Implement new pseudoElement interface on KeyframeEffect

Make target() return the originating element if target_ is a
PseudoElement (EventTarget still returns the layout object).

Add pseudoElement() property which returns the target pseudo-selector
if the target is a pseudo-element (null otherwise).
Invalid and unsupported pseudo-elements will still return a selector
and the originating element (from target()) but will not animated
(EventTarget returns null).

Add pseudoElement option to KeyframeEffect constructor.

Change-Id: Id7d16ea6966c533e56d1170462ff60a79b277fd5
Bug: 981894
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1921343
Commit-Queue: George Steel <gtsteel@chromium.org>
Reviewed-by: Majid Valipour <majidvp@chromium.org>
Reviewed-by: Kevin Ellis <kevers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#726506}

third_party/blink/renderer/core/animation/keyframe_effect.cc

@@ -39,6 +39,7 @@
 #include "third_party/blink/renderer/core/animation/timing_input.h"
 #include "third_party/blink/renderer/core/dom/element.h"
 #include "third_party/blink/renderer/core/dom/node_computed_style.h"
+#include "third_party/blink/renderer/core/dom/pseudo_element.h"
 #include "third_party/blink/renderer/core/frame/web_feature.h"
 #include "third_party/blink/renderer/core/paint/paint_layer.h"
 #include "third_party/blink/renderer/core/style/computed_style.h"
@@ -49,6 +50,34 @@
 
 namespace blink {
 
+namespace {
+
+// Verifies that a pseudo-element selector lexes and canonicalizes legacy forms
+bool ValidateAndCanonicalizePseudo(String& selector) {
+  if (selector.IsEmpty()) {
+    if (!selector.IsNull())
+      selector = String();  // null
+    return true;
+  } else if (selector.StartsWith("::")) {
+    return true;
+  } else if (selector == ":before") {
+    selector = "::before";
+    return true;
+  } else if (selector == ":after") {
+    selector = "::after";
+    return true;
+  } else if (selector == ":first-letter") {
+    selector = "::first-letter";
+    return true;
+  } else if (selector == ":first-line") {
+    selector = "::first-line";
+    return true;
+  }
+  return false;
+}
+
+}  // namespace
+
 KeyframeEffect* KeyframeEffect::Create(
     ScriptState* script_state,
     Element* element,
@@ -61,17 +90,40 @@ KeyframeEffect* KeyframeEffect::Create(
     return nullptr;
 
   EffectModel::CompositeOperation composite = EffectModel::kCompositeReplace;
+  String pseudo = String();
   if (options.IsKeyframeEffectOptions()) {
-    composite = EffectModel::StringToCompositeOperation(
-                    options.GetAsKeyframeEffectOptions()->composite())
+    auto* effect_options = options.GetAsKeyframeEffectOptions();
+    composite =
+        EffectModel::StringToCompositeOperation(effect_options->composite())
             .value();
+    if (RuntimeEnabledFeatures::WebAnimationsAPIEnabled() &&
+        !effect_options->pseudoElement().IsEmpty()) {
+      pseudo = effect_options->pseudoElement();
+      if (!ValidateAndCanonicalizePseudo(pseudo)) {
+        // TODO(gtsteel): update when
+        // https://github.com/w3c/csswg-drafts/issues/4586 resolves
+        exception_state.ThrowDOMException(
+            DOMExceptionCode::kSyntaxError,
+            "A valid pseudo-selector must start with ::.");
+      }
+    }
   }
 
   KeyframeEffectModelBase* model = EffectInput::Convert(
       element, keyframes, composite, script_state, exception_state);
   if (exception_state.HadException())
     return nullptr;
-  return MakeGarbageCollected<KeyframeEffect>(element, model, timing);
+  KeyframeEffect* effect =
+      MakeGarbageCollected<KeyframeEffect>(element, model, timing);
+
+  if (!pseudo.IsEmpty()) {
+    effect->target_pseudo_ = pseudo;
+    if (element) {
+      effect->effect_target_ =
+          element->GetPseudoElement(CSSSelector::ParsePseudoId(pseudo));
+    }
+  }
+  return effect;
 }
 
