Trigger a signal in the UI Process when the web page provides a spatial backdrop

Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml

@@ -8680,6 +8680,23 @@ WebLocksAPIEnabled:
   sharedPreferenceForWebProcess: true
   richJavaScript: true
 
+WebPageSpatialBackdropEnabled:
+  type: bool
+  status: testable
+  category: html
+  condition: ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+  humanReadableName: "Web Page Spatial Backdrop"
+  humanReadableDescription: "Enable Web Page Spatial Backdrop"
+  defaultValue:
+    WebKitLegacy:
+      default: false
+    WebKit:
+      default: false
+    WebCore:
+      default: false
+  disableInLockdownMode: true
+  sharedPreferenceForWebProcess: true
+
 WebRTCAV1CodecEnabled:
   type: bool
   status: preview

Source/WTF/wtf/PlatformEnableCocoa.h

@@ -812,6 +812,10 @@
 #define ENABLE_SPATIAL_IMAGE_DETECTION 1
 #endif
 
+#if !defined(ENABLE_WEB_PAGE_SPATIAL_BACKDROP) && PLATFORM(VISION)
+#define ENABLE_WEB_PAGE_SPATIAL_BACKDROP 1
+#endif
+
 #if !defined(ENABLE_SPEECH_SYNTHESIS) && !PLATFORM(MACCATALYST)
 #define ENABLE_SPEECH_SYNTHESIS 1
 #endif

Source/WebCore/Headers.cmake

@@ -1166,6 +1166,7 @@ set(WebCore_PRIVATE_FRAMEWORK_HEADERS
     dom/SimulatedClickOptions.h
     dom/SlotAssignmentMode.h
     dom/SpaceSplitString.h
+    dom/SpatialBackdropSource.h
     dom/StartViewTransitionOptions.h
     dom/StaticRange.h
     dom/StyledElement.h

Source/WebCore/Sources.txt

@@ -1358,6 +1358,7 @@ dom/SimpleRange.cpp
 dom/SimulatedClick.cpp
 dom/SlotAssignment.cpp
 dom/SpaceSplitString.cpp
+dom/SpatialBackdropSource.cpp
 dom/StaticNodeList.cpp
 dom/StaticRange.cpp
 dom/StringCallback.cpp

