gecko-dev/layout/printing/nsPrintPreviewListener.cpp

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * 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/. */

#include "nsPrintPreviewListener.h"

#include "mozilla/TextEvents.h"
#include "mozilla/dom/Element.h"
#include "mozilla/dom/Event.h" // for nsIDOMEvent::InternalDOMEvent()
#include "nsIDOMWindow.h"
#include "nsPIDOMWindow.h"
#include "nsIDOMElement.h"
#include "nsIDOMKeyEvent.h"
#include "nsIDOMEvent.h"
#include "nsIDocument.h"
#include "nsIDocShell.h"
#include "nsPresContext.h"
#include "nsFocusManager.h"
#include "nsLiteralString.h"

using namespace mozilla;
using namespace mozilla::dom;

NS_IMPL_ISUPPORTS(nsPrintPreviewListener, nsIDOMEventListener)


//
// nsPrintPreviewListener ctor
//
nsPrintPreviewListener::nsPrintPreviewListener(EventTarget* aTarget)
  : mEventTarget(aTarget)
{
  NS_ADDREF_THIS();
} // ctor

nsPrintPreviewListener::~nsPrintPreviewListener()
{
}

//-------------------------------------------------------
//
// AddListeners
//
// Subscribe to the events that will allow us to track various events. 
//
nsresult
nsPrintPreviewListener::AddListeners()
{
  if (mEventTarget) {
    mEventTarget->AddEventListener(NS_LITERAL_STRING("click"), this, true);
    mEventTarget->AddEventListener(NS_LITERAL_STRING("contextmenu"), this, true);
    mEventTarget->AddEventListener(NS_LITERAL_STRING("keydown"), this, true);
    mEventTarget->AddEventListener(NS_LITERAL_STRING("keypress"), this, true);
    mEventTarget->AddEventListener(NS_LITERAL_STRING("keyup"), this, true);
    mEventTarget->AddEventListener(NS_LITERAL_STRING("mousedown"), this, true);
    mEventTarget->AddEventListener(NS_LITERAL_STRING("mousemove"), this, true);
    mEventTarget->AddEventListener(NS_LITERAL_STRING("mouseout"), this, true);
    mEventTarget->AddEventListener(NS_LITERAL_STRING("mouseover"), this, true);
    mEventTarget->AddEventListener(NS_LITERAL_STRING("mouseup"), this, true);

    mEventTarget->AddSystemEventListener(NS_LITERAL_STRING("keydown"),
                                         this, true);
  }

  return NS_OK;
}


//-------------------------------------------------------
//
// RemoveListeners
//
// Unsubscribe from all the various events that we were listening to. 
//
nsresult 
nsPrintPreviewListener::RemoveListeners()
{
  if (mEventTarget) {
    mEventTarget->RemoveEventListener(NS_LITERAL_STRING("click"), this, true);
    mEventTarget->RemoveEventListener(NS_LITERAL_STRING("contextmenu"), this, true);
    mEventTarget->RemoveEventListener(NS_LITERAL_STRING("keydown"), this, true);
    mEventTarget->RemoveEventListener(NS_LITERAL_STRING("keypress"), this, true);
    mEventTarget->RemoveEventListener(NS_LITERAL_STRING("keyup"), this, true);
    mEventTarget->RemoveEventListener(NS_LITERAL_STRING("mousedown"), this, true);
    mEventTarget->RemoveEventListener(NS_LITERAL_STRING("mousemove"), this, true);
    mEventTarget->RemoveEventListener(NS_LITERAL_STRING("mouseout"), this, true);
    mEventTarget->RemoveEventListener(NS_LITERAL_STRING("mouseover"), this, true);
    mEventTarget->RemoveEventListener(NS_LITERAL_STRING("mouseup"), this, true);

    mEventTarget->RemoveSystemEventListener(NS_LITERAL_STRING("keydown"),
                                            this, true);
  }

  return NS_OK;
}

//-------------------------------------------------------
//
// GetActionForEvent
//
// Helper function to let certain key events through
//
enum eEventAction {
  eEventAction_Tab,       eEventAction_ShiftTab,
  eEventAction_Propagate, eEventAction_Suppress,
  eEventAction_StopPropagation
};

