// Copyright (c) 2009 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:

 // Interface for Scene Elements

 // 

 //

 /**

  @publishedPartner

  @prototype

 */

 #ifndef WSELEMENT_H

 #define WSELEMENT_H

 #include <w32std.h>

 #include <graphics/wsgraphicdrawerinterface.h>

 #include <graphics/surface.h>

 /**

  * @brief Window Server Scene Element Interface Definition

  *

  * This interface allows Image Sources to be associated with meta-data

  * to define how the Image Source must be presented within a Scene.

  *

  * For a conceptual overview of Scenes, refer to the @c MWsScene Interface.

  *

  * The following aspects of Image Source presentation may be controlled:

  * @li Source rectangular region

  * @li Destination rectangular region

  * @li Rotation and flipping

  * @li Opacity

  * @li Relative z-order (ordinal position)

  * @li Tags to descriminate the UI from other Elements

  *

  * All co-ordinates are pixels offsets from (0,0) representing the

  * top level of the Image Source or Destination Target (the screen

  * or an off-screen buffer representing the screen), moving rightwards

  * and downwards in x and y co-ordinates respectively.

  *

  * Elements can be marked with flags.  There are two different consumers

  * of flags: Target Renderers and Render Stage Plug-ins.

  * 

  * Target Renderers are sub-systems which actually do composition and

  * rendering on a particular display device or off-screen buffer.

  * The EElementTransparencySource flag tells the Target Renderer that 

  * alpha blending must use the alpha channel in the Surface connected to

  * the Element.

  * 

  * On the other hand, Render Stage Plug-ins need flags to implement

  * specific policies such as "UI always on top".  To facilitate this,

  * Elements have a EElementIsIndirectlyRenderedUserInterface or a

  * EElementIsDirectlyRenderedUserInterface optionally set.  This

  * flag allows Render Stage Plug-ins to keep the relative z-order

  * of Elements aligned to this policy.

  * 

  * To allow compatible updates to be made to flags, all Render Stage

  * Plug-ins must preserve the flags in Elements which they do not operate

  * upon.  Target Renderers may ignore the flags in Elements which they

  * do not operate on.

  *

  * <h2>Intial State</h2>

  * 

  * The initial state for an Element is:

  * @li Fully opaque

  * @li No rotation, nor flipped

  * @li Not part of the Committed Scene

  * @li No connected Surface

  * @li All flags reset

  * @li Local error value set as KErrNone

  * @li Source Rectangle and Destination Rectangle is (0,0,0,0)

  * @il Destination Clipping Rectangle is (0,0,0,0)

  * 

  * When an Image Source is connected, the initial state becomes:

  * @li Source Rectangle is the extent of the Image Source

  * @li Destination Rectangle is set at origin (0,0), whose sized equals the

  *     Image Source size truncated the the target screen size.

  * @li Destination Clipping Rectangle is (0,0,0,0) to represent the entire

  *     area of the target screen.

  * 

  * <h2>Special Rectangle Values</h2>

  * 

  * Sometimes it is desirable to reset a Source, Destination, or Clipping

  * Rectangle so that the actual value used matches the corresponding Source

  * Image or Target Screen size.  In such cases rectangle (0,0,0,0) is used to

  * represent this.

  * 

  * <h2>Extending this interface</h2>

  * 

  * This interface can be extended in two different ways

  * @li Creating optional extension interfaces with 

  *       MWsElement::MWsObjectProvider::ResolveObjectInterface()

  * @li Defining new TElementFlags flag settings; Render Stage Plug-ins

  *       preserve the value of these across the Render Stage Pipeline.

  *

  * <h2>Committed Elements versus Pending Elements</h2>

  * 

  * This interface allows Elements to be modified in terms of their

  * own flag settings, and rotation, as well as their relative position

  * with other Elements.  Queries return the pending values for such

  * Elements.  Any modifications are marked Pending, and affect the Scene

  * according to the rules described by "Rendering" in @c MWsScene.

  * 

  * <h2>Order in which transformations are applied</h2>

  * 

  * A number of different transformations may be specified for an Element.

  * The order in which these are applied to arrive at the view seen in

  * the target is:

  * -# SetSourceRectangle              (Cropping)

  * -# SetSourceFlipping               (Flipping)

  * -# SetSourceRotation               (Rotation)

  * -# SetDestinationRectangle         (Scaling and Positioning)

  * -# SetDestinationClippingRectangle (Scaling and Positioning)

  * -# SetGlobalAlpha                  (Blending)

  */

 class MWsElement : public MWsObjectProvider

     {

 public:

     /**

      * @brief Flags used by Target Renderers.