Source/WebCore/WebCore.xcodeproj/project.pbxproj

@@ -5189,6 +5189,7 @@
 		C6F0900F14327B6100685849 /* MutationObserver.h in Headers */ = {isa = PBXBuildFile; fileRef = C6F0900614327B6100685849 /* MutationObserver.h */; settings = {ATTRIBUTES = (Private, ); }; };
 		C6F0902D14327D4F00685849 /* JSMutationObserver.h in Headers */ = {isa = PBXBuildFile; fileRef = C6F0902514327D4F00685849 /* JSMutationObserver.h */; };
 		C9D467051E60C465008195FB /* AutoplayEvent.h in Headers */ = {isa = PBXBuildFile; fileRef = C9D467041E60C3EB008195FB /* AutoplayEvent.h */; settings = {ATTRIBUTES = (Private, ); }; };
+		CA3344082D16174C007473A1 /* SpatialBackdropSource.h in Headers */ = {isa = PBXBuildFile; fileRef = CA3344072D16174C007473A1 /* SpatialBackdropSource.h */; settings = {ATTRIBUTES = (Private, ); }; };
 		CA3A4AAF25416E40006CDAE2 /* ImageResolution.h in Headers */ = {isa = PBXBuildFile; fileRef = CA3A4AAD25416E3E006CDAE2 /* ImageResolution.h */; };
 		CA3BF67E10D99BAE00E6CE53 /* ScrollAnimator.h in Headers */ = {isa = PBXBuildFile; fileRef = CA3BF67D10D99BAE00E6CE53 /* ScrollAnimator.h */; settings = {ATTRIBUTES = (Private, ); }; };
 		CA6C1530220B98CC0055CBFC /* JSValueInWrappedObject.h in Headers */ = {isa = PBXBuildFile; fileRef = 931AE3B81FB80EAE00F5EFB2 /* JSValueInWrappedObject.h */; settings = {ATTRIBUTES = (Private, ); }; };
@@ -18859,6 +18860,8 @@
 		CA1635DC2072E76900E7D2CE /* ReferrerPolicy.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = ReferrerPolicy.cpp; sourceTree = "<group>"; };
 		CA1933D52407D6400071241A /* PerformancePaintTiming.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = PerformancePaintTiming.h; sourceTree = "<group>"; };
 		CA1933D82407EDCF0071241A /* PerformancePaintTiming.idl */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = PerformancePaintTiming.idl; sourceTree = "<group>"; };
+		CA3344072D16174C007473A1 /* SpatialBackdropSource.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = SpatialBackdropSource.h; sourceTree = "<group>"; };
+		CA3344092D1625B9007473A1 /* SpatialBackdropSource.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = SpatialBackdropSource.cpp; sourceTree = "<group>"; };
 		CA3A4AAB25416E3C006CDAE2 /* ImageResolution.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = ImageResolution.cpp; sourceTree = "<group>"; };
 		CA3A4AAD25416E3E006CDAE2 /* ImageResolution.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ImageResolution.h; sourceTree = "<group>"; };
 		CA3BF67B10D99BAE00E6CE53 /* ScrollAnimator.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = ScrollAnimator.cpp; sourceTree = "<group>"; };
@@ -38781,6 +38784,8 @@
 				9B4F0632289F2F08007831DB /* SlotAssignmentMode.idl */,
 				D01A27AB10C9BFD800026A42 /* SpaceSplitString.cpp */,
 				D01A27AC10C9BFD800026A42 /* SpaceSplitString.h */,
+				CA3344092D1625B9007473A1 /* SpatialBackdropSource.cpp */,
+				CA3344072D16174C007473A1 /* SpatialBackdropSource.h */,
 				EE7A169F2C607BFA0057B563 /* StartViewTransitionOptions.h */,
 				EE7A169E2C607AF00057B563 /* StartViewTransitionOptions.idl */,
 				BC7FA62C0D1F0EFF00DB22A9 /* StaticNodeList.cpp */,
@@ -44044,6 +44049,7 @@
 				72F7E746279B8F7500D82D2D /* SourceImage.h in Headers */,
 				D01A27AE10C9BFD800026A42 /* SpaceSplitString.h in Headers */,
 				46A877482D0D426800DE225E /* SpanCoreAudio.h in Headers */,
+				CA3344082D16174C007473A1 /* SpatialBackdropSource.h in Headers */,
 				B9CA3B402CAB1D3E00B2607C /* SpatialImageControls.h in Headers */,
 				626CDE0F1140424C001E5A68 /* SpatialNavigation.h in Headers */,
 				517C11D52C6DD6A100489490 /* SpatialVideoMetadata.h in Headers */,

Source/WebCore/dom/Document.cpp

@@ -1340,6 +1340,47 @@ const Color& Document::themeColor()
     return m_cachedThemeColor;
 }
 
+#if ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+void Document::spatialBackdropLinkElementChanged()
+{
+    spatialBackdropSourceChanged();
+}
+
+void Document::spatialBackdropSourceChanged()
+{
+    if (!settings().webPageSpatialBackdropEnabled())
+        return;
+
+    auto newSpatialBackdropSource = determineActiveSpatialBackdropSource();
+    if (m_cachedSpatialBackdropSource == newSpatialBackdropSource)
+        return;
+    m_cachedSpatialBackdropSource = WTFMove(newSpatialBackdropSource);
+
+    if (RefPtr page = this->page())
+        page->chrome().client().spatialBackdropSourceChanged();
+}
+
+std::optional<SpatialBackdropSource> Document::determineActiveSpatialBackdropSource() const
+{
+    auto sourceURL = m_url.url();
+    if (!sourceURL.isValid())
+        return std::nullopt;
+
+    for (auto& linkElement : descendantsOfType<HTMLLinkElement>(*this)) {
+        if (!linkElement.isSpatialBackdrop())
+            continue;
+
+        auto modelURL = linkElement.href();
+        if (!modelURL.isValid())
+            return std::nullopt;
+
+        return SpatialBackdropSource { WTFMove(sourceURL), WTFMove(modelURL), linkElement.environmentMap() };
+    }
+
+    return std::nullopt;
+}
+#endif
+
 Color Document::linkColor(const RenderStyle& style) const
 {
     if (m_linkColor.isValid())
@@ -4213,6 +4254,10 @@ void Document::setURL(const URL& url)
     m_documentURI = m_url.url();
     m_adjustedURL = adjustedURL();
     updateBaseURL();
+
+#if ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+    spatialBackdropSourceChanged();
+#endif
 }
 
 const URL& Document::urlForBindings()

