<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head><meta http-equiv="content-type" content="text/html; charset=utf-8" />
<title>[260056] trunk</title>
</head>
<body>

<style type="text/css"><!--
#msg dl.meta { border: 1px #006 solid; background: #369; padding: 6px; color: #fff; }
#msg dl.meta dt { float: left; width: 6em; font-weight: bold; }
#msg dt:after { content:':';}
#msg dl, #msg dt, #msg ul, #msg li, #header, #footer, #logmsg { font-family: verdana,arial,helvetica,sans-serif; font-size: 10pt;  }
#msg dl a { font-weight: bold}
#msg dl a:link    { color:#fc3; }
#msg dl a:active  { color:#ff0; }
#msg dl a:visited { color:#cc6; }
h3 { font-family: verdana,arial,helvetica,sans-serif; font-size: 10pt; font-weight: bold; }
#msg pre { overflow: auto; background: #ffc; border: 1px #fa0 solid; padding: 6px; }
#logmsg { background: #ffc; border: 1px #fa0 solid; padding: 1em 1em 0 1em; }
#logmsg p, #logmsg pre, #logmsg blockquote { margin: 0 0 1em 0; }
#logmsg p, #logmsg li, #logmsg dt, #logmsg dd { line-height: 14pt; }
#logmsg h1, #logmsg h2, #logmsg h3, #logmsg h4, #logmsg h5, #logmsg h6 { margin: .5em 0; }
#logmsg h1:first-child, #logmsg h2:first-child, #logmsg h3:first-child, #logmsg h4:first-child, #logmsg h5:first-child, #logmsg h6:first-child { margin-top: 0; }
#logmsg ul, #logmsg ol { padding: 0; list-style-position: inside; margin: 0 0 0 1em; }
#logmsg ul { text-indent: -1em; padding-left: 1em; }#logmsg ol { text-indent: -1.5em; padding-left: 1.5em; }
#logmsg > ul, #logmsg > ol { margin: 0 0 1em 0; }
#logmsg pre { background: #eee; padding: 1em; }
#logmsg blockquote { border: 1px solid #fa0; border-left-width: 10px; padding: 1em 1em 0 1em; background: white;}
#logmsg dl { margin: 0; }
#logmsg dt { font-weight: bold; }
#logmsg dd { margin: 0; padding: 0 0 0.5em 0; }
#logmsg dd:before { content:'\00bb';}
#logmsg table { border-spacing: 0px; border-collapse: collapse; border-top: 4px solid #fa0; border-bottom: 1px solid #fa0; background: #fff; }
#logmsg table th { text-align: left; font-weight: normal; padding: 0.2em 0.5em; border-top: 1px dotted #fa0; }
#logmsg table td { text-align: right; border-top: 1px dotted #fa0; padding: 0.2em 0.5em; }
#logmsg table thead th { text-align: center; border-bottom: 1px solid #fa0; }
#logmsg table th.Corner { text-align: left; }
#logmsg hr { border: none 0; border-top: 2px dashed #fa0; height: 1px; }
#header, #footer { color: #fff; background: #636; border: 1px #300 solid; padding: 6px; }
#patch { width: 100%; }
#patch h4 {font-family: verdana,arial,helvetica,sans-serif;font-size:10pt;padding:8px;background:#369;color:#fff;margin:0;}
#patch .propset h4, #patch .binary h4 {margin:0;}
#patch pre {padding:0;line-height:1.2em;margin:0;}
#patch .diff {width:100%;background:#eee;padding: 0 0 10px 0;overflow:auto;}
#patch .propset .diff, #patch .binary .diff  {padding:10px 0;}
#patch span {display:block;padding:0 10px;}
#patch .modfile, #patch .addfile, #patch .delfile, #patch .propset, #patch .binary, #patch .copfile {border:1px solid #ccc;margin:10px 0;}
#patch ins {background:#dfd;text-decoration:none;display:block;padding:0 10px;}
#patch del {background:#fdd;text-decoration:none;display:block;padding:0 10px;}
#patch .lines, .info {color:#888;background:#fff;}
--></style>
<div id="msg">
<dl class="meta">
<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/260056">260056</a></dd>
<dt>Author</dt> <dd>simon.fraser@apple.com</dd>
<dt>Date</dt> <dd>2020-04-13 19:59:30 -0700 (Mon, 13 Apr 2020)</dd>
</dl>

<h3>Log Message</h3>
<pre>[Async overflow] Get scroll-snap working with async overflow scrolling on macOS
https://bugs.webkit.org/show_bug.cgi?id=210471
<rdar://problem/61643199>

Reviewed by Wenson Hsieh.