static eEventAction
GetActionForEvent(nsIDOMEvent* aEvent)
{
  WidgetKeyboardEvent* keyEvent =
    aEvent->GetInternalNSEvent()->AsKeyboardEvent();
  if (!keyEvent) {
    return eEventAction_Suppress;
  }

  if (keyEvent->mFlags.mInSystemGroup) {
    NS_ASSERTION(keyEvent->mMessage == eKeyDown,
      "Assuming we're listening only keydown event in system group");
    return eEventAction_StopPropagation;
  }

  if (keyEvent->IsAlt() || keyEvent->IsControl() || keyEvent->IsMeta()) {
    // Don't consume keydown event because following keypress event may be
    // handled as access key or shortcut key.
    return (keyEvent->mMessage == eKeyDown) ? eEventAction_StopPropagation :
                                              eEventAction_Suppress;
  }

  static const uint32_t kOKKeyCodes[] = {
    nsIDOMKeyEvent::DOM_VK_PAGE_UP, nsIDOMKeyEvent::DOM_VK_PAGE_DOWN,
    nsIDOMKeyEvent::DOM_VK_UP,      nsIDOMKeyEvent::DOM_VK_DOWN, 
    nsIDOMKeyEvent::DOM_VK_HOME,    nsIDOMKeyEvent::DOM_VK_END 
  };

  if (keyEvent->keyCode == nsIDOMKeyEvent::DOM_VK_TAB) {
    return keyEvent->IsShift() ? eEventAction_ShiftTab : eEventAction_Tab;
  }

  if (keyEvent->charCode == ' ' || keyEvent->keyCode == NS_VK_SPACE) {
    return eEventAction_Propagate;
  }

  if (keyEvent->IsShift()) {
    return eEventAction_Suppress;
  }

  for (uint32_t i = 0; i < ArrayLength(kOKKeyCodes); ++i) {
    if (keyEvent->keyCode == kOKKeyCodes[i]) {
      return eEventAction_Propagate;
    }
  }

  return eEventAction_Suppress;
}

NS_IMETHODIMP
nsPrintPreviewListener::HandleEvent(nsIDOMEvent* aEvent)
{
  nsCOMPtr<nsIContent> content = do_QueryInterface(
    aEvent ? aEvent->InternalDOMEvent()->GetOriginalTarget() : nullptr);
  if (content && !content->IsXULElement()) {
    eEventAction action = ::GetActionForEvent(aEvent);
    switch (action) {
      case eEventAction_Tab:
      case eEventAction_ShiftTab:
      {
        nsAutoString eventString;
        aEvent->GetType(eventString);
        if (eventString.EqualsLiteral("keydown")) {
          // Handle tabbing explicitly here since we don't want focus ending up
          // inside the content document, bug 244128.
          nsIDocument* doc = content->GetCurrentDoc();
          NS_ASSERTION(doc, "no document");

          nsIDocument* parentDoc = doc->GetParentDocument();
          NS_ASSERTION(parentDoc, "no parent document");

          nsCOMPtr<nsIDOMWindow> win = do_QueryInterface(parentDoc->GetWindow());

          nsIFocusManager* fm = nsFocusManager::GetFocusManager();
          if (fm && win) {
            dom::Element* fromElement = parentDoc->FindContentForSubDocument(doc);
            nsCOMPtr<nsIDOMElement> from = do_QueryInterface(fromElement);

            bool forward = (action == eEventAction_Tab);
            nsCOMPtr<nsIDOMElement> result;
            fm->MoveFocus(win, from,
                          forward ? nsIFocusManager::MOVEFOCUS_FORWARD :
                                    nsIFocusManager::MOVEFOCUS_BACKWARD,
                          nsIFocusManager::FLAG_BYKEY, getter_AddRefs(result));
          }
        }
      }
      // fall-through
      case eEventAction_Suppress:
        aEvent->StopPropagation();
        aEvent->PreventDefault();
        break;
      case eEventAction_StopPropagation:
        aEvent->StopPropagation();
        break;
      case eEventAction_Propagate:
        // intentionally empty
        break;
    }
  }
  return NS_OK;
}