// Copyright (c) 2005-2009 Nokia Corporation and/or its subsidiary(-ies).
// All rights reserved.
// This component and the accompanying materials are made available
// under the terms of the License "Symbian Foundation License v1.0" to Symbian Foundation members and "Symbian Foundation End User License Agreement v1.0" to non-members
// which accompanies this distribution, and is available
// at the URL "http://www.symbianfoundation.org/legal/licencesv10.html".
//
// Initial Contributors:
// Nokia Corporation - initial contribution.
//
// Contributors:
//
// Description:
// This is the extension to the plugin API for the Image Display framework
// 
//

#ifndef EXIFIMAGEDISPLAYEXT_H
#define EXIFIMAGEDISPLAYEXT_H

#include <e32base.h>
#include <icl/imagedisplaypluginext.h>
#include <icl/exifimagedisplay.hrh>

const TUid KExifImageDisplayExtensionUid={KUidExifImageDisplayExtension};

class MExifMetadataReader;

/**
This class extends the functionality of the Image Display Library client API defined 
in the class CImageDisplay. This extension is supported only by the EXIF-specific framework
plug-ins. In order to invoke the extended functionality, the user needs to call the 
CImageDisplay::ExtensionInterface( ) with the KExifImageDisplayExtensionUid interface UID
and an interface pointer to the object of this class.

@publishedAll
@released
*/
class MExifImageDisplayExtension :public MImageDisplayPluginExtension
	{
public:
	/**
	Obtains an MExifMetadataReader that can be used to access the EXIF metadata of the image.
	@param aPtr A reference to a pointer to the MExifMetadataReader that can be used to access the EXIF
				metadata of the image.
	@return A system-wide error code.
	*/
	virtual TInt GetExifMetadataReader(MExifMetadataReader*& aPtr)=0;
	
	/**
	Sets the level of quality for the scaling algorithm.
	If quality level is not set by calling this function then 
	the fastest/lowest quality algorithm is used.
	Note: This function must be called before calling CImageDisplay::Play()
	
	@param aQualityLevel Quality level value for the scaling algorithm.
				See CBitmapScaler::TQualityAlgorithm for a set of possible values.
	@return A system-wide error code.
	*/	
	virtual TInt SetScaleQuality(TInt aQualityLevel)=0;
	
	/**
	Sets the maximum quality reduction factor for image decoding.
	By default, the plug-in calculates an optimal maximum reduction factor 
	and uses it to produce a series of roughly-decoded images, passing each of 
	them to the observer interface with the CImageDisplayPlugin::EStatusPartialFrame flag set.
	Note: This function must be called before calling CImageDisplay::Play().
	
	@param aMaxReductionFactor
				The maximum quality reduction factor.
				Usually the maximum reduction can be specfied in range of 0-3.
				A value of 0 means no quality reduction is allowed, so a full-quality image will be decoded as the first frame.
				A value of 1 means (1/2)^1=1/2 of the original image quality. 
				A value of 3 means (1/2)^3=1/8 of the original image quality. 
				If the reduction factor is not set by calling this function then
				the reduction factor value of 3 is used for jpeg images.
	@return KErrArgument if the aMaxReductionFactor parameter is not in the supported range, or a system-wide error code.
	*/	
	virtual TInt SetMaximumReductionFactor(TInt aMaxReductionFactor)=0;
	};

#endif // EXIFIMAGEDISPLAYEXT_H