      */

     enum TElementTargetRendererFlags

         {

         /**

          * Target renderer must treat the Element as Opaque.

          */

         EElementTransparencyNone                 = 0,

         /**

          * Target renderer must use the Global Alpha Transparency value

          * from the Element

          */

         EElementTransparencyGlobalAlpha          = (1 << 0),

         /**

          * Target renderer must use the Alpha Transparency Channel from

          * the Element

          */

         EElementTransparencySource               = (1 << 1),

         /**

          * Reserved flag value; this must not be set.

          */

         EElementTargetRendererReserved           = (1 << 2)

         };

     /**

      * @brief Flags used by Render Stages.

      */

     enum TElementRenderStageFlags

         {

         /**

          * No flag value set for Render Stage Plug-in

          */

         EElementRenderStageNone                   = 0,

         /**

          * Indirectly Rendered User Interface, i.e. rendering via 

          * MWsGraphicsContext calls originating from client CWindowGc

          * commands

          */

         EElementIsIndirectlyRenderedUserInterface = (1 << 0),

         /**

          * Directly Render User Interface, i.e. rendering where Window

          * Server does not see the graphics commands, as is the case for

          * Direct Screen Access clients.

          */

         EElementIsDirectlyRenderedUserInterface   = (1 << 1),

         /**

          * Reserved values for future Render Stage Plug-in usage

          */

         EElementRenderStageReserved               = (1 << 2)

         };

     /**

      * Amount of rotation of pixel data to apply to the Image Source

      * to obtain the Target Image

      */

     enum TElementRotation

         {

         EElementAntiClockwise0   = 0, /** No rotation */

         EElementAntiClockwise90  = 1, /** 90 Degrees Anti-clockwise in target */

         EElementAntiClockwise180 = 2, /** 180 Degrees Anti-clockwise in target */

         EElementAntiClockwise270 = 3  /** 270 Degrees Anti-clockwise in target */

         };

 public:

     /**

      * @brief Set which portion of the image source is used.

      *

      * Set which rectangular portion of the connected image source

      * will be used when displaying this Element.

      *

      * @param aSrc  The source rectangle of pixels from the connected Image Source.

      *              This rectangle must not include any pixels outside the Image

      *              Source.  (0,0,0,0) means the entire size of the Image Source.

      * @pre     An Image Source must have been connected; @see ConnectSurface()

      * @return  One of the system-wide error codes.  

      *          KErrGeneral, if there is no image source connected.

      *          KErrArgument, if the source rectangle includes pixels not in the 

      *          connected image source, or has negative width or height.  

      *          KErrNone, if successful.

      */

     virtual TInt SetSourceRectangle(const TRect& aSrc) = 0;

     /**

      * @brief Get the portion of the Image Source being used.

      *

      * Get the portion of the connected Image Source being used.  The default

      * value is the entire extent of the connected Image Source.

      *

      * @param aSrc  The source rectangle is updated with the current rectangular

      *              region being used within the Image Source.

      * @pre     An Image Source must have been connected; @see ConnectSurface()

      * @return  One of the system-wide error codes.  

      *          KErrGeneral, if no Image Source has been connected.  

      *          KErrNone, if successful.

      */

     virtual TInt GetSourceRectangle(TRect& aSrc) = 0;

     /**

      * @brief Set the target area where the Image Source should appear.

      * 

      * Set the target area in the target screen (or off-screen buffer)

      * where the Image Source should appear.  Scaling may result if

      * the source and destination rectangles differ.  A platform specific

      * algorithm will be used to interpolate the scaled image.

      * 

      * @param aDest  The destination rectangle in the target.

      * @pre     An Image Source must have been connected; @see ConnectSurface()

      * @return  One of the system-wide error codes.  

      *          KErrGeneral, if there is no image source connected. 

      *          KErrArgument, if the destination rectangle has negative width or 

      *          height.  

      *          KErrNone, if successful.

      */

     virtual TInt SetDestinationRectangle(const TRect& aDest) = 0;

     /**

      * @brief Get the target area where the Image Source would appear.

      * 

      * Get the target area where the Image Source would appear.  The default

      * value is at (0,0) sized to the Image Source clipped to the size

      * of the target.

      * 

      * @param aDest  The destination rectangle is updated with the current

      *               region used in the target screen. 

      * @pre     An Image Source must have been connected; @see ConnectSurface()

      * @return  One of the system-wide error codes.  

      *          KErrGeneral, if no Image Source has been connected.  

      *          KErrNone, if successful.

