #39681)	fonts: Use OS/2 table to determine if font face is already bold when synthesizing bold face for FreeType platform (#39681)
       layout
-    - https://github.com/servo/servo/pull/39633	(@minghuaw, #39633)	fonts: Add synthetic bold face support for Windows (#39633)
+    - DONE https://github.com/servo/servo/pull/39633	(@minghuaw, #39633)	fonts: Add synthetic bold face support for Windows (#39633)
       layout
-    - https://github.com/servo/servo/pull/39691	(@minghuaw, #39691)	fonts: Add synthetic bold face support for macos (#39691)
+    - DONE https://github.com/servo/servo/pull/39691	(@minghuaw, #39691)	fonts: Add synthetic bold face support for macos (#39691)
       layout
-    - https://github.com/servo/servo/pull/39713	(@minghuaw, #39713)	fonts: Do not apply synthetic bold if font is already bold for webfont on FreeType platform (#39713)
+    - DONE https://github.com/servo/servo/pull/39713	(@minghuaw, #39713)	fonts: Do not apply synthetic bold if font is already bold for webfont on FreeType platform (#39713)
       layout
-    - https://github.com/servo/servo/pull/39608	(@arayaryoma, #39608)	fonts: Do not fall back to non-Japanese fonts for Han in Japanese language documents (#39608)
+    - DONE https://github.com/servo/servo/pull/39608	(@arayaryoma, #39608)	fonts: Do not fall back to non-Japanese fonts for Han in Japanese language documents (#39608)
       layout; better automatic font selection for japanese text on macOS and unix
-    - https://github.com/servo/servo/pull/39803	(@yezhizhen, #39803)	fonts: Fix compilation warning due to added fallback mechanism (#39803)
+    - SKIP https://github.com/servo/servo/pull/39803	(@yezhizhen, #39803)	fonts: Fix compilation warning due to added fallback mechanism (#39803)
       layout; font fallback for japanese text
-    - https://github.com/servo/servo/pull/40055	(@atbrakhi, @shubhamg13, @mrobinson, #40055)	compositor: Have viewport meta tag affect the layout viewport (#40055)
+    - DONE https://github.com/servo/servo/pull/40055	(@atbrakhi, @shubhamg13, @mrobinson, #40055)	compositor: Have viewport meta tag affect the layout viewport (#40055)
       layout
     - https://github.com/servo/servo/pull/39930	(@longvatrong111, #39930)	Box tree construction: only unset pseudo elements if the box is rebuilt (#39930)
       layout

tools/commits.txt

@@ -100,7 +100,7 @@
     # Testing: No changes
     # Fixes: #36833
 +https://github.com/servo/servo/pull/36322	(@Loirooriol, #36322)	layout: Let min/max constraints avoid collapsing bottom margins (#36322)
-    layout
+    ;layout
     # When `block-size` was intrinsic and there was no block-end padding or margin, we were allowing the block-end margin of
     # the box to collapse with the block-end margin of its contents.
     # However, due to `min-block-size` or `max-block-size`, the final size can be different than the intrinsic size of the
@@ -136,7 +136,7 @@
     # need these metrics to be added to Perfetto also.
     # Testing: Verified by using Perfetto traces
 +https://github.com/servo/servo/pull/39571	(@Loirooriol, #39571)	layout: Avoid negative corner radii values for border-radius (#39571)
-    layout
+    ;layout
     # The `border-radius` property provides the radii for the border box.  For the curvature of the padding and content boxes,
     # we then subtract the border and padding sizes.  However, we weren't flooring the result by zero, which could make the
     # background completely disappear when using `background-clip: padding-box` or `background-clip: content-box`.
@@ -286,7 +286,7 @@
     # rebase manually by commenting `@dependabot rebase`.
     # [//]: # (dependabot-automerge-start) [//]: # (dependabot-automerge-end)
 +https://github.com/servo/servo/pull/39519	(@minghuaw, #39519)	fonts: Initial draft of synthetic bold face for FreeType (#39519)