Source/WebCore:

Obey the FIXME and move scroll-snap related code to the delegate so that it works for
both frame and overflow nodes.

Tests: tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-stateless.html
       tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow.html

* page/scrolling/mac/ScrollingTreeFrameScrollingNodeMac.mm:
(WebCore::ScrollingTreeFrameScrollingNodeMac::commitStateBeforeChildren):
(WebCore::convertToLayoutUnits): Deleted.
* page/scrolling/mac/ScrollingTreeScrollingNodeDelegateMac.mm:
(WebCore::convertToLayoutUnits):
(WebCore::ScrollingTreeScrollingNodeDelegateMac::updateFromStateNode):

LayoutTests:

Clone some overflow scroll-snap tests, and enable async scrolling for them.

* tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-expected.txt: Added.
* tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-stateless-expected.txt: Added.
* tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-stateless.html: Added.
* tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow.html: Added.</pre>

<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkLayoutTestsChangeLog">trunk/LayoutTests/ChangeLog</a></li>
<li><a href="#trunkSourceWebCoreChangeLog">trunk/Source/WebCore/ChangeLog</a></li>
<li><a href="#trunkSourceWebCorepagescrollingmacScrollingTreeFrameScrollingNodeMacmm">trunk/Source/WebCore/page/scrolling/mac/ScrollingTreeFrameScrollingNodeMac.mm</a></li>
<li><a href="#trunkSourceWebCorepagescrollingmacScrollingTreeScrollingNodeDelegateMacmm">trunk/Source/WebCore/page/scrolling/mac/ScrollingTreeScrollingNodeDelegateMac.mm</a></li>
</ul>

<h3>Added Paths</h3>
<ul>
<li><a href="#trunkLayoutTeststileddrawingscrollingscrollsnapscrollsnapmandatoryasyncoverflowexpectedtxt">trunk/LayoutTests/tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-expected.txt</a></li>
<li><a href="#trunkLayoutTeststileddrawingscrollingscrollsnapscrollsnapmandatoryasyncoverflowstatelessexpectedtxt">trunk/LayoutTests/tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-stateless-expected.txt</a></li>
<li><a href="#trunkLayoutTeststileddrawingscrollingscrollsnapscrollsnapmandatoryasyncoverflowstatelesshtml">trunk/LayoutTests/tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-stateless.html</a></li>
<li><a href="#trunkLayoutTeststileddrawingscrollingscrollsnapscrollsnapmandatoryasyncoverflowhtml">trunk/LayoutTests/tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow.html</a></li>
</ul>

