Public Member Functions | Public Attributes

nsIImageLoadingContent Interface Reference

This interface represents a content node that loads images. More...

import "nsIImageLoadingContent.idl";

Inheritance diagram for nsIImageLoadingContent:
Collaboration diagram for nsIImageLoadingContent:

List of all members.

Public Member Functions

void addObserver (in imgIDecoderObserver aObserver)
 Used to register an image decoder observer.
void removeObserver (in imgIDecoderObserver aObserver)
 Used to unregister an image decoder observer.
imgIRequest getRequest (in long aRequestType)
 Accessor to get the image requests.
long getRequestType (in imgIRequest aRequest)
 Used to find out what type of request one is dealing with (eg which request got passed through to the imgIDecoderObserver interface of an observer).
nsIStreamListener loadImageWithChannel (in nsIChannel aChannel)
 loadImageWithChannel allows data from an existing channel to be used as the image data for this content node.
void forceReload ()
 forceReload forces reloading of the image pointed to by currentURI
void forceImageState (in boolean aForce, in long aState)
 Enables/disables image state forcing.

Public Attributes

const long UNKNOWN_REQUEST = -1
 Request types.
const long CURRENT_REQUEST = 0
const long PENDING_REQUEST = 1
attribute boolean loadingEnabled
 loadingEnabled is used to enable and disable loading in situations where loading images is unwanted.
readonly attribute short imageBlockingStatus
 Returns the image blocking status (.
readonly attribute nsIURI currentURI
 Gets the URI of the current request, if available.

Detailed Description

This interface represents a content node that loads images.

The interface exists to allow getting information on the images that the content node loads and to allow registration of observers for the image loads.

Implementors of this interface should handle all the mechanics of actually loading an image -- getting the URI, checking with content policies and the security manager to see whether loading the URI is allowed, performing the load, firing any DOM events as needed.

An implementation of this interface may support the concepts of a "current" image and a "pending" image. If it does, a request to change the currently loaded image will start a "pending" request which will become current only when the image is loaded. It is the responsibility of observers to check which request they are getting notifications for.

Observers added in mid-load will not get any notifications they missed. We should NOT freeze this interface without considering this issue. (It could be that the image status on imgIRequest is sufficient, when combined with the imageBlockingStatus information.)


Member Function Documentation

void nsIImageLoadingContent::addObserver ( in imgIDecoderObserver  aObserver  ) 

Used to register an image decoder observer.

Typically, this will be a proxy for a frame that wants to paint the image. Notifications from ongoing image loads will be passed to all registered observers. Notifications for all request types, current and pending, will be passed through.

Parameters:
aObserver the observer to register
Exceptions:
NS_ERROR_OUT_OF_MEMORY 
void nsIImageLoadingContent::forceImageState ( in boolean  aForce,
in long  aState 
)

Enables/disables image state forcing.

When |aForce| is PR_TRUE, we force nsImageLoadingContent::ImageState() to return |aState|. Call again with |aForce| as PR_FALSE to revert ImageState() to its original behaviour.

void nsIImageLoadingContent::forceReload (  ) 

forceReload forces reloading of the image pointed to by currentURI

Exceptions:
NS_ERROR_NOT_AVAILABLE if there is no current URI to reload
imgIRequest nsIImageLoadingContent::getRequest ( in long  aRequestType  ) 

Accessor to get the image requests.

Parameters:
aRequestType a value saying which request is wanted
Returns:
the imgIRequest object (may be null, even when no error is thrown)
Exceptions:
NS_ERROR_UNEXPECTED if the request type requested is not known
long nsIImageLoadingContent::getRequestType ( in imgIRequest  aRequest  ) 

Used to find out what type of request one is dealing with (eg which request got passed through to the imgIDecoderObserver interface of an observer).

Parameters:
aRequest the request whose type we want to know
Returns:
an enum value saying what type this request is
Exceptions:
NS_ERROR_UNEXPECTED if aRequest is not known
nsIStreamListener nsIImageLoadingContent::loadImageWithChannel ( in nsIChannel  aChannel  ) 

loadImageWithChannel allows data from an existing channel to be used as the image data for this content node.

Parameters:
aChannel the channel that will deliver the data
Returns:
a stream listener to pump the image data into
See also:
imgILoader::loadImageWithChannel
Exceptions:
NS_ERROR_NULL_POINTER if aChannel is null
void nsIImageLoadingContent::removeObserver ( in imgIDecoderObserver  aObserver  ) 

Used to unregister an image decoder observer.

Parameters:
aObserver the observer to unregister

Member Data Documentation

Gets the URI of the current request, if available.

Otherwise, returns the last URI that this content tried to load, or null if there haven't been any such attempts.

Returns the image blocking status (.

See also:
nsIContentPolicy). This will always be an nsIContentPolicy REJECT_* status for cases when the image was blocked. This status always refers to the CURRENT_REQUEST load.

loadingEnabled is used to enable and disable loading in situations where loading images is unwanted.

Note that enabling loading will *not* automatically trigger an image load.

Request types.

Image loading content nodes attempt to do atomic image changes when the image url is changed. This means that when the url changes the new image load will start, but the old image will remain the "current" request until the new image is fully loaded. At that point, the old "current" request will be discarded and the "pending" request will become "current".


The documentation for this interface was generated from the following file: