/*****************************************************************
 KWin - the KDE window manager
 This file is part of the KDE project.

Copyright (C) 2008 Cédric Borgese <cedric.borgese@gmail.com>

You can Freely distribute this program under the GNU General Public
License. See the file "COPYING" for the exact licensing terms.
******************************************************************/


#include "wobblywindows.h"

#include <kdebug.h>
#include <kconfiggroup.h>
#include <math.h>

#define USE_ASSERT
#ifdef USE_ASSERT
#define ASSERT1 assert
#else
#define ASSERT1
#endif

//#define COMPUTE_STATS

// if you enable it and run kwin in a terminal from the session it manages,
// be sure to redirect the output of kwin in a file or
// you'll propably get deadlocks.
//#define VERBOSE_MODE

#if defined COMPUTE_STATS && !defined VERBOSE_MODE
#   ifdef __GNUC__
#       warning "You enable COMPUTE_STATS without VERBOSE_MODE, computed stats will not be printed."
#   endif
#endif

namespace KWin
{

static const qreal STIFFNESS = 0.15;
static const qreal DRAG = 0.80;
static const qreal MOVEFACTOR = 0.10;

static const int XTESSELATION = 20;
static const int YTESSELATION = 20;

static const qreal MINVELOCITY = 0.0;
static const qreal MAXVELOCITY = 1000.0;
static const qreal STOPVELOCITY = 0.5;
static const qreal MINACCELERATION = 0.0;
static const qreal MAXACCELERATION = 1000.0;
static const qreal STOPACCELERATION = 5.0;

struct ParameterSet
{
    qreal stiffness;
    qreal drag;
    qreal move_factor;

    qreal xTesselation;
    qreal yTesselation;

    qreal minVelocity;
    qreal maxVelocity;
    qreal stopVelocity;
    qreal minAcceleration;
    qreal maxAcceleration;
    qreal stopAcceleration;

    bool moveEffectEnabled;
    bool openEffectEnabled;
    bool closeEffectEnabled;
};

static const ParameterSet set_0 =
{
    0.15,
    0.80,
    0.10,
    20.0,
    20.0,
    0.0,
    1000.0,
    0.5,
    0.0,
    1000.0,
    0.5,
    true,
    false,
    false
};

static const ParameterSet set_1 =
{
    0.10,
    0.85,
    0.10,
    20.0,
    20.0,
    0.0,
    1000.0,
    0.5,
    0.0,
    1000.0,
    0.5,
    true,
    false,
    false
};

static const ParameterSet set_2 =
{
    0.06,
    0.90,
    0.10,
    20.0,
    20.0,
    0.0,
    1000.0,
    0.5,
    0.0,
    1000.0,
    0.5,
    true,
    false,
    false
};

static const ParameterSet set_3 =
{
    0.03,
    0.92,
    0.20,
    20.0,
    20.0,
    0.0,
    1000.0,
    0.5,
    0.0,
    1000.0,
    0.5,
    true,
    false,
    false
};

static const ParameterSet set_4 =
{
    0.01,
    0.97,
    0.25,
    20.0,
    20.0,
    0.0,
    1000.0,
    0.5,
    0.0,
    1000.0,
    0.5,
    true,
    false,
    false
};

static const ParameterSet pset[5] = { set_0, set_1, set_2, set_3, set_4 };

KWIN_EFFECT(wobblywindows, WobblyWindowsEffect)
KWIN_EFFECT_SUPPORTED(wobblywindows, WobblyWindowsEffect::supported())

WobblyWindowsEffect::WobblyWindowsEffect()
{
    reconfigure( ReconfigureAll );
}

WobblyWindowsEffect::~WobblyWindowsEffect()
{
    if (!windows.empty())
    {
        // we should be empty at this point...
        // emit a warning and clean the list.
        kDebug(1212) << "Windows list not empty. Left items : " << windows.count();
        QHash< const EffectWindow*,  WindowWobblyInfos >::iterator i;
        for (i = windows.begin(); i != windows.end(); ++i)
        {
            freeWobblyInfo(i.value());
        }
    }
}

void WobblyWindowsEffect::reconfigure( ReconfigureFlags )
{
    KConfigGroup conf = effects->effectConfig("Wobbly");


    QString settingsMode = conf.readEntry("Settings", "Auto");
    if (settingsMode != "Custom")
    {
        unsigned int wobblynessLevel = conf.readEntry("WobblynessLevel", 0);
        if (wobblynessLevel > 4)
        {
            kDebug(1212) << "Wrong value for \"WobblynessLevel\" : " << wobblynessLevel;
            wobblynessLevel = 4;
        }
        setParameterSet(pset[wobblynessLevel]);
        
        if (conf.readEntry("AdvancedMode", false))
        {
            m_stiffness = conf.readEntry("Stiffness", STIFFNESS * 100.0) / 100.0;
            m_drag = conf.readEntry("Drag", DRAG * 100.0) / 100.0;
            m_move_factor = conf.readEntry("MoveFactor", MOVEFACTOR * 100.0) / 100.0;
        }
    }
    else // Custom method, read all values from config file.
    {
        m_stiffness = conf.readEntry("Stiffness", STIFFNESS);
        m_drag = conf.readEntry("Drag", DRAG);
        m_move_factor = conf.readEntry("MoveFactor", MOVEFACTOR);

        m_xTesselation = conf.readEntry("XTesselation", XTESSELATION);
        m_yTesselation = conf.readEntry("YTesselation", YTESSELATION);

        m_minVelocity = conf.readEntry("MinVelocity", MINVELOCITY);
        m_maxVelocity = conf.readEntry("MaxVelocity", MAXVELOCITY);
        m_stopVelocity = conf.readEntry("StopVelocity", STOPVELOCITY);
        m_minAcceleration = conf.readEntry("MinAcceleration", MINACCELERATION);
        m_maxAcceleration = conf.readEntry("MaxAcceleration", MAXACCELERATION);
        m_stopAcceleration = conf.readEntry("StopAcceleration", STOPACCELERATION);

        m_moveEffectEnabled = conf.readEntry("MoveEffect", true);
        m_openEffectEnabled = conf.readEntry("OpenEffect", false);
        // disable close effect by default for now as it doesn't do what I want.
        m_closeEffectEnabled = conf.readEntry("CloseEffect", false);
    }

    m_moveWobble = conf.readEntry("MoveWobble", true);
    m_resizeWobble = conf.readEntry("ResizeWobble", true);