 KeyframeEffect* KeyframeEffect::Create(ScriptState* script_state,
@@ -103,23 +155,63 @@ KeyframeEffect::KeyframeEffect(Element* target,
                                EventDelegate* event_delegate)
     : AnimationEffect(timing, event_delegate),
       effect_target_(target),
+      target_element_(target),
+      target_pseudo_(),
       model_(model),
       sampled_effect_(nullptr),
       priority_(priority) {
   DCHECK(model_);
+
+  // fix target for css animations and transitions
+  if (target && target->IsPseudoElement()) {
+    target_element_ = target->parentElement();
+    DCHECK(!target_element_->IsPseudoElement());
+    target_pseudo_ = target->tagName();
+  }
 }
 
 KeyframeEffect::~KeyframeEffect() = default;
 
-void KeyframeEffect::setTarget(Element* target) {
-  if (effect_target_ == target)
-    return;
+void KeyframeEffect::setTarget(Element* new_target) {
+  DCHECK(!new_target || !new_target->IsPseudoElement());
+  target_element_ = new_target;
+  RefreshTarget();
+}
+
+const String& KeyframeEffect::pseudoElement() {
+  return target_pseudo_;
+}
+
+void KeyframeEffect::setPseudoElement(String pseudo,
+                                      ExceptionState& exception_state) {
+  if (ValidateAndCanonicalizePseudo(pseudo)) {
+    target_pseudo_ = pseudo;
+  } else {
+    exception_state.ThrowDOMException(
+        DOMExceptionCode::kSyntaxError,
+        "A valid pseudo-selector must start with ::.");
+  }
 
+  RefreshTarget();
+}
+
+void KeyframeEffect::RefreshTarget() {
+  Element* new_target;
+  if (!target_element_) {
+    new_target = nullptr;
+  } else if (target_pseudo_.IsEmpty()) {
+    new_target = target_element_;
+  } else {
+    PseudoId pseudoId = CSSSelector::ParsePseudoId(target_pseudo_);
+    new_target = target_element_->GetPseudoElement(pseudoId);
+  }
+
+  if (new_target != effect_target_) {
     DetachTarget(GetAnimation());
-  effect_target_ = target;
+    effect_target_ = new_target;
     AttachTarget(GetAnimation());
-
     InvalidateAndNotifyOwner();
+  }
 }
 
 String KeyframeEffect::composite() const {
@@ -320,6 +412,7 @@ bool KeyframeEffect::HasPlayingAnimation() const {
 
 void KeyframeEffect::Trace(blink::Visitor* visitor) {
   visitor->Trace(effect_target_);
+  visitor->Trace(target_element_);
   visitor->Trace(model_);
   visitor->Trace(sampled_effect_);
   AnimationEffect::Trace(visitor);

third_party/blink/renderer/core/animation/keyframe_effect.h

@@ -77,8 +77,13 @@ class CORE_EXPORT KeyframeEffect final : public AnimationEffect {
   bool IsKeyframeEffect() const override { return true; }
 
   // IDL implementation.
-  Element* target() const { return effect_target_; }
+
+  // Returns the target element. If the animation targets a pseudo-element,
+  // this returns the originating element.
+  Element* target() const { return target_element_; }
   void setTarget(Element*);
+  const String& pseudoElement();
+  void setPseudoElement(String, ExceptionState&);
   String composite() const;
   void setComposite(String);
   HeapVector<ScriptValue> getKeyframes(ScriptState*);
@@ -138,6 +143,7 @@ class CORE_EXPORT KeyframeEffect final : public AnimationEffect {
   void Detach() override;
   void AttachTarget(Animation*);
   void DetachTarget(Animation*);
+  void RefreshTarget();
   AnimationTimeDelta CalculateTimeToEffectChange(
       bool forwards,
       base::Optional<double> inherited_time,
@@ -148,6 +154,8 @@ class CORE_EXPORT KeyframeEffect final : public AnimationEffect {
   bool AnimationsPreserveAxisAlignment(const PropertyHandle&) const;
 
