From c2fa93089b2251e72973ded1fa042ef4207dfa34 Mon Sep 17 00:00:00 2001 From: Andreu Botella Date: Mon, 2 Sep 2024 13:57:00 +0200 Subject: [PATCH 01/13] [css-overflow-4] Draft spec for `continue: collapse` (#7708) --- css-overflow-4/Overview.bs | 119 ++++++++++++++++++++++++++++--------- 1 file changed, 91 insertions(+), 28 deletions(-) diff --git a/css-overflow-4/Overview.bs b/css-overflow-4/Overview.bs index 6dc3db0d26c..3f828d3ac9b 100644 --- a/css-overflow-4/Overview.bs +++ b/css-overflow-4/Overview.bs @@ -707,12 +707,15 @@ Indicating Block-Axis Overflow: the 'block-ellipsis' property This property allows inserting content into the last line box - before a (forced or unforced) region break - to indicate the continuity of truncated/interrupted content. + before a (forced or unforced) region break or a [=clamp point=] + to indicate the continuity of truncated / interrupted content. It only affects line boxes contained directly by the block container itself, but as it inherits, will have an effect on descendants’ line boxes unless overridden. - If the box contains no line box immediately preceding a region break, - then this property has no effect. + + This property only affects a line box if there is eiher a [=region break=] or a [=clamp point=] + after it in the [=block formatting context=], and there are no boxes or line boxes in between. + If the [=clamp point=] is placed at the end of the [=line-clamp container=], then the line will + not be affected. Note: See [[css-overflow-4#fragmentation]] for a way to generate boxes with such a [=region break=]. @@ -777,10 +780,12 @@ Indicating Block-Axis Overflow: the 'block-ellipsis' property The [=block overflow ellipsis=] must not be included in either the ''::first-letter'' nor the ''::first-line'' pseudo-elements. - If there is a subsequent fragmentation container in the [=fragmentation context=] + If the [=block overflow ellipsis=] is placed before a [=region break=] and + there is a subsequent fragmentation container in the [=fragmentation context=] that would receive subsequent content, then the content displaced by the block overflow ellipsis - must be pushed to that fragmentation container. + must be pushed to that fragmentation container. If it is placed before a [=clamp point=], + then the displaced content must be pushed to the remainder of the [=inline formatting context=]. The UA must treat the block overflow ellipsis as an unbreakable string, If any part of the [=block overflow ellipsis=] overflows, @@ -844,7 +849,7 @@ Limiting Visible Lines: the 'line-clamp' shorthand property
<>
<'block-ellipsis'>
- Sets 'continue' to ''discard'' + Sets 'continue' to ''collapse'' if either or both values ares specified. Sets 'max-lines' to the specified <> @@ -901,7 +906,7 @@ Legacy compatibility For compatibility with legacy content, UAs that support 'line-clamp' must also support the '-webkit-line-clamp' property - and the additional ''-webkit-discard'' value for the 'continue' property. + and the additional ''-webkit-collapse'' value for the 'continue' property. 
 		Name: -webkit-line-clamp
@@ -912,17 +917,17 @@ Legacy compatibility
 
 	
 		Name: continue
-		New Values: -webkit-discard
+		New Values: -webkit-collapse
 	

 
 	Like 'line-clamp', '-webkit-line-clamp' is a shorthand of 'max-lines', 'continue', and 'block-ellipsis',
 	except that:
 
 	* its syntax is ''line-clamp/none'' | <>
-	* it sets 'continue' to ''-webkit-discard'' instead of ''discard''
+	* it sets 'continue' to ''-webkit-collapse'' instead of ''collapse''
 	* it unconditionally sets 'block-ellipsis' to ''block-ellipsis/auto''
 