#if defined VERBOSE_MODE
    kDebug(1212) << "Parameters :\n" <<
        "move : " << m_moveEffectEnabled << ", open : " << m_openEffectEnabled << ", close : " << m_closeEffectEnabled << "\n"
        "grid(" << m_stiffness << ", " << m_drag << ", " << m_move_factor << ")\n" <<
        "velocity(" << m_minVelocity << ", " << m_maxVelocity << ", " << m_stopVelocity << ")\n" <<
        "acceleration(" << m_minAcceleration << ", " << m_maxAcceleration << ", " << m_stopAcceleration << ")\n" <<
        "tesselation(" << m_xTesselation <<  ", " << m_yTesselation << ")";
#endif
}

bool WobblyWindowsEffect::supported()
    {
    return effects->compositingType() == OpenGLCompositing;
    }

void WobblyWindowsEffect::setParameterSet(const ParameterSet& pset)
{
    m_stiffness = pset.stiffness;
    m_drag = pset.drag;
    m_move_factor = pset.move_factor;

    m_xTesselation = pset.xTesselation;
    m_yTesselation = pset.yTesselation;

    m_minVelocity =  pset.minVelocity;
    m_maxVelocity =  pset.maxVelocity;
    m_stopVelocity =  pset.stopVelocity;
    m_minAcceleration =  pset.minAcceleration;
    m_maxAcceleration =  pset.maxAcceleration;
    m_stopAcceleration =  pset.stopAcceleration;

    m_moveEffectEnabled =  pset.moveEffectEnabled;
    m_openEffectEnabled =  pset.openEffectEnabled;
    m_closeEffectEnabled =  pset.closeEffectEnabled;
}

void WobblyWindowsEffect::setVelocityThreshold(qreal m_minVelocity)
{
    this->m_minVelocity = m_minVelocity;
}

void WobblyWindowsEffect::setMoveFactor(qreal factor)
{
    m_move_factor = factor;
}

void WobblyWindowsEffect::setStiffness(qreal stiffness)
{
    m_stiffness = stiffness;
}

void WobblyWindowsEffect::setDrag(qreal drag)
{
    m_drag = drag;
}

void WobblyWindowsEffect::prePaintScreen(ScreenPrePaintData& data, int time)
{
    // We need to mark the screen windows as transformed. Otherwise the whole
    // screen won't be repainted, resulting in artefacts.
    // Could we just set a subset of the screen to be repainted ?
    if (windows.count() != 0)
    {
        data.mask |= PAINT_SCREEN_WITH_TRANSFORMED_WINDOWS;
    }

    // this set the QRect invalid.
    m_updateRegion.setWidth(0);

    effects->prePaintScreen(data, time);
}
const qreal maxTime = 10.0;
void WobblyWindowsEffect::prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time)
{
    if (windows.contains(w))
    {
        data.setTransformed();
        data.quads = data.quads.makeRegularGrid(m_xTesselation, m_yTesselation);
        bool stop = false;
        qreal updateTime = time;

        while (!stop && (updateTime > maxTime))
        {
#if defined VERBOSE_MODE
            kDebug(1212) << "loop time " << updateTime << " / " << time;
#endif
            stop = !updateWindowWobblyDatas(w, maxTime);
            updateTime -= maxTime;
        }
        if (!stop && updateTime > 0)
        {
            updateWindowWobblyDatas(w, updateTime);
        }
    }

    effects->prePaintWindow(w, data, time);
}

void WobblyWindowsEffect::paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data)
{
    if(windows.contains(w))
    {
        WindowWobblyInfos& wwi = windows[w];
        int tx = w->geometry().x();
        int ty = w->geometry().y();
        for (int i = 0; i < data.quads.count(); ++i)
        {
            for(int j = 0; j < 4; ++j)
            {
                WindowVertex& v = data.quads[i][j];
                Pair oldPos = {tx + v.x(), ty + v.y()};
                Pair newPos = computeBezierPoint(wwi, oldPos);
                v.move(newPos.x - tx, newPos.y - ty);
            }
        }
    }

    // Call the next effect.
    effects->paintWindow(w, mask, region, data);
}

void WobblyWindowsEffect::postPaintScreen()
{
    if (!windows.isEmpty())
    {
        effects->addRepaint(m_updateRegion);
    }

