/*

* 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:   Implementation of scrolling decelerator

*

*/

// INCLUDE FILES

#include <../bidi.h>

#include "WebScrollingDeceleratorGH.h"

#include "WebView.h"

#include "WebFrame.h"

#include "WebFrameView.h"

#include "WebPageScrollHandler.h"

#include "PlatformScrollbar.h"

#include "WebScrollbarDrawer.h"

#include "WebKitLogger.h"

using namespace RT_GestureHelper;

// constants

const int KRecordSize = 4;

// The following deceleration curve is generated by a script

// It lists the timeout dt values in microseconds.

const int KDecelCurveSize = 10;

const int KScrollIntervalTimeout = 60000; // scroll timer interval in microseconds

const float KDecceleration = -700.0;

int decelTimerCB(TAny* ptr);

// ============================ MEMBER FUNCTIONS ===============================

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

// WebScrollingDeceleratorGH::NewL

// The two-phase Symbian constructor

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

//

WebScrollingDeceleratorGH* WebScrollingDeceleratorGH::NewL(WebView& webView)

{

    WebScrollingDeceleratorGH* self = new (ELeave) WebScrollingDeceleratorGH(webView);

    CleanupStack::PushL(self);

    self->ConstructL();

    CleanupStack::Pop(); //self

    return self;

}

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

// WebScrollingDeceleratorGH::WebScrollingDeceleratorGH

// C++ default constructor can NOT contain any code, that

// might leave.

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

//

WebScrollingDeceleratorGH::WebScrollingDeceleratorGH(WebView& webView)

:  m_webView( webView )

{

}

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

// WebScrollingDeceleratorGH::ConstructL

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

void WebScrollingDeceleratorGH::ConstructL()

{

    m_decelTimer = CPeriodic::NewL(CActive::EPriorityStandard);

}

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

// Destructor

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

WebScrollingDeceleratorGH::~WebScrollingDeceleratorGH()

{

    delete m_decelTimer;

}

int WebScrollingDeceleratorGH::getDecceleration()

{

   return  KDecceleration;  

}

int decelTimerCB(TAny* ptr)

{

    (static_cast<WebScrollingDeceleratorGH*>(ptr))->scroll();

    return false;

}

void WebScrollingDeceleratorGH::cancelDecel() 

{ 

    m_decelelatorSwitch = false;

    if (m_decelTimer->IsActive()) {

        m_decelTimer->Cancel();

    }

}

void WebScrollingDeceleratorGH::startDecel(TRealPoint& speed, WebScrollbarDrawer* scrollbarDrawer)

{

    m_decelelatorSwitch = true;

    m_scrollbarDrawer = scrollbarDrawer;

    m_initSpeed.iX = (-1) * speed.iX;

    m_initSpeed.iY = (-1) * speed.iY;

    m_numscrollsteps = 0;

    if (m_decelTimer->IsActive()) {

        m_decelTimer->Cancel();

    }

    WebFrameView* scrollingView = m_webView.pageScrollHandler()->currentScrollingFrameView();

    if (scrollingView) {

        m_startPos = scrollingView->contentPos();

        m_lastPos = m_startPos;

        m_decelTimer->Start(0, KScrollIntervalTimeout, 

                            TCallBack(&decelTimerCB, this));

    }

}

void WebScrollingDeceleratorGH::scroll()

{

    if (!m_decelelatorSwitch) return;

    // X = Vst*t - 0.5*a*(t * t)    

    TPoint dist;

    TReal32 intervalInSec = static_cast<TReal32>(KScrollIntervalTimeout) / 1000000;

    TReal32 t = (m_numscrollsteps++) * intervalInSec;

    TReal32 dx = 0.0;

    TReal32 dy = 0.0;

    TReal32 vx = 0.0;

    TReal32 vy = 0.0;

    TReal32 accelX = 0.0;

    TReal32 accelY = 0.0;

    if (m_initSpeed.iX) {

        accelX = (m_initSpeed.iX > 0) ?  KDecceleration : (-1) * KDecceleration;

        vx = m_initSpeed.iX + accelX * t;

        dx = m_initSpeed.iX * t + 0.5 * accelX * (t * t);

    }

    if (m_initSpeed.iY) {

        accelY = (m_initSpeed.iY > 0) ?  KDecceleration : (-1) * KDecceleration;

        vy = m_initSpeed.iY + accelY * t;

        dy = m_initSpeed.iY * t + 0.5 * accelY * (t * t);

    }

    dist.SetXY(static_cast<TInt>(dx), static_cast<TInt>(dy));

    WebFrameView* scrollingView = m_webView.pageScrollHandler()->currentScrollingFrameView();

    TPoint cpos = scrollingView->contentPos();

    dist = scrollingView->toDocCoords(dist);

    TPoint pos = m_startPos + dist;

    WebPageScrollHandler* handler = m_webView.pageScrollHandler();

    if ((vx * m_initSpeed.iX < 0) || (vy * m_initSpeed.iY < 0) || (vx + vy == 0) || 

        (m_numscrollsteps > 1 && !scrollingView->needScroll(pos) && 

        !handler->currentScrollingElement())) {

        if (m_scrollbarDrawer) {

            m_scrollbarDrawer->fadeScrollbar();

        }

        m_decelTimer->Cancel();

        handler->clearScrollingElement();

        m_webView.setViewIsScrolling(false);

        m_webView.toggleRepaintTimer(true);

    }

    else {

        TPoint scrollDelta = pos - m_lastPos;

        handler->scrollContent(scrollDelta);

        m_lastPos = pos;

    }  

}

//  End of File