-	The -webkit-discard value behaves identically to ''discard'',
+	The -webkit-collapse value behaves identically to ''collapse'',
 	except that it only takes effect
 	if the [=specified value=] of the 'display' property
 	is ''-webkit-box'' or ''-webkit-inline-box''
@@ -947,28 +952,33 @@ Forcing a Break After a Set Number of Lines: the 'max-lines' property
 		Name: max-lines
 		Value: ''none'' | <>
 		Initial: ''none''
-		Applies to: block containers which are also [=fragmentation containers=] that capture [=region breaks=]
+		Applies to: block containers which are also either [=fragmentation containers=] that capture [=region breaks=] or [=line-clamp containers=]
 		Inherited: no
 		Percentages: N/A
 		Computed value: the keyword ''max-lines/none'' or an integer
 		Animation type: by computed value type
- This property only has an effect on boxes that are [=fragmentation containers=] that capture [=region breaks=]. + If the value of 'max-lines' is not none, then, where + N is the computed value of 'max-lines': + + - If the box is a [=fragmentation container=] that captures [=region breaks=], + a region break or + is forced after its Nth + descendant in-flow line box. + If fewer than N line boxes exist, + then 'max-lines' introduces no region break. + - If the box is a [=line-clamp container=], its [=clamp point=] is set after its Nth + descendant in-flow line box. + If fewer than N line boxes exist, then the clamp point is set to the end of the + line-clamp container. - Also, if the value of 'max-lines' is not none, - a region break - is forced after its Nth - descendant in-flow line box, - where N is the specified value of 'max-lines'. - Only lines boxes in the same Block Formatting Context + + Only line boxes in the same Block Formatting Context are counted: the contents of descendants that establish independent formatting contexts are skipped over while counting line boxes. - If fewer than N line boxes exist, - then 'max-lines' introduces no region break. - Note: This implies that 'max-lines' has no effect when applied to [=multi-column containers=], since any line box they contain are nested into [=independent formatting contexts=]. @@ -1004,7 +1014,7 @@ Fragmentation of Overflow: the 'continue' property 
 		Name: continue
-		Value: auto | discard
+		Value: auto | discard | collapse
 		Initial: ''continue/auto''
 		Applies to: [=block containers=] and [=multicol containers=]
 		Inherited: no
@@ -1014,10 +1024,11 @@ Fragmentation of Overflow: the 'continue' property
The 'continue' property gives authors the ability - to turn a box into a [=fragmentation container=] (see [[!CSS-BREAK-3]]) - and to specify that content after the [=fragmentation break=] must be discarded. + to truncate/interrupt the content inside a box, by either visually hiding + the remaining content, or by turning the box into a [=fragmentation container=] (see [[!CSS-BREAK-3]]) + and discarding the content after the [=fragmentation break=]. - Issue: This property is meant to generalize and replace the region-fragment property from [[CSS-REGIONS-1]]. + Issue: ''continue: discard'' is meant to generalize and replace the region-fragment property from [[CSS-REGIONS-1]]. Once it is sufficiently stable in this specification, region-fragment should be removed from the regions specification in favor of this. @@ -1048,6 +1059,15 @@ Fragmentation of Overflow: the 'continue' property Breaks applying to other [=fragmentation contexts=] (such as pagination of this box itself) do not cause any content to be discarded. + +
collapse +
+ If the box is a [=block container=], then it must + [=establish an independent formatting context=] that also becomes a [=line-clamp container=]. + This causes all content after the [=clamp point=] to be visually hidden, and to not be + taken into account for the box's [=automatic block size=]. + + This keyword has no effect on [=multicol containers=].
@@ -1115,6 +1135,9 @@ Fragmentation of Overflow: the 'continue' property would cause intrinsic sizes to depend on layout, which would cause circularities. --> + Note: This differs from the ''visibility: hidden''-like behavior of content after the [=clamp + point=] with ''continue: collapse''. + Note: In the case of parallel fragmentation flows, content occurring after the fragmentation break in the box tree could still be rendered, @@ -1123,12 +1146,12 @@ Fragmentation of Overflow: the 'continue' property Additionaliy, for compatibility (see [[#webkit-line-clamp]]), - when the [=computed value=] of the 'continue' property is ''discard'' + when the [=computed value=] of the 'continue' property is ''collapse'' or ''-webkit-collapse'' and the [=computed value=] of the '-webkit-box-orient' property is ''vertical'': * If the [=specified value=] of the 'display' property is ''-webkit-box'', the [=computed value=] becomes ''flow-root'' and the box establishes a [=BFC=]. - * If the [=specified value=] of the 'display property is ''-webkit-inline-box'', + * If the [=specified value=] of the 'display' property is ''-webkit-inline-box'', the [=computed value=] becomes ''inline-block'' and the box establishes a [=BFC=]. @@ -1140,6 +1163,46 @@ Fragmentation of Overflow: the 'continue' property as the box would be a [=flex container=] rather than a [=block container=], and thus the 'continue' property would not apply. +

Line-clamp containers

+ + A line-clamp container is an [=independent formatting context|independent=] [=block formatting context=] that + additionally follows the rules in this section. All line-clamp containers contain a + clamp point, which is one of the following positions inside it: + + - The start of the line-clamp container. + - A point between two [=in-flow=] sibling boxes in the line-clamp + container's [=block formatting context=]. + - A point between two [=line boxes=] in an in-flow [=inline formatting + context=] inside the line-clamp container's [=block formatting context=]. + - The end of the line-clamp container. + + Note: The [=clamp point=] can never be before a parent box's first child, or + after a parent box's last child, unless that parent box is the line-clamp + container. Similarly, the clamp point can never be before the first line or + after the first line of an [=inline formatting context=]. It can also never + be in [=out-of-flow=] content, or inside an [=independent formatting + context=]. + + If the [=line-clamp container=]'s [=block formatting context root=] has a [=computed value=] of + 'max-lines' other than ''max-lines/none'', then that property will determine the [=clamp point=]. + Otherwise, the clamp point will be set to the last possible clamp point such that, for it and + all previous possible clamp points, the line-clamp container's [=automatic block size=] (as + determined below) is not greater than the [=block size=] the box would have if its automatic + block size were infinite. + + Any boxes in a [=line-clamp container=] that follow its [=clamp point=] in the box tree, as well + as any [=line boxes=] that follow it inside an [=inline formatting context=], will be invisible + (behaving like ''visibility: hidden''). This includes [=independent formatting contexts=] as + well as [=out-of-flow=] boxes, and all of their descendants. Any overflow such boxes and line + boxes might have is always counted as [=ink overflow=] rather than [=scrollable overflow=]. + + NOTE: This differs from the ''display: none''-like behavior of not rendered content with + ''continue: discard''. + + If a [=block container=] contains a [=clamp point=], within itself or in any of its descendants, + its [=automatic block size=] will not take into account any of its children after the clamp point. + This also applies for the [=line-clamp container=] itself. +

Appendix A: Possible extensions for ''scrollbar-gutter''

From c7df9c98f80dca9cae99369a8f30162928f6e50e Mon Sep 17 00:00:00 2001 From: Andreu Botella Date: Sun, 15 Sep 2024 01:25:50 +0200 Subject: [PATCH 02/13] Clarification about float clearance in the automatic block size --- css-overflow-4/Overview.bs | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/css-overflow-4/Overview.bs b/css-overflow-4/Overview.bs index 3f828d3ac9b..c322df1d40c 100644 --- a/css-overflow-4/Overview.bs +++ b/css-overflow-4/Overview.bs @@ -1203,6 +1203,12 @@ Fragmentation of Overflow: the 'continue' property its [=automatic block size=] will not take into account any of its children after the clamp point. This also applies for the [=line-clamp container=] itself. + NOTE: If there are any floats before the [=clamp point=], the [=line-clamp container=]'s + automatic size must grow to encompass the clearance, just like it would if it were a regular + [=block formatting context=] root that only contained its contents before the [=clamp point=]. + This is regardless of whether this would cause any content after the [=clamp point=] to be + within the container's bounds. +

Appendix A: Possible extensions for ''scrollbar-gutter''

From 1699d89b19296b9715e79d5092f4e41ab30ee35c Mon Sep 17 00:00:00 2001 From: Andreu Botella Date: Fri, 4 Oct 2024 08:36:34 +0900 Subject: [PATCH 03/13] Update to only allow clamping after a line --- css-overflow-4/Overview.bs | 24 ++++++++---------------- 1 file changed, 8 insertions(+), 16 deletions(-) diff --git a/css-overflow-4/Overview.bs b/css-overflow-4/Overview.bs index c322df1d40c..56013f5f97d 100644 --- a/css-overflow-4/Overview.bs +++ b/css-overflow-4/Overview.bs @@ -712,8 +712,8 @@ Indicating Block-Axis Overflow: the 'block-ellipsis' property It only affects line boxes contained directly by the block container itself, but as it inherits, will have an effect on descendants’ line boxes unless overridden. - This property only affects a line box if there is eiher a [=region break=] or a [=clamp point=] - after it in the [=block formatting context=], and there are no boxes or line boxes in between. + This property only affects a line box if it immediately precedes + eiher a [=region break=] or a [=clamp point=] in the [=block formatting context=]. If the [=clamp point=] is placed at the end of the [=line-clamp container=], then the line will not be affected. @@ -1169,26 +1169,18 @@ Fragmentation of Overflow: the 'continue' property additionally follows the rules in this section. All line-clamp containers contain a clamp point, which is one of the following positions inside it: - - The start of the line-clamp container. - - A point between two [=in-flow=] sibling boxes in the line-clamp - container's [=block formatting context=]. - - A point between two [=line boxes=] in an in-flow [=inline formatting - context=] inside the line-clamp container's [=block formatting context=]. - - The end of the line-clamp container. - - Note: The [=clamp point=] can never be before a parent box's first child, or - after a parent box's last child, unless that parent box is the line-clamp - container. Similarly, the clamp point can never be before the first line or - after the first line of an [=inline formatting context=]. It can also never - be in [=out-of-flow=] content, or inside an [=independent formatting - context=]. + - A point immediately after a [=line box=] in the line-clamp container's [=block formatting + context=]. + - The end of the line-clamp container, if there are any boxes after the last [=inline formatting + context=] in the line-clamp container's [=block formatting context=]. If the [=line-clamp container=]'s [=block formatting context root=] has a [=computed value=] of 'max-lines' other than ''max-lines/none'', then that property will determine the [=clamp point=]. Otherwise, the clamp point will be set to the last possible clamp point such that, for it and all previous possible clamp points, the line-clamp container's [=automatic block size=] (as determined below) is not greater than the [=block size=] the box would have if its automatic - block size were infinite. + block size were infinite; or if that is not the case for any clamp points, to the first clamp + point in the block formatting context. Any boxes in a [=line-clamp container=] that follow its [=clamp point=] in the box tree, as well as any [=line boxes=] that follow it inside an [=inline formatting context=], will be invisible From ee8fab92fae27523e90748eb604f4dc83fc88ebf Mon Sep 17 00:00:00 