dom/base/nsIImageLoadingContent.idl

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "imgINotificationObserver.idl"
   7
   8 %{C++
   9 #include "mozilla/Maybe.h"
  10 #include "Visibility.h"
  11 %}
  12
  13 interface imgIRequest;
  14 interface nsIChannel;
  15 interface nsIStreamListener;
  16 interface nsIURI;
  17 interface nsIFrame;
  18
  19 [ref] native MaybeOnNonvisible(const mozilla::Maybe<mozilla::OnNonvisible>);
  20 native Visibility(mozilla::Visibility);
  21
  22 /**
  23  * This interface represents a content node that loads images.  The interface
  24  * exists to allow getting information on the images that the content node
  25  * loads and to allow registration of observers for the image loads.
  26  *
  27  * Implementors of this interface should handle all the mechanics of actually
  28  * loading an image -- getting the URI, checking with content policies and
  29  * the security manager to see whether loading the URI is allowed, performing
  30  * the load, firing any DOM events as needed.
  31  *
  32  * An implementation of this interface may support the concepts of a
  33  * "current" image and a "pending" image.  If it does, a request to change
  34  * the currently loaded image will start a "pending" request which will
  35  * become current only when the image is loaded.  It is the responsibility of
  36  * observers to check which request they are getting notifications for.
  37  *
  38  * Please make sure to update the MozImageLoadingContent WebIDL
  39  * mixin to mirror this interface when changing it.
  40  */
  41
  42 // We can't make this interface noscript yet, because there is JS code doing
  43 // "instanceof Ci.nsIImageLoadingContent" and using the nsIImageLoadingContent
  44 // constants.
  45 [scriptable, builtinclass, uuid(0357123d-9224-4d12-a47e-868c32689777)]
  46 interface nsIImageLoadingContent : imgINotificationObserver
  47 {
  48   /**
  49    * Request types.  Image loading content nodes attempt to do atomic
  50    * image changes when the image url is changed.  This means that
  51    * when the url changes the new image load will start, but the old
  52    * image will remain the "current" request until the new image is
  53    * fully loaded.  At that point, the old "current" request will be
  54    * discarded and the "pending" request will become "current".
  55    */
  56   const long UNKNOWN_REQUEST = -1;
  57   const long CURRENT_REQUEST = 0;
  58   const long PENDING_REQUEST = 1;
  59
  60   /**
  61    * setLoadingEnabled is used to enable and disable loading in
  62    * situations where loading images is unwanted.  Note that enabling
  63    * loading will *not* automatically trigger an image load.
  64    */
  65   [notxpcom, nostdcall] void setLoadingEnabled(in boolean aEnabled);
  66
  67   /**
  68    * Used to register an image decoder observer.  Typically, this will
  69    * be a proxy for a frame that wants to paint the image.
  70    * Notifications from ongoing image loads will be passed to all
  71    * registered observers.  Notifications for all request types,
  72    * current and pending, will be passed through.
  73    *
  74    * @param aObserver the observer to register
  75    */
  76   [notxpcom, nostdcall] void addNativeObserver(in imgINotificationObserver aObserver);
  77
  78   /**
  79    * Used to unregister an image decoder observer.
  80    *
  81    * @param aObserver the observer to unregister
  82    */
  83   [notxpcom, nostdcall] void removeNativeObserver(in imgINotificationObserver aObserver);
  84
  85   /**
  86    * Accessor to get the image requests
  87    *
  88    * @param aRequestType a value saying which request is wanted
  89    *
  90    * @return the imgIRequest object (may be null, even when no error
  91    * is thrown)
  92    *
  93    * @throws NS_ERROR_UNEXPECTED if the request type requested is not
  94    * known
  95    */
  96   [noscript] imgIRequest getRequest(in long aRequestType);
  97
  98   /**
  99    * Used to notify the image loading content node that a frame has been
 100    * created.
 101    */
 102   [notxpcom] void frameCreated(in nsIFrame aFrame);
 103
 104   /**
 105    * Used to notify the image loading content node that a frame has been
 106    * destroyed.
 107    */
 108   [notxpcom] void frameDestroyed(in nsIFrame aFrame);
 109
 110   /**
 111    * Used to find out what type of request one is dealing with (eg
 112    * which request got passed through to the imgINotificationObserver
 113    * interface of an observer)
 114    *
 115    * @param aRequest the request whose type we want to know
 116    *
 117    * @return an enum value saying what type this request is
 118    *
 119    * @throws NS_ERROR_UNEXPECTED if aRequest is not known
 120    */
 121   [noscript] long getRequestType(in imgIRequest aRequest);
 122
 123   /**
 124    * Gets the URI of the current request, if available.
 125    * Otherwise, returns the last URI that this content tried to load, or
 126    * null if there haven't been any such attempts.
 127    */
 128   [noscript, infallible] readonly attribute nsIURI currentURI;
 129
 130   /**
 131    * Gets the sync-decoding hint set by the decoding attribute.
 132    */
 133   [noscript, infallible] readonly attribute boolean syncDecodingHint;
 134
 135   /**
 136    * loadImageWithChannel allows data from an existing channel to be
 137    * used as the image data for this content node.
 138    *
 139    * @param aChannel the channel that will deliver the data
 140    *
 141    * @return a stream listener to pump the image data into
 142    *
 143    * @see imgILoader::loadImageWithChannel
 144    *
 145    * @throws NS_ERROR_NULL_POINTER if aChannel is null
 146    */
 147   [noscript] nsIStreamListener loadImageWithChannel(in nsIChannel aChannel);
 148
 149   /**
 150    * Called by layout to announce when the frame associated with this content
 151    * has changed its visibility state.
 152    *
 153    * @param aNewVisibility    The new visibility state.
 154    * @param aNonvisibleAction A requested action if the frame has become
 155    *                          nonvisible. If Nothing(), no action is
 156    *                          requested. If DISCARD_IMAGES is specified, the
 157    *                          frame is requested to ask any images it's
 158    *                          associated with to discard their surfaces if
 159    *                          possible.
 160    */
 161   [noscript, notxpcom] void onVisibilityChange(in Visibility aNewVisibility,
 162                                                in MaybeOnNonvisible aNonvisibleAction);
 163 };