    // Call the next effect.
    effects->postPaintScreen();
}

void WobblyWindowsEffect::windowUserMovedResized(EffectWindow* w, bool first, bool last)
{
    if (!m_moveEffectEnabled || w->isSpecialWindow())
        return;

    if (first)
    {
        if(last && m_moveWobble && m_resizeWobble)
        {
            // both first and last - a step change like Maximize
            stepMovedResized(w);
        }
        else if ((w->isUserMove() && m_moveWobble) || (w->isUserResize() && m_resizeWobble))
        {
            startMovedResized(w);
        }
    }

    if (last)
    {
        if (windows.contains(w))
        {
            WindowWobblyInfos& wwi = windows[w];
            wwi.status = Free;
        }
    }

    if (windows.contains(w))
    {
        WindowWobblyInfos& wwi = windows[w];
        QRect rect = w->geometry();
        if(rect.y()!=wwi.resize_original_rect.y()) wwi.can_wobble_top = true;
        if(rect.x()!=wwi.resize_original_rect.x()) wwi.can_wobble_left = true;
        if(rect.right()!=wwi.resize_original_rect.right()) wwi.can_wobble_right = true;
        if(rect.bottom()!=wwi.resize_original_rect.bottom()) wwi.can_wobble_bottom = true;
    }
}


void WobblyWindowsEffect::startMovedResized(EffectWindow* w)
{
    if (!windows.contains(w))
    {
        WindowWobblyInfos new_wwi;
        initWobblyInfo(new_wwi, w->geometry());
        windows[w] = new_wwi;
    }

    WindowWobblyInfos& wwi = windows[w];
    wwi.status = Moving;
    const QRectF& rect = w->geometry();

    qreal x_increment = rect.width() / (wwi.width-1.0);
    qreal y_increment = rect.height() / (wwi.height-1.0);

    Pair picked = {cursorPos().x(), cursorPos().y()};
    int indx = (picked.x - rect.x()) / x_increment + 0.5;
    int indy = (picked.y - rect.y()) / y_increment + 0.5;
    int pickedPointIndex = indy*wwi.width + indx;
    if (pickedPointIndex < 0)
    {
        kDebug(1212) << "Picked index == " << pickedPointIndex << " with (" << cursorPos().x() << "," << cursorPos().y() << ")";
        pickedPointIndex = 0;
    }
    else if (static_cast<unsigned int>(pickedPointIndex) > wwi.count - 1)
    {
        kDebug(1212) << "Picked index == " << pickedPointIndex << " with (" << cursorPos().x() << "," << cursorPos().y() << ")";
        pickedPointIndex = wwi.count - 1;
    }
#if defined VERBOSE_MODE
    kDebug(1212) << "Original Picked point -- x : " << picked.x << " - y : " << picked.y;
#endif
    wwi.constraint[pickedPointIndex] = true;

    if (w->isUserResize())
    {
        // on a resize, do not allow any edges to wobble until it has been moved from
        // its original location
        wwi.can_wobble_top = wwi.can_wobble_left = wwi.can_wobble_right = wwi.can_wobble_bottom = false;
        wwi.resize_original_rect = w->geometry();
    }
    else
    {
        wwi.can_wobble_top = wwi.can_wobble_left = wwi.can_wobble_right = wwi.can_wobble_bottom = true;
    }
}

void WobblyWindowsEffect::stepMovedResized(EffectWindow* w)
{
    QRect new_geometry = w->geometry();
    if (!windows.contains(w))
    {
        WindowWobblyInfos new_wwi;
        initWobblyInfo(new_wwi, new_geometry);
        windows[w] = new_wwi;
    }

    WindowWobblyInfos& wwi = windows[w];
    wwi.status = Free;

    QRect maximized_area = effects->clientArea(MaximizeArea,w);
    bool throb_direction_out = (new_geometry.top()==maximized_area.top()&&new_geometry.bottom()==maximized_area.bottom()) || 
                               (new_geometry.left()==maximized_area.left()&&new_geometry.right()==maximized_area.right());
    qreal magnitude = throb_direction_out ? 10 : -30; // a small throb out when maximized, a larger throb inwards when restored
    for (unsigned int j=0; j<wwi.height; ++j)
    {
        for (unsigned int i=0; i<wwi.width; ++i)
        {
            Pair v = { magnitude*(i/qreal(wwi.width-1)-0.5), magnitude*(j/qreal(wwi.height-1)-0.5) };
            wwi.velocity[j*wwi.width+i] = v;
        }
    }

    // constrain the middle of the window, so that any asymetry wont cause it to drift off-center
    for (unsigned int j=1; j<wwi.height-1; ++j)
    {
        for (unsigned int i=1; i<wwi.width-1; ++i)
        {
            wwi.constraint[j*wwi.width+i] = true;
        }
    }
}

void WobblyWindowsEffect::windowAdded(EffectWindow* w)
{
    if (m_openEffectEnabled)
    {
        if(windows.contains(w))
        {
            // could this happen ??
            WindowWobblyInfos& wwi = windows[w];
            wobblyOpenInit(wwi);
        }
        else
        {
            WindowWobblyInfos new_wwi;
            initWobblyInfo(new_wwi, w->geometry());
            wobblyOpenInit(new_wwi);
            windows[w] = new_wwi;
        }
    }
}

void WobblyWindowsEffect::windowClosed(EffectWindow* w)
{
    if(windows.contains(w))
    {
        WindowWobblyInfos& wwi = windows[w];
        if (m_closeEffectEnabled)
        {
            wobblyCloseInit(wwi, w);
            w->refWindow();
        }
        else
        {
            freeWobblyInfo(wwi);
            windows.remove(w);
            if( windows.isEmpty() )
                effects->addRepaintFull();
        }
    }
    else if (m_closeEffectEnabled)
    {
        WindowWobblyInfos new_wwi;
        initWobblyInfo(new_wwi, w->geometry());
        wobblyCloseInit(new_wwi, w);
        windows[w] = new_wwi;
        w->refWindow();
    }
}

void WobblyWindowsEffect::wobblyOpenInit(WindowWobblyInfos& wwi) const
{
    Pair middle = { (wwi.origin[0].x + wwi.origin[15].x)/2, (wwi.origin[0].y + wwi.origin[15].y)/2 };