</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkLayoutTestsChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/LayoutTests/ChangeLog (260055 => 260056)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/ChangeLog      2020-04-14 02:40:03 UTC (rev 260055)
+++ trunk/LayoutTests/ChangeLog 2020-04-14 02:59:30 UTC (rev 260056)
</span><span class="lines">@@ -1,3 +1,18 @@
</span><ins>+2020-04-13  Simon Fraser  <simon.fraser@apple.com>
+
+        [Async overflow] Get scroll-snap working with async overflow scrolling on macOS
+        https://bugs.webkit.org/show_bug.cgi?id=210471
+        <rdar://problem/61643199>
+
+        Reviewed by Wenson Hsieh.
+
+        Clone some overflow scroll-snap tests, and enable async scrolling for them.
+
+        * tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-expected.txt: Added.
+        * tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-stateless-expected.txt: Added.
+        * tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-stateless.html: Added.
+        * tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow.html: Added.
+
</ins><span class="cx"> 2020-04-13  Zalan Bujtas  <zalan@apple.com>
</span><span class="cx"> 
</span><span class="cx">         Do not cache definite height against perpendicular flex items.
</span></span></pre></div>
<a id="trunkLayoutTeststileddrawingscrollingscrollsnapscrollsnapmandatoryasyncoverflowexpectedtxt"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-expected.txt (0 => 260056)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-expected.txt                          (rev 0)
+++ trunk/LayoutTests/tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-expected.txt     2020-04-14 02:59:30 UTC (rev 260056)
</span><span class="lines">@@ -0,0 +1,13 @@
</span><ins>+Tests that the scroll-snap feature works properly in overflow regions.
+ Testing scroll-snap glide for horizontalTarget:
+PASS div scrolled to next window.
+Testing scroll-snap snap for horizontalTarget:
+PASS div honored snap points.
+Testing scroll-snap glide for verticalTarget:
+PASS div scrolled to next window.
+Testing scroll-snap snap for verticalTarget:
+PASS div honored snap points.
+PASS successfullyParsed is true
+
+TEST COMPLETE
+
</ins></span></pre></div>
<a id="trunkLayoutTeststileddrawingscrollingscrollsnapscrollsnapmandatoryasyncoverflowstatelessexpectedtxt"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-stateless-expected.txt (0 => 260056)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-stateless-expected.txt                                (rev 0)
+++ trunk/LayoutTests/tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-stateless-expected.txt   2020-04-14 02:59:30 UTC (rev 260056)
</span><span class="lines">@@ -0,0 +1,6 @@
</span><ins>+Tests that the scroll-snap feature works properly in overflow regions when using a mechanical mouse wheel.
+ PASS div honored snap points.
+PASS successfullyParsed is true
+
+TEST COMPLETE
+
</ins></span></pre></div>
<a id="trunkLayoutTeststileddrawingscrollingscrollsnapscrollsnapmandatoryasyncoverflowstatelesshtml"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-stateless.html (0 => 260056)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-stateless.html                                (rev 0)
+++ trunk/LayoutTests/tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-stateless.html   2020-04-14 02:59:30 UTC (rev 260056)
</span><span class="lines">@@ -0,0 +1,99 @@
</span><ins>+<!DOCTYPE html> <!-- webkit-test-runner [ internal:AsyncOverflowScrollingEnabled=true ] -->
+<html>
+    <head>
+        <style>
+            .gallery {
+                width: 400px;
+                height: 400px;
+                display: inline-block;
+                overflow-x: hidden;
+                overflow-y: auto;
+                scroll-snap-type: y mandatory;
+            }
+            .colorBox {
+                height: 400px;
+                width: 400px;
+                scroll-snap-align: start;
+            }
+            #item0, #item2 { background-color: red; }
+            #item1 { background-color: green; }
+        </style>
+        <script src="../../../resources/js-test.js"></script>
+        <script>
+        window.jsTestIsAsync = true;
+
+        function locationInWindowCoordinates(element)
+        {
+            var position = {};
+            position.x = element.offsetLeft;
+            position.y = element.offsetTop;
+
+            while (element.offsetParent) {
+                position.x = position.x + element.offsetParent.offsetLeft;
+                position.y = position.y + element.offsetParent.offsetTop;
+                if (element == document.getElementsByTagName("body")[0])
+                    break;
+
+                element = element.offsetParent;
+            }
+
+            return position;
+        }
+
+        function scrollSnapTest()
+        {
+            var divTarget = document.getElementById("target");
+            var windowPosition = locationInWindowCoordinates(divTarget);
+
+            var startPosX = windowPosition.x + 0.5 * divTarget.clientWidth;
+            var startPosY = windowPosition.y + 0.5 * divTarget.clientHeight;
+            eventSender.mouseMoveTo(startPosX, startPosY);
+            // Each unit of stateless scroll is scaled by 10 pixels.
+            eventSender.mouseScrollByWithWheelAndMomentumPhases(0, -10, "none", "none");
+            eventSender.mouseScrollByWithWheelAndMomentumPhases(0, -10, "none", "none");
+            eventSender.mouseScrollByWithWheelAndMomentumPhases(0, -10, "none", "none");
+            // Wait for the snapping to finish.
+            setTimeout(function() {
+                if (divTarget.scrollTop != 400)
