Adding support for Smart GO NEXT feature in Android Chrome

Source/web/WebViewImpl.cpp

Index: Source/web/WebViewImpl.cpp
diff --git a/Source/web/WebViewImpl.cpp b/Source/web/WebViewImpl.cpp
index 640748994f2cc102c31d19601cf721b0828302e2..24b52eb6643c92b5afac8160dd8de246c00f2efc 100644
--- a/Source/web/WebViewImpl.cpp
+++ b/Source/web/WebViewImpl.cpp
@@ -37,6 +37,7 @@
 #include "core/clipboard/DataObject.h"
 #include "core/dom/Document.h"
 #include "core/dom/DocumentMarkerController.h"
+#include "core/dom/ElementTraversal.h"
 #include "core/dom/Fullscreen.h"
 #include "core/dom/LayoutTreeBuilderTraversal.h"
 #include "core/dom/Text.h"
@@ -59,6 +60,7 @@
 #include "core/frame/Settings.h"
 #include "core/frame/SmartClip.h"
 #include "core/frame/TopControls.h"
+#include "core/html/HTMLFormElement.h"
 #include "core/html/HTMLInputElement.h"
 #include "core/html/HTMLMediaElement.h"
 #include "core/html/HTMLPlugInElement.h"
@@ -116,6 +118,7 @@
 #include "public/platform/WebCompositeAndReadbackAsyncCallback.h"
 #include "public/platform/WebDragData.h"
 #include "public/platform/WebFloatPoint.h"
+#include "public/platform/WebFocusType.h"
 #include "public/platform/WebGestureCurve.h"
 #include "public/platform/WebImage.h"
 #include "public/platform/WebLayerTreeView.h"
@@ -2516,9 +2519,100 @@ int WebViewImpl::textInputFlags()
         }
     }
 
+    if (isListeningToKeyboardEvents(element))
+        flags |= WebTextInputFlagListeningToKeyboardEvents;
+
+    if (nextFocusableElementInForm(element, WebFocusTypeForward))
+        flags |= WebTextInputFlagHaveNextFocusableElement;
+
+    if (nextFocusableElementInForm(element, WebFocusTypeBackward))
+        flags |= WebTextInputFlagHavePreviousFocusableElement;
+
     return flags;
 }
 
+Element* WebViewImpl::nextFocusableElementInForm(Element* element, WebFocusType focusType)
+{
+    if (!element->isFormControlElement() && !element->isContentEditable())
+        return nullptr;
+
+    HTMLFormElement* formOwner = nullptr;
+    if (element->isContentEditable())
+        formOwner = Traversal<HTMLFormElement>::firstAncestor(*element);
+    else
+        formOwner = toHTMLFormControlElement(element)->formOwner();
+
+    if (!formOwner)
+        return nullptr;
+
+    Node* nextNode = element;
+    while ((nextNode = page()->focusController().findFocusableNode(focusType, *nextNode))) {
+        if (nextNode->isContentEditable() && nextNode->isDescendantOf(formOwner))
+            return toElement(nextNode);
+        if (!toElement(nextNode)->isFormControlElement())
+            continue;
+        HTMLFormControlElement* formElement = toHTMLFormControlElement(nextNode);
+        if (formElement->formOwner() != formOwner)
+            continue;
+        LayoutObject* layout = nextNode->layoutObject();
+        if (layout && layout->isTextControl()) {
+            // TODO(ajith.v) Extend it for Select element, Radio button and Check boxes
+            return toElement(nextNode);
+        }
+    }
+    return nullptr;
+}
+
+bool WebViewImpl::isListeningToKeyboardEvents(Element* element)
+{
+    if (!element->isFormControlElement() && !element->isContentEditable())
+        return false;
+
+    bool hasKeyEventListener = element->hasEventListeners(EventTypeNames::keydown) || element->hasEventListeners(EventTypeNames::keypress) || element->hasEventListeners(EventTypeNames::keyup);
+    if (hasKeyEventListener)
+        return true;
+
+    Document& document = element->document();
+    hasKeyEventListener = document.hasEventListeners(EventTypeNames::keydown) || document.hasEventListeners(EventTypeNames::keypress) || document.hasEventListeners(EventTypeNames::keyup);
+    if (hasKeyEventListener)
+        return true;
+
+    HTMLFormElement* formOwner = nullptr;
+    if (element->isContentEditable())
+        formOwner = Traversal<HTMLFormElement>::firstAncestor(*element);
+    else
+        formOwner = toHTMLFormControlElement(element)->formOwner();
+
+    if (!formOwner)
+        return false;
+
+    hasKeyEventListener = formOwner->hasEventListeners(EventTypeNames::keydown) || formOwner->hasEventListeners(EventTypeNames::keypress) || formOwner->hasEventListeners(EventTypeNames::keyup);

[tkent, 2015/04/21 07:41:27]

You don't need to check event listeners on the form owner.  Non-ancestor form
owner doesn't receive key events on a form control.  The following parent lookup
is enough.

[AKV, 2015/04/21 07:52:59]

Thanks. My idea was to return early, rather than traversing in parent chain. But
as you said, Non-ancestor form owner doesn't receive key events on form control
may cause logic break if I keep this. So I am removing it.

+    if (hasKeyEventListener)
+        return true;
+
+    Element* parent = element;
+    while ((parent = parent->parentElement())) {

[tkent, 2015/04/21 07:41:27]

Node* node = element;
do {
    if (node->hasEventListener(....
        return true;
} while ((node = node->parentNode()));  // Not parentElement().
return false;

is enough.  You don't need to check Document and |element| independently.

[AKV, 2015/04/21 07:52:59]

For returning early purpose, I added Element and Document check early on top. If
you recommend only this loop is sufficient, then I will make changes according
to that.

+        hasKeyEventListener = parent->hasEventListeners(EventTypeNames::keydown) || parent->hasEventListeners(EventTypeNames::keypress) || parent->hasEventListeners(EventTypeNames::keyup);
+        if (hasKeyEventListener)
+            return true;
+    }
+    return hasKeyEventListener;
+}
+
+void WebViewImpl::advanceFocusInForm(WebFocusType focusType)
+{
+    Element* element = focusedElement();
+    if (!element)
+        return;
+
+    RefPtrWillBeRawPtr<Element> nextElement = nextFocusableElementInForm(element, focusType);
+    if (!nextElement)
+        return;
+
+    nextElement->scrollIntoViewIfNeeded(true /*centerIfNeeded*/);
+    nextElement->focus(false, focusType);
+}
+
 WebString WebViewImpl::inputModeOfFocusedElement()
 {
     if (!RuntimeEnabledFeatures::inputModeAttributeEnabled())