    for (unsigned int j=0; j<4; ++j)
    {
        for (unsigned int i=0; i<4; ++i)
        {
            unsigned int idx = j*4 + i;
            wwi.constraint[idx] = false;
            wwi.position[idx].x = (wwi.position[idx].x + 3*middle.x)/4;
            wwi.position[idx].y = (wwi.position[idx].y + 3*middle.y)/4;
        }
    }
    wwi.status = Openning;
    wwi.can_wobble_top = wwi.can_wobble_left = wwi.can_wobble_right = wwi.can_wobble_bottom = true;
}

void WobblyWindowsEffect::wobblyCloseInit(WindowWobblyInfos& wwi, EffectWindow* w) const
{
    const QRectF& rect = w->geometry();
    QPointF center = rect.center();
    int x1 = (rect.x() + 3*center.x())/4;
    int x2 = (rect.x() + rect.width() + 3*center.x())/4;
    int y1 = (rect.y() + 3*center.y())/4;
    int y2 = (rect.y() + rect.height() + 3*center.y())/4;
    wwi.closeRect.setCoords(x1, y1, x2, y2);

    // for closing, not yet used...
    for (unsigned int j=0; j<4; ++j)
    {
        for (unsigned int i=0; i<4; ++i)
        {
            unsigned int idx = j*4 + i;
            wwi.constraint[idx] = false;
        }
    }
    wwi.status = Closing;
}

void WobblyWindowsEffect::initWobblyInfo(WindowWobblyInfos& wwi, QRect geometry) const
{
    wwi.count = 4*4;
    wwi.width = 4;
    wwi.height = 4;

    wwi.bezierWidth = m_xTesselation;
    wwi.bezierHeight = m_yTesselation;
    wwi.bezierCount = m_xTesselation * m_yTesselation;

    wwi.origin = new Pair[wwi.count];
    wwi.position = new Pair[wwi.count];
    wwi.velocity = new Pair[wwi.count];
    wwi.acceleration = new Pair[wwi.count];
    wwi.buffer = new Pair[wwi.count];
    wwi.constraint = new bool[wwi.count];

    wwi.bezierSurface = new Pair[wwi.bezierCount];

    wwi.status = Moving;

    qreal x = geometry.x(), y = geometry.y();
    qreal width = geometry.width(), height = geometry.height();

    Pair initValue = {x, y};
    static const Pair nullPair = {0.0, 0.0};

    qreal x_increment = width / (wwi.width-1.0);
    qreal y_increment = height / (wwi.height-1.0);

    for (unsigned int j=0; j<4; ++j)
    {
        for (unsigned int i=0; i<4; ++i)
        {
            unsigned int idx = j*4 + i;
            wwi.origin[idx] = initValue;
            wwi.position[idx] = initValue;
            wwi.velocity[idx] = nullPair;
            wwi.constraint[idx] = false;
            if (i != 4-2) // x grid count - 2, i.e. not the last point
            {
                initValue.x += x_increment;
            }
            else
            {
                initValue.x = width + x;
            }
            initValue.x = initValue.x;
        }
        initValue.x = x;
        initValue.x = initValue.x;
        if (j != 4-2) // y grid count - 2, i.e. not the last point
        {
            initValue.y += y_increment;
        }
        else
        {
            initValue.y = height + y;
        }
        initValue.y = initValue.y;
    }
}

void WobblyWindowsEffect::freeWobblyInfo(WindowWobblyInfos& wwi) const
{
    delete[] wwi.origin;
    delete[] wwi.position;
    delete[] wwi.velocity;
    delete[] wwi.acceleration;
    delete[] wwi.buffer;
    delete[] wwi.constraint;

    delete[] wwi.bezierSurface;
}

WobblyWindowsEffect::Pair WobblyWindowsEffect::computeBezierPoint(const WindowWobblyInfos& wwi, Pair point) const
{
    // compute the input value
    Pair topleft = wwi.origin[0];
    Pair bottomright = wwi.origin[wwi.count-1];

//    ASSERT1(point.x >= topleft.x);
//    ASSERT1(point.y >= topleft.y);
//    ASSERT1(point.x <= bottomright.x);
//    ASSERT1(point.y <= bottomright.y);

    qreal tx = (point.x - topleft.x) / (bottomright.x - topleft.x);
    qreal ty = (point.y - topleft.y) / (bottomright.y - topleft.y);

//    ASSERT1(tx >= 0);
//    ASSERT1(tx <= 1);
//    ASSERT1(ty >= 0);
//    ASSERT1(ty <= 1);

    // compute polynomial coeff

    qreal px[4];
    px[0] = (1-tx)*(1-tx)*(1-tx);
    px[1] = 3*(1-tx)*(1-tx)*tx;
    px[2] = 3*(1-tx)*tx*tx;
    px[3] = tx*tx*tx;

    qreal py[4];
    py[0] = (1-ty)*(1-ty)*(1-ty);
    py[1] = 3*(1-ty)*(1-ty)*ty;
    py[2] = 3*(1-ty)*ty*ty;
    py[3] = ty*ty*ty;