Source/WebCore/dom/Document.h

@@ -48,6 +48,7 @@
 #include "RenderPtr.h"
 #include "ReportingClient.h"
 #include "ScriptExecutionContext.h"
+#include "SpatialBackdropSource.h"
 #include "StringWithDirection.h"
 #include "Supplementable.h"
 #include "TextIndicator.h"
@@ -917,6 +918,10 @@ class Document
 
     const Color& themeColor();
 
+#if ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+    const std::optional<SpatialBackdropSource>& spatialBackdropSource() const { return m_cachedSpatialBackdropSource; }
+#endif
+
     void setTextColor(const Color& color) { m_textColor = color; }
     const Color& textColor() const { return m_textColor; }
 
@@ -1107,6 +1112,10 @@ class Document
 
     void metaElementThemeColorChanged(HTMLMetaElement&);
 
+#if ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+    void spatialBackdropLinkElementChanged();
+#endif
+
 #if ENABLE(DARK_MODE_CSS)
     void processColorScheme(const String& colorScheme);
     void metaElementColorSchemeChanged();
@@ -2069,6 +2078,11 @@ class Document
     WeakPtr<HTMLMetaElement, WeakPtrImplWithEventTargetData> determineActiveThemeColorMetaElement();
     void themeColorChanged();
 
+#if ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+    std::optional<SpatialBackdropSource> determineActiveSpatialBackdropSource() const;
+    void spatialBackdropSourceChanged();
+#endif
+
     void invalidateAccessKeyCacheSlowCase();
     void buildAccessKeyCache();
 
@@ -2230,6 +2244,10 @@ class Document
     WeakPtr<HTMLMetaElement, WeakPtrImplWithEventTargetData> m_activeThemeColorMetaElement;
     Color m_applicationManifestThemeColor;
 
+#if ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+    std::optional<SpatialBackdropSource> m_cachedSpatialBackdropSource;
+#endif
+
     Color m_textColor { Color::black };
     Color m_linkColor;
     Color m_visitedLinkColor;

Source/WebCore/dom/SpatialBackdropSource.cpp

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2025 Apple Inc. All rights reserved.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public License
+ * along with this library; see the file COPYING.LIB.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#if ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+#include "config.h"
+#include "SpatialBackdropSource.h"
+
+namespace WebCore {
+
+SpatialBackdropSource::SpatialBackdropSource(URL&& sourceURL, URL&& modelURL, std::optional<URL>&& environmentMapURL)
+    : m_sourceURL(WTFMove(sourceURL))
+    , m_modelURL(WTFMove(modelURL))
+    , m_environmentMapURL(WTFMove(environmentMapURL))
+{
+}
+
+SpatialBackdropSource::SpatialBackdropSource(URL&& sourceURL, URL&& modelURL, URL&& environmentMapURL)
+    : m_sourceURL(WTFMove(sourceURL))
+    , m_modelURL(WTFMove(modelURL))
+    , m_environmentMapURL(environmentMapURL.isValid() ? std::make_optional(WTFMove(environmentMapURL)) : std::nullopt)
+{
+}
+
+} // namespace WebCore
+#endif

Source/WebCore/dom/SpatialBackdropSource.h

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2025 Apple Inc. All rights reserved.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public License
+ * along with this library; see the file COPYING.LIB.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#pragma once
+
+#if ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+
+#include <wtf/URL.h>
+
+namespace WebCore {
+
+struct SpatialBackdropSource {
+public:
+    URL m_sourceURL;
+    URL m_modelURL;
+    std::optional<URL> m_environmentMapURL;
+
+    WEBCORE_EXPORT SpatialBackdropSource(URL&& sourceURL, URL&& modelURL, std::optional<URL>&& environmentMapURL);
+    SpatialBackdropSource(URL&& sourceURL, URL&& modelURL, URL&& environmentMapURL);
+
+    friend bool operator==(const SpatialBackdropSource&, const SpatialBackdropSource&) = default;
+};
+
+} // namespace WebCore
+#endif

