/*
* Copyright 2014  Martin Gräßlin <mgraesslin@kde.org>
* Copyright 2014  Hugo Pereira Da Costa <hugo.pereira@free.fr>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License or (at your option) version 3 or any later version
* accepted by the membership of KDE e.V. (or its successor approved
* by the membership of KDE e.V.), which shall act as a proxy
* defined in Section 14 of version 3 of the license.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "breezedecoration.h"

#include "breeze.h"
#include "breezesettingsprovider.h"
#include "config-breeze.h"
#include "config/breezeconfigwidget.h"

#include "breezebutton.h"
#include "breezesizegrip.h"

#include <KDecoration2/DecoratedClient>
#include <KDecoration2/DecorationButtonGroup>
#include <KDecoration2/DecorationSettings>
#include <KDecoration2/DecorationShadow>

#include <KConfigGroup>
#include <KColorUtils>
#include <KSharedConfig>
#include <KPluginFactory>

#include <QPainter>
#include <QTextStream>
#include <QTimer>

#if BREEZE_HAVE_X11
#include <QX11Info>
#endif

#include <cmath>

K_PLUGIN_FACTORY_WITH_JSON(
    BreezeDecoFactory,
    "breeze.json",
    registerPlugin<Breeze::Decoration>();
    registerPlugin<Breeze::Button>(QStringLiteral("button"));
    registerPlugin<Breeze::ConfigWidget>(QStringLiteral("kcmodule"));
)

namespace Breeze
{

    using KDecoration2::ColorRole;
    using KDecoration2::ColorGroup;

    //________________________________________________________________
    static int g_sDecoCount = 0;
    static int g_shadowSize = 0;
    static int g_shadowStrength = 0;
    static QColor g_shadowColor = Qt::black;
    static QSharedPointer<KDecoration2::DecorationShadow> g_sShadow;

    //________________________________________________________________
    Decoration::Decoration(QObject *parent, const QVariantList &args)
        : KDecoration2::Decoration(parent, args)
        , m_animation( new QPropertyAnimation( this ) )
    {
        g_sDecoCount++;
    }

    //________________________________________________________________
    Decoration::~Decoration()
    {
        g_sDecoCount--;
        if (g_sDecoCount == 0) {
            // last deco destroyed, clean up shadow
            g_sShadow.clear();
        }

        deleteSizeGrip();

    }

    //________________________________________________________________
    void Decoration::setOpacity( qreal value )
    {
        if( m_opacity == value ) return;
        m_opacity = value;
        update();

        if( m_sizeGrip ) m_sizeGrip->update();
    }

    //________________________________________________________________
    QColor Decoration::titleBarColor() const
    {

        auto c = client().data();
        if( hideTitleBar() ) return c->color( ColorGroup::Inactive, ColorRole::TitleBar );
        else if( m_animation->state() == QPropertyAnimation::Running )
        {
            return KColorUtils::mix(
                c->color( ColorGroup::Inactive, ColorRole::TitleBar ),
                c->color( ColorGroup::Active, ColorRole::TitleBar ),
                m_opacity );
        } else return c->color( c->isActive() ? ColorGroup::Active : ColorGroup::Inactive, ColorRole::TitleBar );

    }

    //________________________________________________________________
    QColor Decoration::outlineColor() const
    {

        auto c( client().data() );
        if( !m_useSeparator ) return QColor();
        if( m_animation->state() == QPropertyAnimation::Running )
        {
            QColor color( c->palette().color( QPalette::Highlight ) );
            color.setAlpha( color.alpha()*m_opacity );
            return color;
        } else if( c->isActive() ) return c->palette().color( QPalette::Highlight );
        else return QColor();
    }

    //________________________________________________________________
    QColor Decoration::fontColor() const
    {

        auto c = client().data();
        if( m_animation->state() == QPropertyAnimation::Running )
        {
            return KColorUtils::mix(
                c->color( ColorGroup::Inactive, ColorRole::Foreground ),
                c->color( ColorGroup::Active, ColorRole::Foreground ),
                m_opacity );
        } else return  c->color( c->isActive() ? ColorGroup::Active : ColorGroup::Inactive, ColorRole::Foreground );

