/*

* 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 "WebScrollingDecelerator.h"

#include "WebView.h"

#include "WebFrame.h"

#include "WebFrameView.h"

#include "WebPageScrollHandler.h"

#include "PlatformScrollbar.h"

// 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 = 40000; // scroll timer interval in microseconds

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

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

// WebScrollingDecelerator::NewL

// The two-phase Symbian constructor

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

//

WebScrollingDecelerator* WebScrollingDecelerator::NewL(WebView& webView)

{

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

    CleanupStack::PushL(self);

    self->ConstructL();

    CleanupStack::Pop(); //self

    return self;

}

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

// WebScrollingDecelerator::WebScrollingDecelerator

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

// might leave.

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

//

WebScrollingDecelerator::WebScrollingDecelerator(WebView& webView)

: CTimer(EPriorityHigh), m_webView( webView )

{

}

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

// WebScrollingDecelerator::ConstructL

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

void WebScrollingDecelerator::ConstructL()

{

    CTimer::ConstructL();

    CActiveScheduler::Add( this );

    m_dragPosition.Reset();

}

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

// Destructor

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

WebScrollingDecelerator::~WebScrollingDecelerator()

{

    Cancel();

}

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

// WebScrollingDecelerator::updatePos

// update record of position

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

//

void WebScrollingDecelerator::updatePos()

{

    if (m_dragPosition.Count() >= KRecordSize)

      {

        // pop item from front   

        m_dragPosition.Remove(0);

      }

    // and add this one to the end

    TPoint currPosition = m_webView.pageScrollHandler()->currentScrollingFrameView()->contentPos();

    m_dragPosition.Append(currPosition);

}

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

// WebScrollingDecelerator::startDecel

// initialize and start deceleration

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

//

void WebScrollingDecelerator::startDecelL()

{

    int count = m_dragPosition.Count();

    m_normalizedCurrentPosition.iX = m_webView.pageScrollHandler()->currentScrollingFrameView()->contentPos().iX * 100;

    m_normalizedCurrentPosition.iY = m_webView.pageScrollHandler()->currentScrollingFrameView()->contentPos().iY * 100;

    if (count > 0)

      {     

      // set the delta based upon the change span of points collected averaged over the span, so long as we have moved

        int dx = (m_dragPosition[count - 1].iX - m_dragPosition[0].iX)* 100;

        int dy = (m_dragPosition[count - 1].iY - m_dragPosition[0].iY) * 100;

        if (abs(dx) > 0 || abs(dy) > 0)

            {           

            m_scrolldelta.SetXY( (dx/count), (dy/count) );

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

            m_scrolldelta = view->toDocCoords(m_scrolldelta);

            // init num steps

            m_numscrollsteps = 0;

            // call the RunL function directly, this first time. CTimer will call it from now on.

            m_decelelatorSwitch = ETrue;

            RunL();

            }

        }

        m_dragPosition.Reset();

}

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

// WebScrollingDecelerator::RunL

// continue deceleration

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

//

void WebScrollingDecelerator::RunL()

{

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

    // use a pre-calulated deceleration curve to calculate dt

    if ((m_numscrollsteps >= KDecelCurveSize ) || !m_decelelatorSwitch)

      {

        // done

        Cancel();

        m_webView.setViewIsScrolling(false);

        return;

      }

    // step to next

    m_numscrollsteps++;

    // do the scrolling

    if (m_webView.pageScrollHandler() && scrollingView) {

        TPoint newpos;

        /* With each step decrease m_scrolldelta by 50% */

        m_scrolldelta.iX = m_scrolldelta.iX >> 1;

        m_scrolldelta.iY = m_scrolldelta.iY >> 1;

        m_normalizedCurrentPosition += m_scrolldelta;

        newpos.iX = m_normalizedCurrentPosition.iX/100;

        newpos.iY = m_normalizedCurrentPosition.iY/100;

        scrollingView->scrollTo(newpos);

        if (scrollingView->vScrollbar()) {

            scrollingView->vScrollbar()->setValue(newpos.iY);

        }

        if (scrollingView->hScrollbar()) {

            scrollingView->hScrollbar()->setValue(newpos.iX);

        }

        After(KScrollIntervalTimeout);

    }

}

//  End of File