+                    testFailed("div did not snap to the green region. Expected 400, but got " + divTarget.scrollTop + ".");
+                else
+                    testPassed("div honored snap points.");
+
+                finishJSTest();
+            }, 2000);
+        }
+
+
+        function onLoad()
+        {
+            if (window.eventSender) {
+                eventSender.monitorWheelEvents();
+                internals.setPlatformMomentumScrollingPredictionEnabled(false);
+                setTimeout(scrollSnapTest, 0);
+            } else {
+                var messageLocationH = document.getElementById("item0");
+                var message = document.createElement("div");
+                message.innerHTML = "This test is better run under DumpRenderTree. To manually<br/>"
+                    + "test it, place the mouse pointer inside the red region at the<br/>"
+                    + "top of the page, and then, using a mechanical mouse wheel,<br/>"
+                    + "scroll so that the green region takes up more of the<br/>"
+                    + "container than the surrounding red regions. After a brief<br/>"
+                    + "pause, the target should scroll so that the green region is<br/>"
+                    + "fully visible, and no red is visible.";
+                messageLocationH.appendChild(message);
+            }
+        }
+        </script>
+    </head>
+    <body onload="onLoad();">
+        <div style="position: relative; width: 400px">
+            <div>Tests that the scroll-snap feature works properly in overflow regions when using a mechanical mouse wheel.</div>
+            <div class="gallery" id="target">
+                <div id="item0" class="colorBox"></div>
+                <div id="item1" class="colorBox"></div>
+                <div id="item2" class="colorBox"></div>
+            </div>
+            <div id="console"></div>
+        </div>
+    </body>
+</html>
</ins><span class="cx">\ No newline at end of file
</span></span></pre></div>
<a id="trunkLayoutTeststileddrawingscrollingscrollsnapscrollsnapmandatoryasyncoverflowhtml"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow.html (0 => 260056)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow.html                          (rev 0)
+++ trunk/LayoutTests/tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow.html     2020-04-14 02:59:30 UTC (rev 260056)
</span><span class="lines">@@ -0,0 +1,218 @@
</span><ins>+<!DOCTYPE html> <!-- webkit-test-runner [ internal:AsyncOverflowScrollingEnabled=true ] -->
+<html>
+    <head>
+        <style>
+            .horizontalGallery {
+                width: 300px;
+                height: 300px;
+                overflow-y: hidden;
+                overflow-x: auto;
+                margin-bottom: 2px;
+                scroll-snap-type: x mandatory;
+            }
+            .horizontalGalleryDrawer {
+                width: 1800px;
+                height: 300px;
+            }
+            .verticalGallery {
+                width: 300px;
+                height: 300px;
+                display: inline-block;
+                overflow-x: hidden;
+                overflow-y: auto;
+                margin-top: 2px;
+                scroll-snap-type: y mandatory;
+            }
+            .verticalGalleryDrawer {
+                width: 300px;
+                height: 1800px;
+            }
+            .colorBox {
+                height: 300px;
+                width: 300px;
+                float: left;
+                scroll-snap-align: start;
+            }
+            #itemH0, #itemV0 { background-color: red; }
+            #itemH1, #itemV1 { background-color: green; }
+            #itemH2, #itemV2 { background-color: blue; }
+            #itemH3, #itemV3 { background-color: aqua; }
+            #itemH4, #itemV4 { background-color: yellow; }
+            #itemH5, #itemV5 { background-color: fuchsia; }
+        </style>
+        <script src="../../../resources/js-test.js"></script>
+        <script>
+        window.jsTestIsAsync = true;
+
+        var divScrollPositionBeforeGlide;
+        var divScrollPositionBeforeSnap;
+
+        function locationInWindowCoordinates(element)
+        {
+            var position = {};
+            position.x = element.offsetLeft;
+            position.y = element.offsetTop;
+
+            while (element.offsetParent) {
+                position.x = position.x + element.offsetParent.offsetLeft;
+                position.y = position.y + element.offsetParent.offsetTop;
+                if (element == document.getElementsByTagName("body")[0])
+                    break;
+
+                element = element.offsetParent;
+            }
+
+            return position;
+        }
+
+        function checkForScrollSnap(targetLabel)
+        {
+            var divTarget = document.getElementById(targetLabel);
+
+            var actualPosition = divTarget.scrollTop;
+            if (targetLabel == 'horizontalTarget')
+                actualPosition = divTarget.scrollLeft;
+
+            // The div should have snapped back to the previous position
+            if (actualPosition != divScrollPositionBeforeSnap)
+                testFailed("div did not snap back to proper location for " + targetLabel +". Expected " + divScrollPositionBeforeSnap + ", but got " + actualPosition);
+            else
+                testPassed("div honored snap points.");
+
+            if (targetLabel == 'horizontalTarget')
+                setTimeout(function() { scrollGlideTest('verticalTarget') }, 0);
+            else   
+                finishJSTest();
+        }
+
+        function scrollSnapTest(targetLabel)
+        {
+            debug("Testing scroll-snap snap for " + targetLabel + ":");
+            var divTarget = document.getElementById(targetLabel);