2001 From: Andreu Botella Date: Tue, 3 Dec 2024 10:10:19 +0100 Subject: [PATCH 04/13] Apply suggestions from code review Co-authored-by: Florian Rivoal --- css-overflow-4/Overview.bs | 112 +++++++++++++++++++++---------------- 1 file changed, 65 insertions(+), 47 deletions(-) diff --git a/css-overflow-4/Overview.bs b/css-overflow-4/Overview.bs index 56013f5f97d..7b6b6c4750e 100644 --- a/css-overflow-4/Overview.bs +++ b/css-overflow-4/Overview.bs @@ -712,10 +712,11 @@ Indicating Block-Axis Overflow: the 'block-ellipsis' property It only affects line boxes contained directly by the block container itself, but as it inherits, will have an effect on descendants’ line boxes unless overridden. - This property only affects a line box if it immediately precedes - eiher a [=region break=] or a [=clamp point=] in the [=block formatting context=]. - If the [=clamp point=] is placed at the end of the [=line-clamp container=], then the line will - not be affected. + This property only affects a line box + if it immediately precedes eiher a [=region break=] + or a [=clamp point=] in the [=block formatting context=]. + If the [=clamp point=] is placed at the end of the [=line-clamp container=], + then the line will not be affected. Note: See [[css-overflow-4#fragmentation]] for a way to generate boxes with such a [=region break=]. @@ -784,7 +785,8 @@ Indicating Block-Axis Overflow: the 'block-ellipsis' property there is a subsequent fragmentation container in the [=fragmentation context=] that would receive subsequent content, then the content displaced by the block overflow ellipsis - must be pushed to that fragmentation container. If it is placed before a [=clamp point=], + must be pushed to that fragmentation container. + If it is placed before a [=clamp point=], then the displaced content must be pushed to the remainder of the [=inline formatting context=]. The UA must treat the block overflow ellipsis as an unbreakable string, @@ -849,6 +851,9 @@ Limiting Visible Lines: the 'line-clamp' shorthand property
<>
<'block-ellipsis'>
+ + Issue(7708): Whether this should imply ''discard'' or ''collapse'' is an unresolved question. + Sets 'continue' to ''collapse'' if either or both values ares specified. @@ -959,19 +964,20 @@ Forcing a Break After a Set Number of Lines: the 'max-lines' property Animation type: by computed value type - If the value of 'max-lines' is not none, then, where - N is the computed value of 'max-lines': + If the value of 'max-lines' is not none, + then, given a [=computed value=] of N: - If the box is a [=fragmentation container=] that captures [=region breaks=], - a region break or + a region break is forced after its Nth descendant in-flow line box. If fewer than N line boxes exist, then 'max-lines' introduces no region break. - - If the box is a [=line-clamp container=], its [=clamp point=] is set after its Nth + - If the box is a [=line-clamp container=], + its [=clamp point=] is set after its Nth descendant in-flow line box. - If fewer than N line boxes exist, then the clamp point is set to the end of the - line-clamp container. + If fewer than N line boxes exist, + then the clamp point is set to the end of the line-clamp container. Only line boxes in the same Block Formatting Context @@ -1024,8 +1030,9 @@ Fragmentation of Overflow: the 'continue' property The 'continue' property gives authors the ability - to truncate/interrupt the content inside a box, by either visually hiding - the remaining content, or by turning the box into a [=fragmentation container=] (see [[!CSS-BREAK-3]]) + to truncate/interrupt the content inside a box, + either by visually hiding the remaining content, + or by turning the box into a [=fragmentation container=] (see [[!CSS-BREAK-3]]) and discarding the content after the [=fragmentation break=]. Issue: ''continue: discard'' is meant to generalize and replace the region-fragment property from [[CSS-REGIONS-1]]. @@ -1135,8 +1142,8 @@ Fragmentation of Overflow: the 'continue' property would cause intrinsic sizes to depend on layout, which would cause circularities. --> - Note: This differs from the ''visibility: hidden''-like behavior of content after the [=clamp - point=] with ''continue: collapse''. + Note: This differs from the ''visibility: hidden''-like behavior + of content after the [=clamp point=] with ''continue: collapse''. Note: In the case of parallel fragmentation flows, content occurring after the fragmentation break in the box tree @@ -1165,41 +1172,52 @@ Fragmentation of Overflow: the 'continue' property

