widget/nsScreenManagerProxy.cpp
author Chris H-C <chutten@mozilla.com>
Mon, 04 Jul 2016 11:16:05 -0400
changeset 312997 df28918fe2361f0b54ca9ce4773a29c4c0675d06
parent 310949 564549c354b038a465c0b3fc245da3cab8753eab
permissions -rw-r--r--
bug 1218576 - Support remote accumulation via JS histograms. r=gfritzsche The JS histograms, too, need to dispatch their accumulations from child to parent. JSHistograms_Add now only supports histograms that are in gHistogramsMap or that were created in the parent process. After bug 1288745, maybe we'll be able to change this to be less convoluted. MozReview-Commit-ID: 3qTH89YKbGP

/* -*- 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 "mozilla/Unused.h"
#include "mozilla/dom/ContentChild.h"
#include "nsScreenManagerProxy.h"
#include "nsServiceManagerUtils.h"
#include "nsContentUtils.h"
#include "nsIAppShell.h"
#include "nsIScreen.h"
#include "nsIScreenManager.h"
#include "nsWidgetsCID.h"

static NS_DEFINE_CID(kAppShellCID, NS_APPSHELL_CID);

using namespace mozilla;
using namespace mozilla::dom;
using namespace mozilla::widget;

NS_IMPL_ISUPPORTS(nsScreenManagerProxy, nsIScreenManager)

nsScreenManagerProxy::nsScreenManagerProxy()
  : mNumberOfScreens(-1)
  , mSystemDefaultScale(1.0)
  , mCacheValid(true)
  , mCacheWillInvalidate(false)
{
  bool success = false;
  Unused << ContentChild::GetSingleton()->SendPScreenManagerConstructor(
                                            this,
                                            &mNumberOfScreens,
                                            &mSystemDefaultScale,
                                            &success);

  if (!success) {
    // We're in bad shape. We'll return the default values, but we'll basically
    // be lying.
    NS_WARNING("Setting up communications with the parent nsIScreenManager failed.");
  }

  InvalidateCacheOnNextTick();

  // nsScreenManagerProxy is a service, which will always have a reference
  // held to it by the Component Manager once the service is requested.
  // However, nsScreenManagerProxy also implements PScreenManagerChild, and
  // that means that the manager of the PScreenManager protocol (PContent
  // in this case) needs to know how to deallocate this actor. We AddRef here
  // so that in the event that PContent tries to deallocate us either before
  // or after process shutdown, we don't try to do a double-free.
  AddRef();
}

/**
 * nsIScreenManager
 **/

NS_IMETHODIMP
nsScreenManagerProxy::GetPrimaryScreen(nsIScreen** outScreen)
{
  InvalidateCacheOnNextTick();

  if (!mPrimaryScreen) {
    ScreenDetails details;
    bool success = false;
    Unused << SendGetPrimaryScreen(&details, &success);
    if (!success) {
      return NS_ERROR_FAILURE;
    }

    mPrimaryScreen = new ScreenProxy(this, details);
  }
  NS_ADDREF(*outScreen = mPrimaryScreen);
  return NS_OK;
}

NS_IMETHODIMP
nsScreenManagerProxy::ScreenForId(uint32_t aId, nsIScreen** outScreen)
{
  // At this time, there's no need for child processes to query for
  // screens by ID.
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsScreenManagerProxy::ScreenForRect(int32_t inLeft,
                                    int32_t inTop,
                                    int32_t inWidth,
                                    int32_t inHeight,
                                    nsIScreen** outScreen)
{
  bool success = false;
  ScreenDetails details;
  Unused << SendScreenForRect(inLeft, inTop, inWidth, inHeight, &details, &success);
  if (!success) {
    return NS_ERROR_FAILURE;
  }

  RefPtr<ScreenProxy> screen = new ScreenProxy(this, details);
  NS_ADDREF(*outScreen = screen);

  return NS_OK;
}

NS_IMETHODIMP
nsScreenManagerProxy::ScreenForNativeWidget(void* aWidget,
                                            nsIScreen** outScreen)
{
  // Because ScreenForNativeWidget can be called numerous times
  // indirectly from content via the DOM Screen API, we cache the
  // results for this tick of the event loop.
  TabChild* tabChild = static_cast<TabChild*>(aWidget);

  // Enumerate the cached screen array, looking for one that has
  // the TabChild that we're looking for...
  for (uint32_t i = 0; i < mScreenCache.Length(); ++i) {
      ScreenCacheEntry& curr = mScreenCache[i];
      if (curr.mTabChild == aWidget) {
          NS_ADDREF(*outScreen = static_cast<nsIScreen*>(curr.mScreenProxy));
          return NS_OK;
      }
  }

  // Never cached this screen, so we have to ask the parent process
  // for it.
  bool success = false;
  ScreenDetails details;
  Unused << SendScreenForBrowser(tabChild->GetTabId(), &details, &success);
  if (!success) {
    return NS_ERROR_FAILURE;
  }

  ScreenCacheEntry newEntry;
  RefPtr<ScreenProxy> screen = new ScreenProxy(this, details);

  newEntry.mScreenProxy = screen;
  newEntry.mTabChild = tabChild;

  mScreenCache.AppendElement(newEntry);

  NS_ADDREF(*outScreen = screen);

  InvalidateCacheOnNextTick();
  return NS_OK;
}

NS_IMETHODIMP
nsScreenManagerProxy::GetNumberOfScreens(uint32_t* aNumberOfScreens)
{
  if (!EnsureCacheIsValid()) {
    return NS_ERROR_FAILURE;
  }

  *aNumberOfScreens = mNumberOfScreens;
  return NS_OK;
}

NS_IMETHODIMP
nsScreenManagerProxy::GetSystemDefaultScale(float *aSystemDefaultScale)
{
  if (!EnsureCacheIsValid()) {
    return NS_ERROR_FAILURE;
  }

  *aSystemDefaultScale = mSystemDefaultScale;
  return NS_OK;
}

bool
nsScreenManagerProxy::EnsureCacheIsValid()
{
  if (mCacheValid) {
    return true;
  }

  bool success = false;
  // Kick off a synchronous IPC call to the parent to get the
  // most up-to-date information.
  Unused << SendRefresh(&mNumberOfScreens, &mSystemDefaultScale, &success);
  if (!success) {
    NS_WARNING("Refreshing nsScreenManagerProxy failed in the parent process.");
    return false;
  }

  mCacheValid = true;

  InvalidateCacheOnNextTick();
  return true;
}

void
nsScreenManagerProxy::InvalidateCacheOnNextTick()
{
  if (mCacheWillInvalidate) {
    return;
  }

  mCacheWillInvalidate = true;

  nsContentUtils::RunInStableState(NewRunnableMethod(this, &nsScreenManagerProxy::InvalidateCache));
}

void
nsScreenManagerProxy::InvalidateCache()
{
  mCacheValid = false;
  mCacheWillInvalidate = false;

  if (mPrimaryScreen) {
    mPrimaryScreen = nullptr;
  }
  for (int32_t i = mScreenCache.Length() - 1; i >= 0; --i) {
    mScreenCache.RemoveElementAt(i);
  }
}