    }

    //________________________________________________________________
    void Decoration::init()
    {
        auto c = client().data();
        m_useSeparator = (c->palette().color( QPalette::Window ) != c->color( ColorGroup::Active, ColorRole::TitleBar ) );

        // active state change animation
        m_animation->setStartValue( 0 );
        m_animation->setEndValue( 1.0 );
        m_animation->setTargetObject( this );
        m_animation->setPropertyName( "opacity" );
        m_animation->setEasingCurve( QEasingCurve::InOutQuad );

        reconfigure();
        updateTitleBar();
        auto s = settings();
        connect(s.data(), &KDecoration2::DecorationSettings::borderSizeChanged, this, &Decoration::recalculateBorders);

        // a change in font might cause the borders to change
        connect(s.data(), &KDecoration2::DecorationSettings::fontChanged, this, &Decoration::recalculateBorders);
        connect(s.data(), &KDecoration2::DecorationSettings::spacingChanged, this, &Decoration::recalculateBorders);

        // buttons
        connect(s.data(), &KDecoration2::DecorationSettings::spacingChanged, this, &Decoration::updateButtonsGeometryDelayed);
        connect(s.data(), &KDecoration2::DecorationSettings::decorationButtonsLeftChanged, this, &Decoration::updateButtonsGeometryDelayed);
        connect(s.data(), &KDecoration2::DecorationSettings::decorationButtonsRightChanged, this, &Decoration::updateButtonsGeometryDelayed);

        // full reconfiguration
        connect(s.data(), &KDecoration2::DecorationSettings::reconfigured, this, &Decoration::reconfigure);
        connect(s.data(), &KDecoration2::DecorationSettings::reconfigured, SettingsProvider::self(), &SettingsProvider::reconfigure, Qt::UniqueConnection );
        connect(s.data(), &KDecoration2::DecorationSettings::reconfigured, this, &Decoration::updateButtonsGeometryDelayed);

        connect(c, &KDecoration2::DecoratedClient::adjacentScreenEdgesChanged, this, &Decoration::recalculateBorders);
        connect(c, &KDecoration2::DecoratedClient::maximizedHorizontallyChanged, this, &Decoration::recalculateBorders);
        connect(c, &KDecoration2::DecoratedClient::maximizedVerticallyChanged, this, &Decoration::recalculateBorders);
        connect(c, &KDecoration2::DecoratedClient::captionChanged, this,
            [this]()
            {
                // update the caption area
                update(titleBar());
            }
        );

        connect(c, &KDecoration2::DecoratedClient::activeChanged, this, &Decoration::updateAnimationState);
        connect(c, &KDecoration2::DecoratedClient::paletteChanged, this,
            [this]() {
                auto c = client().data();
                m_useSeparator = (c->palette().color( QPalette::Window ) != c->color( ColorGroup::Active, ColorRole::TitleBar ) );
                update();
            }
        );
        connect(c, &KDecoration2::DecoratedClient::widthChanged, this, &Decoration::updateTitleBar);
        connect(c, &KDecoration2::DecoratedClient::maximizedChanged, this, &Decoration::updateTitleBar);
        connect(c, &KDecoration2::DecoratedClient::maximizedChanged, this, &Decoration::setOpaque);

        connect(c, &KDecoration2::DecoratedClient::widthChanged, this, &Decoration::updateButtonsGeometry);
        connect(c, &KDecoration2::DecoratedClient::maximizedChanged, this, &Decoration::updateButtonsGeometry);
        connect(c, &KDecoration2::DecoratedClient::shadedChanged, this, &Decoration::recalculateBorders);
        connect(c, &KDecoration2::DecoratedClient::shadedChanged, this, &Decoration::updateButtonsGeometry);

        createButtons();
        createShadow();
    }

    //________________________________________________________________
    void Decoration::updateTitleBar()
    {
        auto s = settings();
        auto c = client().data();
        const bool maximized = isMaximized();
        const int width =  maximized ? c->width() : c->width() - 2*s->largeSpacing()*Metrics::TitleBar_SideMargin;
        const int height = maximized ? borderTop() : borderTop() - s->smallSpacing()*Metrics::TitleBar_TopMargin;
        const int x = maximized ? 0 : s->largeSpacing()*Metrics::TitleBar_SideMargin;
        const int y = maximized ? 0 : s->smallSpacing()*Metrics::TitleBar_TopMargin;
        setTitleBar(QRect(x, y, width, height));
    }