      */

     virtual TInt GetDestinationRectangle(TRect& aDest) const = 0;

     /**

      * @brief Clip the target area where the Image Source would appear.

      * 

      * Set clipping area where the Image Source would appear.  The default

      * value is the area of the target screen.

      * 

      * @param aDestClipRect  The clipping rectangle in the target.  (0,0,0,0)

      *                       means the entire size of the Target Screen.

      * @return  One of the system-wide error codes.  

      *          KErrGeneral, if no Image Source has been connected. 

      *          KErrArgument, if the rectangle has negative width or height  

      *          KErrNone, if successful.

      */

     virtual TInt SetDestinationClippingRect(const TRect& aDestClipRect) = 0;

     /**

      * @brief Get the clipping area in the target.

      * 

      * Get the clipping area which limits where in the target screen the

      * element may appear.

      * 

      * @param aDestClipRect  The clipping rectangle is updated with the current

      *                       clipping area used in the target screen.

      * @return  One of the system-wide error codes.  KErrGeneral means no Image

      *          Source has been connected.  KErrNone is returned upon success.      

      */

     virtual TInt GetDestinationClippingRect(TRect& aDestClipRect) const = 0;

     /**

      * @brief Set the rotation that should appear in the target for the

      * Image Source.

      * 

      * Set the rotation which describes how the connected Image Source

      * should be rotated to appear in the target.

      * 

      * @param aElementRotation  The amount of rotation in the target.

      * @pre     An Image Source must have been connected; @see ConnectSurface()

      * @return  One of the system-wide error codes.  

      *          KErrGeneral, if no Image Source has been connected.  

      *          KErrArgument, if an out of bounds rotation value has been 

      *          supplied.  

      *          KErrNone, if successful.

      */

     virtual TInt SetSourceRotation(const TElementRotation aElementRotation) = 0;

     /**

      * @brief Get the pending rotation setting as it would appear in the target.

      * 

      * Get the pending rotation setting for the connected Image Source.

      * By default, the rotation is EElementAntiClockwise0 and this is returned

      * if there is no connected Image Source.

      * 

      * @return  The pending rotation setting.

      */

     virtual TElementRotation SourceRotation() const = 0 ;

     /**

      * @brief Set flipping about the image horizontal centerline.

      * 

      * Set the pending flipping setting for the connected Image Source.

      * When flipped, the Image Source appears in the target as inverted

      * about its horizontal centerline.  This effect can be combined

      * with rotation effects.

      * By default, the Image Source is not flipped.

      * 

      * @param aFlip  If ETrue, the connected Image is flipped, else

      *               it is not flipped.

      * @pre     An Image Source must have been connected; @see ConnectSurface()

      * @return  One of the system-wide error codes.  

      *          KErrGeneral, if no Image Source has been connceted.  

      *          KErrNotSupported, if the platform does not support the feature.  

      *          KErrNone, if successful.

      */

     virtual TInt SetSourceFlipping(const TBool aFlip) = 0;

     /**

      * @brief Get the pending flipping setting.

      * 

      * Get the pending flipping setting for the connected Image Source.

      * By default, the image is not flipped.

      * 

      * @return  The pending flipping setting.  If no Image is connected, return

      *          EFalse.

      */

     virtual TBool SourceFlipping() const = 0 ;

     /**

      * @brief Set Target Renderer Flags associated with this Element

      * 

      * Set the Target Renderer flags to be associated with this Element.

      * 

      * @note    Flags which are not recognised by an implementation must

      *          be kept to allow the interface to be extended in a 

      *          compatible manner.

      * @param aTargetRendererFlags  Flags to set for Target Renderer;

      *                              @see TElementTargetRendererFlags

      * @return  One of the system-wide error codes.  

      *          KErrNotSupported, if the platform does not support the given 

      *          flags.  

      *          KErrArgument, if incompatible flag settings have been made.  

      *          KErrNone, if successful.

      */

     virtual TInt SetTargetRendererFlags(const TUint32& aTargetRendererFlags) = 0;

     /**

      * @brief Set Render Stage Flags associated with this Element

      * 

      * Set the Render Stage flags to be associated with this Element.

      * 

      * @note    Flags which are not recognised by an implementation must

      *          be kept to allow the interface to be extended in a 

      *          compatible manner.

      * @param aRenderStageFlags  Flags to set for Render Stage Plug-ins;

      *                           @see TElementRenderStageFlags

      * @return  One of the system-wide error codes.  

      *          KErrNotSupported, if the platform does not support the given 

      *          flags.  