+            var dx = 0;
+            var dy = 0;
+            if (targetLabel == 'horizontalTarget') {
+                divScrollPositionBeforeSnap = divTarget.scrollLeft;
+                dx = -1;
+            } else {
+                divScrollPositionBeforeSnap = divTarget.scrollTop;
+                dy = -1;
+            }
+
+            var windowPosition = locationInWindowCoordinates(divTarget);
+
+            var startPosX = windowPosition.x + 0.5 * divTarget.clientWidth;
+            var startPosY = windowPosition.y + 0.5 * divTarget.clientHeight;
+            eventSender.monitorWheelEvents();
+            eventSender.mouseMoveTo(startPosX, startPosY); // Make sure we are just outside the iFrame
+            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'began', 'none');
+            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'changed', 'none');
+            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'changed', 'none');
+            eventSender.mouseScrollByWithWheelAndMomentumPhases(0, 0, 'ended', 'none');
+            eventSender.callAfterScrollingCompletes(function() { return checkForScrollSnap(targetLabel); });
+        }
+
+        function checkForScrollGlide(targetLabel)
+        {
+            var divTarget = document.getElementById(targetLabel);
+
+            var actualPosition = divTarget.scrollTop;
+            var expectedPosition = divTarget.clientHeight;
+            if (targetLabel == 'horizontalTarget') {
+                actualPosition = divTarget.scrollLeft;
+                expectedPosition = divTarget.clientWidth;
+            }
+
+            // The div should have scrolled (glided) to the next snap point.
+            if (actualPosition == expectedPosition)
+                testPassed("div scrolled to next window.");
+            else
+                testFailed("div did not honor snap points. Expected " + expectedPosition + ", but got " + actualPosition);
+
+            setTimeout(function() { scrollSnapTest(targetLabel) }, 0);
+        }
+
+        function scrollGlideTest(targetLabel)
+        {
+            debug("Testing scroll-snap glide for " + targetLabel + ":");
+            var divTarget = document.getElementById(targetLabel);

+            var dx = 0;
+            var dy = 0;
+            if (targetLabel == 'horizontalTarget') {
+                divScrollPositionBeforeGlide = divTarget.scrollLeft;
+                dx = -1;
+            } else {
+                divScrollPositionBeforeGlide = divTarget.scrollTop;
+                dy = -1;
+            }
+
+            var windowPosition = locationInWindowCoordinates(divTarget);
+
+            var startPosX = windowPosition.x + 0.5 * divTarget.clientWidth;
+            var startPosY = windowPosition.y + 0.5 * divTarget.clientHeight;
+            eventSender.monitorWheelEvents();
+            eventSender.mouseMoveTo(startPosX, startPosY);
+            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'began', 'none');
+            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'changed', 'none');
+            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'changed', 'none');
+            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'changed', 'none');
+            eventSender.mouseScrollByWithWheelAndMomentumPhases(0, 0, 'ended', 'none');
+            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'none', 'begin');
+            eventSender.mouseScrollByWithWheelAndMomentumPhases(dx, dy, 'none', 'continue');
+            eventSender.mouseScrollByWithWheelAndMomentumPhases(0, 0, 'none', 'end');
+            eventSender.callAfterScrollingCompletes(function() { return checkForScrollGlide(targetLabel); });
+        }
+
+        function onLoad()
+        {
+            if (window.eventSender) {
+                internals.setPlatformMomentumScrollingPredictionEnabled(false);
+                setTimeout(function() { scrollGlideTest('horizontalTarget') }, 0);
+            } else {
+                var messageLocationH = document.getElementById('itemH0');
+                var message = document.createElement('div');
+                message.innerHTML = "<p>This test is better run under DumpRenderTree.<br/>To manually test it, place the mouse pointer<br/>"
+                    + "inside the red region at the top of the page,<br/>and then use the mouse wheel or a two-finger<br/>swipe to make a"
+                    + "small swipe gesture with<br/>some momentum.<br/><br/>"
+                    + "The region should scroll to show a green region.<br/><br/>"
+                    + "Next, perform a small scroll gesture that does<br/>not involve momentum. You should begin to<br/>see one of the colors "
+                    + "to the side of the current<br/>green box. When you release the wheel, the<br/>region should scroll back to a single color.";
+                messageLocationH.appendChild(message);
+
+                var messageLocationV = document.getElementById('itemV0');
+                var message = document.createElement('div');
+                message.innerHTML = "<p>You should also be able to repeat these tests steps for this vertical region.<br/>"
+                messageLocationV.appendChild(message);
+            }
+        }
+        </script>
+    </head>
+    <body onload="onLoad();">
+        <div style="position: relative; width: 300px">
+            <div>Tests that the scroll-snap feature works properly in overflow regions.</div>
+            <div class="horizontalGallery" id="horizontalTarget">
+                <div class="horizontalGalleryDrawer">
+                    <div id="itemH0" class="colorBox"></div>
+                    <div id="itemH1" class="colorBox"></div>
+                    <div id="itemH2" class="colorBox"></div>
+                    <div id="itemH3" class="colorBox"></div>
+                    <div id="itemH4" class="colorBox"></div>
+                    <div id="itemH5" class="colorBox"></div>
+                </div>
+            </div>
+            <div class="verticalGallery" id="verticalTarget">
+                <div class="verticalGalleryDrawer">
+                    <div id="itemV0" class="colorBox"></div>
+                    <div id="itemV1" class="colorBox"></div>
+                    <div id="itemV2" class="colorBox"></div>
+                    <div id="itemV3" class="colorBox"></div>
+                    <div id="itemV4" class="colorBox"></div>
+                    <div id="itemV5" class="colorBox"></div>
+                </div>
+            </div>
+            <div id="console"></div>
+        </div>
+    </body>
+</html>
</ins><span class="cx">\ No newline at end of file
</span></span></pre></div>
<a id="trunkSourceWebCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/ChangeLog (260055 => 260056)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/ChangeLog   2020-04-14 02:40:03 UTC (rev 260055)
+++ trunk/Source/WebCore/ChangeLog      2020-04-14 02:59:30 UTC (rev 260056)
</span><span class="lines">@@ -1,3 +1,24 @@
</span><ins>+2020-04-13  Simon Fraser  <simon.fraser@apple.com>
+
+        [Async overflow] Get scroll-snap working with async overflow scrolling on macOS
+        https://bugs.webkit.org/show_bug.cgi?id=210471
+        <rdar://problem/61643199>
+
+        Reviewed by Wenson Hsieh.
+
+        Obey the FIXME and move scroll-snap related code to the delegate so that it works for
+        both frame and overflow nodes.
+
+        Tests: tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow-stateless.html
+               tiled-drawing/scrolling/scroll-snap/scroll-snap-mandatory-async-overflow.html
+
+        * page/scrolling/mac/ScrollingTreeFrameScrollingNodeMac.mm:
+        (WebCore::ScrollingTreeFrameScrollingNodeMac::commitStateBeforeChildren):
+        (WebCore::convertToLayoutUnits): Deleted.
+        * page/scrolling/mac/ScrollingTreeScrollingNodeDelegateMac.mm:
+        (WebCore::convertToLayoutUnits):
+        (WebCore::ScrollingTreeScrollingNodeDelegateMac::updateFromStateNode):
+
</ins><span class="cx"> 2020-04-13  Zalan Bujtas  <zalan@apple.com>
</span><span class="cx"> 
</span><span class="cx">         Do not cache definite height against perpendicular flex items.
</span></span></pre></div>
<a id="trunkSourceWebCorepagescrollingmacScrollingTreeFrameScrollingNodeMacmm"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/page/scrolling/mac/ScrollingTreeFrameScrollingNodeMac.mm (260055 => 260056)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/page/scrolling/mac/ScrollingTreeFrameScrollingNodeMac.mm    2020-04-14 02:40:03 UTC (rev 260055)
+++ trunk/Source/WebCore/page/scrolling/mac/ScrollingTreeFrameScrollingNodeMac.mm       2020-04-14 02:59:30 UTC (rev 260056)
</span><span class="lines">@@ -57,28 +57,6 @@
</span><span class="cx"> 
</span><span class="cx"> ScrollingTreeFrameScrollingNodeMac::~ScrollingTreeFrameScrollingNodeMac() = default;
</span><span class="cx"> 
</span><del>-#if ENABLE(CSS_SCROLL_SNAP)
-static inline Vector<LayoutUnit> convertToLayoutUnits(const Vector<float>& snapOffsetsAsFloat)
-{
-    Vector<LayoutUnit> snapOffsets;
-    snapOffsets.reserveInitialCapacity(snapOffsetsAsFloat.size());
-    for (auto offset : snapOffsetsAsFloat)
-        snapOffsets.uncheckedAppend(offset);
-
-    return snapOffsets;
-}
-
-static inline Vector<ScrollOffsetRange<LayoutUnit>> convertToLayoutUnits(const Vector<ScrollOffsetRange<float>>& snapOffsetRangesAsFloat)
-{
-    Vector<ScrollOffsetRange<LayoutUnit>> snapOffsetRanges;
-    snapOffsetRanges.reserveInitialCapacity(snapOffsetRangesAsFloat.size());
-    for (auto range : snapOffsetRangesAsFloat)
-        snapOffsetRanges.uncheckedAppend({ LayoutUnit(range.start), LayoutUnit(range.end) });
-
-    return snapOffsetRanges;
-}
-#endif
-
</del><span class="cx"> void ScrollingTreeFrameScrollingNodeMac::commitStateBeforeChildren(const ScrollingStateNode& stateNode)
</span><span class="cx"> {
</span><span class="cx">     ScrollingTreeFrameScrollingNode::commitStateBeforeChildren(stateNode);
</span><span class="lines">@@ -111,21 +89,6 @@
</span><span class="cx"> 
</span><span class="cx">     m_delegate.updateFromStateNode(scrollingStateNode);
</span><span class="cx"> 
</span><del>-#if ENABLE(CSS_SCROLL_SNAP)
-    // FIXME: this should move to the delegate and be shared with overflow.
-    if (scrollingStateNode.hasChangedProperty(ScrollingStateFrameScrollingNode::HorizontalSnapOffsets) || scrollingStateNode.hasChangedProperty(ScrollingStateFrameScrollingNode::HorizontalSnapOffsetRanges))
-        m_delegate.updateScrollSnapPoints(ScrollEventAxis::Horizontal, convertToLayoutUnits(scrollingStateNode.horizontalSnapOffsets()), convertToLayoutUnits(scrollingStateNode.horizontalSnapOffsetRanges()));
-
-    if (scrollingStateNode.hasChangedProperty(ScrollingStateFrameScrollingNode::VerticalSnapOffsets) || scrollingStateNode.hasChangedProperty(ScrollingStateFrameScrollingNode::VerticalSnapOffsetRanges))
-        m_delegate.updateScrollSnapPoints(ScrollEventAxis::Vertical, convertToLayoutUnits(scrollingStateNode.verticalSnapOffsets()), convertToLayoutUnits(scrollingStateNode.verticalSnapOffsetRanges()));
-
-    if (scrollingStateNode.hasChangedProperty(ScrollingStateScrollingNode::CurrentHorizontalSnapOffsetIndex))
-        m_delegate.setActiveScrollSnapIndexForAxis(ScrollEventAxis::Horizontal, scrollingStateNode.currentHorizontalSnapPointIndex());
-    
-    if (scrollingStateNode.hasChangedProperty(ScrollingStateScrollingNode::CurrentVerticalSnapOffsetIndex))
-        m_delegate.setActiveScrollSnapIndexForAxis(ScrollEventAxis::Vertical, scrollingStateNode.currentVerticalSnapPointIndex());
-#endif
-
</del><span class="cx">     m_hadFirstUpdate = true;
</span><span class="cx"> }
</span><span class="cx"> 
</span></span></pre></div>
<a id="trunkSourceWebCorepagescrollingmacScrollingTreeScrollingNodeDelegateMacmm"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/page/scrolling/mac/ScrollingTreeScrollingNodeDelegateMac.mm (260055 => 260056)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/page/scrolling/mac/ScrollingTreeScrollingNodeDelegateMac.mm 2020-04-14 02:40:03 UTC (rev 260055)
+++ trunk/Source/WebCore/page/scrolling/mac/ScrollingTreeScrollingNodeDelegateMac.mm    2020-04-14 02:59:30 UTC (rev 260056)
</span><span class="lines">@@ -49,6 +49,28 @@
</span><span class="cx">     releaseReferencesToScrollerImpsOnTheMainThread();
</span><span class="cx"> }
</span><span class="cx"> 
</span><ins>+#if ENABLE(CSS_SCROLL_SNAP)
+static inline Vector<LayoutUnit> convertToLayoutUnits(const Vector<float>& snapOffsetsAsFloat)
+{
+    Vector<LayoutUnit> snapOffsets;
+    snapOffsets.reserveInitialCapacity(snapOffsetsAsFloat.size());
+    for (auto offset : snapOffsetsAsFloat)
+        snapOffsets.uncheckedAppend(offset);
+
+    return snapOffsets;
+}
+
+static inline Vector<ScrollOffsetRange<LayoutUnit>> convertToLayoutUnits(const Vector<ScrollOffsetRange<float>>& snapOffsetRangesAsFloat)
+{
+    Vector<ScrollOffsetRange<LayoutUnit>> snapOffsetRanges;
+    snapOffsetRanges.reserveInitialCapacity(snapOffsetRangesAsFloat.size());
+    for (auto range : snapOffsetRangesAsFloat)
+        snapOffsetRanges.uncheckedAppend({ LayoutUnit(range.start), LayoutUnit(range.end) });
+
+    return snapOffsetRanges;
+}
+#endif
+
</ins><span class="cx"> void ScrollingTreeScrollingNodeDelegateMac::updateFromStateNode(const ScrollingStateScrollingNode& scrollingStateNode)
</span><span class="cx"> {
</span><span class="cx">     if (scrollingStateNode.hasChangedProperty(ScrollingStateScrollingNode::PainterForScrollbar)) {
</span><span class="lines">@@ -56,6 +78,20 @@
</span><span class="cx">         m_verticalScrollerImp = scrollingStateNode.verticalScrollerImp();
</span><span class="cx">         m_horizontalScrollerImp = scrollingStateNode.horizontalScrollerImp();
</span><span class="cx">     }
</span><ins>+
+#if ENABLE(CSS_SCROLL_SNAP)
+    if (scrollingStateNode.hasChangedProperty(ScrollingStateFrameScrollingNode::HorizontalSnapOffsets) || scrollingStateNode.hasChangedProperty(ScrollingStateFrameScrollingNode::HorizontalSnapOffsetRanges))
+        updateScrollSnapPoints(ScrollEventAxis::Horizontal, convertToLayoutUnits(scrollingStateNode.horizontalSnapOffsets()), convertToLayoutUnits(scrollingStateNode.horizontalSnapOffsetRanges()));
+
+    if (scrollingStateNode.hasChangedProperty(ScrollingStateFrameScrollingNode::VerticalSnapOffsets) || scrollingStateNode.hasChangedProperty(ScrollingStateFrameScrollingNode::VerticalSnapOffsetRanges))
+        updateScrollSnapPoints(ScrollEventAxis::Vertical, convertToLayoutUnits(scrollingStateNode.verticalSnapOffsets()), convertToLayoutUnits(scrollingStateNode.verticalSnapOffsetRanges()));
+
+    if (scrollingStateNode.hasChangedProperty(ScrollingStateScrollingNode::CurrentHorizontalSnapOffsetIndex))
+        setActiveScrollSnapIndexForAxis(ScrollEventAxis::Horizontal, scrollingStateNode.currentHorizontalSnapPointIndex());
+    
+    if (scrollingStateNode.hasChangedProperty(ScrollingStateScrollingNode::CurrentVerticalSnapOffsetIndex))
+        setActiveScrollSnapIndexForAxis(ScrollEventAxis::Vertical, scrollingStateNode.currentVerticalSnapPointIndex());
+#endif
</ins><span class="cx"> }
</span><span class="cx"> 
</span><span class="cx"> void ScrollingTreeScrollingNodeDelegateMac::updateScrollSnapPoints(ScrollEventAxis axis, const Vector<LayoutUnit>& snapOffsets, const Vector<ScrollOffsetRange<LayoutUnit>>& snapRanges)
</span></span></pre>
</div>
</div>

</body>
</html>