    //________________________________________________________________
    void Decoration::updateAnimationState()
    {
        if( m_internalSettings->animationsEnabled() )
        {

            auto c = client().data();
            m_animation->setDirection( c->isActive() ? QPropertyAnimation::Forward : QPropertyAnimation::Backward );
            if( m_animation->state() != QPropertyAnimation::Running ) m_animation->start();

        } else {

            update();

        }
    }

    //________________________________________________________________
    void Decoration::updateSizeGripVisibility()
    {
        auto c = client().data();
        if( m_sizeGrip )
        { m_sizeGrip->setVisible( c->isResizeable() && !isMaximized() && !c->isShaded() ); }
    }

    //________________________________________________________________
    int Decoration::borderSize(bool bottom) const
    {
        const int baseSize = settings()->smallSpacing();
        if( m_internalSettings && (m_internalSettings->mask() & BorderSize ) )
        {
            switch (m_internalSettings->borderSize()) {
                case InternalSettings::BorderNone: return 0;
                case InternalSettings::BorderNoSides: return bottom ? qMax(4, baseSize) : 0;
                default:
                case InternalSettings::BorderTiny: return bottom ? qMax(4, baseSize) : baseSize;
                case InternalSettings::BorderNormal: return baseSize*2;
                case InternalSettings::BorderLarge: return baseSize*3;
                case InternalSettings::BorderVeryLarge: return baseSize*4;
                case InternalSettings::BorderHuge: return baseSize*5;
                case InternalSettings::BorderVeryHuge: return baseSize*6;
                case InternalSettings::BorderOversized: return baseSize*10;
            }

        } else {

            switch (settings()->borderSize()) {
                case KDecoration2::BorderSize::None: return 0;
                case KDecoration2::BorderSize::NoSides: return bottom ? qMax(4, baseSize) : 0;
                default:
                case KDecoration2::BorderSize::Tiny: return bottom ? qMax(4, baseSize) : baseSize;
                case KDecoration2::BorderSize::Normal: return baseSize*2;
                case KDecoration2::BorderSize::Large: return baseSize*3;
                case KDecoration2::BorderSize::VeryLarge: return baseSize*4;
                case KDecoration2::BorderSize::Huge: return baseSize*5;
                case KDecoration2::BorderSize::VeryHuge: return baseSize*6;
                case KDecoration2::BorderSize::Oversized: return baseSize*10;

            }

        }
    }

    //________________________________________________________________
    void Decoration::reconfigure()
    {

        m_internalSettings = SettingsProvider::self()->internalSettings( this );

        // animation
        m_animation->setDuration( m_internalSettings->animationsDuration() );

        // borders
        recalculateBorders();

        // shadow
        createShadow();

        // size grip
        if( hasNoBorders() && m_internalSettings->drawSizeGrip() ) createSizeGrip();
        else deleteSizeGrip();

    }

    //________________________________________________________________
    void Decoration::recalculateBorders()
    {
        auto s = settings();
        const auto c = client().data();
        const Qt::Edges edges = c->adjacentScreenEdges();

        // left, right and bottom borders
        auto testFlag = [&]( Qt::Edge edge ) { return edges.testFlag(edge) && !m_internalSettings->drawBorderOnMaximizedWindows(); };
        const int left   = isMaximizedHorizontally() || testFlag(Qt::LeftEdge) ? 0 : borderSize();
        const int right  = isMaximizedHorizontally() || testFlag(Qt::RightEdge) ? 0 : borderSize();
        const int bottom = isMaximizedVertically() || c->isShaded() || testFlag(Qt::BottomEdge) ? 0 : borderSize(true);

        int top = 0;
        if( hideTitleBar() ) top = bottom;
        else {

            QFontMetrics fm(s->font());
            top += qMax(fm.boundingRect(c->caption()).height(), buttonHeight() );