Line-clamp containers

- A line-clamp container is an [=independent formatting context|independent=] [=block formatting context=] that - additionally follows the rules in this section. All line-clamp containers contain a - clamp point, which is one of the following positions inside it: - - - A point immediately after a [=line box=] in the line-clamp container's [=block formatting - context=]. - - The end of the line-clamp container, if there are any boxes after the last [=inline formatting - context=] in the line-clamp container's [=block formatting context=]. - - If the [=line-clamp container=]'s [=block formatting context root=] has a [=computed value=] of - 'max-lines' other than ''max-lines/none'', then that property will determine the [=clamp point=]. - Otherwise, the clamp point will be set to the last possible clamp point such that, for it and - all previous possible clamp points, the line-clamp container's [=automatic block size=] (as - determined below) is not greater than the [=block size=] the box would have if its automatic - block size were infinite; or if that is not the case for any clamp points, to the first clamp - point in the block formatting context. - - Any boxes in a [=line-clamp container=] that follow its [=clamp point=] in the box tree, as well - as any [=line boxes=] that follow it inside an [=inline formatting context=], will be invisible - (behaving like ''visibility: hidden''). This includes [=independent formatting contexts=] as - well as [=out-of-flow=] boxes, and all of their descendants. Any overflow such boxes and line - boxes might have is always counted as [=ink overflow=] rather than [=scrollable overflow=]. - - NOTE: This differs from the ''display: none''-like behavior of not rendered content with - ''continue: discard''. - - If a [=block container=] contains a [=clamp point=], within itself or in any of its descendants, + A line-clamp container is an [=independent formatting context|independent=] [=block formatting context=] + that additionally follows the rules in this section. + All line-clamp containers contain a clamp point, + which is one of the following positions inside it: + + - A point immediately after a [=line box=] + in the line-clamp container's [=block formatting context=]. + - The end of the line-clamp container, + if there are any boxes after the last [=inline formatting context=] + in the line-clamp container's [=block formatting context=]. + + If the [=line-clamp container=]'s [=block formatting context root=] + has a [=computed value=] of 'max-lines' other than ''max-lines/none'', + then that property will determine the [=clamp point=]. + Otherwise, the clamp point will be set to the last possible clamp point + such that, for it and all previous possible clamp points, + the line-clamp container's [=automatic block size=] + (as determined below) + is not greater than the [=block size=] the box would have + if its automatic block size were infinite; + or if that is not the case for any possible clamp points, + to the first possible clamp point in the block formatting context. + + Any boxes in a [=line-clamp container=] that follow its [=clamp point=] in the box tree, + as well as any [=line boxes=] that follow it inside an [=inline formatting context=], + will be invisible (behaving like ''visibility: hidden''). + This includes [=independent formatting contexts=] + as well as [=out-of-flow=] boxes, + and all of their descendants. + Any overflow such boxes and line boxes might have + is always counted as [=ink overflow=] rather than [=scrollable overflow=]. + + NOTE: This differs from the ''display: none''-like behavior + of not rendered content with ''continue: discard''. + + If a [=block container=] contains a [=clamp point=], + within itself or in any of its descendants, its [=automatic block size=] will not take into account any of its children after the clamp point. This also applies for the [=line-clamp container=] itself. - NOTE: If there are any floats before the [=clamp point=], the [=line-clamp container=]'s - automatic size must grow to encompass the clearance, just like it would if it were a regular - [=block formatting context=] root that only contained its contents before the [=clamp point=]. - This is regardless of whether this would cause any content after the [=clamp point=] to be - within the container's bounds. + NOTE: If there are any floats before the [=clamp point=], + the [=line-clamp container=]'s automatic size must grow to encompass the clearance, + just like it would if it were a regular [=block formatting context=] root + that only contained its contents before the [=clamp point=]. + This is regardless of whether this would cause any content after the [=clamp point=] + to be within the container's bounds.

Appendix A: Possible extensions for ''scrollbar-gutter''

