Bug 1922298 - Add a fast way of tagging frames as captured, and make that view-transition-name a stacking-context-creating property. r=view-transitions-reviewers,boris

Differential Revision: https://phabricator.services.mozilla.com/D239377

layout/generic/nsIFrame.cpp

@@ -59,6 +59,7 @@
 #include "nsFlexContainerFrame.h"
 #include "nsFocusManager.h"
 #include "nsFrameList.h"
+#include "nsFrameState.h"
 #include "nsTextControlFrame.h"
 #include "nsPlaceholderFrame.h"
 #include "nsIBaseWindow.h"
@@ -1757,6 +1758,7 @@ bool nsIFrame::Extend3DContext(const nsStyleDisplay* aStyleDisplay,
          !GetClipPropClipRect(disp, effects, GetSize()) &&
          !SVGIntegrationUtils::UsingEffectsForFrame(this) &&
          !effects->HasMixBlendMode() &&
+         !ForcesStackingContextForViewTransition() &&
          disp->mIsolation != StyleIsolation::Isolate;
 }
 
@@ -2738,6 +2740,19 @@ Maybe<nsRect> nsIFrame::GetClipPropClipRect(const nsStyleDisplay* aDisp,
   return Some(rect);
 }
 
+// https://drafts.csswg.org/css-view-transitions-1/#named-and-transitioning
+//
+// Note https://github.com/w3c/csswg-drafts/issues/11772, however, for the root
+// style check.
+bool nsIFrame::ForcesStackingContextForViewTransition() const {
+  auto* style = Style();
+  return (style->StyleUIReset()->HasViewTransitionName() ||
+          HasAnyStateBits(NS_FRAME_CAPTURED_IN_VIEW_TRANSITION) ||
+          style->StyleDisplay()->mWillChange.bits &
+              mozilla::StyleWillChangeBits::VIEW_TRANSITION_NAME) &&
+         !style->IsRootElementStyle();
+}
+
 /**
  * If the CSS 'overflow' property applies to this frame, and is not
  * handled by constructing a dedicated nsHTML/XULScrollFrame, set up clipping
@@ -11566,6 +11581,11 @@ bool nsIFrame::IsStackingContext(const nsStyleDisplay* aStyleDisplay,
       return true;
     }
   }
+
+  if (ForcesStackingContextForViewTransition()) {
+    return true;
+  }
+
   // strictly speaking, 'perspective' doesn't require visual atomicity,
   // but the spec says it acts like the rest of these
   if (aStyleDisplay->HasPerspectiveStyle() ||
@@ -11580,6 +11600,9 @@ bool nsIFrame::IsStackingContext(const nsStyleDisplay* aStyleDisplay,
       return true;
     }
   }
+  // Elements captured in a view transition during a view transition or whose
+  // view-transition-name computed value is not none (at any time) form a s
+  // https://drafts.csswg.org/css-view-transitions-1/#named-and-transitioning
   return aStyleEffects->mMixBlendMode != StyleBlend::Normal ||
          SVGIntegrationUtils::UsingEffectsForFrame(this) ||
          aStyleDisplay->IsPositionForcingStackingContext() ||