1 files changed, 246 insertions, 0 deletions
diff --git a/dom/html/HTMLLabelElement.cpp b/dom/html/HTMLLabelElement.cpp
new file mode 100644
index 0000000000..32acbd06be
--- /dev/null
+++ b/dom/html/HTMLLabelElement.cpp
@@ -0,0 +1,246 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * Implementation of HTML <label> elements.
+ */
+#include "HTMLLabelElement.h"
+#include "mozilla/EventDispatcher.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/dom/HTMLLabelElementBinding.h"
+#include "mozilla/dom/MouseEventBinding.h"
+#include "nsFocusManager.h"
+#include "nsIFrame.h"
+#include "nsContentUtils.h"
+#include "nsQueryObject.h"
+#include "mozilla/dom/ShadowRoot.h"
+
+// construction, destruction
+
+NS_IMPL_NS_NEW_HTML_ELEMENT(Label)
+
+namespace mozilla::dom {
+
+HTMLLabelElement::~HTMLLabelElement() = default;
+
+JSObject* HTMLLabelElement::WrapNode(JSContext* aCx,
+                                     JS::Handle<JSObject*> aGivenProto) {
+  return HTMLLabelElement_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+// nsIDOMHTMLLabelElement
+
+NS_IMPL_ELEMENT_CLONE(HTMLLabelElement)
+
+HTMLFormElement* HTMLLabelElement::GetForm() const {
+  nsGenericHTMLElement* control = GetControl();
+  if (!control) {
+    return nullptr;
+  }
+
+  // Not all labeled things have a form association.  Stick to the ones that do.
+  nsCOMPtr<nsIFormControl> formControl = do_QueryObject(control);
+  if (!formControl) {
+    return nullptr;
+  }
+
+  return formControl->GetForm();
+}
+
+void HTMLLabelElement::Focus(const FocusOptions& aOptions,
+                             const CallerType aCallerType,
+                             ErrorResult& aError) {
+  {
+    nsIFrame* frame = GetPrimaryFrame(FlushType::Frames);
+    if (frame && frame->IsFocusable()) {
+      return nsGenericHTMLElement::Focus(aOptions, aCallerType, aError);
+    }
+  }
+
+  if (RefPtr<Element> elem = GetLabeledElement()) {
+    return elem->Focus(aOptions, aCallerType, aError);
+  }
+}
+
+nsresult HTMLLabelElement::PostHandleEvent(EventChainPostVisitor& aVisitor) {
+  WidgetMouseEvent* mouseEvent = aVisitor.mEvent->AsMouseEvent();
+  if (mHandlingEvent ||
+      (!(mouseEvent && mouseEvent->IsLeftClickEvent()) &&
+       aVisitor.mEvent->mMessage != eMouseDown) ||
+      aVisitor.mEventStatus == nsEventStatus_eConsumeNoDefault ||
+      !aVisitor.mPresContext ||
+      // Don't handle the event if it's already been handled by another label
+      aVisitor.mEvent->mFlags.mMultipleActionsPrevented) {
+    return NS_OK;
+  }
+
+  nsCOMPtr<Element> target =
+      do_QueryInterface(aVisitor.mEvent->GetOriginalDOMEventTarget());
+  if (nsContentUtils::IsInInteractiveHTMLContent(target, this)) {
+    return NS_OK;
+  }
+
+  // Strong ref because event dispatch is going to happen.
+  RefPtr<Element> content = GetLabeledElement();
+
+  if (!content || content->IsDisabled()) {
+    return NS_OK;
+  }
+
+  mHandlingEvent = true;
+  switch (aVisitor.mEvent->mMessage) {
+    case eMouseDown:
+      if (mouseEvent->mButton == MouseButton::ePrimary) {
+        // We reset the mouse-down point on every event because there is
+        // no guarantee we will reach the eMouseClick code below.
+        LayoutDeviceIntPoint* curPoint =
+            new LayoutDeviceIntPoint(mouseEvent->mRefPoint);
+        SetProperty(nsGkAtoms::labelMouseDownPtProperty,
+                    static_cast<void*>(curPoint),
+                    nsINode::DeleteProperty<LayoutDeviceIntPoint>);
+      }
+      break;
+
+    case eMouseClick:
+      if (mouseEvent->IsLeftClickEvent()) {
+        LayoutDeviceIntPoint* mouseDownPoint =
+            static_cast<LayoutDeviceIntPoint*>(
+                GetProperty(nsGkAtoms::labelMouseDownPtProperty));
+
+        bool dragSelect = false;
+        if (mouseDownPoint) {
+          LayoutDeviceIntPoint dragDistance = *mouseDownPoint;
+          RemoveProperty(nsGkAtoms::labelMouseDownPtProperty);
+
+          dragDistance -= mouseEvent->mRefPoint;
+          const int CLICK_DISTANCE = 2;
+          dragSelect = dragDistance.x > CLICK_DISTANCE ||
+                       dragDistance.x < -CLICK_DISTANCE ||
+                       dragDistance.y > CLICK_DISTANCE ||
+                       dragDistance.y < -CLICK_DISTANCE;
+        }
+        // Don't click the for-content if we did drag-select text or if we
+        // have a kbd modifier (which adjusts a selection).