            // padding below
            // extra pixel is used for the active window outline
            const int baseSize = settings()->smallSpacing();
            top += baseSize*Metrics::TitleBar_BottomMargin + 1;

            // padding above
            top += baseSize*TitleBar_TopMargin;

        }

        setBorders(QMargins(left, top, right, bottom));

        // extended sizes
        const int extSize = s->largeSpacing();
        int extSides = 0;
        int extBottom = 0;
        if( hasNoBorders() )
        {
            extSides = extSize;
            extBottom = extSize;

        } else if( hasNoSideBorders() ) {

            extSides = extSize;

        }

        setResizeOnlyBorders(QMargins(extSides, 0, extSides, extBottom));
    }

    //________________________________________________________________
    void Decoration::createButtons()
    {
        m_leftButtons = new KDecoration2::DecorationButtonGroup(KDecoration2::DecorationButtonGroup::Position::Left, this, &Button::create);
        m_rightButtons = new KDecoration2::DecorationButtonGroup(KDecoration2::DecorationButtonGroup::Position::Right, this, &Button::create);
        updateButtonsGeometry();
    }

    //________________________________________________________________
    void Decoration::updateButtonsGeometryDelayed()
    { QTimer::singleShot( 0, this, &Decoration::updateButtonsGeometry ); }

    //________________________________________________________________
    void Decoration::updateButtonsGeometry()
    {
        auto s = settings();

        // adjust button position
        const int bHeight = captionHeight() + (isMaximized() ? s->smallSpacing()*Metrics::TitleBar_TopMargin:0);
        const int bWidth = buttonHeight();
        const int verticalOffset = (isMaximized() ? s->smallSpacing()*Metrics::TitleBar_TopMargin:0) + (captionHeight()-buttonHeight())/2;
        foreach( const QPointer<KDecoration2::DecorationButton>& button, m_leftButtons->buttons() + m_rightButtons->buttons() )
        {
            button.data()->setGeometry( QRectF( QPoint( 0, 0 ), QSizeF( bWidth, bHeight ) ) );
            static_cast<Button*>( button.data() )->setOffset( QPointF( 0, verticalOffset ) );
            static_cast<Button*>( button.data() )->setIconSize( QSize( bWidth, bWidth ) );
        }

        // left buttons
        if( !m_leftButtons->buttons().isEmpty() )
        {

            // spacing
            m_leftButtons->setSpacing(s->smallSpacing()*Metrics::TitleBar_ButtonSpacing);

            // padding
            const int vPadding = isMaximized() ? 0 : s->smallSpacing()*Metrics::TitleBar_TopMargin;
            const int hPadding = s->smallSpacing()*Metrics::TitleBar_SideMargin;
            if( isMaximizedHorizontally() )
            {
                // add offsets on the side buttons, to preserve padding, but satisfy Fitts law
                auto button = static_cast<Button*>( m_leftButtons->buttons().front().data() );
                button->setGeometry( QRectF( QPoint( 0, 0 ), QSizeF( bWidth + hPadding, bHeight ) ) );
                button->setFlag( Button::FlagFirstInList );
                button->setHorizontalOffset( hPadding );

                m_leftButtons->setPos(QPointF(0, vPadding));

            } else m_leftButtons->setPos(QPointF(hPadding + borderLeft(), vPadding));

        }

        // right buttons
        if( !m_rightButtons->buttons().isEmpty() )
        {

            // spacing
            m_rightButtons->setSpacing(s->smallSpacing()*Metrics::TitleBar_ButtonSpacing);