-    layout
+    ;layout
     # This is an initial attempt at implementing synthetic bold face for font families that lack actual bold faces.  The
     # overall approach borrowed implementations from Chromium and FireFox.  WPT expectations will be updated after
     # https://github.com/servo/stylo/pull/244 lands
@@ -883,7 +883,7 @@
     # triggered when the button up and down cross frame boundaries.
     # Testing: This should be covered by existing tests.
 +https://github.com/servo/servo/pull/39681	(@minghuaw, @mrobinson, #39681)	fonts: Use OS/2 table to determine if font face is already bold when synthesizing bold face for FreeType platform (#39681)
-    layout
+    ;layout
     # The previous implementation in #39519 mistakenly used the `FontTemplateDescriptor` to determine whether the font face
     # itself is already bold.  This PR fixes that by using the `usWeightClass` in the `OS/2` table of the font face to
     # determine if the font face is bold already.
@@ -1070,7 +1070,7 @@
     # Testing: No behaviour change Fixes: #39497 Fixes: #39649
 >>> 2025-10-10T06:17:29Z
 +https://github.com/servo/servo/pull/39633	(@minghuaw, #39633)	fonts: Add synthetic bold face support for Windows (#39633)
-    layout
+    ;layout
     # This PR follows #39519 and adds synthetic bold face support for Windows platform.
     # Testing: There are existing WPT testcases for font synthesis (wpt/css/css-fonts/font-synthesis-*).  A new test that
     # checks for "double emboldening" (a bold font gets emboldened again) is getting added to the upstream WPT repo
@@ -1190,7 +1190,7 @@
     # Testing: Unneeded, no change in behavior
     # Stylo PR: https://github.com/servo/stylo/pull/251
 +https://github.com/servo/servo/pull/39691	(@minghuaw, #39691)	fonts: Add synthetic bold face support for macos (#39691)
-    layout
+    ;layout
     # This PR follows https://github.com/servo/servo/pull/39519 and adds synthetic bold face support for MacOs platform.
     # Testing: There are existing WPT testcases for font synthesis (wpt/css/css-fonts/font-synthesis-*).  A new test checking
     # that a bold face font does not get "double emboldened" is getting added in #39713 Part of #39637
@@ -1273,7 +1273,7 @@
     # Testing: Unnecessary, there should be no behavior change Fixes: #39710
     # Stylo PR: https://github.com/servo/stylo/pull/250
 +https://github.com/servo/servo/pull/39713	(@minghuaw, #39713)	fonts: Do not apply synthetic bold if font is already bold for webfont on FreeType platform (#39713)
-    layout
+    ;layout
     # This is to fix my oversight in the previous PR #39681 where the use of OS/2 table to determine a synthetic bold face
     # should be applied is not applied to web font.
     # Testing: Added a new test `tests/wpt/mozilla/tests/css/font_synthesis_weight_webfont_bold.html` that checks if an
@@ -1456,7 +1456,7 @@
     # order matters.  This PR addresses this.
     # Testing: Added 8 subtests to wdspec.  Fixes: Part of #38083.
 +https://github.com/servo/servo/pull/39608	(@arayaryoma, #39608)	fonts: Do not fall back to non-Japanese fonts for Han in Japanese language documents (#39608)
-    layout; better automatic font selection for japanese text on macOS and unix
+    ;layout; better automatic font selection for japanese text on macOS and unix
     # ## Motivations
     # This PR improves fallback font algorithm for Japanese documents on macos and Linux.
     # For Japanese documents, we generally use a same font for Hiragana/Katakana/Kanji(Han).  Since their is a fallback
@@ -1670,7 +1670,7 @@ https://github.com/servo/servo/pull/39775	(@TimvdLippe, #39775)	Add policy conta
     # `import_key_hmac` and `import_key_pbkdf2` are removed since they are no longer in use.
     # Testing: Refactoring.  Existing WPT tests suffice.  Fixes: Part of #39368
 +https://github.com/servo/servo/pull/39803	(@yezhizhen, #39803)	fonts: Fix compilation warning due to added fallback mechanism (#39803)
-    layout; font fallback for japanese text
+    ;layout; font fallback for japanese text
     # #39608 added a mechanism to read document language from layout.  It was used to make sure fallback font for
     # Hiragana/Katakana/Kanji is same for Japanese document.
     # Right now, the mechanism is only used for FreeType/macOS.  For Windows, it already did the job correctly even before
@@ -2766,7 +2766,7 @@ https://github.com/servo/servo/pull/39794	(@TimvdLippe, #39794)	Implement docume
     # (which need to be upgraded to 2.0) and a few other crates.
     # Testing: No testing needed.
 +https://github.com/servo/servo/pull/40055	(@atbrakhi, @shubhamg13, @mrobinson, #40055)	compositor: Have viewport meta tag affect the layout viewport (#40055)
-    layout
+    ;layout
     # The CSS specifications defines two viewports[^1], the "layout viewport" and the visual viewport.  The layout viewport
     # affects layout and the visual viewport is the result of applying pinch zoom.  This changes makes it so that the
     # initial-scale property of `` affects the layout viewport.