   Member<Element> effect_target_;
+  Member<Element> target_element_;
+  String target_pseudo_;
   Member<KeyframeEffectModelBase> model_;
   Member<SampledEffect> sampled_effect_;
 

third_party/blink/renderer/core/animation/keyframe_effect.idl

@@ -39,6 +39,7 @@ enum CompositeOperation { "replace", "add", "accumulate" };
   [CallWith=ScriptState, RaisesException] constructor(Element? target, object? keyframes, optional (unrestricted double or KeyframeEffectOptions) options);
   [CallWith=ScriptState, RaisesException] constructor(KeyframeEffect source);
   attribute Element? target;
+  [RuntimeEnabled=WebAnimationsAPI, RaisesException=Setter] attribute CSSOMString? pseudoElement;
   [RuntimeEnabled=WebAnimationsAPI] attribute CompositeOperation composite;
   [CallWith=ScriptState, RuntimeEnabled=WebAnimationsAPI] sequence<object> getKeyframes();
   [CallWith=ScriptState, RaisesException, RuntimeEnabled=WebAnimationsAPI] void setKeyframes(object? keyframes);

third_party/blink/renderer/core/animation/keyframe_effect_options.idl

@@ -7,4 +7,5 @@
 dictionary KeyframeEffectOptions : EffectTiming {
     // TODO(alancutter): Implement iterationComposite
   CompositeOperation composite = "replace";
+  CSSOMString?       pseudoElement = null;
 };

third_party/blink/web_tests/external/wpt/css/css-animations/Document-getAnimations.tentative-expected.txt

@@ -12,6 +12,6 @@ PASS Finished but not filling CSS Animations are not returned
 PASS Yet-to-start CSS Animations are returned
 PASS CSS Animations canceled via the API are not returned
 PASS CSS Animations canceled and restarted via the API are returned
-FAIL CSS Animations targetting (pseudo-)elements should have correct order after sorting assert_equals: Animation #1 has null pseudo type expected (object) null but got (undefined) undefined
+FAIL CSS Animations targetting (pseudo-)elements should have correct order after sorting assert_equals: Animation #3 has expected target expected Element node <div id="parent" style="animation: animBottom 100s"><div ... but got Element node <div style="animation: animBottom 100s"></div>
 Harness: the test ran to completion.
 

third_party/blink/web_tests/external/wpt/css/css-animations/Element-getAnimations.tentative-expected.txt

@@ -17,9 +17,9 @@ PASS getAnimations returns objects with the same identity
 PASS getAnimations for CSS Animations that are canceled
 FAIL getAnimations for CSS Animations follows animation-name order assert_equals: animation order after prepending to list expected "anim1" but got "anim2"
 PASS { subtree: false } on a leaf element returns the element's animations and ignore pseudo-elements
-FAIL { subtree: true } on a leaf element returns the element's animations and its pseudo-elements' animations assert_equals: The animation targeting the parent element should be returned first expected (object) null but got (undefined) undefined
+PASS { subtree: true } on a leaf element returns the element's animations and its pseudo-elements' animations
 PASS { subtree: false } on an element with a child returns only the element's animations
-FAIL { subtree: true } on an element with a child returns animations from the element, its pseudo-elements, its child and its child pseudo-elements assert_equals: The animation targeting the parent element should be returned first expected (object) null but got (undefined) undefined
+FAIL { subtree: true } on an element with a child returns animations from the element, its pseudo-elements, its child and its child pseudo-elements assert_equals: The animation targeting the ::after pesudo-element should be returned third expected (string) "::after" but got (object) null
 PASS { subtree: true } on an element with many descendants returns animations from all the descendants
 Harness: the test ran to completion.
 

third_party/blink/web_tests/external/wpt/css/css-transitions/Document-getAnimations.tentative-expected.txt

 This is a testharness.js-based test.
 PASS getAnimations for non-animated content
 PASS getAnimations for CSS Transitions
-FAIL CSS Transitions targetting (pseudo-)elements should have correct order after sorting assert_equals: Transition #1 has null pseudo type expected (object) null but got (undefined) undefined
+FAIL CSS Transitions targetting (pseudo-)elements should have correct order after sorting assert_equals: Transition #3 has expected target expected Element node <div style="display: list-item; left: 100px; transition: ... but got Element node <div style="left: 100px; transition: left 100s ease 0s;">...
 PASS Transitions are not returned after they have finished
 Harness: the test ran to completion.
 

third_party/blink/web_tests/external/wpt/web-animations/idlharness.window-expected.txt

 This is a testharness.js-based test.
-Found 143 tests; 131 PASS, 12 FAIL, 0 TIMEOUT, 0 NOTRUN.
+Found 143 tests; 133 PASS, 10 FAIL, 0 TIMEOUT, 0 NOTRUN.
 PASS idl_test setup
 PASS idl_test validation
 PASS Partial interface Document: original interface defined
@@ -107,14 +107,14 @@ PASS KeyframeEffect interface: existence and properties of interface prototype o
 PASS KeyframeEffect interface: existence and properties of interface prototype object's "constructor" property
 PASS KeyframeEffect interface: existence and properties of interface prototype object's @@unscopables property
 PASS KeyframeEffect interface: attribute target
-FAIL KeyframeEffect interface: attribute pseudoElement assert_true: The prototype object must have a property "pseudoElement" expected true got false
+PASS KeyframeEffect interface: attribute pseudoElement
 PASS KeyframeEffect interface: attribute composite
 PASS KeyframeEffect interface: operation getKeyframes()
 PASS KeyframeEffect interface: operation setKeyframes(object)
 PASS KeyframeEffect must be primary interface of new KeyframeEffect(null, null)
 PASS Stringification of new KeyframeEffect(null, null)
 PASS KeyframeEffect interface: new KeyframeEffect(null, null) must inherit property "target" with the proper type
-FAIL KeyframeEffect interface: new KeyframeEffect(null, null) must inherit property "pseudoElement" with the proper type assert_inherits: property "pseudoElement" not found in prototype chain
+PASS KeyframeEffect interface: new KeyframeEffect(null, null) must inherit property "pseudoElement" with the proper type
 PASS KeyframeEffect interface: new KeyframeEffect(null, null) must inherit property "composite" with the proper type
 PASS KeyframeEffect interface: new KeyframeEffect(null, null) must inherit property "getKeyframes()" with the proper type
 PASS KeyframeEffect interface: new KeyframeEffect(null, null) must inherit property "setKeyframes(object)" with the proper type

third_party/blink/web_tests/external/wpt/web-animations/interfaces/KeyframeEffect/style-change-events-expected.txt

 This is a testharness.js-based test.
-FAIL All property keys are recognized assert_in_array: Test property 'iterationComposite' should be one of the properties on  KeyframeEffect value "iterationComposite" not in array ["getTiming", "getComputedTiming", "updateTiming", "target", "composite", "getKeyframes", "setKeyframes", "KeyframeEffect constructor", "KeyframeEffect copy constructor"]
+FAIL All property keys are recognized assert_in_array: Test property 'iterationComposite' should be one of the properties on  KeyframeEffect value "iterationComposite" not in array ["getTiming", "getComputedTiming", "updateTiming", "target", "composite", "pseudoElement", "getKeyframes", "setKeyframes", "KeyframeEffect constructor", "KeyframeEffect copy constructor"]
 PASS KeyframeEffect.getTiming does NOT trigger a style change event
 PASS KeyframeEffect.getComputedTiming does NOT trigger a style change event
 PASS KeyframeEffect.updateTiming does NOT trigger a style change event
 PASS KeyframeEffect.target does NOT trigger a style change event
 PASS KeyframeEffect.composite does NOT trigger a style change event
+PASS KeyframeEffect.pseudoElement does NOT trigger a style change event
 PASS KeyframeEffect.getKeyframes does NOT trigger a style change event
 PASS KeyframeEffect.setKeyframes does NOT trigger a style change event
 PASS KeyframeEffect.KeyframeEffect constructor does NOT trigger a style change event

third_party/blink/web_tests/external/wpt/web-animations/interfaces/KeyframeEffect/style-change-events.html