            // padding
            const int vPadding = isMaximized() ? 0 : s->smallSpacing()*Metrics::TitleBar_TopMargin;
            const int hPadding = s->smallSpacing()*Metrics::TitleBar_SideMargin;
            if( isMaximizedHorizontally() )
            {

                auto button = static_cast<Button*>( m_rightButtons->buttons().back().data() );
                button->setGeometry( QRectF( QPoint( 0, 0 ), QSizeF( bWidth + hPadding, bHeight ) ) );
                button->setFlag( Button::FlagLastInList );

                m_rightButtons->setPos(QPointF(size().width() - m_rightButtons->geometry().width(), vPadding));

            } else m_rightButtons->setPos(QPointF(size().width() - m_rightButtons->geometry().width() - hPadding - borderRight(), vPadding));

        }

        update();


    }

    //________________________________________________________________
    void Decoration::paint(QPainter *painter, const QRect &repaintRegion)
    {
        // TODO: optimize based on repaintRegion
        auto c = client().data();
        auto s = settings();

        // paint background
        if( !c->isShaded() )
        {
            painter->fillRect(rect(), Qt::transparent);
            painter->save();
            painter->setRenderHint(QPainter::Antialiasing);
            painter->setPen(Qt::NoPen);
            painter->setBrush( c->color( c->isActive() ? ColorGroup::Active : ColorGroup::Inactive, ColorRole::Frame ) );

            // clip away the top part
            if( !hideTitleBar() ) painter->setClipRect(0, borderTop(), size().width(), size().height() - borderTop(), Qt::IntersectClip);

            if( s->isAlphaChannelSupported() ) painter->drawRoundedRect(rect(), Metrics::Frame_FrameRadius, Metrics::Frame_FrameRadius);
            else painter->drawRect( rect() );

            painter->restore();
        }

        if( !hideTitleBar() ) paintTitleBar(painter, repaintRegion);

        if( hasBorders() && !s->isAlphaChannelSupported() )
        {
            painter->save();
            painter->setRenderHint(QPainter::Antialiasing, false);
            painter->setBrush( Qt::NoBrush );
            painter->setPen( c->isActive() ?
                c->color( ColorGroup::Active, ColorRole::TitleBar ):
                c->color( ColorGroup::Inactive, ColorRole::Foreground ) );

            painter->drawRect( rect().adjusted( 0, 0, -1, -1 ) );
            painter->restore();
        }

    }

    //________________________________________________________________
    void Decoration::paintTitleBar(QPainter *painter, const QRect &repaintRegion)
    {
        const auto c = client().data();
        const QRect titleRect(QPoint(0, 0), QSize(size().width(), borderTop()));

        painter->save();
        painter->setPen(Qt::NoPen);

        // render a linear gradient on title area
        if( c->isActive() && m_internalSettings->drawBackgroundGradient() )
        {

            const QColor titleBarColor( this->titleBarColor() );
            QLinearGradient gradient( 0, 0, 0, titleRect.height() );
            gradient.setColorAt(0.0, titleBarColor.lighter( 120 ) );
            gradient.setColorAt(0.8, titleBarColor);
            painter->setBrush(gradient);

        } else {

            painter->setBrush( titleBarColor() );

        }

        auto s = settings();
        if( isMaximized() || !s->isAlphaChannelSupported() )
        {

            painter->drawRect(titleRect);

        } else if( c->isShaded() ) {

            painter->drawRoundedRect(titleRect, Metrics::Frame_FrameRadius, Metrics::Frame_FrameRadius);

        } else {

            // we make the rect a little bit larger to be able to clip away the rounded corners on bottom
            painter->setClipRect(titleRect, Qt::IntersectClip);
            painter->drawRoundedRect(titleRect.adjusted(0, 0, 0, Metrics::Frame_FrameRadius), Metrics::Frame_FrameRadius, Metrics::Frame_FrameRadius);

        }

        const QColor outlineColor( this->outlineColor() );
        if( !c->isShaded() && outlineColor.isValid() )
        {
            // outline
            painter->setRenderHint( QPainter::Antialiasing, false );
            painter->setBrush( Qt::NoBrush );
            painter->setPen( outlineColor );
            painter->drawLine( titleRect.bottomLeft(), titleRect.bottomRight() );
        }

        painter->restore();