    Pair res = {0.0, 0.0};

    for (unsigned int j = 0; j < 4; ++j)
    {
        for (unsigned int i = 0; i < 4; ++i)
        {
            // this assume the grid is 4*4
            res.x += px[i] * py[j] * wwi.position[i + j * wwi.width].x;
            res.y += px[i] * py[j] * wwi.position[i + j * wwi.width].y;
        }
    }

    return res;
}

namespace
{

static inline void fixVectorBounds(WobblyWindowsEffect::Pair& vec, qreal min, qreal max)
{
    if (fabs(vec.x) < min)
    {
        vec.x = 0.0;
    }
    else if (fabs(vec.x) > max)
    {
        if (vec.x > 0.0)
        {
            vec.x = max;
        }
        else
        {
            vec.x = -max;
        }
    }

    if (fabs(vec.y) < min)
    {
        vec.y = 0.0;
    }
    else if (fabs(vec.y) > max)
    {
        if (vec.y > 0.0)
        {
            vec.y = max;
        }
        else
        {
            vec.y = -max;
        }
    }
}

static inline void computeVectorBounds(WobblyWindowsEffect::Pair& vec, WobblyWindowsEffect::Pair& bound)
{
    if (fabs(vec.x) < bound.x)
    {
        bound.x = fabs(vec.x);
    }
    else if (fabs(vec.x) > bound.y)
    {
        bound.y = fabs(vec.x);
    }
    if (fabs(vec.y) < bound.x)
    {
        bound.x = fabs(vec.y);
    }
    else if (fabs(vec.y) > bound.y)
    {
        bound.y = fabs(vec.y);
    }
}

} // close the anonymous namespace

bool WobblyWindowsEffect::updateWindowWobblyDatas(EffectWindow* w, qreal time)
{
    QRectF rect = w->geometry();
    WindowWobblyInfos& wwi = windows[w];

    if (wwi.status == Closing)
    {
        rect = wwi.closeRect;
    }

    qreal x_length = rect.width() / (wwi.width-1.0);
    qreal y_length = rect.height() / (wwi.height-1.0);

#if defined VERBOSE_MODE
    kDebug(1212) << "time " << time;
    kDebug(1212) << "increment x " << x_length << " // y" <<  y_length;
#endif

    Pair origine = {rect.x(), rect.y()};

    for (unsigned int j=0; j<wwi.height; ++j)
    {
        for (unsigned int i=0; i<wwi.width; ++i)
        {
            wwi.origin[wwi.width*j + i] = origine;
            if (i != wwi.width-2)
            {
                origine.x += x_length;
            }
            else
            {
                origine.x = rect.width() + rect.x();
            }
         }
        origine.x = rect.x();
        if (j != wwi.height-2)
        {
            origine.y += y_length;
        }
        else
        {
            origine.y = rect.height() + rect.y();
        }
    }

    Pair neibourgs[4];
    Pair acceleration;

    qreal acc_sum = 0.0;
    qreal vel_sum = 0.0;

    // compute acceleration, velocity and position for each point

    // for corners

    // top-left

    if (wwi.constraint[0])
    {
        Pair window_pos = wwi.origin[0];
        Pair current_pos = wwi.position[0];
        Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
        Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
        wwi.acceleration[0] = accel;
    }
    else
    {
        Pair& pos = wwi.position[0];
        neibourgs[0] = wwi.position[1];
        neibourgs[1] = wwi.position[wwi.width];

        acceleration.x = ((neibourgs[0].x - pos.x) - x_length)*m_stiffness + (neibourgs[1].x - pos.x)*m_stiffness;
        acceleration.y = ((neibourgs[1].y - pos.y) - y_length)*m_stiffness + (neibourgs[0].y - pos.y)*m_stiffness;

        acceleration.x /= 2;
        acceleration.y /= 2;

        wwi.acceleration[0] = acceleration;
    }

    // top-right

    if (wwi.constraint[wwi.width-1])
    {
        Pair window_pos = wwi.origin[wwi.width-1];
        Pair current_pos = wwi.position[wwi.width-1];
        Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
        Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
        wwi.acceleration[wwi.width-1] = accel;
    }
    else
    {
        Pair& pos = wwi.position[wwi.width-1];
        neibourgs[0] = wwi.position[wwi.width-2];
        neibourgs[1] = wwi.position[2*wwi.width-1];

        acceleration.x = (x_length - (pos.x - neibourgs[0].x))*m_stiffness + (neibourgs[1].x - pos.x)*m_stiffness;
        acceleration.y = ((neibourgs[1].y - pos.y) - y_length)*m_stiffness + (neibourgs[0].y - pos.y)*m_stiffness;

        acceleration.x /= 2;
        acceleration.y /= 2;

        wwi.acceleration[wwi.width-1] = acceleration;
    }

    // bottom-left

    if (wwi.constraint[wwi.width*(wwi.height-1)])
    {
        Pair window_pos = wwi.origin[wwi.width*(wwi.height-1)];
        Pair current_pos = wwi.position[wwi.width*(wwi.height-1)];
        Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
        Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
        wwi.acceleration[wwi.width*(wwi.height-1)] = accel;
    }
    else
    {
        Pair& pos = wwi.position[wwi.width*(wwi.height-1)];
        neibourgs[0] = wwi.position[wwi.width*(wwi.height-1)+1];
        neibourgs[1] = wwi.position[wwi.width*(wwi.height-2)];

        acceleration.x = ((neibourgs[0].x - pos.x) - x_length)*m_stiffness + (neibourgs[1].x - pos.x)*m_stiffness;
        acceleration.y = (y_length - (pos.y - neibourgs[1].y))*m_stiffness + (neibourgs[0].y - pos.y)*m_stiffness;

        acceleration.x /= 2;
        acceleration.y /= 2;

        wwi.acceleration[wwi.width*(wwi.height-1)] = acceleration;
    }

    // bottom-right

    if (wwi.constraint[wwi.count-1])
    {
        Pair window_pos = wwi.origin[wwi.count-1];
        Pair current_pos = wwi.position[wwi.count-1];
        Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
        Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
        wwi.acceleration[wwi.count-1] = accel;
    }
    else
    {
        Pair& pos = wwi.position[wwi.count-1];
        neibourgs[0] = wwi.position[wwi.count-2];
        neibourgs[1] = wwi.position[wwi.width*(wwi.height-1)-1];