      *          KErrArgument, if incompatible flag settings have been requested.  

      *          KErrNone, if successful.

      */

     virtual TInt SetRenderStageFlags(const TUint32& aRenderStageFlags) = 0;

     /**

      * @brief Get Target Renderer Flags associated with this Element

      * 

      * Get the Target Renderer flags associated with this Element.

      *   

      * @note    Flags which are not recognised by an implementation must

      *          be kept to allow the interface to be extended in a 

      *          compatible manner.

      * @param aTargetRendererFlags  Variable to receive TElementTargetRendererFlags

      */

     virtual void GetTargetRendererFlags(TUint32& aTargetRendererFlags) const = 0;

     /**

       * @brief Get Render Stage Flags associated with this Element

       * 

       * Get the Render Stage flags associated with this Element.

       *   

       * @note    Flags which are not recognised by an implementation must

       *          be kept to allow the interface to be extended in a 

       *          compatible manner.

       * @param aRenderStageFlags  Variable to receive TElementRenderStageFlags

       */

      virtual void GetRenderStageFlags(TUint32& aRenderStageFlags) const = 0;   

     /**

      * @brief Get the Element above this Element.

      * 

      * Get the Element which is above this Element in the Pending Scene.

      * If the Element is the top-most element, NULL is returned.  If the

      * Element is not in the Scene, NULL is returned.

      * 

      * @return Element above, or NULL.

      */

     virtual MWsElement *ElementAbove() = 0;

     /**

      * @brief Get the Element below this Element.

      * 

      * Get the Element which is below this Element in the Pending Scene.

      * If the Element is the bottom-most element, NULL is returned.  If the

      * Element is not in the Scene, NULL is returned.

      * 

      * @return Element below, or NULL.

      */

     virtual MWsElement *ElementBelow() = 0;

     /**

      * @brief Connect or re-Connect a Surface to this Element.

      * 

      * Connect the given Surface to this Element, or re-Connect a new

      * Surface to this Element which already has a connected Surface.

      * The Element does not need to be in the Scene when this call is made.

      * 

      * @note    The Source Rectangle of the Element is updated to correspond

      *          to match the Source Rectangle of the Surface.  Thus any

      *          prior Source Rectangle setting will be overwritten.

      * 

      * @param aSurface  Surface to connect to.  If this is the Null

      *                  Surface, then the Source Rectangle of the

      *                  Element is set to (0,0,0,0).

      * @return  One of the system-wide error codes.  

      *          KErrArgument, if supplied Surface cannot be connected.  For 

      *          example the Element has a flag indicating it has an Alpha 

      *          Channel but the Surface does not.  

      *          KErrNone, if successful.

      */

     virtual TInt ConnectSurface(const TSurfaceId& aSurface) = 0;

     /**

      * @brief Get the Surface connected to this Element

      * 

      * @return  The Surface Identifier of the Connected Surface.  This

      *          identifier may represent the Null Surface Id if there

      *          was no Surface connected in the Pending Scene for this

      *          Element.

      */

     virtual const TSurfaceId& ConnectedSurface() const = 0;

     /**

      * @brief Set the Global Alpha Transparency value

      * 

      * Sets the Global Alpha Transparency value for this Element.  Elements

      * are by default fully opaque, represented by opacity 255.  On platforms

      * that support it, the Alpha Transparency value can be reduced down

      * to 0 representing fully transparent.  The purpose of this is to

      * allow the fading in and fading out of Elements into the Scene.

      * 

      * @param aAlpha  The Alpha Transparency value desired.  Values

      *                are clamped to be within the range [0, 255] where 0

      *                represents fully transparent, and 255 represents

      *                fully opaque.

      * @note    This setting has no effect unless the flag

      *          Target Renderer flag EElementTransparencyGlobalAlpha

      *          is set; @see SetTargetRendererFlags()

      * @note    Out of range values are clamped silently, and do not cause

      *          error conditions.

      * @return  One of the system-wide error codes.  

      *          KErrNotSupported, if the supplied value, once clamped, is not 

      *          supported on the platform.

      *          KErrNone, if successful.

      */

     virtual TInt SetGlobalAlpha(const TInt aAlpha) = 0;

     /**

      * @brief Get the Global Alpha Transparency value

      * 

      * Gets the Global Alpha Transparency value for this Element.  Elements

      * are by default fully opaque, represented by opacity 255.

      * 

      * @param aAlpha  Variable which receives the Global Alpha Transparency

      *                value.

      */

     virtual void GlobalAlpha(TInt& aAlpha) const = 0;

     };

 #endif // WSELEMENT_H