        // draw caption
        painter->setFont(s->font());
        painter->setPen( fontColor() );
        const auto cR = captionRect();
        const QString caption = painter->fontMetrics().elidedText(c->caption(), Qt::ElideMiddle, cR.first.width());
        painter->drawText(cR.first, cR.second | Qt::TextSingleLine, caption);

        // draw all buttons
        m_leftButtons->paint(painter, repaintRegion);
        m_rightButtons->paint(painter, repaintRegion);
    }

    //________________________________________________________________
    int Decoration::buttonHeight() const
    {
        const int baseSize = settings()->gridUnit();
        switch( m_internalSettings->buttonSize() )
        {
            case InternalSettings::ButtonTiny: return baseSize;
            case InternalSettings::ButtonSmall: return baseSize*1.5;
            default:
            case InternalSettings::ButtonDefault: return baseSize*2;
            case InternalSettings::ButtonLarge: return baseSize*2.5;
            case InternalSettings::ButtonVeryLarge: return baseSize*3.5;
        }

    }

    //________________________________________________________________
    int Decoration::captionHeight() const
    { return hideTitleBar() ? borderTop() : borderTop() - settings()->smallSpacing()*(Metrics::TitleBar_BottomMargin + Metrics::TitleBar_TopMargin ) - 1; }

    //________________________________________________________________
    QPair<QRect,Qt::Alignment> Decoration::captionRect() const
    {
        if( hideTitleBar() ) return qMakePair( QRect(), Qt::AlignCenter );
        else {

            auto c = client().data();
            const int leftOffset = m_leftButtons->buttons().isEmpty() ?
                Metrics::TitleBar_SideMargin*settings()->smallSpacing():
                m_leftButtons->geometry().x() + m_leftButtons->geometry().width() + Metrics::TitleBar_SideMargin*settings()->smallSpacing();

            const int rightOffset = m_rightButtons->buttons().isEmpty() ?
                Metrics::TitleBar_SideMargin*settings()->smallSpacing() :
                size().width() - m_rightButtons->geometry().x() + Metrics::TitleBar_SideMargin*settings()->smallSpacing();

            const int yOffset = settings()->smallSpacing()*Metrics::TitleBar_TopMargin;
            const QRect maxRect( leftOffset, yOffset, size().width() - leftOffset - rightOffset, captionHeight() );

            switch( m_internalSettings->titleAlignment() )
            {
                case InternalSettings::AlignLeft:
                return qMakePair( maxRect, Qt::AlignVCenter|Qt::AlignLeft );

                case InternalSettings::AlignRight:
                return qMakePair( maxRect, Qt::AlignVCenter|Qt::AlignRight );

                case InternalSettings::AlignCenter:
                return qMakePair( maxRect, Qt::AlignCenter );

                default:
                case InternalSettings::AlignCenterFullWidth:
                {

                    // full caption rect
                    const QRect fullRect = QRect( 0, yOffset, size().width(), captionHeight() );
                    QRect boundingRect( settings()->fontMetrics().boundingRect( c->caption()).toRect() );

                    // text bounding rect
                    boundingRect.setTop( yOffset );
                    boundingRect.setHeight( captionHeight() );
                    boundingRect.moveLeft( ( size().width() - boundingRect.width() )/2 );

                    if( boundingRect.left() < leftOffset ) return qMakePair( maxRect, Qt::AlignVCenter|Qt::AlignLeft );
                    else if( boundingRect.right() > size().width() - rightOffset ) return qMakePair( maxRect, Qt::AlignVCenter|Qt::AlignRight );
                    else return qMakePair(fullRect, Qt::AlignCenter);

                }

            }

        }

    }

    //________________________________________________________________
    void Decoration::createShadow()
    {

        // assign global shadow if exists and parameters match
        if(
            !g_sShadow  ||
            g_shadowSize != m_internalSettings->shadowSize() ||
            g_shadowStrength != m_internalSettings->shadowStrength() ||
            g_shadowColor != m_internalSettings->shadowColor()
            )
        {
            // assign parameters
            g_shadowSize = m_internalSettings->shadowSize();
            g_shadowStrength = m_internalSettings->shadowStrength();
            g_shadowColor = m_internalSettings->shadowColor();
            const int shadowOffset = qMax( 6*g_shadowSize/16, Metrics::Shadow_Overlap*2 );