        acceleration.x = (x_length - (pos.x - neibourgs[0].x))*m_stiffness + (neibourgs[1].x - pos.x)*m_stiffness;
        acceleration.y = (y_length - (pos.y - neibourgs[1].y))*m_stiffness + (neibourgs[0].y - pos.y)*m_stiffness;

        acceleration.x /= 2;
        acceleration.y /= 2;

        wwi.acceleration[wwi.count-1] = acceleration;
    }


    // for borders

    // top border
    for (unsigned int i=1; i<wwi.width-1; ++i)
    {
        if (wwi.constraint[i])
        {
            Pair window_pos = wwi.origin[i];
            Pair current_pos = wwi.position[i];
            Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
            Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
            wwi.acceleration[i] = accel;
        }
        else
        {
            Pair& pos = wwi.position[i];
            neibourgs[0] = wwi.position[i-1];
            neibourgs[1] = wwi.position[i+1];
            neibourgs[2] = wwi.position[i+wwi.width];

            acceleration.x = (x_length - (pos.x - neibourgs[0].x))*m_stiffness + ((neibourgs[1].x - pos.x) - x_length)*m_stiffness + (neibourgs[2].x - pos.x)*m_stiffness;
            acceleration.y = ((neibourgs[2].y - pos.y) - y_length)*m_stiffness + (neibourgs[0].y - pos.y)*m_stiffness + (neibourgs[1].y - pos.y)*m_stiffness;

            acceleration.x /= 3;
            acceleration.y /= 3;

            wwi.acceleration[i] = acceleration;
        }
    }

    // bottom border
    for (unsigned int i=wwi.width*(wwi.height-1)+1; i<wwi.count-1; ++i)
    {
        if (wwi.constraint[i])
        {
            Pair window_pos = wwi.origin[i];
            Pair current_pos = wwi.position[i];
            Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
            Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
            wwi.acceleration[i] = accel;
        }
        else
        {
            Pair& pos = wwi.position[i];
            neibourgs[0] = wwi.position[i-1];
            neibourgs[1] = wwi.position[i+1];
            neibourgs[2] = wwi.position[i-wwi.width];

            acceleration.x = (x_length - (pos.x - neibourgs[0].x))*m_stiffness + ((neibourgs[1].x - pos.x) - x_length)*m_stiffness + (neibourgs[2].x - pos.x)*m_stiffness;
            acceleration.y = (y_length - (pos.y - neibourgs[2].y))*m_stiffness + (neibourgs[0].y - pos.y)*m_stiffness + (neibourgs[1].y - pos.y)*m_stiffness;

            acceleration.x /= 3;
            acceleration.y /= 3;

            wwi.acceleration[i] = acceleration;
        }
    }

    // left border
    for (unsigned int i=wwi.width; i<wwi.width*(wwi.height-1); i+=wwi.width)
    {
        if (wwi.constraint[i])
        {
            Pair window_pos = wwi.origin[i];
            Pair current_pos = wwi.position[i];
            Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
            Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
            wwi.acceleration[i] = accel;
        }
        else
        {
            Pair& pos = wwi.position[i];
            neibourgs[0] = wwi.position[i+1];
            neibourgs[1] = wwi.position[i-wwi.width];
            neibourgs[2] = wwi.position[i+wwi.width];

            acceleration.x = ((neibourgs[0].x - pos.x) - x_length)*m_stiffness + (neibourgs[1].x - pos.x)*m_stiffness + (neibourgs[2].x - pos.x)*m_stiffness;
            acceleration.y = (y_length - (pos.y - neibourgs[1].y))*m_stiffness + ((neibourgs[2].y - pos.y) - y_length)*m_stiffness + (neibourgs[0].y - pos.y)*m_stiffness;

            acceleration.x /= 3;
            acceleration.y /= 3;

            wwi.acceleration[i] = acceleration;
        }
    }

    // right border
    for (unsigned int i=2*wwi.width-1; i<wwi.count-1; i+=wwi.width)
    {
        if (wwi.constraint[i])
        {
            Pair window_pos = wwi.origin[i];
            Pair current_pos = wwi.position[i];
            Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
            Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
            wwi.acceleration[i] = accel;
        }
        else
        {
            Pair& pos = wwi.position[i];
            neibourgs[0] = wwi.position[i-1];
            neibourgs[1] = wwi.position[i-wwi.width];
            neibourgs[2] = wwi.position[i+wwi.width];

            acceleration.x = (x_length - (pos.x - neibourgs[0].x))*m_stiffness + (neibourgs[1].x - pos.x)*m_stiffness + (neibourgs[2].x - pos.x)*m_stiffness;
            acceleration.y = (y_length - (pos.y - neibourgs[1].y))*m_stiffness + ((neibourgs[2].y - pos.y) - y_length)*m_stiffness + (neibourgs[0].y - pos.y)*m_stiffness;

            acceleration.x /= 3;
            acceleration.y /= 3;

            wwi.acceleration[i] = acceleration;
        }
    }

    // for the inner points
    for (unsigned int j=1; j<wwi.height-1; ++j)
    {
        for (unsigned int i=1; i<wwi.width-1; ++i)
        {
            unsigned int index = i+j*wwi.width;

            if (wwi.constraint[index])
            {
            Pair window_pos = wwi.origin[index];
            Pair current_pos = wwi.position[index];
            Pair move = {window_pos.x - current_pos.x, window_pos.y - current_pos.y};
            Pair accel = {move.x*m_stiffness, move.y*m_stiffness};
            wwi.acceleration[index] = accel;
            }
            else
            {
                Pair& pos = wwi.position[index];
                neibourgs[0] = wwi.position[index-1];
                neibourgs[1] = wwi.position[index+1];
                neibourgs[2] = wwi.position[index-wwi.width];
                neibourgs[3] = wwi.position[index+wwi.width];

                acceleration.x = ((neibourgs[0].x - pos.x) - x_length)*m_stiffness +
                                 (x_length - (pos.x - neibourgs[1].x))*m_stiffness +
                                 (neibourgs[2].x - pos.x)*m_stiffness +
                                 (neibourgs[3].x - pos.x)*m_stiffness;
                acceleration.y = (y_length - (pos.y - neibourgs[2].y))*m_stiffness +
                                 ((neibourgs[3].y - pos.y) - y_length)*m_stiffness +
                                 (neibourgs[0].y - pos.y)*m_stiffness +
                                 (neibourgs[1].y - pos.y)*m_stiffness;

                acceleration.x /= 4;
                acceleration.y /= 4;

                wwi.acceleration[index] = acceleration;
            }
        }
    }

    heightRingLinearMean(&wwi.acceleration, wwi);

