/*

* Copyright (c) 2008 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 "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:  Gesture helper implementation

*

*/

#include "gesturerecogniser.h"

#include <e32math.h>

#include "gesturedefs.h"

#include "rt_gestureobserver.h"

#include "pointarray.h"

#include "utils.h"

using namespace RT_GestureHelper;

/**

 * Vector class (math)

 */

NONSHARABLE_CLASS( TVector )

    {

public:

    /** 

     * Constructor

     * @param aFrom starting point of the vector

     * @param aTo ending point of the vector

     */

    TVector( const TPoint& aFrom, const TPoint& aTo )

            : iX( aTo.iX - aFrom.iX ),

              iY( aTo.iY - aFrom.iY )

        {

        }

    /** @return angle of the vector */

    TReal Angle() const

        {

        TReal angle = 0;   

        TReal length = Length();

        if ( length != 0 )

            {

            Math::ACos( angle, iX / Length() );

            if ( iY < 0 )

                {

                angle = 2 * KPi - angle;

                }

            }

        return Degrees( angle ); 

        }

    /** @return length of the vector */

    TReal Length() const

        {

        TReal length = 0;

        Math::Sqrt( length, iX * iX + iY * iY );

        return length;

        }

private:

    /** @return radians in degrees */

    inline TReal Degrees( TReal aRadians ) const

        {

        return aRadians * 180 / KPi;

        }

public:

    /// x coordinate that represent the vector

    TReal iX;

    /// y coordinate that represent the vector

    TReal iY;

    };

inline TPoint LastPoint( const TPointArray& aPoints ) 

    {

    __ASSERT_DEBUG( aPoints.Count() > 0, Panic( EGesturePanicIllegalLogic ) );

    return aPoints[ aPoints.Count() - 1 ] ;

    }

/** 

 * @return Length of the gesture in points

 */

inline TReal GestureLength( const TPointArray& aPoints )

    {

    return TVector( aPoints[0], LastPoint( aPoints ) ).Length();

    }

/** 

 * @return ETrue if aAngleUnderTest is almost aAngle

 *         Closeness of the angles is controlled by KAngleTolerance

 */

static TBool IsNear( TReal aAngleUnderTest, TReal aAngle )

    {

    return aAngle - KAngleTolerance <= aAngleUnderTest && 

           aAngleUnderTest <= aAngle + KAngleTolerance;

    }

/**

 * @return the angle as a direction flags of TGesture

 */

inline TGestureCode Direction( TReal aAngle ) 

    {

    TGestureCode direction = EGestureUnknown;

    if ( IsNear( aAngle, 90.0 ) )

        {

        direction = EGestureSwipeDown;

        }

    else if ( IsNear( aAngle, 180.0 ) )

        {

        direction = EGestureSwipeLeft;

        }

    else if ( IsNear( aAngle, 270.0 ) )

        {

        direction = EGestureSwipeUp;

        }

    else if ( 360.0 - KAngleTolerance <= aAngle || aAngle <= KAngleTolerance )

        {

        direction = EGestureSwipeRight;

        }

    else // for lint warning

        {

        // unknown angle

        }

    return direction;

    }

/** @return direction between points */

inline TGestureCode Direction( const TPoint& aFromPoint, const TPoint& aToPoint )

    {

    return Direction( TVector( aFromPoint, aToPoint ).Angle() );

    }

/** @return overall direction between points */

static TGestureCode GeneralDirection( const TPointArray& aPoints ) 

    {

    // If the start and end points are too close to each other, direction

    // is undefined

    if ( ToleranceRect( aPoints[0] ).Contains( LastPoint( aPoints ) ) )

        {

        return EGestureUnknown;

        }

    return Direction( aPoints[0], LastPoint( aPoints ) );

    }

// function type to get a point in the point array

typedef TPoint (TPointArray::*PointByIndexFunc)( TInt aIndex ) const;    

/// @return latest point outside tolerance area or KErrNotFound if not point outside it

TInt LatestCertainPointIndex( const TPointArray& aPoints, PointByIndexFunc aPointByIndex )   

    {

    __ASSERT_DEBUG( aPoints.Count() > 0, Panic( EGesturePanicIllegalLogic ) );

    int i = aPoints.Count();

    TRect toleranceRect = ToleranceRect( (aPoints.*aPointByIndex)( aPoints.Count() - 1 ) );

    // Find out the first point from the end of the array  

    // that is not contained in the tolerance rect.

    while( 0 <= --i )

        {

        // if the point does not belong inside tolerance rect, it is the first point

        // outside the rect

        if( !toleranceRect.Contains( (aPoints.*aPointByIndex)(i) ) )

            {

            break;

            }

        }

    return i;

    }

/** @return last direction of dragging */

inline TGestureCode LastDirection( const TPointArray& aPoints ) 

    {

    TInt latestPointIndex = LatestCertainPointIndex( aPoints, TPointArray::operator[] );

    if ( KErrNotFound != latestPointIndex )

        {

        return Direction( aPoints[latestPointIndex], LastPoint( aPoints ) );

        }

    // no points were outside the rect, and hence the direction is unknown

    return EGestureUnknown;

    }

/**

 * @return ETrue if points for a tap event

 */

inline TBool IsTap( const TPointArray& aPoints )

    {

    return KErrNotFound == LatestCertainPointIndex( aPoints, TPointArray::Raw );

    }  

// ----------------------------------------------------------------------------

// Return gesture code of a gesture formed by a sequence of points

// ----------------------------------------------------------------------------

//

TGestureCode TGestureRecogniser::GestureCode( const TPointArray& aPoints ) const

    {

    __ASSERT_DEBUG( aPoints.Count() > 0, Panic( EGesturePanicIllegalLogic ) );

    // tap needs to be treated separately, because recognising that needs to consider

    // raw points (and not points in which x or y axis has been filtered out)

    if ( IsTap( aPoints ) )

        {

        return EGestureTap;

        }

    TGestureCode direction = GeneralDirection( aPoints );

    // if last direction is opposite of the general one, user has cancelled a swipe

    if ( direction != LastDirection( aPoints ) )

        {

        direction = EGestureUnknown;

        }

    return direction;

    }