+        if (dragSelect || mouseEvent->IsShift() || mouseEvent->IsControl() ||
+            mouseEvent->IsAlt() || mouseEvent->IsMeta()) {
+          break;
+        }
+        // Only set focus on the first click of multiple clicks to prevent
+        // to prevent immediate de-focus.
+        if (mouseEvent->mClickCount <= 1) {
+          if (RefPtr<nsFocusManager> fm = nsFocusManager::GetFocusManager()) {
+            // Use FLAG_BYMOVEFOCUS here so that the label is scrolled to.
+            // Also, within HTMLInputElement::PostHandleEvent, inputs will
+            // be selected only when focused via a key or when the navigation
+            // flag is used and we want to select the text on label clicks as
+            // well.
+            // If the label has been clicked by the user, we also want to
+            // pass FLAG_BYMOUSE so that we get correct focus ring behavior,
+            // but we don't want to pass FLAG_BYMOUSE if this click event was
+            // caused by the user pressing an accesskey.
+            bool byMouse = (mouseEvent->mInputSource !=
+                            MouseEvent_Binding::MOZ_SOURCE_KEYBOARD);
+            bool byTouch = (mouseEvent->mInputSource ==
+                            MouseEvent_Binding::MOZ_SOURCE_TOUCH);
+            fm->SetFocus(content,
+                         nsIFocusManager::FLAG_BYMOVEFOCUS |
+                             (byMouse ? nsIFocusManager::FLAG_BYMOUSE : 0) |
+                             (byTouch ? nsIFocusManager::FLAG_BYTOUCH : 0));
+          }
+        }
+        // Dispatch a new click event to |content|
+        //    (For compatibility with IE, we do only left click.  If
+        //    we wanted to interpret the HTML spec very narrowly, we
+        //    would do nothing.  If we wanted to do something
+        //    sensible, we might send more events through like
+        //    this.)  See bug 7554, bug 49897, and bug 96813.
+        nsEventStatus status = aVisitor.mEventStatus;
+        // Ok to use aVisitor.mEvent as parameter because DispatchClickEvent
+        // will actually create a new event.
+        EventFlags eventFlags;
+        eventFlags.mMultipleActionsPrevented = true;
+        DispatchClickEvent(aVisitor.mPresContext, mouseEvent, content, false,
+                           &eventFlags, &status);
+        // Do we care about the status this returned?  I don't think we do...
+        // Don't run another <label> off of this click
+        mouseEvent->mFlags.mMultipleActionsPrevented = true;
+      }
+      break;
+
+    default:
+      break;
+  }
+  mHandlingEvent = false;
+  return NS_OK;
+}
+
+Result<bool, nsresult> HTMLLabelElement::PerformAccesskey(
+    bool aKeyCausesActivation, bool aIsTrustedEvent) {
+  if (!aKeyCausesActivation) {
+    RefPtr<Element> element = GetLabeledElement();
+    if (element) {
+      return element->PerformAccesskey(aKeyCausesActivation, aIsTrustedEvent);
+    }
+    return Err(NS_ERROR_ABORT);
+  }
+
+  RefPtr<nsPresContext> presContext = GetPresContext(eForUncomposedDoc);
+  if (!presContext) {
+    return Err(NS_ERROR_UNEXPECTED);
+  }
+
+  // Click on it if the users prefs indicate to do so.
+  AutoHandlingUserInputStatePusher userInputStatePusher(aIsTrustedEvent);
+  AutoPopupStatePusher popupStatePusher(
+      aIsTrustedEvent ? PopupBlocker::openAllowed : PopupBlocker::openAbused);
+  DispatchSimulatedClick(this, aIsTrustedEvent, presContext);
+
+  // XXXedgar, do we need to check whether the focus is really changed?
+  return true;
+}
+
+nsGenericHTMLElement* HTMLLabelElement::GetLabeledElement() const {
+  nsAutoString elementId;
+
+  if (!GetAttr(nsGkAtoms::_for, elementId)) {
+    // No @for, so we are a label for our first form control element.
+    // Do a depth-first traversal to look for the first form control element.
+    return GetFirstLabelableDescendant();
+  }
+
+  // We have a @for. The id has to be linked to an element in the same tree
+  // and this element should be a labelable form control.
+  Element* element = nullptr;
+
+  if (ShadowRoot* shadowRoot = GetContainingShadow()) {
+    element = shadowRoot->GetElementById(elementId);
+  } else if (Document* doc = GetUncomposedDoc()) {
+    element = doc->GetElementById(elementId);
+  } else {
+    element =
+        nsContentUtils::MatchElementId(SubtreeRoot()->AsContent(), elementId);
+  }
+
+  if (element && element->IsLabelable()) {
+    return static_cast<nsGenericHTMLElement*>(element);
+  }
+
+  return nullptr;
+}
+
+nsGenericHTMLElement* HTMLLabelElement::GetFirstLabelableDescendant() const {
+  for (nsIContent* cur = nsINode::GetFirstChild(); cur;
+       cur = cur->GetNextNode(this)) {
+    Element* element = Element::FromNode(cur);
+    if (element && element->IsLabelable()) {
+      return static_cast<nsGenericHTMLElement*>(element);
+    }
+  }
+
+  return nullptr;
+}
+
+}  // namespace mozilla::dom