#if defined COMPUTE_STATS
    Pair accBound = {m_maxAcceleration, m_minAcceleration};
    Pair velBound = {m_maxVelocity, m_minVelocity};
#endif

    // compute the new velocity of each vertex.
    for (unsigned int i = 0; i < wwi.count; ++i)
    {
        Pair acc = wwi.acceleration[i];
        fixVectorBounds(acc, m_minAcceleration, m_maxAcceleration);

#if defined COMPUTE_STATS
        computeVectorBounds(acc, accBound);
#endif

        Pair& vel = wwi.velocity[i];
        vel.x = acc.x*time + vel.x*m_drag;
        vel.y = acc.y*time + vel.y*m_drag;

        acc_sum += fabs(acc.x) + fabs(acc.y);
    }

    heightRingLinearMean(&wwi.velocity, wwi);

    Pair topLeftCorner = {-10000.0, -10000.0};
    Pair bottomRightCorner = {10000.0, 10000.0};

    // compute the new pos of each vertex.
    for (unsigned int i = 0; i < wwi.count; ++i)
    {
        Pair& pos = wwi.position[i];
        Pair& vel = wwi.velocity[i];

        fixVectorBounds(vel, m_minVelocity, m_maxVelocity);
#if defined COMPUTE_STATS
        computeVectorBounds(vel, velBound);
#endif

        pos.x += vel.x*time*m_move_factor;
        pos.y += vel.y*time*m_move_factor;

        if (pos.x < topLeftCorner.x)
        {
            topLeftCorner.x = pos.x;
        }
        if (pos.x > bottomRightCorner.x)
        {
            bottomRightCorner.x = pos.x;
        }
        if (pos.y < topLeftCorner.y)
        {
            topLeftCorner.y = pos.y;
        }
        if (pos.y > bottomRightCorner.y)
        {
            bottomRightCorner.y = pos.y;
        }

        vel_sum += fabs(vel.x) + fabs(vel.y);

#if defined VERBOSE_MODE
        if (wwi.constraint[i])
        {
            kDebug(1212) << "Constraint point ** vel : " << vel.x << "," << vel.y << " ** move : " << vel.x*time << "," << vel.y*time;
        }
#endif
    }

    if(!wwi.can_wobble_top)
    {
        for (unsigned int i=0; i<wwi.width; ++i)
            for(unsigned j=0;j<wwi.width-1;++j)
                wwi.position[i+wwi.width*j].y = wwi.origin[i+wwi.width*j].y;
    }
    if(!wwi.can_wobble_bottom)
    {
        for (unsigned int i=wwi.width*(wwi.height-1); i<wwi.count; ++i)
            for(unsigned j=0;j<wwi.width-1;++j)
                wwi.position[i-wwi.width*j].y = wwi.origin[i-wwi.width*j].y;
    }
    if(!wwi.can_wobble_left)
    {
        for (unsigned int i=0; i<wwi.count; i+=wwi.width)
            for(unsigned j=0;j<wwi.width-1;++j)
                wwi.position[i+j].x = wwi.origin[i+j].x;
    }
    if(!wwi.can_wobble_right)
    {
        for (unsigned int i=wwi.width-1; i<wwi.count; i+=wwi.width)
            for(unsigned j=0;j<wwi.width-1;++j)
                wwi.position[i-j].x = wwi.origin[i-j].x;
    }

#if defined VERBOSE_MODE
#   if defined COMPUTE_STATS
        kDebug(1212) << "Acceleration bounds (" << accBound.x << ", " << accBound.y << ")";
        kDebug(1212) << "Velocity bounds (" << velBound.x << ", " << velBound.y << ")";
#   endif
    kDebug(1212) << "sum_acc : " << acc_sum << "  ***  sum_vel :" << vel_sum;
#endif

    if (wwi.status != Moving && acc_sum < m_stopAcceleration && vel_sum < m_stopVelocity)
    {
        if (wwi.status == Closing)
        {
            w->unrefWindow();
        }
        freeWobblyInfo(wwi);
        windows.remove(w);
        if( windows.isEmpty() )
            effects->addRepaintFull();
        return false;
    }

    QRect windowRect(topLeftCorner.x, topLeftCorner.y,
        bottomRightCorner.x - topLeftCorner.x, bottomRightCorner.y - topLeftCorner.y);
    if (m_updateRegion.isValid())
    {
        m_updateRegion = m_updateRegion.united(windowRect);
    }
    else
    {
        m_updateRegion = windowRect;
    }

    return true;
}

void WobblyWindowsEffect::heightRingLinearMean(Pair** datas_pointer, WindowWobblyInfos& wwi)
{
    Pair* datas = *datas_pointer;
    Pair neibourgs[8];

    // for corners

    // top-left
    {
        Pair& res = wwi.buffer[0];
        Pair vit = datas[0];
        neibourgs[0] = datas[1];
        neibourgs[1] = datas[wwi.width];
        neibourgs[2] = datas[wwi.width+1];

        res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + 3.0*vit.x) / 6.0;
        res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + 3.0*vit.y) / 6.0;
    }


