gecko/image/src/imgRequestProxy.h

/* -*- 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 imgRequestProxy_h__
#define imgRequestProxy_h__

#include "imgIRequest.h"
#include "imgIDecoderObserver.h"
#include "nsISecurityInfoProvider.h"

#include "nsIRequestObserver.h"
#include "nsIChannel.h"
#include "nsILoadGroup.h"
#include "nsISupportsPriority.h"
#include "nsITimedChannel.h"
#include "nsCOMPtr.h"
#include "nsAutoPtr.h"
#include "nsThreadUtils.h"

#include "imgRequest.h"

#define NS_IMGREQUESTPROXY_CID \
{ /* 20557898-1dd2-11b2-8f65-9c462ee2bc95 */         \
     0x20557898,                                     \
     0x1dd2,                                         \
     0x11b2,                                         \
    {0x8f, 0x65, 0x9c, 0x46, 0x2e, 0xe2, 0xbc, 0x95} \
}

class imgRequestNotifyRunnable;
class imgStatusNotifyRunnable;

namespace mozilla {
namespace image {
class Image;
} // namespace image
} // namespace mozilla

class imgRequestProxy : public imgIRequest, 
                        public nsISupportsPriority, 
                        public nsISecurityInfoProvider,
                        public nsITimedChannel
{
public:
  NS_DECL_ISUPPORTS
  NS_DECL_IMGIREQUEST
  NS_DECL_NSIREQUEST
  NS_DECL_NSISUPPORTSPRIORITY
  NS_DECL_NSISECURITYINFOPROVIDER
  // nsITimedChannel declared below

  imgRequestProxy();
  virtual ~imgRequestProxy();

  // Callers to Init or ChangeOwner are required to call NotifyListener after
  // (although not immediately after) doing so.
  nsresult Init(imgRequest *request, nsILoadGroup *aLoadGroup,
                mozilla::image::Image* aImage,
                nsIURI* aURI, imgIDecoderObserver *aObserver);

  nsresult ChangeOwner(imgRequest *aNewOwner); // this will change mOwner.  Do not call this if the previous
                                               // owner has already sent notifications out!

  void AddToLoadGroup();
  void RemoveFromLoadGroup(bool releaseLoadGroup);

  inline bool HasObserver() const {
    return mListener != nullptr;
  }

  void SetPrincipal(nsIPrincipal *aPrincipal);

  // Asynchronously notify this proxy's listener of the current state of the
  // image, and, if we have an imgRequest mOwner, any status changes that
  // happen between the time this function is called and the time the
  // notification is scheduled.
  void NotifyListener();

  // Synchronously notify this proxy's listener of the current state of the
  // image. Only use this function if you are currently servicing an
  // asynchronously-called function.
  void SyncNotifyListener();

  // Whether we want notifications from imgStatusTracker to be deferred until
  // an event it has scheduled has been fired.
  bool NotificationsDeferred() const
  {
    return mDeferNotifications;
  }
  void SetNotificationsDeferred(bool aDeferNotifications)
  {
    mDeferNotifications = aDeferNotifications;
  }

  // Setter for our |mImage| pointer, for imgRequest to use, once it
  // instantiates an Image.
  void SetImage(mozilla::image::Image* aImage);

  // Removes all animation consumers that were created with
  // IncrementAnimationConsumers. This is necessary since we need
  // to do it before the proxy itself is destroyed. See
  // imgRequest::RemoveProxy
  void ClearAnimationConsumers();

protected:
  friend class imgStatusTracker;
  friend class imgStatusNotifyRunnable;
  friend class imgRequestNotifyRunnable;

  class imgCancelRunnable;
  friend class imgCancelRunnable;

  class imgCancelRunnable : public nsRunnable
  {
    public:
      imgCancelRunnable(imgRequestProxy* owner, nsresult status)
        : mOwner(owner), mStatus(status)
      {}

      NS_IMETHOD Run() {
        mOwner->DoCancel(mStatus);
        return NS_OK;
      }

    private:
      nsRefPtr<imgRequestProxy> mOwner;
      nsresult mStatus;
  };

  // The following notification functions are protected to ensure that (friend
  // class) imgStatusTracker is the only class allowed to send us
  // notifications.

  /* non-virtual imgIDecoderObserver methods */
  void OnStartDecode     ();
  void OnStartContainer  (imgIContainer *aContainer);
  void OnStartFrame      (PRUint32 aFrame);
  void OnDataAvailable   (bool aCurrentFrame, const nsIntRect * aRect);
  void OnStopFrame       (PRUint32 aFrame);
  void OnStopContainer   (imgIContainer *aContainer);
  void OnStopDecode      (nsresult status, const PRUnichar *statusArg);
  void OnDiscard         ();
  void OnImageIsAnimated ();

  /* non-virtual imgIContainerObserver methods */
  void FrameChanged(imgIContainer *aContainer,
                    const nsIntRect *aDirtyRect);

  /* non-virtual sort-of-nsIRequestObserver methods */
  void OnStartRequest();
  void OnStopRequest(bool aLastPart);

  /* non-virtual imgIOnloadBlocker methods */
  void BlockOnload();
  void UnblockOnload();

  /* Finish up canceling ourselves */
  void DoCancel(nsresult status);

  /* Do the proper refcount management to null out mListener */
  void NullOutListener();

  void DoRemoveFromLoadGroup() {
    RemoveFromLoadGroup(true);
  }

  // Return the imgStatusTracker associated with mOwner and/or mImage. It may
  // live either on mOwner or mImage, depending on whether
  //   (a) we have an mOwner at all
  //   (b) whether mOwner has instantiated its image yet
  imgStatusTracker& GetStatusTracker();

  nsITimedChannel* TimedChannel()
  {
    if (!mOwner)
      return nullptr;
    return mOwner->mTimedChannel;
  }

public:
  NS_FORWARD_SAFE_NSITIMEDCHANNEL(TimedChannel())

private:
  friend class imgCacheValidator;

  // We maintain the following invariant:
  // The proxy is registered at most with a single imgRequest as an observer,
  // and whenever it is, mOwner points to that object. This helps ensure that
  // imgRequestProxy::~imgRequestProxy unregisters the proxy as an observer
  // from whatever request it was registered with (if any). This, in turn,
  // means that imgRequest::mObservers will not have any stale pointers in it.
  nsRefPtr<imgRequest> mOwner;

  // The URI of our request.
  nsCOMPtr<nsIURI> mURI;

  // The image we represent. Is null until data has been received, and is then
  // set by imgRequest.
  nsRefPtr<mozilla::image::Image> mImage;

  // Our principal. Is null until data has been received from the channel, and
  // is then set by imgRequest.
  nsCOMPtr<nsIPrincipal> mPrincipal;

  // mListener is only promised to be a weak ref (see imgILoader.idl),
  // but we actually keep a strong ref to it until we've seen our
  // first OnStopRequest.
  imgIDecoderObserver* mListener;
  nsCOMPtr<nsILoadGroup> mLoadGroup;

  nsLoadFlags mLoadFlags;
  PRUint32    mLockCount;
  PRUint32    mAnimationConsumers;
  bool mCanceled;
  bool mIsInLoadGroup;
  bool mListenerIsStrongRef;
  bool mDecodeRequested;

  // Whether we want to defer our notifications by the non-virtual Observer
  // interfaces as image loads proceed.
  bool mDeferNotifications;

  // We only want to send OnStartContainer once for each proxy, but we might
  // get multiple OnStartContainer calls.
  bool mSentStartContainer;
};

#endif // imgRequestProxy_h__