From 178c050a2cc44d97d48ba970e3b0c7b59f8821ab Mon Sep 17 00:00:00 2001 From: Andreu Botella Date: Tue, 3 Dec 2024 10:35:22 +0100 Subject: [PATCH 05/13] Update css-overflow-4/Overview.bs Co-authored-by: Florian Rivoal --- css-overflow-4/Overview.bs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/css-overflow-4/Overview.bs b/css-overflow-4/Overview.bs index 7b6b6c4750e..4e5b7d63bc5 100644 --- a/css-overflow-4/Overview.bs +++ b/css-overflow-4/Overview.bs @@ -1153,7 +1153,7 @@ Fragmentation of Overflow: the 'continue' property Additionaliy, for compatibility (see [[#webkit-line-clamp]]), - when the [=computed value=] of the 'continue' property is ''collapse'' or ''-webkit-collapse'' + when the [=computed value=] of the 'continue' property is '''collapse'', ''-webkit-collapse'', or ''discard'' and the [=computed value=] of the '-webkit-box-orient' property is ''vertical'': * If the [=specified value=] of the 'display' property is ''-webkit-box'', the [=computed value=] becomes ''flow-root'' and From c9aadd345fcfe908fdabd4f3ca642db8e80dac32 Mon Sep 17 00:00:00 2001 From: "Tab Atkins Jr." Date: Fri, 23 May 2025 15:37:14 -0700 Subject: [PATCH 06/13] Update css-overflow-4/Overview.bs --- css-overflow-4/Overview.bs | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/css-overflow-4/Overview.bs b/css-overflow-4/Overview.bs index 4e5b7d63bc5..f7731eb9b0b 100644 --- a/css-overflow-4/Overview.bs +++ b/css-overflow-4/Overview.bs @@ -968,16 +968,16 @@ Forcing a Break After a Set Number of Lines: the 'max-lines' property then, given a [=computed value=] of N: - If the box is a [=fragmentation container=] that captures [=region breaks=], - a region break - is forced after its Nth - descendant in-flow line box. - If fewer than N line boxes exist, - then 'max-lines' introduces no region break. + a region break + is forced after its Nth + descendant in-flow line box. + If fewer than N line boxes exist, + then 'max-lines' introduces no region break. - If the box is a [=line-clamp container=], - its [=clamp point=] is set after its Nth - descendant in-flow line box. - If fewer than N line boxes exist, - then the clamp point is set to the end of the line-clamp container. + its [=clamp point=] is set after its Nth + descendant in-flow line box. + If fewer than N line boxes exist, + then the clamp point is set to the end of the line-clamp container. Only line boxes in the same Block Formatting Context From ce29a7af28906cb5db5b414b901a89fa711396ad Mon Sep 17 00:00:00 2001 From: "Tab Atkins Jr." Date: Fri, 23 May 2025 15:37:22 -0700 Subject: [PATCH 07/13] Update css-overflow-4/Overview.bs --- css-overflow-4/Overview.bs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/css-overflow-4/Overview.bs b/css-overflow-4/Overview.bs index f7731eb9b0b..85c8eecf00a 100644 --- a/css-overflow-4/Overview.bs +++ b/css-overflow-4/Overview.bs @@ -980,7 +980,7 @@ Forcing a Break After a Set Number of Lines: the 'max-lines' property then the clamp point is set to the end of the line-clamp container. - Only line boxes in the same Block Formatting Context + Only line boxes in the same block formatting context are counted: the contents of descendants that establish independent formatting contexts are skipped over while counting line boxes. From 716ddfc64183bee79fec40ba8f7b3ac1ecd5f14e Mon Sep 17 00:00:00 2001 From: "Tab Atkins Jr." Date: Fri, 23 May 2025 15:37:30 -0700 Subject: [PATCH 08/13] Update css-overflow-4/Overview.bs --- css-overflow-4/Overview.bs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/css-overflow-4/Overview.bs b/css-overflow-4/Overview.bs index 85c8eecf00a..c456f164ed3 100644 --- a/css-overflow-4/Overview.bs +++ b/css-overflow-4/Overview.bs @@ -1172,7 +1172,7 @@ Fragmentation of Overflow: the 'continue' property