    // top-right
    {
        Pair& res = wwi.buffer[wwi.width-1];
        Pair vit = datas[wwi.width-1];
        neibourgs[0] = datas[wwi.width-2];
        neibourgs[1] = datas[2*wwi.width-1];
        neibourgs[2] = datas[2*wwi.width-2];

        res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + 3.0*vit.x) / 6.0;
        res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + 3.0*vit.y) / 6.0;
    }


    // bottom-left
   {
        Pair& res = wwi.buffer[wwi.width*(wwi.height-1)];
        Pair vit = datas[wwi.width*(wwi.height-1)];
        neibourgs[0] = datas[wwi.width*(wwi.height-1)+1];
        neibourgs[1] = datas[wwi.width*(wwi.height-2)];
        neibourgs[2] = datas[wwi.width*(wwi.height-2)+1];

        res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + 3.0*vit.x) / 6.0;
        res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + 3.0*vit.y) / 6.0;
    }


    // bottom-right
    {
        Pair& res = wwi.buffer[wwi.count-1];
        Pair vit = datas[wwi.count-1];
        neibourgs[0] = datas[wwi.count-2];
        neibourgs[1] = datas[wwi.width*(wwi.height-1)-1];
        neibourgs[2] = datas[wwi.width*(wwi.height-1)-2];

        res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + 3.0*vit.x) / 6.0;
        res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + 3.0*vit.y) / 6.0;
    }


    // for borders

    // top border
    for (unsigned int i=1; i<wwi.width-1; ++i)
    {
        Pair& res = wwi.buffer[i];
        Pair vit = datas[i];
        neibourgs[0] = datas[i-1];
        neibourgs[1] = datas[i+1];
        neibourgs[2] = datas[i+wwi.width];
        neibourgs[3] = datas[i+wwi.width-1];
        neibourgs[4] = datas[i+wwi.width+1];

        res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + neibourgs[3].x + neibourgs[4].x + 5.0*vit.x) / 10.0;
        res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + neibourgs[3].y + neibourgs[4].y + 5.0*vit.y) / 10.0;
    }

    // bottom border
    for (unsigned int i=wwi.width*(wwi.height-1)+1; i<wwi.count-1; ++i)
    {
        Pair& res = wwi.buffer[i];
        Pair vit = datas[i];
        neibourgs[0] = datas[i-1];
        neibourgs[1] = datas[i+1];
        neibourgs[2] = datas[i-wwi.width];
        neibourgs[3] = datas[i-wwi.width-1];
        neibourgs[4] = datas[i-wwi.width+1];

        res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + neibourgs[3].x + neibourgs[4].x + 5.0*vit.x) / 10.0;
        res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + neibourgs[3].y + neibourgs[4].y + 5.0*vit.y) / 10.0;
    }

    // left border
    for (unsigned int i=wwi.width; i<wwi.width*(wwi.height-1); i+=wwi.width)
    {
        Pair& res = wwi.buffer[i];
        Pair vit = datas[i];
        neibourgs[0] = datas[i+1];
        neibourgs[1] = datas[i-wwi.width];
        neibourgs[2] = datas[i+wwi.width];
        neibourgs[3] = datas[i-wwi.width+1];
        neibourgs[4] = datas[i+wwi.width+1];

        res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + neibourgs[3].x + neibourgs[4].x + 5.0*vit.x) / 10.0;
        res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + neibourgs[3].y + neibourgs[4].y + 5.0*vit.y) / 10.0;
    }

    // right border
    for (unsigned int i=2*wwi.width-1; i<wwi.count-1; i+=wwi.width)
    {
        Pair& res = wwi.buffer[i];
        Pair vit = datas[i];
        neibourgs[0] = datas[i-1];
        neibourgs[1] = datas[i-wwi.width];
        neibourgs[2] = datas[i+wwi.width];
        neibourgs[3] = datas[i-wwi.width-1];
        neibourgs[4] = datas[i+wwi.width-1];

        res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + neibourgs[3].x + neibourgs[4].x + 5.0*vit.x) / 10.0;
        res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + neibourgs[3].y + neibourgs[4].y + 5.0*vit.y) / 10.0;
    }

    // for the inner points
    for (unsigned int j=1; j<wwi.height-1; ++j)
    {
        for (unsigned int i=1; i<wwi.width-1; ++i)
        {
            unsigned int index = i+j*wwi.width;

            Pair& res = wwi.buffer[index];
            Pair& vit = datas[index];
            neibourgs[0] = datas[index-1];
            neibourgs[1] = datas[index+1];
            neibourgs[2] = datas[index-wwi.width];
            neibourgs[3] = datas[index+wwi.width];
            neibourgs[4] = datas[index-wwi.width-1];
            neibourgs[5] = datas[index-wwi.width+1];
            neibourgs[6] = datas[index+wwi.width-1];
            neibourgs[7] = datas[index+wwi.width+1];

            res.x = (neibourgs[0].x + neibourgs[1].x + neibourgs[2].x + neibourgs[3].x + neibourgs[4].x + neibourgs[5].x + neibourgs[6].x + neibourgs[7].x + 8.0*vit.x) / 16.0;
            res.y = (neibourgs[0].y + neibourgs[1].y + neibourgs[2].y + neibourgs[3].y + neibourgs[4].y + neibourgs[5].y + neibourgs[6].y + neibourgs[7].y + 8.0*vit.y) / 16.0;
        }
    }

    Pair* tmp = datas;
    *datas_pointer = wwi.buffer;
    wwi.buffer = tmp;
}


} // namespace KWin