Source/WebCore/html/HTMLLinkElement.cpp

@@ -197,11 +197,18 @@ void HTMLLinkElement::attributeChanged(const QualifiedName& name, const AtomStri
     case AttributeNames::relAttr: {
         auto parsedRel = LinkRelAttribute(document(), newValue);
         auto didMutateRel = parsedRel != m_relAttribute;
+#if ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+        auto wasSpatialBackdrop = m_relAttribute.isSpatialBackdrop;
+#endif
         m_relAttribute = WTFMove(parsedRel);
         if (m_relList)
             m_relList->associatedAttributeValueChanged();
         if (didMutateRel)
             process();
+#if ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+        if (wasSpatialBackdrop && !m_relAttribute.isSpatialBackdrop)
+            document().spatialBackdropLinkElementChanged();
+#endif
         break;
     }
     case AttributeNames::hrefAttr: {
@@ -212,6 +219,16 @@ void HTMLLinkElement::attributeChanged(const QualifiedName& name, const AtomStri
         process();
         break;
     }
+#if ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+    case AttributeNames::environmentmapAttr: {
+        URL environmentMapURL = getNonEmptyURLAttribute(environmentmapAttr);
+        if (environmentMapURL == m_environmentMapURL)
+            return;
+        m_environmentMapURL = WTFMove(environmentMapURL);
+        process();
+        break;
+    }
+#endif
     case AttributeNames::typeAttr:
         if (newValue == m_type)
             return;
@@ -300,6 +317,11 @@ void HTMLLinkElement::process()
     if (m_isHandlingBeforeLoad)
         return;
 
+#if ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+    if (m_relAttribute.isSpatialBackdrop)
+        document().spatialBackdropLinkElementChanged();
+#endif
+
     processInternalResourceLink();
     if (m_relAttribute.isInternalResourceLink)
         return;
@@ -528,6 +550,11 @@ void HTMLLinkElement::removedFromAncestor(RemovalType removalType, ContainerNode
 
     bool wasLoading = styleSheetIsLoading();
 
+#if ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+    if (m_relAttribute.isSpatialBackdrop)
+        oldParentOfRemovedTree.document().spatialBackdropLinkElementChanged();
+#endif
+
     if (m_sheet)
         clearSheet();
 
@@ -728,7 +755,11 @@ void HTMLLinkElement::startLoadingDynamicSheet()
 
 bool HTMLLinkElement::isURLAttribute(const Attribute& attribute) const
 {
-    return attribute.name().localName() == hrefAttr || HTMLElement::isURLAttribute(attribute);
+    return attribute.name().localName() == hrefAttr
+#if ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+    || attribute.name().localName() == environmentmapAttr
+#endif
+    || HTMLElement::isURLAttribute(attribute);
 }
 
 URL HTMLLinkElement::href() const
@@ -741,6 +772,13 @@ const AtomString& HTMLLinkElement::rel() const
     return attributeWithoutSynchronization(relAttr);
 }
 
+#if ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+URL HTMLLinkElement::environmentMap() const
+{
+    return document().completeURL(attributeWithoutSynchronization(environmentmapAttr));
+}
+#endif
+
 AtomString HTMLLinkElement::target() const
 {
     return attributeWithoutSynchronization(targetAttr);

Source/WebCore/html/HTMLLinkElement.h

@@ -57,6 +57,11 @@ class HTMLLinkElement final : public HTMLElement, public CachedStyleSheetClient,
     URL href() const;
     WEBCORE_EXPORT const AtomString& rel() const;
 
+#if ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+    URL environmentMap() const;
+    bool isSpatialBackdrop() const { return m_relAttribute.isSpatialBackdrop; }
+#endif
+
     AtomString target() const final;
 
     const AtomString& type() const;
@@ -162,6 +167,9 @@ class HTMLLinkElement final : public HTMLElement, public CachedStyleSheetClient,
     String m_media;
     String m_integrityMetadataForPendingSheetRequest;
     URL m_url;
+#if ENABLE(WEB_PAGE_SPATIAL_BACKDROP)
+    URL m_environmentMapURL;
+#endif
     std::unique_ptr<DOMTokenList> m_sizes;
     std::unique_ptr<DOMTokenList> m_relList;
     std::unique_ptr<DOMTokenList> m_blockingList;

Source/WebCore/html/HTMLLinkElement.idl

@@ -27,6 +27,7 @@
     [Reflect] attribute boolean disabled;
     [CEReactions=NotNeeded, Reflect] attribute DOMString charset;
     [CEReactions=NotNeeded, Reflect, URL] attribute USVString href;
+    [CEReactions=NotNeeded, Conditional=WEB_PAGE_SPATIAL_BACKDROP, EnabledBySetting=WebPageSpatialBackdropEnabled, Reflect, URL] attribute USVString environmentMap;
     [CEReactions=NotNeeded, Reflect] attribute DOMString hreflang;
     [CEReactions=NotNeeded, Reflect] attribute DOMString media;
     [CEReactions=NotNeeded, Reflect] attribute DOMString rel;