michael@0: /* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "nsIStreamListener.idl"
michael@0: 
michael@0: interface nsIInputStream;
michael@0: 
michael@0: /**
michael@0:  * nsIStreamConverter provides an interface to implement when you have code
michael@0:  * that converts data from one type to another.
michael@0:  *
michael@0:  * Suppose you had code that converted plain text into HTML. You could implement
michael@0:  * this interface to allow everyone else to use your conversion logic using a 
michael@0:  * standard api.
michael@0:  * <p>
michael@0:  * <b>STREAM CONVERTER USERS</b>
michael@0:  *
michael@0:  * There are currently two ways to use a stream converter:
michael@0:  * <ol>
michael@0:  * <li> <b>SYNCHRONOUS</b> Stream to Stream
michael@0:  *    You can supply the service with a stream of type X
michael@0:  *    and it will convert it to your desired output type and return
michael@0:  *    a converted (blocking) stream to you.</li>
michael@0:  *
michael@0:  * <li> <b>ASYNCHRONOUS</b> nsIStreamListener to nsIStreamListener
michael@0:  *    You can supply data directly to the converter by calling it's
michael@0:  *    nsIStreamListener::OnDataAvailable() method. It will then
michael@0:  *    convert that data from type X to your desired output type and
michael@0:  *    return converted data to you via the nsIStreamListener you passed
michael@0:  *    in by calling its OnDataAvailable() method.</li>
michael@0:  * </ol>
michael@0:  * <p>
michael@0:  *
michael@0:  * <b>STREAM CONVERTER SUPPLIERS</b>
michael@0:  *
michael@0:  * Registering a stream converter:
michael@0:  * Stream converter registration is a two step process. First of all the stream
michael@0:  * converter implementation must register itself with the component manager using
michael@0:  * a contractid in the format below. Second, the stream converter must add the contractid
michael@0:  * to the registry.
michael@0:  *
michael@0:  * Stream converter contractid format (the stream converter root key is defined in this
michael@0:  * file):
michael@0:  *
michael@0:  * <pre>@mozilla.org/streamconv;1?from=FROM_MIME_TYPE&to=TO_MIME_TYPE</pre>
michael@0:  *
michael@0:  * @author Jud Valeski
michael@0:  * @see nsIStreamConverterService
michael@0:  */
michael@0: 
michael@0: [scriptable, uuid(0b6e2c69-5cf5-48b0-9dfd-c95950e2cc7b)]
michael@0: interface nsIStreamConverter : nsIStreamListener {
michael@0: 
michael@0:     /**
michael@0:      * <b>SYNCRONOUS VERSION</b>
michael@0:      * Converts a stream of one type, to a stream of another type.
michael@0:      *
michael@0:      * Use this method when you have a stream you want to convert.
michael@0:      *
michael@0:      * @param aFromStream   The stream representing the original/raw data.
michael@0:      * @param aFromType     The MIME type of aFromStream.
michael@0:      * @param aToType       The MIME type of the returned stream.
michael@0:      * @param aCtxt         Either an opaque context, or a converter specific context
michael@0:      *                      (implementation specific).
michael@0:      * @return              The converted stream. NOTE: The returned stream may not
michael@0:      *                      already be converted. An efficient stream converter
michael@0:      *                      implementation will converter data on demand rather than
michael@0:      *                      buffering the converted data until it is used.
michael@0:      */
michael@0:     nsIInputStream convert(in nsIInputStream aFromStream,
michael@0:                            in string aFromType,
michael@0:                            in string aToType,
michael@0:                            in nsISupports aCtxt);
michael@0: 
michael@0:     /**
michael@0:      * <b>ASYNCRONOUS VERSION</b>
michael@0:      * Converts data arriving via the converter's nsIStreamListener::OnDataAvailable() 
michael@0:      * method from one type to another, pushing the converted data out to the caller 
michael@0:      * via aListener::OnDataAvailable().
michael@0:      *
michael@0:      * Use this method when you want to proxy (and convert) nsIStreamListener callbacks
michael@0:      * asynchronously.
michael@0:      *
michael@0:      * @param aFromType     The MIME type of the original/raw data.
michael@0:      * @param aToType       The MIME type of the converted data.
michael@0:      * @param aListener     The listener who receives the converted data.
michael@0:      * @param aCtxt         Either an opaque context, or a converter specific context
michael@0:      *                      (implementation specific).
michael@0:      */
michael@0:     void asyncConvertData(in string aFromType,
michael@0:                           in string aToType,
michael@0:                           in nsIStreamListener aListener,
michael@0:                           in nsISupports aCtxt);
michael@0: };
michael@0: 
michael@0: %{C++
michael@0: #define NS_ISTREAMCONVERTER_KEY         "@mozilla.org/streamconv;1"
michael@0: %}