CSS4: Implement :placeholder-shown pseudo class

Source/core/html/HTMLTextFormControlElement.cpp

Index: Source/core/html/HTMLTextFormControlElement.cpp
diff --git a/Source/core/html/HTMLTextFormControlElement.cpp b/Source/core/html/HTMLTextFormControlElement.cpp
index 089cee6f743ad112f2c10b97127bd081ec9e4466..1c24d783f696324f14f365d4c6ea26a4530d851e 100644
--- a/Source/core/html/HTMLTextFormControlElement.cpp
+++ b/Source/core/html/HTMLTextFormControlElement.cpp
@@ -63,6 +63,7 @@ HTMLTextFormControlElement::HTMLTextFormControlElement(const QualifiedName& tagN
     , m_cachedSelectionStart(0)
     , m_cachedSelectionEnd(0)
     , m_cachedSelectionDirection(SelectionHasNoDirection)
+    , m_isPlaceholderVisible(false)

[esprehn, 2015/08/21 10:18:10]

remove

[ramya.v, 2015/08/25 10:24:45]

Done.

 {
 }
 
@@ -83,7 +84,7 @@ Node::InsertionNotificationRequest HTMLTextFormControlElement::insertedInto(Cont
 void HTMLTextFormControlElement::dispatchFocusEvent(Element* oldFocusedElement, WebFocusType type, InputDevice* sourceDevice)
 {
     if (supportsPlaceholder())
-        updatePlaceholderVisibility(false);
+        updatePlaceholderVisibility();
     handleFocusEvent(oldFocusedElement, type);
     HTMLFormControlElementWithState::dispatchFocusEvent(oldFocusedElement, type, sourceDevice);
 }
@@ -91,7 +92,7 @@ void HTMLTextFormControlElement::dispatchFocusEvent(Element* oldFocusedElement,
 void HTMLTextFormControlElement::dispatchBlurEvent(Element* newFocusedElement, WebFocusType type, InputDevice* sourceDevice)
 {
     if (supportsPlaceholder())
-        updatePlaceholderVisibility(false);
+        updatePlaceholderVisibility();
     handleBlurEvent();
     HTMLFormControlElementWithState::dispatchBlurEvent(newFocusedElement, type, sourceDevice);
 }
@@ -147,8 +148,7 @@ bool HTMLTextFormControlElement::placeholderShouldBeVisible() const
     return supportsPlaceholder()
         && isEmptyValue()
         && isEmptySuggestedValue()
-        && !isPlaceholderEmpty()
-        && (!layoutObject() || layoutObject()->style()->visibility() == VISIBLE);
+        && !isPlaceholderEmpty();

[esprehn, 2015/08/21 10:18:10]

This is a behavior change, can you explain why you did this?

[ramya.v, 2015/08/25 10:24:45]

In Webkit patch, below point is mentioned.
Remove the dependencies between the Element's style and the placeholder's style.
This is done by simply using display:none; on the placeholder so that its
parent's visibility is irrelevant.
Test is also added for (visible and invisible renderers not to affect
placeholder visibility state)(placeholder-shown-style-update.html)
Taken the same.

 }
 
 HTMLElement* HTMLTextFormControlElement::placeholderElement() const
@@ -156,17 +156,21 @@ HTMLElement* HTMLTextFormControlElement::placeholderElement() const
     return toHTMLElement(userAgentShadowRoot()->getElementById(ShadowElementNames::placeholder()));
 }
 
-void HTMLTextFormControlElement::updatePlaceholderVisibility(bool placeholderValueChanged)
+void HTMLTextFormControlElement::updatePlaceholderVisibility()
 {
-    if (!supportsPlaceholder())
-        return;
-    if (!placeholderElement() || placeholderValueChanged)
-        updatePlaceholderText();
     HTMLElement* placeholder = placeholderElement();
-    if (!placeholder)
+    if (!placeholder) {
+        updatePlaceholderText();
         return;
+    }
 
-    placeholder->setInlineStyleProperty(CSSPropertyDisplay, placeholderShouldBeVisible() ? CSSValueBlock : CSSValueNone);
+    bool placeHolderWasVisible = m_isPlaceholderVisible;
+    m_isPlaceholderVisible = placeholderShouldBeVisible();
+    if (placeHolderWasVisible == m_isPlaceholderVisible)
+        return;
+
+    setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::PseudoClass));

[esprehn, 2015/08/21 10:18:10]

This should use the StyleInvalidator, you need to update
RuleFeatureSet::invalidationSetForSelector and then use
pseudoStateChanged(CSSSelector::PseudoPlaceholderShown)

[ramya.v, 2015/08/25 10:24:45]

Done.

+    placeholder->setInlineStyleProperty(CSSPropertyDisplay, m_isPlaceholderVisible ? CSSValueBlock : CSSValueNone, true);
 }
 
 void HTMLTextFormControlElement::setSelectionStart(int start)
@@ -607,7 +611,8 @@ void HTMLTextFormControlElement::parseAttribute(const QualifiedName& name, const
         UseCounter::count(document(), UseCounter::AutocapitalizeAttribute);
 
     if (name == placeholderAttr) {
-        updatePlaceholderVisibility(true);
+        updatePlaceholderText();
+        updatePlaceholderVisibility();
         UseCounter::count(document(), UseCounter::PlaceholderAttribute);
     } else {
         HTMLFormControlElementWithState::parseAttribute(name, value);