/*

* Copyright (c) 2004-2008 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:  Alpha Blend provides functionality to combine masked images with Porter-Duff

*                operations.

*

*/

#ifndef AKNSRLEFFECTPLUGINALPHABLEND_H

#define AKNSRLEFFECTPLUGINALPHABLEND_H

//  INCLUDES

#include "AknsRlEffectPlugin.h"

#include <AknsRlEffect.h>

// CONSTANTS

// Effect plugin UID

const TInt KAknsRlEffectPluginAlphaBlendUID = 0x10204ADD;

// Constants for parameter names

_LIT( KAknsRlEffectAlphaBlendARed,   "ar" );

_LIT( KAknsRlEffectAlphaBlendAGreen, "ag" );

_LIT( KAknsRlEffectAlphaBlendABlue,  "ab" );

_LIT( KAknsRlEffectAlphaBlendBRed,   "br" );

_LIT( KAknsRlEffectAlphaBlendBGreen, "bg" );

_LIT( KAknsRlEffectAlphaBlendBBlue,  "bb" );

_LIT( KAknsRlEffectAlphaBlendAMask,  "am" );

_LIT( KAknsRlEffectAlphaBlendBMask,  "bm" );

_LIT( KAknsRlEffectAlphaBlendMode,   "m" );

// FORWARD DECLARATIONS

class CAknsRlScanlines;

// CLASS DECLARATION

/**

* Alpha Blend provides functionality to combine masked images with Porter-Duff

* operations. The used blend modes follow reference: T. Porter and T. Duff,

* "Compositing Digital Images", SIGGRAPH 84, 253-259.

*

* Blending modes have A, B and Clear been dropped because they are pointless.

* Also the plus mode has not been implemented.

*

* @since 2.8

*/

NONSHARABLE_CLASS(CAknsRlEffectPluginAlphaBlend):

    public CAknsRlEffectPlugin,

    public MAknsRlEffect

    {

    public:

        /**

        * Flags for marking set parameters, internally used.

        */

        enum TConstantFlag

            {

            EConstantAColor = 0x01,

            EConstantBColor = 0x02,

            EConstantAMask  = 0x04,

            EConstantBMask  = 0x08

            };

    public: // Constructors and destructor

        /**

        * Default constructor.

        *

        * @since 2.8

        */

        CAknsRlEffectPluginAlphaBlend();

        /**

        * Destructor.

        *

        * @since 2.8

        */

        virtual ~CAknsRlEffectPluginAlphaBlend();

    public: // Functions from base classes

        TUid EffectUid() const;

        MAknsRlEffect* Effect( const TInt aInterface );

    public: // Implementation of MAknsRlEffect

        void InitializeL();

        void Release();

        void ActivateL( MAknsRlEffectContext* aContext );

        void Deactivate();

        /**

        * Accepted named parameters:

        *

        * Constant color A:

        * - "ar", integer, channel value for red, truncated to range [0, 255]

        * - "ag", integer, channel value for green, truncated to range [0, 255]

        * - "ab", integer, channel value for blue, truncated to range [0, 255]

        * Constant color B:

        * - "br", integer, channel value for red, truncated to range [0, 255]

        * - "bg", integer, channel value for green, truncated to range [0, 255]

        * - "bb", integer, channel value for blue, truncated to range [0, 255]

        * Constant mask A:

        * - "am", integer, 8-bit shade, truncated to range [0, 255]

        * Constant mask B:

        * - "bm", integer, 8-bit shade, truncated to range [0, 255]

        * Blend mode:

        * - "m", integer (enumeration), one of the Porter-Duff blend modes

        *

        * Constant color A and B:

        * If any of the A color channel values is set the processing will use a

        * constant color for A. The same goes with B. If the processed bitmaps

        * are grayscale the constant colors are converted to grayscale shade.

        *

        * The next input/output combinations are supported:

        *

        *      A | B | T    A | B | T     A | B | T

        *      ---------    ----------    ----------

        *      8 | 8 | 8    16| 16| 16    32| 32| 32

        *      8 | C | 8    16| C | 16    32| C | 32

        *      C | 8 | 8    C | 16| 16    C | 32| 32

        *      C | C | 8    C | C | 16    C | C | 32

        *

        *  A = input layer A, B = input layer B, T = target layer

        *  8 = 8-bit grayscale bitmap (EGray256)

        * 16 = 16-bit RGB bitmap (EColor64K)

        * 32 = 24-bit unpacked RGB bitmap (EColor16MU)

        *  C = 24-bit constant color (converted to 8-bit gray if

        *      needed)

        *

        * Constant mask A and B:

        * If constant mask A is set the processing will use constant mask for

        * A. The same goes for mask B. The next mask combinations are

        * supported:

        *

        *      MA|MB

        *      -----

        *      8 | 8       MA = input mask A, MB = input mask B

        *      8 | C       8 = 8-bit grayscale bitmap (EGray256)

        *      C | 8       C = 8-bit constant shade

        *      C | C

        *

        * Blend mode:

        * Defines the used alpha blend operation. Possible values are defined

        * in enumeration TAknsRlAlphaBlendMode. Using any other value will

        * cause leave.

        *

        * Default values:

        * - "ar" = 255

        * - "ag" = 255

        * - "ab" = 255

        * - "br" = 255

        * - "bg" = 255

        * - "bb" = 255

        * - "am" = 255

        * - "bm" = 255

        * - "m"  = EAknsRlAlphaBlendAOverB

        *

        * Note that constant color and constant mask values are not used by

        * default. You must pass at least one value per constant (yes, a

        * default value for constant mask is actually quite pointless).

        */

        void SetParametersL( MAknsRlParameterIterator& aParameters );

        /**

        * Supported modes:

        * - EColor64K -> EColor64K

        * - EColor16MU -> EColor16MU

        * - EGray256 -> EGray256

        */

        void GetCapabilities( TAknsRlEffectCaps& aCaps );

        /**

        * Defining constants allows dropping layers. If color constant and mask

        * constant are both defined the corresponding layer is never queried.

        * In other cases the layer is queried but defining a constant allows

        * omitting the corresponding bitmap.

        *

        * The target layer may or may not have mask bitmap. If target mask

        * bitmap exists it is filled with white.

        */

        TInt Render( const TAknsRlRenderOpParam& aParam );

        void DoRenderL( const TAknsRlRenderOpParam& aParam );

    private:

        MAknsRlEffectContext* iContext;

        TUint8 iBlendMode;

        /**

        * Any constants set during the parameter iteration are flagged here

        * using TConstantFlags.

        */

        TUint8 iFlags;

        TUint8 iARed;

        TUint8 iAGreen;

        TUint8 iABlue;

        TUint8 iBRed;

        TUint8 iBGreen;

        TUint8 iBBlue;

        TUint8 iAMask;

        TUint8 iBMask;

        // Cache for constant scanlines, reduces memory allocations for

        // constant scanlines during animations.

        CAknsRlScanlines* iScans;

    };

#endif // AKNSRLEFFECTPLUGINALPHABLEND_H

// End of File