/*

* Copyright (c) 2003 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:  SVG Engine header file

 *

*/

#ifndef __INC_MSVGREQUESTOBSERVER__

#define __INC_MSVGREQUESTOBSERVER__

class   CSvgElementImpl;

/**

 * This interface is the callback mechanism for the SVG Engine to communicate to

 * interested clients and to request for external data, such as images.

 * The callbacks will be active when the methods of this interace are implemented and

 * the pointer to the implementation object is passed in as the second parameter

 * of the 'ConstructL' method of the CSvgEngineInterface.  A 'null' value may be

 * passed-in if the callbacks are to be ignored.

 *

 *  @lib SVGEngine.lib

 *  @since 1.0

 */

class MSvgRequestObserver

    {

    public:

        /**

         * This method is called by the SVG Engine when all data for a certain

         * step, such as animation frame, have been updated.  This usually means

         * the off-screen image (passed in to 'ConstructL' of CSvgEngineInterface)

         * has been updated.  The client usually redraws the image onto

         * the screen.

         *

         * @since 1.0

         * @param : none

         * @return : none

         */

        virtual void    UpdateScreen() = 0;

        /**

         * This method is for future extension, in which an external script engine

         * could be used to evaluate a script description.

         *

         * @since 1.0

         * @param : aScript -- A description of script from the "on" attribute.

         *

         * @param : aCallerElement -- The element that calls the script by a

         *                            an event of the "on" attribute.

         * @return : For future use.  Value is ignored.

         */

        virtual TBool   ScriptCall( const TDesC& aScript,

                                    CSvgElementImpl* aCallerElement ) = 0;

        /**

         * This method is called to retrieve the file handle of an image name.

         * The session (RFs) object passed in is guaranteed to be connected, so

         * the client must NOT call aSession.Connect().

         *

         * The implementation for the client of this method is usually if not always:

         * TInt X::FetchImage( const TDesC& aFilename, RFs& aSession, RFile& aFileHandle )

         *     {

         *     // Check for "http", get data from remote site, save to disk

         *     // Get absolute path to aFilename: absolutepath

         *     return aFileHandle.Open( aSession, absolutepath, EFileRead );

         *     }

         *

         * Note: Use EFileShareReadersOnly to prevent file locking.

         *

         * The API AssignImageData() can be used to avoid block the parsing

         * thread due this method taking too long to return.  This is

         * accomplished by returning a non-KErrNone value  (i.e. KErrNotFound),

         * and storing the URI parameter.  The image data then could be

         * assigned the the URI in another thread/Active-Object.

         *

         * @since 1.0

         * @param : aUri -- the relative path of an image file.

         * @param : aSession -- File session used by client to open file.

         * @param : aFileHandle -- File handle used by client to open file.

         * @return : KErrNone if Open command successful, otherwise error-code

         *           from Open command.  The SVG engine will proceed loading the file

         *           only if the return value is KErrNone.

         */

        virtual TInt FetchImage( const TDesC& aUri, RFs& aSession, RFile& aFileHandle ) = 0;

		/**

         * This method is called to retrieve the file handle of an svg font file.

         * This file must be SVG 1.1 .svg file.  When the engine comes acrossed

         * a font-family name that it doesnt know it will request "fontfamilyname".svg

         * file through this method.  The client can either provide the svg file

         * or the engine will default to system text.

         *

         * The usage of this method is exactly the same as the FetchImage method above

         *

         * @since 1.0

         * @param : aUri -- the relative path of an image file.

         * @param : aSession -- File session used by client to open file.

         * @param : aFileHandle -- File handle used by client to open file.

         * @return : KErrNone if Open command successful, otherwise error-code

         *           from Open command.  The SVG engine will proceed loading the file

         *           only if the return value is KErrNone.

         */

		virtual TInt FetchFont( const TDesC& aUri, RFs& aSession, RFile& aFileHandle ) = 0;

        /**

         * This Method updates the presentation status

         * @since 1.0

         * @param : TInt32&  aNoOfAnimation

         * @return :

         */

        virtual  void UpdatePresentation(const TInt32&  aNoOfAnimation)=0;

    };

#endif /*__INC_MSvgRequestObserver__*/