From 82cba891e4011c6e8a895464fe21dc06e9ad6a3d Mon Sep 17 00:00:00 2001 From: Ryan Hunt Date: Wed, 2 Jan 2019 14:55:19 -0600 Subject: [PATCH 1/4] [css-scroll-anchoring-1] Fix link-defaults for content-area and css2 properties --- css-scroll-anchoring-1/Overview.bs | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/css-scroll-anchoring-1/Overview.bs b/css-scroll-anchoring-1/Overview.bs index 008f7a81c1d..4dac7aced86 100644 --- a/css-scroll-anchoring-1/Overview.bs +++ b/css-scroll-anchoring-1/Overview.bs @@ -18,7 +18,8 @@ Abstract: This spec also proposes an API for web developers to opt-out of this b 
-spec:css22;
+spec:css-box-3; type:dfn; text:content area
+spec:css2;
 	type:property;
 		text:max-height
 		text:min-height

From 7adba8ccbbe493a7934677b5e1c4fa917dd72ae2 Mon Sep 17 00:00:00 2001
From: Ryan Hunt 
Date: Tue, 18 Dec 2018 16:13:32 -0600
Subject: [PATCH 2/4] [css-scroll-anchoring-1] Make `position: sticky` an
 excluded subtree

`position: sticky` nodes aren't suitable anchor candidates as they may
become stuck in the future, which causes them to behave similarly to
`position: fixed`.
---
 css-scroll-anchoring-1/Overview.bs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/css-scroll-anchoring-1/Overview.bs b/css-scroll-anchoring-1/Overview.bs
index 4dac7aced86..5a0a73fac23 100644
--- a/css-scroll-anchoring-1/Overview.bs
+++ b/css-scroll-anchoring-1/Overview.bs
@@ -122,6 +122,7 @@ the implementation may wait until the anchor node is needed before computing it.
 
 	* |N|’s computed value of the 'display' property is ''display/none''.
 	* |N|’s computed value of the 'position' property is ''position/fixed''.
+	* |N|’s computed value of the 'position' property is ''position/sticky''.
 	* |N|’s computed value of the 'position' property is ''position/absolute''
 		and |N|’s containing block is an ancestor of the scrolling box.
 	* |N|’s computed value of the 'overflow-anchor' property is ''overflow-anchor/none''.

From 3f7adf174d48717e18f7c5327d6a82386de6d677 Mon Sep 17 00:00:00 2001
From: Ryan Hunt 
Date: Tue, 18 Dec 2018 16:48:06 -0600
Subject: [PATCH 3/4] [css-scroll-anchoring-1] Add condition to not select
 scroll anchor when not scrolled from origin

---
 css-scroll-anchoring-1/Overview.bs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/css-scroll-anchoring-1/Overview.bs b/css-scroll-anchoring-1/Overview.bs
index 5a0a73fac23..01ddbbb8eaa 100644
--- a/css-scroll-anchoring-1/Overview.bs
+++ b/css-scroll-anchoring-1/Overview.bs
@@ -19,6 +19,7 @@ Abstract: This spec also proposes an API for web developers to opt-out of this b
 
 
 spec:css-box-3; type:dfn; text:content area
+spec:cssom-view-1; type:dfn; text:scrolling area
 spec:css2;
 	type:property;
 		text:max-height
@@ -79,7 +80,9 @@ In some cases, a scrolling box may not select any anchor node.
 	1. If |S| is associated with an element
 		whose computed value of the 'overflow-anchor' property is ''overflow-anchor/none'',
 		then do not select an anchor node for |S|.
-	2. Otherwise, for each DOM child |N| of the element or document associated with |S|,
+	2. If |S| is not scrolled away from the origin of its scrolling area in its
+		block flow direction, then do not select an anchor node for |S|.
+	3. Otherwise, for each DOM child |N| of the element or document associated with |S|,
 		perform the candidate examination algorithm for |N| in |S|,
 		and terminate if it selects an anchor node.
 

From c87b95bf6e4127e29972c65baa29d11ff826b68f Mon Sep 17 00:00:00 2001
From: Ryan Hunt 
Date: Wed, 2 Jan 2019 15:41:48 -0600
Subject: [PATCH 4/4] [css-scroll-anchoring-1] Move and expand section on
 anchor node invalidation

This commit moves the existing paragraph about anchor node invalidation into
a subsection, and adds precise conditions upon when an anchor node is considered
invalidated.
---
 css-scroll-anchoring-1/Overview.bs | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/css-scroll-anchoring-1/Overview.bs b/css-scroll-anchoring-1/Overview.bs
index 01ddbbb8eaa..b9f8fda8702 100644
--- a/css-scroll-anchoring-1/Overview.bs
+++ b/css-scroll-anchoring-1/Overview.bs
@@ -114,11 +114,6 @@ In some cases, a scrolling box may not select any anchor node.
 		content to shift without triggering any scroll anchoring adjustment.
 
 
-Conceptually, a new anchor node is computed for every scrolling box
-whenever the scroll position of any scrolling box changes.
-(As a performance optimization,
-the implementation may wait until the anchor node is needed before computing it.)
-
 

 	A DOM node |N| is an excluded subtree
 	if it is an element and any of the following conditions holds:
@@ -152,6 +147,18 @@ the implementation may wait until the anchor node is needed before computing it.
 	or the bounding rect of its line boxes if |N| is a text node.
 

 
+

+Invalidation

+
+An anchor node is considered valid for a scrolling box until any of the following occur:
+	* The scroll position of the scrolling box changes (excluding adjustments originating from scroll anchoring).
+	* A suppression trigger suppresses a scroll adjustment.
+	* The anchor node is removed from the DOM.
+
+Once an anchor node has become invalid, the anchor node selection algorithm must be run again to compute the anchor node
+
+As a performance optimization, implementations may wait until the anchor node is needed before computing it.
+
 

 Scroll Adjustment