[css-scroll-snap-1] Emphasize that scroll-padding and scroll-margin apply even when snapping is off. w3c#3721

Author: fantasai

css-scroll-snap-1/Overview.bs

@@ -5,6 +5,7 @@ Shortname: css-scroll-snap
 TR: https://www.w3.org/TR/css-scroll-snap-1/
 Level: 1
 Status: ED
+Previous Version: https://www.w3.org/TR/2019/CR-css-scroll-snap-1-20190131/
 Previous Version: https://www.w3.org/TR/2018/CR-css-scroll-snap-1-20180814/
 Previous Version: https://www.w3.org/TR/2017/CR-css-scroll-snap-1-20171214/
 Previous Version: https://www.w3.org/TR/2017/CR-css-scroll-snap-1-20170824/
@@ -53,12 +54,22 @@ Introduction {#intro}
     it is difficult for web developers to guarantee a well-controlled scrolling experience,
     in particular creating the effect of paging through content.
     For instance, it is easy for a user to land at an awkward scroll position
-    which leaves a page partially on-screen when panning.
+    which leaves an item partially on-screen when panning.
 
-    To this end, we introduce scroll snap positions
+    To this end, this module introduces <a>scroll snap positions</a>
     which enforce the scroll positions that a <a>scroll container’s</a> scrollport may end at
     after a scrolling operation has completed.
 
+    Also, to offer better control over paging and scroll positioning
+    even when snapping is off,
+    this module defines the 'scroll-padding' property
+    for use on all <a>scroll containers</a>,
+    to adjust the <a>scroll container</a>’s <a>optimal viewing region</a>
+    for the purpose of paging and scroll-into-view operations.
+    Similarly the 'scroll-margin' property can be used on any box
+    to adjust its visual area
+    for the purpose of scroll-into-view operations.
+
 Module interactions {#placement}
 --------------------------------
 
@@ -200,10 +211,11 @@ Motivating Examples {#examples}
  ███████     ███    ████████ ██     ██    ███    ████ ████████  ███  ███
 -->
 
-Overview {#overview}
-====================
+Scroll Snap Model {#overview}
+=============================
 
-    This module introduces control over <dfn lt="scroll snap position" local-lt="snap position">scroll snap positions</dfn>,
+    This module defines controls fo
+    <dfn lt="scroll snap position" local-lt="snap position">scroll snap positions</dfn>,
     which are scroll positions that produce particular alignments
     of content within a scroll container.
     Using the 'scroll-snap-type' property on the relevant <a>scroll container</a>,
@@ -413,10 +425,12 @@ Scroll Snapport: the 'scroll-padding' property {#scroll-padding}
     Animation type: by computed value type
     </pre>
 
-    This property specifies offsets that define the
-    <dfn export>optimal viewing region</dfn> of the scrollport:
+    This property specifies
+    (for all <a>scroll containers</a>, not just <a>scroll snap containers</a>)
+    offsets that define the
+    <dfn export>optimal viewing region</dfn> of a scrollport:
     the region used as the target region for placing things in view of the user.
-    This allows the author to exclude regions of the scrollport
+    This allows the author to exclude regions of the <a>scrollport</a>
     that are obscured by other content
     (such as fixed-positioned toolbars or sidebars)
     or simply to put more breathing room
@@ -542,7 +556,9 @@ Scroll Snapping Area: the 'scroll-margin' property {#scroll-margin}
     the UA should use the element's <a>scroll snap area</a>,
     rather than just its border box,
     to determine which area of the <a>scrollable overflow region</a>
-    to bring into view.
+    to bring into view,
+    <em>even when snapping is off
+    or not applied on this element</em>.
 
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    ███    ██       ████  ██████   ██    ██
@@ -1117,6 +1133,43 @@ Changes Since 14 August 2018 CR {#changes-20180814}
 
 	Changes since the <a href="https://www.w3.org/TR/2018/CR-css-scroll-snap-1-20180814/">14 August 2018 Candidate Recommendation</a> include:
 
+	<ul>
+		<li id="change-2019-clarify-nonsnapping">
+			Emphasized that 'scroll-padding' and 'scroll-margin' do apply
+			even when scroll snapping is off.
+			(<a href="https://github.com/w3c/csswg-drafts/issues/3721">Issue 3721</a>)
+			<blockquote>
+				<ins><p>Also, to offer better control over paging and scroll positioning
+				even when snapping is off,
+				this module defines the 'scroll-padding' property
+				for use on all <a>scroll containers</a>,
+				to adjust the <a>scroll container</a>’s <a>optimal viewing region</a>
+				for the purpose of paging and scroll-into-view operations;
+				similarly the 'scroll-margin' property can be used on any box
+				to adjust its visual area
+				for the purpose of scroll-into-view operations.</p></ins>
+			</blockquote>
+			<blockquote>
+				<p>This property specifies
+				<ins>(for all <a>scroll containers</a>, not just <a>scroll snap containers</a>)</ins>
+				offsets that define the
+				<a>optimal viewing region</a> of a scrollport&hellip;</p>
+			</blockquote>
+			<blockquote>
+				<p>If a page is navigated to a fragment that defines a target element
+				(one that would be matched by '':target'',
+				or the target of {{scrollIntoView()}}),
+				the UA should use the element's <a>scroll snap area</a>,
+				rather than just its border box,
+				to determine which area of the <a>scrollable overflow region</a>
+				to bring into view<ins>,
+				<em>even when snapping is off
+				or not applied on this element</em></ins>.</p>
+			</blockquote>
+	</ul>
+
+	Changes since the <a href="https://www.w3.org/TR/2018/CR-css-scroll-snap-1-20180814/">14 August 2018 Candidate Recommendation</a> include:
+
 	<ul>
 		<li id="change-2018-padding-intial">
 			Corrected 'scroll-padding' longhands to list the new ''scroll-padding/auto'' keyword in their property definition tables.