@@ -121,6 +121,15 @@ const tests = {
       },
     });
   },
+  pseudoElement: MakeInEffectTest({
+    setup: elem => elem.animate(
+      {opacity: [0.5, 1]},
+      {duration: 100 * MS_PER_SEC, pseudoElement: '::before'}
+    ),
+    test: effect => {
+      effect.pseudoElement = null;
+    },
+  }),
   iterationComposite: UsePropertyTest(effect => {
     // Get iterationComposite
     effect.iterationComposite;

third_party/blink/web_tests/external/wpt/web-animations/interfaces/KeyframeEffect/target-expected.txt

@@ -4,19 +4,19 @@ PASS Test setting target from null to a valid target
 PASS Test setting target from a valid target to null
 PASS Test setting target from a valid target to another target
 PASS Target element can be set to a foreign element
-FAIL Change target from null to an existing pseudoElement setting target first. assert_equals: Value at 50% progress after setting new target expected "50px" but got "10px"
-FAIL Change target from null to an existing pseudoElement setting pseudoElement first. assert_equals: Value at 50% progress after setting new target expected "50px" but got "10px"
+PASS Change target from null to an existing pseudoElement setting target first.
+PASS Change target from null to an existing pseudoElement setting pseudoElement first.
 PASS Change target from an existing pseudo-element to the originating element.
-FAIL Change target from an existing to a different existing pseudo-element by setting target. assert_equals: Animation targets specified pseudo-element (pseudo-selector) expected (string) "::before" but got (undefined) undefined
-FAIL Change target from an existing to a different existing pseudo-element by setting pseudoElement. assert_equals: Value of 2nd element (currently targeted) after changing the effect target expected "50px" but got "20px"
-FAIL Change target from a non-existing to a different existing pseudo-element by setting target. assert_equals: Animation targets specified pseudo-element (pseudo-selector) expected (string) "::before" but got (undefined) undefined
-FAIL Change target from a non-existing to a different existing pseudo-element by setting pseudoElement. assert_equals: Value of 2nd element (currently targeted) after changing the effect target expected "50px" but got "20px"
+PASS Change target from an existing to a different existing pseudo-element by setting target.
+PASS Change target from an existing to a different existing pseudo-element by setting pseudoElement.
+PASS Change target from a non-existing to a different existing pseudo-element by setting target.
+PASS Change target from a non-existing to a different existing pseudo-element by setting pseudoElement.
 FAIL Change target from null to a non-existing pseudoElement setting target first. assert_equals: Value at 50% progress after setting new target expected "50px" but got "10px"
 FAIL Change target from null to a non-existing pseudoElement setting pseudoElement first. assert_equals: Value at 50% progress after setting new target expected "50px" but got "10px"
 PASS Change target from a non-existing pseudo-element to the originating element.
-FAIL Change target from an existing to a different non-existing pseudo-element by setting target. assert_equals: Animation targets specified pseudo-element (pseudo-selector) expected (string) "::before" but got (undefined) undefined
+FAIL Change target from an existing to a different non-existing pseudo-element by setting target. assert_equals: Value of 2nd element (currently targeted) after changing the effect target expected "50px" but got "20px"
 FAIL Change target from an existing to a different non-existing pseudo-element by setting pseudoElement. assert_equals: Value of 2nd element (currently targeted) after changing the effect target expected "50px" but got "20px"
-FAIL Change target from a non-existing to a different non-existing pseudo-element by setting target. assert_equals: Animation targets specified pseudo-element (pseudo-selector) expected (string) "::before" but got (undefined) undefined
+FAIL Change target from a non-existing to a different non-existing pseudo-element by setting target. assert_equals: Value of 2nd element (currently targeted) after changing the effect target expected "50px" but got "20px"
 FAIL Change target from a non-existing to a different non-existing pseudo-element by setting pseudoElement. assert_equals: Value of 2nd element (currently targeted) after changing the effect target expected "50px" but got "20px"
 Harness: the test ran to completion.
 

third_party/blink/web_tests/webexposed/global-interface-listing-expected.txt

@@ -4613,11 +4613,13 @@ interface KeyboardLayoutMap
 interface KeyframeEffect : AnimationEffect
     attribute @@toStringTag
     getter composite
+    getter pseudoElement
     getter target
     method constructor
     method getKeyframes
     method setKeyframes
     setter composite
+    setter pseudoElement
     setter target
 interface LargestContentfulPaint : PerformanceEntry
     attribute @@toStringTag