widget/nsScreenManagerProxy.h
author Rob Wu <rob@robwu.nl>
Sat, 24 Sep 2016 11:16:32 +0200
changeset 320058 a41f871e2d1b37754bbd1001c36c075511b49342
parent 268184 e8c7dfe727cd970e2c3294934e2927b14143c205
permissions -rw-r--r--
Bug 1299411 - Decouple Port implementation from API r=aswan Decoupled the API from the implementation. From now on it is possible to create Port instances without generating an API. This allows us to internally use Ports to pass around messages with minimal overhead (in the form of unnecessary clones of messages). This will be used by native messaging. This commit has no behavioral change, it is mostly moving around some code and storing the internal message listener in a set. MozReview-Commit-ID: 4h0LNJvTH9R

/* -*- Mode: C++; tab-width: 2; 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/. */

#ifndef nsScreenManagerProxy_h
#define nsScreenManagerProxy_h

#include "nsIScreenManager.h"
#include "mozilla/dom/PScreenManagerChild.h"
#include "mozilla/dom/TabChild.h"
#include "ScreenProxy.h"

/**
 * The nsScreenManagerProxy is used by the content process to get
 * information about system screens. It uses the PScreenManager protocol
 * to communicate with a PScreenManagerParent to get this information,
 * and also caches the information it gets back.
 *
 * We cache both the system screen information that nsIScreenManagers
 * provide, as well as the nsIScreens that callers can query for.
 *
 * Both of these caches are invalidated on the next tick of the event
 * loop.
 */
class nsScreenManagerProxy final : public nsIScreenManager,
                                   public mozilla::dom::PScreenManagerChild
{
public:
  nsScreenManagerProxy();

  NS_DECL_ISUPPORTS
  NS_DECL_NSISCREENMANAGER

private:
  ~nsScreenManagerProxy() {};

  bool EnsureCacheIsValid();
  void InvalidateCacheOnNextTick();
  void InvalidateCache();

  uint32_t mNumberOfScreens;
  float mSystemDefaultScale;
  bool mCacheValid;
  bool mCacheWillInvalidate;

  RefPtr<mozilla::widget::ScreenProxy> mPrimaryScreen;

  // nsScreenManagerProxy caches the results to repeated calls to
  // ScreenForNativeWidget, which can be triggered indirectly by
  // web content using the DOM Screen API. This allows us to bypass
  // a lot of IPC traffic.
  //
  // The cache stores ScreenProxy's mapped to the TabChild that
  // asked for the ScreenForNativeWidget was called with via
  // ScreenCacheEntry's. The cache is cleared on the next tick of
  // the event loop.
  struct ScreenCacheEntry
  {
    RefPtr<mozilla::widget::ScreenProxy> mScreenProxy;
    RefPtr<mozilla::dom::TabChild> mTabChild;
  };

  nsTArray<ScreenCacheEntry> mScreenCache;
};

#endif // nsScreenManagerProxy_h