            // create image
            QImage image(2*g_shadowSize, 2*g_shadowSize, QImage::Format_ARGB32_Premultiplied);
            image.fill(Qt::transparent);

            // create gradient
            // gaussian delta function
            auto alpha = [](qreal x) { return std::exp( -x*x/0.15 ); };

            // color calculation delta function
            auto gradientStopColor = [](QColor color, int alpha)
            {
                color.setAlpha(alpha);
                return color;
            };

            QRadialGradient radialGradient( g_shadowSize, g_shadowSize, g_shadowSize );
            for( int i = 0; i < 10; ++i )
            {
                const qreal x( qreal( i )/9 );
                radialGradient.setColorAt(x,  gradientStopColor( g_shadowColor, alpha(x)*g_shadowStrength ) );
            }

            radialGradient.setColorAt(1, gradientStopColor( g_shadowColor, 0 ) );

            // fill
            QPainter painter(&image);
            painter.setRenderHint( QPainter::Antialiasing, true );
            painter.fillRect( image.rect(), radialGradient);

            // contrast pixel
            QRectF innerRect = QRectF(
                g_shadowSize - shadowOffset - Metrics::Shadow_Overlap, g_shadowSize - shadowOffset - Metrics::Shadow_Overlap,
                shadowOffset + 2*Metrics::Shadow_Overlap, shadowOffset + 2*Metrics::Shadow_Overlap );

            painter.setPen( gradientStopColor( g_shadowColor, g_shadowStrength*0.5 ) );
            painter.setBrush( Qt::NoBrush );
            painter.drawRoundedRect( innerRect, -0.5 + Metrics::Frame_FrameRadius, -0.5 + Metrics::Frame_FrameRadius );

            // mask out inner rect
            painter.setPen( Qt::NoPen );
            painter.setBrush( Qt::black );
            painter.setCompositionMode(QPainter::CompositionMode_DestinationOut );
            painter.drawRoundedRect( innerRect, 0.5 + Metrics::Frame_FrameRadius, 0.5 + Metrics::Frame_FrameRadius );

            painter.end();

            g_sShadow = QSharedPointer<KDecoration2::DecorationShadow>::create();
            g_sShadow->setPadding( QMargins(
                g_shadowSize - shadowOffset - Metrics::Shadow_Overlap,
                g_shadowSize - shadowOffset - Metrics::Shadow_Overlap,
                g_shadowSize - Metrics::Shadow_Overlap,
                g_shadowSize - Metrics::Shadow_Overlap ) );

            g_sShadow->setInnerShadowRect(QRect( g_shadowSize, g_shadowSize, 1, 1) );

            // assign image
            g_sShadow->setShadow(image);

        }

        setShadow(g_sShadow);

    }

    //_________________________________________________________________
    void Decoration::createSizeGrip( void )
    {

        // do nothing if size grip already exist
        if( m_sizeGrip ) return;

        #if BREEZE_HAVE_X11
        if( !QX11Info::isPlatformX11() ) return;

        // access client
        auto c = client().data();
        if( !c ) return;

        if( c->windowId() != 0 )
        {
            m_sizeGrip = new SizeGrip( this );
            connect( c, &KDecoration2::DecoratedClient::maximizedChanged, this, &Decoration::updateSizeGripVisibility );
            connect( c, &KDecoration2::DecoratedClient::shadedChanged, this, &Decoration::updateSizeGripVisibility );
            connect( c, &KDecoration2::DecoratedClient::resizeableChanged, this, &Decoration::updateSizeGripVisibility );
        }
        #endif

    }

    //_________________________________________________________________
    void Decoration::deleteSizeGrip( void )
    {
        if( m_sizeGrip )
        {
            m_sizeGrip->deleteLater();
            m_sizeGrip = nullptr;
        }
    }

} // namespace


#include "breezedecoration.moc"
