[LegacySVG] Margin collapsing should not occur at the foreignObject boundary

Ahmad-S792 · Ahmad Saleem · commit 45d2ff003832 · 2025-12-23T16:59:34.000-08:00
https://bugs.webkit.org/show_bug.cgi?id=23963 rdar://97208795 Reviewed by Alan Baradlay. This patch aligns WebKit with Gecko / Firefox and Blink / Chromium. Merge: https://chromium.googlesource.com/chromium/src.git/+/eb26f063d73fce4d8a2cf64541667e0863cb6421 This patch makes foreignObject a block formatting context (BFC) which prevents margin collapsing across the foreignObject boundary. This function (createsNewFormattingContext) is limited to BFC context nowadays. https://svgwg.org/svg2-draft/single-page.html#embedded-ForeignObjectElement * Source/WebCore/rendering/RenderBlock.cpp: (WebCore::RenderBlock::createsNewFormattingContext const): * LayoutTests/platform/glib/svg/custom/dominant-baseline-hanging-expected.txt: * LayoutTests/platform/ios/svg/custom/dominant-baseline-hanging-expected.txt: * LayoutTests/platform/mac/svg/custom/dominant-baseline-hanging-expected.txt: * LayoutTests/platform/win/svg/custom/dominant-baseline-hanging-expected.txt: * LayoutTests/imported/w3c/web-platform-tests/svg/extensibility/foreignObject/containing-block-expected.txt: Progressions * LayoutTests/imported/w3c/web-platform-tests/svg/extensibility/foreignObject/getboundingclientrect-expected.txt: Progressions Canonical link: https://commits.webkit.org/304916@main
diff --git a/LayoutTests/imported/w3c/web-platform-tests/svg/extensibility/foreignObject/containing-block-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/svg/extensibility/foreignObject/containing-block-expected.txt
@@ -1,3 +1,3 @@
 
-FAIL position assert_equals: offsetTop expected 5 but got 0
+PASS position
 
diff --git a/LayoutTests/imported/w3c/web-platform-tests/svg/extensibility/foreignObject/getboundingclientrect-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/svg/extensibility/foreignObject/getboundingclientrect-expected.txt
@@ -1,3 +1,3 @@
 
-FAIL foreignObject: Element.prototype.getBoundingClientRect() assert_equals: top expected 24 but got 18
+PASS foreignObject: Element.prototype.getBoundingClientRect()
 
diff --git a/LayoutTests/platform/glib/svg/custom/dominant-baseline-hanging-expected.txt b/LayoutTests/platform/glib/svg/custom/dominant-baseline-hanging-expected.txt
@@ -22,7 +22,7 @@ layer at (0,0) size 400x400
         RenderSVGInlineText {#text} at (0,0) size 323x22
           chunk 1 text run 1 at (2.00,14.40) startOffset 0 endOffset 40 width 323.00: "This is hanging from the top-left corner"
     RenderSVGForeignObject {foreignObject} at (10,45) size 380x150
-      RenderBlock {html} at (0,0) size 380x124
+      RenderBlock {html} at (0,16) size 380x124
         RenderBody {body} at (8,0) size 364x124
           RenderBlock {p} at (0,0) size 364x90
             RenderText {#text} at (0,0) size 347x35
diff --git a/LayoutTests/platform/ios/svg/custom/dominant-baseline-hanging-expected.txt b/LayoutTests/platform/ios/svg/custom/dominant-baseline-hanging-expected.txt
@@ -22,7 +22,7 @@ layer at (0,0) size 400x400
         RenderSVGInlineText {#text} at (0,0) size 317x23
           chunk 1 text run 1 at (2.00,14.40) startOffset 0 endOffset 40 width 316.58: "This is hanging from the top-left corner"
     RenderSVGForeignObject {foreignObject} at (10,45) size 380x150
-      RenderBlock {html} at (0,0) size 380x136
+      RenderBlock {html} at (0,16) size 380x136
         RenderBody {body} at (8,0) size 364x136
           RenderBlock {p} at (0,0) size 364x100
             RenderText {#text} at (0,0) size 353x39
diff --git a/LayoutTests/platform/mac/svg/custom/dominant-baseline-hanging-expected.txt b/LayoutTests/platform/mac/svg/custom/dominant-baseline-hanging-expected.txt
@@ -22,7 +22,7 @@ layer at (0,0) size 400x400
         RenderSVGInlineText {#text} at (0,0) size 317x23
           chunk 1 text run 1 at (2.00,14.40) startOffset 0 endOffset 40 width 316.58: "This is hanging from the top-left corner"
     RenderSVGForeignObject {foreignObject} at (10,45) size 380x150
-      RenderBlock {html} at (0,0) size 380x124
+      RenderBlock {html} at (0,16) size 380x124
         RenderBody {body} at (8,0) size 364x124
           RenderBlock {p} at (0,0) size 364x90
             RenderText {#text} at (0,0) size 353x36
diff --git a/LayoutTests/platform/win/svg/custom/dominant-baseline-hanging-expected.txt b/LayoutTests/platform/win/svg/custom/dominant-baseline-hanging-expected.txt
@@ -22,7 +22,7 @@ layer at (0,0) size 400x400
         RenderSVGInlineText {#text} at (0,0) size 308x22
           chunk 1 text run 1 at (2.00,13.60) startOffset 0 endOffset 40 width 308.00: "This is hanging from the top-left corner"
     RenderSVGForeignObject {foreignObject} at (10,45) size 380x150
-      RenderBlock {html} at (0,0) size 380x136
+      RenderBlock {html} at (0,16) size 380x136
         RenderBody {body} at (8,0) size 364x136
           RenderBlock {p} at (0,0) size 364x100
             RenderText {#text} at (0,0) size 349x39
diff --git a/Source/WebCore/rendering/RenderBlock.cpp b/Source/WebCore/rendering/RenderBlock.cpp
@@ -1355,7 +1355,7 @@ bool RenderBlock::createsNewFormattingContext() const
         || isFieldset()
         || isDocumentElementRenderer()
         || isRenderFragmentedFlow()
-        || isRenderSVGForeignObject()
+        || isRenderOrLegacyRenderSVGForeignObject()
         || style.specifiesColumns()
         || style.columnSpan() == ColumnSpan::All
         || style.display() == DisplayType::FlowRoot

Original file line number	Diff line number	Diff line change
`@@ -1,3 +1,3 @@`
`1`	`1`
`2`		`-FAIL position assert_equals: offsetTop expected 5 but got 0`
	`2`	`+PASS position`
`3`	`3`
Original file line number	Diff line number	Diff line change
`@@ -1,3 +1,3 @@`
`1`	`1`
`2`		`-FAIL foreignObject: Element.prototype.getBoundingClientRect() assert_equals: top expected 24 but got 18`
	`2`	`+PASS foreignObject: Element.prototype.getBoundingClientRect()`
`3`	`3`