/*

* Copyright (c) 2004 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:    Image Transforms subsystem.

*

*/

#ifndef CVTIMAGESCALERIMPL_H

#define CVTIMAGESCALERIMPL_H

// INCLUDE FILES

#include <e32base.h>

#include <bitmaptransforms.h>

// FORWARD DECLARATIONS

class CVtImage;

// CLASS DECLARATIONS

/**

*  Image scaler implementation.

*

*  @lib videosource.lib

*/

class CVtImageScalerImpl : public CActive

    {

    protected:

        /**

         * Constructor.

         */

        CVtImageScalerImpl();

    public:

        /**

         * Destructor.

         */

        ~CVtImageScalerImpl();

        /**

        * Sets scaler params.

        * @param "aParams" Scaling params, including source and target images.

        * @exception In error situation leaves with one of the system wide

        * error codes.

        */

        void SetSourceTargetL( const CVtImage& aSource, CVtImage& aTarget );

        /**

        * Method to check whether bitmap heap locking is needed or not during

        * scaling process.

        * @exception In error situation leaves with one of the system wide

        * error codes.

        * @return ETrue if bitmap heap lock is needed, EFalse otherwise.

        */

        TBool NeedHeapLock() const;

        /**

        * Pure virtual scaling method.

        * @param "aContinue" When method returns, this parameter will contain

        * ETrue if new call is needed (i.e. scaling is not yet finished) or

        * EFalse if scaling is complete.

        * @return KErrNone or one of the system wide error codes.

        */

        virtual TInt Scale( TBool& aContinue ) = 0;

    protected:

        /**

         * Scales using CBitmapScaler, which is slow but works with any

         * Symbian color mode.

         * @param aQuality Scaling quality @see CBitmapScaler::TQualityAlgorithm

         * @exception In error situation leaves with one of the system wide

         * error codes.

         */

        void ScaleWithBitmapScalerL(

            const CBitmapScaler::TQualityAlgorithm aQuality );

    private:

        /**

        * Pure virtual source and target image validation method.

        * @param "aSource" Constant reference to source image.

        * @param "aTarget" Constant reference to target image.

        * @exception If source or target is not valid, this method leaves

        * with KErrNotSupported.

        */

        virtual void ValidateSourceTargetL(

            const CVtImage& aSource,

            CVtImage& aTarget ) = 0;

        /**

        * Method for validating image size.

        * @param "aSize" Size to be validated.

        * @param "aMinSize" Minimum allowed size. If this is not given a default

        * size of TSize( 1, 1 ) is used.

        * @exception If size is not valid within given parameters, this

        * method leaves with KErrNotSupported.

        */

        void LeaveIfNotValidSizeL(

            const TSize& aSize,

            const TSize aMinSize = TSize( 1, 1 ) );

    private: // from CActive

        /**

         * @see CActive::RunL

         */

        void RunL();

        /**

         * @see CActive::DoCancel

         */

        void DoCancel();

    protected:

        // Source for scaling

        const CVtImage* iSource; // not owned

        // Target image (will hold scaled source)

        CVtImage* iTarget; // not owned

        // Bitmap scaler instance

        CBitmapScaler* iScaler;

        // Active scheduler waiter object

        CActiveSchedulerWait iActiveSchedulerWait;

    };

#endif // CVTIMAGESCALERIMPL_H

// End of File