/* -*- 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/. */

/* table of images used in a document, for batch locking/unlocking and

 * animating */

#include "ImageTracker.h"

#include "imgIRequest.h"

#include "mozilla/Preferences.h"

#include "nsXULAppAPI.h"

namespace mozilla {

namespace dom {

ImageTracker::ImageTracker()

  : mLocking(false)

  , mAnimating(true)

{

}

ImageTracker::~ImageTracker()

{

  SetLockingState(false);

}

nsresult

ImageTracker::Add(imgIRequest* aImage)

{

  MOZ_ASSERT(aImage);

  nsresult rv = NS_OK;

  auto entry = mImages.LookupForAdd(aImage);

  if (entry) {

    // The image is already in the hashtable.  Increment its count.

    uint32_t oldCount = entry.Data();

    MOZ_ASSERT(oldCount > 0, "Entry in the image tracker with count 0!");

    entry.Data() = oldCount + 1;

  } else {

    // A new entry was inserted - set the count to 1.

    entry.OrInsert([]() { return 1; });

    // If we're locking images, lock this image too.

    if (mLocking) {

      rv = aImage->LockImage();

    }

    // If we're animating images, request that this image be animated too.

    if (mAnimating) {

      nsresult rv2 = aImage->IncrementAnimationConsumers();

      rv = NS_SUCCEEDED(rv) ? rv2 : rv;

    }

  }

  return rv;

}

nsresult

ImageTracker::Remove(imgIRequest* aImage, uint32_t aFlags)

{

  NS_ENSURE_ARG_POINTER(aImage);

  // Get the old count. It should exist and be > 0.

  if (auto entry = mImages.Lookup(aImage)) {

    MOZ_ASSERT(entry.Data() > 0, "Entry in the image tracker with count 0!");

    // If the count becomes zero, remove it from the tracker.

    if (--entry.Data() == 0) {

      entry.Remove();

    } else {

      return NS_OK;

    }

  } else {

    MOZ_ASSERT_UNREACHABLE("Removing image that wasn't in the tracker!");

    return NS_OK;

  }

  nsresult rv = NS_OK;

  // Now that we're no longer tracking this image, unlock it if we'd

  // previously locked it.

  if (mLocking) {

    rv = aImage->UnlockImage();

  }

  // If we're animating images, remove our request to animate this one.

  if (mAnimating) {

    nsresult rv2 = aImage->DecrementAnimationConsumers();

    rv = NS_SUCCEEDED(rv) ? rv2 : rv;

  }

  if (aFlags & REQUEST_DISCARD) {

    // Request that the image be discarded if nobody else holds a lock on it.

    // Do this even if !mLocking, because even if we didn't just unlock

    // this image, it might still be a candidate for discarding.

    aImage->RequestDiscard();

  }

  return rv;

}

nsresult

ImageTracker::SetLockingState(bool aLocked)

{

  if (XRE_IsContentProcess() &&

      !Preferences::GetBool("image.mem.allow_locking_in_content_processes", true)) {

    return NS_OK;

  }

  // If there's no change, there's nothing to do.

  if (mLocking == aLocked)

    return NS_OK;

  // Otherwise, iterate over our images and perform the appropriate action.

  for (auto iter = mImages.Iter(); !iter.Done(); iter.Next()) {

    imgIRequest* image = iter.Key();

    if (aLocked) {

      image->LockImage();

    } else {

      image->UnlockImage();

    }

  }

  // Update state.

  mLocking = aLocked;

  return NS_OK;

}

void

ImageTracker::SetAnimatingState(bool aAnimating)

{

  // If there's no change, there's nothing to do.

  if (mAnimating == aAnimating)

    return;

  // Otherwise, iterate over our images and perform the appropriate action.

  for (auto iter = mImages.Iter(); !iter.Done(); iter.Next()) {

    imgIRequest* image = iter.Key();

    if (aAnimating) {

      image->IncrementAnimationConsumers();

    } else {

      image->DecrementAnimationConsumers();

    }

  }

  // Update state.

  mAnimating = aAnimating;

}

void

ImageTracker::RequestDiscardAll()

{

  for (auto iter = mImages.Iter(); !iter.Done(); iter.Next()) {

    iter.Key()->RequestDiscard();

  }

}

} // namespace dom

} // namespace mozilla