dom/html/HTMLLabelElement.cpp
author Nicholas Nethercote <nnethercote@mozilla.com>
Fri, 03 Mar 2017 15:32:11 +1100
changeset 374836 4e196d802c7be7f3a3c147cc6c5b6406656584b1
parent 323706 c4bde82ab5934ff314072d653abd983579ea0d23
permissions -rw-r--r--
Bug 1344118 - Fix the profiler's sleeping threads optimization. r=jseward. When ProfilerBuffer::reset() is called, DuplicateLastSample() will start failing for all sleeping threads because there will be no prior thread data in the buffer to duplicate. But the sampling loop doesn't detect such failure. This causes two problems: - Missing samples. - CPU usage goes through the roof, because each time around the sampling loop the length of the failing search increases. The fix is simple: detect failure in the sampling loop and do a normal sample in that case. The patch also removes ThreadInfo::DuplicateLastSample(), because it just calls onto ProfileBuffer::DuplicateLastSample().

/* -*- 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 "nsFocusManager.h"
#include "nsIDOMMouseEvent.h"
#include "nsQueryObject.h"

// construction, destruction

NS_IMPL_NS_NEW_HTML_ELEMENT(Label)

namespace mozilla {
namespace dom {

HTMLLabelElement::~HTMLLabelElement()
{
}

JSObject*
HTMLLabelElement::WrapNode(JSContext *aCx, JS::Handle<JSObject*> aGivenProto)
{
  return HTMLLabelElementBinding::Wrap(aCx, this, aGivenProto);
}

// nsISupports

NS_IMPL_ISUPPORTS_INHERITED(HTMLLabelElement, nsGenericHTMLElement,
                            nsIDOMHTMLLabelElement)

// nsIDOMHTMLLabelElement

NS_IMPL_ELEMENT_CLONE(HTMLLabelElement)

NS_IMETHODIMP
HTMLLabelElement::GetForm(nsIDOMHTMLFormElement** aForm)
{
  RefPtr<nsIDOMHTMLFormElement> form = GetForm();
  form.forget(aForm);
  return NS_OK;
}

NS_IMETHODIMP
HTMLLabelElement::GetControl(nsIDOMHTMLElement** aElement)
{
  nsCOMPtr<nsIDOMHTMLElement> element = do_QueryObject(GetLabeledElement());
  element.forget(aElement);
  return NS_OK;
}

NS_IMETHODIMP
HTMLLabelElement::SetHtmlFor(const nsAString& aHtmlFor)
{
  ErrorResult rv;
  SetHtmlFor(aHtmlFor, rv);
  return rv.StealNSResult();
}

NS_IMETHODIMP
HTMLLabelElement::GetHtmlFor(nsAString& aHtmlFor)
{
  nsString htmlFor;
  GetHtmlFor(htmlFor);
  aHtmlFor = htmlFor;
  return NS_OK;
}

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 static_cast<HTMLFormElement*>(formControl->GetFormElement());
}

void
HTMLLabelElement::Focus(ErrorResult& aError)
{
  // retarget the focus method at the for content
  nsIFocusManager* fm = nsFocusManager::GetFocusManager();
  if (fm) {
    nsCOMPtr<nsIDOMElement> elem = do_QueryObject(GetLabeledElement());
    if (elem)
      fm->SetFocus(elem, 0);
  }
}

static bool
InInteractiveHTMLContent(nsIContent* aContent, nsIContent* aStop)
{
  nsIContent* content = aContent;
  while (content && content != aStop) {
    if (content->IsElement() &&
        content->AsElement()->IsInteractiveHTMLContent(true)) {
      return true;
    }
    content = content->GetParent();
  }
  return false;
}

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<nsIContent> target = do_QueryInterface(aVisitor.mEvent->mTarget);
  if (InInteractiveHTMLContent(target, this)) {
    return NS_OK;
  }

  // Strong ref because event dispatch is going to happen.
  RefPtr<Element> content = GetLabeledElement();

  if (content) {
    mHandlingEvent = true;
    switch (aVisitor.mEvent->mMessage) {
      case eMouseDown:
        if (mouseEvent->button == WidgetMouseEvent::eLeftButton) {
          // 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;
            DeleteProperty(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) {
            nsIFocusManager* fm = nsFocusManager::GetFocusManager();
            if (fm) {
              // 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.
              nsCOMPtr<nsIDOMElement> elem = do_QueryInterface(content);
              bool byMouse = (mouseEvent->inputSource != nsIDOMMouseEvent::MOZ_SOURCE_KEYBOARD);
              bool byTouch = (mouseEvent->inputSource == nsIDOMMouseEvent::MOZ_SOURCE_TOUCH);
              fm->SetFocus(elem, 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;
}

bool
HTMLLabelElement::PerformAccesskey(bool aKeyCausesActivation,
                                   bool aIsTrustedEvent)
{
  if (!aKeyCausesActivation) {
    RefPtr<Element> element = GetLabeledElement();
    if (element) {
      return element->PerformAccesskey(aKeyCausesActivation, aIsTrustedEvent);
    }
  } else {
    nsPresContext *presContext = GetPresContext(eForUncomposedDoc);
    if (!presContext) {
      return false;
    }

    // Click on it if the users prefs indicate to do so.
    WidgetMouseEvent event(aIsTrustedEvent, eMouseClick,
                           nullptr, WidgetMouseEvent::eReal);
    event.inputSource = nsIDOMMouseEvent::MOZ_SOURCE_KEYBOARD;

    nsAutoPopupStatePusher popupStatePusher(aIsTrustedEvent ?
                                            openAllowed : openAbused);

    EventDispatcher::Dispatch(static_cast<nsIContent*>(this), presContext,
                              &event);
  }

  return aKeyCausesActivation;
}

nsGenericHTMLElement*
HTMLLabelElement::GetLabeledElement() const
{
  nsAutoString elementId;

  if (!GetAttr(kNameSpaceID_None, 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 document
  // and this element should be a labelable form control.
  //XXXsmaug It is unclear how this should work in case the element is in
  //         Shadow DOM.
  //         See https://www.w3.org/Bugs/Public/show_bug.cgi?id=26365.
  nsIDocument* doc = GetUncomposedDoc();
  if (!doc) {
    return nullptr;
  }

  Element* element = doc->GetElementById(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 = cur->IsElement() ? cur->AsElement() : nullptr;
    if (element && element->IsLabelable()) {
      return static_cast<nsGenericHTMLElement*>(element);
    }
  }

  return nullptr;
}

} // namespace dom
} // namespace mozilla