/* -*- 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/. */

#include "nsISupports.idl"
#include "nsIRequest.idl"

interface imgIContainer;
interface imgIDecoderObserver;
interface nsIURI;
interface nsIPrincipal;

/**
 * imgIRequest interface
 *
 * @author Stuart Parmenter <stuart@mozilla.com>
 * @version 0.1
 * @see imagelib2
 */
[scriptable, uuid(a5a785a8-9881-11e1-aaff-001fbc092072)]
interface imgIRequest : nsIRequest
{
  /**
   * the image container...
   * @return the image object associated with the request.
   * @attention NEED DOCS
   */
  readonly attribute imgIContainer image;

  /**
   * Bits set in the return value from imageStatus
   * @name statusflags
   *
   * Meanings:
   *
   * STATUS_NONE: Nothing to report.
   *
   * STATUS_SIZE_AVAILABLE: We received enough image data
   * from the network or filesystem that we know the width
   * and height of the image, and have thus called SetSize()
   * on the container.
   *
   * STATUS_LOAD_PARTIAL: Used internally by imgRequest to
   * flag that a request is being cancelled as a result of
   * a failure of a proxy holder and not an internal failure.
   * At least I think that's what it does. Regardless, there's
   * no reason for this flag to be public, and it should either
   * go away or become a private state flag within imgRequest.
   * Don't rely on it.
   *
   * STATUS_LOAD_COMPLETE: The data has been fully loaded
   * to memory, but not necessarily fully decoded.
   *
   * STATUS_ERROR: An error occurred loading the image.
   *
   * STATUS_FRAME_COMPLETE: The first frame has been
   * completely decoded.
   *
   * STATUS_DECODE_COMPLETE: The whole image has been decoded.
   */
  //@{
  const long STATUS_NONE             = 0x0;
  const long STATUS_SIZE_AVAILABLE   = 0x1;
  const long STATUS_LOAD_PARTIAL     = 0x2;
  const long STATUS_LOAD_COMPLETE    = 0x4;
  const long STATUS_ERROR            = 0x8;
  const long STATUS_FRAME_COMPLETE   = 0x10;
  const long STATUS_DECODE_COMPLETE  = 0x20;
  //@}

  /**
   * Status flags of the STATUS_* variety.
   */
  readonly attribute unsigned long imageStatus;

  /**
   * The URI the image load was started with.  Note that this might not be the
   * actual URI for the image (e.g. if HTTP redirects happened during the
   * load).
   */
  readonly attribute nsIURI URI;

  readonly attribute imgIDecoderObserver decoderObserver;

  readonly attribute string mimeType;

  /**
   * Clone this request; the returned request will have aObserver as the
   * observer.  aObserver will be notified synchronously (before the clone()
   * call returns) with all the notifications that have already been dispatched
   * for this image load.
   */
  imgIRequest clone(in imgIDecoderObserver aObserver);

  /**
   * The principal gotten from the channel the image was loaded from.
   */
  readonly attribute nsIPrincipal imagePrincipal;

  /**
   * Whether the request is multipart (ie, multipart/x-mixed-replace)
   */
  readonly attribute bool multipart;

  /**
   * CORS modes images can be loaded with.
   *
   * By default, all images are loaded with CORS_NONE and cannot be used
   * cross-origin in context like WebGL.
   *
   * If an HTML img element has the crossorigin attribute set, the imgIRequest
   * will be validated for cross-origin usage with CORS, and, if successful,
   * will have its CORS mode set to the relevant type.
   */
  //@{
  const long CORS_NONE = 1;
  const long CORS_ANONYMOUS = 2;
  const long CORS_USE_CREDENTIALS = 3;
  //@}

  /**
   * The CORS mode that this image was loaded with. 
   */
  readonly attribute long CORSMode;

  /**
   * Cancels this request as in nsIRequest::Cancel(); further, also nulls out
   * decoderObserver so it gets no further notifications from us.
   *
   * NOTE: You should not use this in any new code; instead, use cancel(). Note
   * that cancel() is asynchronous, which means that some time after you call
   * it, the listener/observer will get an OnStopRequest(). This means that, if
   * you're the observer, you can't call cancel() from your destructor.
   */
  void cancelAndForgetObserver(in nsresult aStatus);

  /**
   * Requests a decode for the image.
   *
   * imgIContainer has a requestDecode() method, but callers may want to request
   * a decode before the container has necessarily been instantiated. Calling
   * requestDecode() on the imgIRequest simply forwards along the request if the
   * container already exists, or calls it once it gets OnStartContainer if the
   * container does not yet exist.
   */
  void requestDecode();

  /**
   * Locks an image. If the image does not exist yet, locks it once it becomes
   * available. The lock persists for the lifetime of the imgIRequest (until
   * unlockImage is called) even if the underlying image changes.
   *
   * If you don't call unlockImage() by the time this imgIRequest goes away, it
   * will be called for you automatically.
   *
   * @see imgIContainer::lockImage for documentation of the underlying call.
   */
  void lockImage();

  /**
   * Unlocks an image.
   *
   * @see imgIContainer::unlockImage for documentation of the underlying call.
   */
  void unlockImage();

  /**
   * If this image is unlocked, discard the image's decoded data.  If the image
   * is locked or is already discarded, do nothing.
   */
  void requestDiscard();

  /**
   * If this request is for an animated image, the method creates a new
   * request which contains the current frame of the image.
   * Otherwise returns the same request.
   */
  imgIRequest getStaticRequest();

  /**
   * Requests that the image animate (if it has an animation).
   *
   * @see Image::IncrementAnimationConsumers for documentation of the underlying call.
   */
  void incrementAnimationConsumers();

  /**
   * Tell the image it can forget about a request that the image animate.
   *
   * @see Image::DecrementAnimationConsumers for documentation of the underlying call.
   */
  void decrementAnimationConsumers();
};