/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* 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 "nsIThreadRetargetableStreamListener.idl"
interface nsIChannel;
interface nsIInputStream;
/**
* nsIStreamConverter provides an interface to implement when you have code
* that converts data from one type to another.
*
* Suppose you had code that converted plain text into HTML. You could implement
* this interface to allow everyone else to use your conversion logic using a
* standard api.
* <p>
* <b>STREAM CONVERTER USERS</b>
*
* There are currently two ways to use a stream converter:
* <ol>
* <li> <b>SYNCHRONOUS</b> Stream to Stream
* You can supply the service with a stream of type X
* and it will convert it to your desired output type and return
* a converted (blocking) stream to you.</li>
*
* <li> <b>ASYNCHRONOUS</b> nsIStreamListener to nsIStreamListener
* You can supply data directly to the converter by calling it's
* nsIStreamListener::OnDataAvailable() method. It will then
* convert that data from type X to your desired output type and
* return converted data to you via the nsIStreamListener you passed
* in by calling its OnDataAvailable() method.</li>
* </ol>
* <p>
*
* <b>STREAM CONVERTER SUPPLIERS</b>
*
* Registering a stream converter:
* Stream converter registration is a two step process. First of all the stream
* converter implementation must register itself with the component manager using
* a contractid in the format below. Second, the stream converter must add the contractid
* to the registry.
*
* Stream converter contractid format (the stream converter root key is defined in this
* file):
*
* <pre>@mozilla.org/streamconv;1?from=FROM_MIME_TYPE&to=TO_MIME_TYPE</pre>
*
* @author Jud Valeski
* @see nsIStreamConverterService
*/
[scriptable, uuid(0b6e2c69-5cf5-48b0-9dfd-c95950e2cc7b)]
interface nsIStreamConverter : nsIThreadRetargetableStreamListener {
/**
* <b>SYNCRONOUS VERSION</b>
* Converts a stream of one type, to a stream of another type.
*
* Use this method when you have a stream you want to convert.
*
* @param aFromStream The stream representing the original/raw data.
* @param aFromType The MIME type of aFromStream.
* @param aToType The MIME type of the returned stream.
* @param aCtxt Either an opaque context, or a converter specific context
* (implementation specific).
* @return The converted stream. NOTE: The returned stream may not
* already be converted. An efficient stream converter
* implementation will converter data on demand rather than
* buffering the converted data until it is used.
*/
nsIInputStream convert(in nsIInputStream aFromStream,
in string aFromType,
in string aToType,
in nsISupports aCtxt);
/**
* <b>ASYNCRONOUS VERSION</b>
* Converts data arriving via the converter's nsIStreamListener::OnDataAvailable()
* method from one type to another, pushing the converted data out to the caller
* via aListener::OnDataAvailable().
*
* Use this method when you want to proxy (and convert) nsIStreamListener callbacks
* asynchronously.
*
* @param aFromType The MIME type of the original/raw data.
* @param aToType The MIME type of the converted data.
* @param aListener The listener who receives the converted data.
* @param aCtxt Either an opaque context, or a converter specific context
* (implementation specific).
*/
void asyncConvertData(in string aFromType,
in string aToType,
in nsIStreamListener aListener,
in nsISupports aCtxt);
/**
* This is called after the request has installed the stream converter as its listener
* giving the stream converter the option to request retargetting of onDataAvailable.
*/
void maybeRetarget(in nsIRequest request);
/**
* Returns the content type that the stream listener passed to asyncConvertData will
* see on the channel if the conversion is being done from aFromType to * /*.
*
* @param aFromType The type of the content prior to conversion.
* @param aChannel The channel that we'd like to convert. May be null.
*
* @throws if the converter does not support conversion to * /* or if it doesn't know
* the type in advance.
*/
ACString getConvertedType(in ACString aFromType, in nsIChannel aChannel);
};
%{C++
#define NS_ISTREAMCONVERTER_KEY "@mozilla.org/streamconv;1"
%}