Line-clamp containers

- A line-clamp container is an [=independent formatting context|independent=] [=block formatting context=] + A line-clamp container is an [=independent formatting context|independent=] [=block formatting context=] that additionally follows the rules in this section. All line-clamp containers contain a clamp point, which is one of the following positions inside it: From 0db0a52ee017693c517897f019c195a34eefddc1 Mon Sep 17 00:00:00 2001 From: "Tab Atkins Jr." Date: Fri, 23 May 2025 15:37:37 -0700 Subject: [PATCH 09/13] Update css-overflow-4/Overview.bs --- css-overflow-4/Overview.bs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/css-overflow-4/Overview.bs b/css-overflow-4/Overview.bs index c456f164ed3..37f8b4415b1 100644 --- a/css-overflow-4/Overview.bs +++ b/css-overflow-4/Overview.bs @@ -1175,7 +1175,7 @@ Fragmentation of Overflow: the 'continue' property A line-clamp container is an [=independent formatting context|independent=] [=block formatting context=] that additionally follows the rules in this section. All line-clamp containers contain a clamp point, - which is one of the following positions inside it: + which is one of the following block-axis positions inside it: - A point immediately after a [=line box=] in the line-clamp container's [=block formatting context=]. From e5b5c69d0f88172b0cba290149a198be78a28134 Mon Sep 17 00:00:00 2001 From: "Tab Atkins Jr." Date: Fri, 23 May 2025 15:37:45 -0700 Subject: [PATCH 10/13] Update css-overflow-4/Overview.bs --- css-overflow-4/Overview.bs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/css-overflow-4/Overview.bs b/css-overflow-4/Overview.bs index 37f8b4415b1..2cee7415f8d 100644 --- a/css-overflow-4/Overview.bs +++ b/css-overflow-4/Overview.bs @@ -1197,7 +1197,7 @@ Fragmentation of Overflow: the 'continue' property Any boxes in a [=line-clamp container=] that follow its [=clamp point=] in the box tree, as well as any [=line boxes=] that follow it inside an [=inline formatting context=], - will be invisible (behaving like ''visibility: hidden''). + become [=invisible boxes=]. This includes [=independent formatting contexts=] as well as [=out-of-flow=] boxes, and all of their descendants. From 6398998ae529e7079069775f7fe53bdca2dcbbb3 Mon Sep 17 00:00:00 2001 From: Andreu Botella Date: Tue, 22 Apr 2025 17:37:19 +0200 Subject: [PATCH 11/13] Update for #10439 --- css-overflow-4/Overview.bs | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/css-overflow-4/Overview.bs b/css-overflow-4/Overview.bs index 2cee7415f8d..bae50cb89a5 100644 --- a/css-overflow-4/Overview.bs +++ b/css-overflow-4/Overview.bs @@ -817,7 +817,7 @@ Limiting Visible Lines: the 'line-clamp' shorthand property 
 		Name: line-clamp
-		Value: none | <> || <<'block-ellipsis'>>
+		Value: none | [<> || <<'block-ellipsis'>>] ''-webkit-legacy''?
 		Initial: none
 		Percentages: N/A
@@ -855,13 +855,17 @@ Limiting Visible Lines: the 'line-clamp' shorthand property Issue(7708): Whether this should imply ''discard'' or ''collapse'' is an unresolved question. Sets 'continue' to ''collapse'' - if either or both values ares specified. + if either or both values are specified, + unless the ''line-clamp/-webkit-legacy'' keyword is also specified. Sets 'max-lines' to the specified <> or to ''max-lines/none'' if omitted, and 'block-ellipsis' to other component of the value if specified or to ''block-ellipsis/auto'' if omitted. +
-webkit-legacy +
Sets 'continue' to ''continue/-webkit-legacy''. + See the corresponding longhand properties for details @@ -911,7 +915,7 @@ Legacy compatibility For compatibility with legacy content, UAs that support 'line-clamp' must also support the '-webkit-line-clamp' property - and the additional ''-webkit-collapse'' value for the 'continue' property. + and the additional ''continue/-webkit-legacy'' value for the 'continue' property. 
 		Name: -webkit-line-clamp
@@ -922,17 +926,18 @@ Legacy compatibility
 
 	
 		Name: continue
-		New Values: -webkit-collapse
+		New Values: -webkit-legacy
 	

 
 	Like 'line-clamp', '-webkit-line-clamp' is a shorthand of 'max-lines', 'continue', and 'block-ellipsis',
 	except that:
 
 	* its syntax is ''line-clamp/none'' | <>
-	* it sets 'continue' to ''-webkit-collapse'' instead of ''collapse''
+	* it sets 'continue' to ''continue/-webkit-legacy'' instead of ''collapse''
+	    (as if the ''line-clamp/-webkit-legacy'' keyword was set on 'line-clamp')
 	* it unconditionally sets 'block-ellipsis' to ''block-ellipsis/auto''
 
-	The -webkit-collapse value behaves identically to ''collapse'',
+	The -webkit-legacy value behaves identically to ''collapse'',
 	except that it only takes effect
 	if the [=specified value=] of the 'display' property
 	is ''-webkit-box'' or ''-webkit-inline-box''
@@ -1153,7 +1158,7 @@ Fragmentation of Overflow: the 'continue' property
 
 	Additionaliy,
 	for compatibility (see [[#webkit-line-clamp]]),
-	when the [=computed value=] of the 'continue' property is '''collapse'', ''-webkit-collapse'', or ''discard''
+	when the [=computed value=] of the 'continue' property is ''collapse'', ''continue/-webkit-legacy'', or ''discard''
 	and the [=computed value=] of the '-webkit-box-orient' property is ''vertical'':
 	* If the [=specified value=] of the 'display' property is ''-webkit-box'',
 		the [=computed value=] becomes ''flow-root'' and

From 94503b348f370b31b2f3210470f537f9c1bee05d Mon Sep 17 00:00:00 2001
From: Andreu Botella 
Date: Tue, 22 Apr 2025 17:43:26 +0200
Subject: [PATCH 12/13] Update for #11962

---
 css-overflow-4/Overview.bs | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/css-overflow-4/Overview.bs b/css-overflow-4/Overview.bs
index bae50cb89a5..36e74377d6a 100644
--- a/css-overflow-4/Overview.bs
+++ b/css-overflow-4/Overview.bs
@@ -1200,13 +1200,20 @@ Fragmentation of Overflow: the 'continue' property
 	or if that is not the case for any possible clamp points,
 	to the first possible clamp point in the block formatting context.
 
-	Any boxes in a [=line-clamp container=] that follow its [=clamp point=] in the box tree,
-	as well as any [=line boxes=] that follow it inside an [=inline formatting context=],
-	become [=invisible boxes=].
-	This includes [=independent formatting contexts=]
-	as well as [=out-of-flow=] boxes,
-	and all of their descendants.
-	Any overflow such boxes and line boxes might have
+	Within a [=line-clamp container=],
+	the following boxes and line boxes become [=invisible boxes=]:
+
+	- Any [=in-flow=] or floating boxes
+		that follow the [=clamp point=] in the box tree.
+		This includes [=independent formatting contexts=]
+		and all of their descendants.
+	- Any [=line boxes=] that follow the [=clamp point=]
+		inside an [=inline formatting context=].
+	- Any [=absolutely positioned box=]
+		which has an invisible box within its [=containing block chain=],
+		and all of its descendants.
+
+	Any overflow such invisible boxes and line boxes might have
 	is always counted as [=ink overflow=] rather than [=scrollable overflow=].
 
 	NOTE: This differs from the ''display: none''-like behavior
@@ -1214,7 +1221,7 @@ Fragmentation of Overflow: the 'continue' property
 
 	If a [=block container=] contains a [=clamp point=],
 	within itself or in any of its descendants,
-	its [=automatic block size=] will not take into account any of its children after the clamp point.
+	its [=automatic block size=] will not take into account any invisible boxes.
 	This also applies for the [=line-clamp container=] itself.
 
 	NOTE: If there are any floats before the [=clamp point=],

From cb6491ab802366fbb27ba164bb0d0b7caaef9c85 Mon Sep 17 00:00:00 2001
From: Andreu Botella 
Date: Tue, 22 Apr 2025 17:43:58 +0200
Subject: [PATCH 13/13] Update for #10868

---
 css-overflow-4/Overview.bs | 28 +++++++++++++++-------------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/css-overflow-4/Overview.bs b/css-overflow-4/Overview.bs
index 36e74377d6a..6aae232a529 100644
--- a/css-overflow-4/Overview.bs
+++ b/css-overflow-4/Overview.bs
@@ -715,8 +715,6 @@ Indicating Block-Axis Overflow: the 'block-ellipsis' property
 	This property only affects a line box
 	if it immediately precedes eiher a [=region break=]
 	or a [=clamp point=] in the [=block formatting context=].
-	If the [=clamp point=] is placed at the end of the [=line-clamp container=],
-	then the line will not be affected.
 
 	Note: See [[css-overflow-4#fragmentation]] for a way to generate boxes with such a [=region break=].
 
@@ -853,7 +851,7 @@ Limiting Visible Lines: the 'line-clamp' shorthand property
 		

 
 			Issue(7708): Whether this should imply ''discard'' or ''collapse'' is an unresolved question.
-                        
+
 			Sets 'continue' to ''collapse''
 			if either or both values are specified,
 			unless the ''line-clamp/-webkit-legacy'' keyword is also specified.
@@ -979,10 +977,13 @@ Forcing a Break After a Set Number of Lines: the 'max-lines' property
 		If fewer than N line boxes exist,
 		then 'max-lines' introduces no region break.
 	- If the box is a [=line-clamp container=],
-		its [=clamp point=] is set after its Nth
+		its [=clamp point=] is set
+		to the first possible clamp point after
+		its Nth
 		descendant in-flow line box.
 		If fewer than N line boxes exist,
-		then the clamp point is set to the end of the line-clamp container.
+		or if there are no clamp points after it,
+		then that line-clamp container has no clamp point.
 
 
 	Only line boxes in the same block formatting context
@@ -1179,13 +1180,14 @@ Fragmentation of Overflow: the 'continue' property
 
 	A line-clamp container is an [=independent formatting context|independent=] [=block formatting context=]
 	that additionally follows the rules in this section.
-	All line-clamp containers contain a clamp point,
+	Line-clamp containers can have a clamp point,
 	which is one of the following block-axis positions inside it:
 
-	- A point immediately after a [=line box=]
-		in the line-clamp container's [=block formatting context=].
-	- The end of the line-clamp container,
-		if there are any boxes after the last [=inline formatting context=]
+	- The start of the [=line-clamp container=].
+	- A point between two consecutive [=line boxes=]
+		in an [=inline formatting context=]
+		contained by the line-clamp container's [=block formatting context=].
+	- A point between two [=in-flow=] [=block-level=] sibling boxes
 		in the line-clamp container's [=block formatting context=].
 
 	If the [=line-clamp container=]'s [=block formatting context root=]
@@ -1196,9 +1198,9 @@ Fragmentation of Overflow: the 'continue' property
 	the line-clamp container's [=automatic block size=]
 	(as determined below)
 	is not greater than the [=block size=] the box would have
-	if its automatic block size were infinite;
-	or if that is not the case for any possible clamp points,
-	to the first possible clamp point in the block formatting context.
+	if its automatic block size were infinite.
+	If the [=block size=] would be infinite,
+	then there is no clamp point.
 
 	Within a [=line-clamp container=],
 	the following boxes and line boxes become [=invisible boxes=]: