tor-browser

commit 2b54f26fc923d586e1a59f6f6387ff32015bc653
parent cfade7054a4ae0a80d3c39f71224b5738ad3bf2a
Author: Emilio Cobos Álvarez <emilio@crisal.io>
Date:   Sat, 13 Dec 2025 09:31:09 +0000

Bug 2005683 - Don't apply overflow clipping to list controls. r=layout-reviewers,dshin

I can't repro missing content like comment 0 but I can repro broken
scrollport handling.

And clean up ShouldApplyOverflowClipping while at it:

 * Deal with scrollers (including list controls) explicitly at the top.
 * Deal with suppressed scrollable blocks for print inside the if where
   we check if overflow is scrollable already.
 * Remove now redundant SVG check. An SVG layout frame can never be a
   suppressed scrollable block.

I'm not sure how would I go about testing this...

Differential Revision: https://phabricator.services.mozilla.com/D276154

Diffstat:
M
layout/generic/nsIFrame.cpp
 | 
34
+++++++++++++++-------------------

1 file changed, 15 insertions(+), 19 deletions(-)
diff --git a/layout/generic/nsIFrame.cpp b/layout/generic/nsIFrame.cpp
@@ -12288,13 +12288,15 @@ PhysicalAxes nsIFrame::ShouldApplyOverflowClipping(
     const nsStyleDisplay* aDisp) const {
   MOZ_ASSERT(aDisp == StyleDisplay(), "Wrong display struct");
 
-  // 'contain:paint', which we handle as 'overflow:clip' here. Except for
-  // scrollframes we don't need contain:paint to add any clipping, because
-  // the scrollable frame will already clip overflowing content, and because
-  // 'contain:paint' should prevent all means of escaping that clipping
-  // (e.g. because it forms a fixed-pos containing block).
-  if (aDisp->IsContainPaint() && !IsScrollContainerFrame() &&
-      SupportsContainLayoutAndPaint()) {
+  if (IsScrollContainerOrSubclass()) {
+    // Scrollers deal with overflow on their own.
+    return {};
+  }
+
+  // 'contain:paint', which we handle as 'overflow:clip' here. 'contain:paint'
+  // should prevent all means of escaping that clipping (e.g. because it forms a
+  // fixed-pos containing block).
+  if (aDisp->IsContainPaint() && SupportsContainLayoutAndPaint()) {
     return kPhysicalAxesBoth;
   }
 
@@ -12305,7 +12307,6 @@ PhysicalAxes nsIFrame::ShouldApplyOverflowClipping(
     switch (type) {
       case LayoutFrameType::CheckboxRadio:
       case LayoutFrameType::ComboboxControl:
-      case LayoutFrameType::ListControl:
       case LayoutFrameType::Progress:
       case LayoutFrameType::Range:
       case LayoutFrameType::SubDocument:
@@ -12333,13 +12334,13 @@ PhysicalAxes nsIFrame::ShouldApplyOverflowClipping(
       default:
         break;
     }
+    if (IsSuppressedScrollableBlockForPrint()) {
+      return kPhysicalAxesBoth;
+    }
   }
 
-  // clip overflow:clip, except for nsListControlFrame which is
-  // a ScrollContainerFrame sub-class.
-  if (MOZ_UNLIKELY((aDisp->mOverflowX == StyleOverflow::Clip ||
-                    aDisp->mOverflowY == StyleOverflow::Clip) &&
-                   !IsListControlFrame())) {
+  if (aDisp->mOverflowX == StyleOverflow::Clip ||
+      aDisp->mOverflowY == StyleOverflow::Clip) {
     // FIXME: we could use GetViewportScrollStylesOverrideElement() here instead
     // if that worked correctly in a print context. (see bug 1654667)
     const auto* element = Element::FromNodeOrNull(GetContent());
@@ -12356,12 +12357,7 @@ PhysicalAxes nsIFrame::ShouldApplyOverflowClipping(
     }
   }
 
-  if (HasAnyStateBits(NS_FRAME_SVG_LAYOUT)) {
-    return PhysicalAxes();
-  }
-
-  return IsSuppressedScrollableBlockForPrint() ? kPhysicalAxesBoth
-                                               : PhysicalAxes();
+  return PhysicalAxes();
 }
 
 bool nsIFrame::IsSuppressedScrollableBlockForPrint() const {