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

Copyright (C) 2007 Lubos Lunak <l.lunak@kde.org>
Copyright (C) 2010 Martin Gräßlin <kde@martin-graesslin.com>

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) any later version.

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 "showpaint.h"

#include <kwinconfig.h>

#include <kwinglutils.h>
#ifdef KWIN_HAVE_XRENDER_COMPOSITING
#include <X11/Xlib.h>
#include <X11/extensions/Xrender.h>
#endif

#include <math.h>

#include <qcolor.h>

namespace KWin
{

KWIN_EFFECT(showpaint, ShowPaintEffect)

static QColor colors[] = { Qt::red, Qt::green, Qt::blue, Qt::cyan, Qt::magenta,
                           Qt::yellow, Qt::gray
                         };

ShowPaintEffect::ShowPaintEffect()
    : color_index(0)
{
}

ShowPaintEffect::~ShowPaintEffect()
{
}

void ShowPaintEffect::paintScreen(int mask, QRegion region, ScreenPaintData& data)
{
    painted = QRegion();
    effects->paintScreen(mask, region, data);
    if (effects->compositingType() == OpenGLCompositing)
        paintGL();
#ifdef KWIN_HAVE_XRENDER_COMPOSITING
    if (effects->compositingType() == XRenderCompositing)
        paintXrender();
#endif
    if (++color_index == sizeof(colors) / sizeof(colors[ 0 ]))
        color_index = 0;
}

void ShowPaintEffect::paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data)
{
    painted |= region;
    effects->paintWindow(w, mask, region, data);
}

void ShowPaintEffect::paintGL()
{
    GLVertexBuffer *vbo = GLVertexBuffer::streamingBuffer();
    vbo->reset();
    vbo->setUseColor(true);
    if (ShaderManager::instance()->isValid()) {
        ShaderManager::instance()->pushShader(ShaderManager::ColorShader);
    }
    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    QColor color = colors[ color_index ];
    color.setAlphaF(0.2);
    vbo->setColor(color);
    QVector<float> verts;
    verts.reserve(painted.rects().count() * 12);
    foreach (const QRect & r, painted.rects()) {
        verts << r.x() + r.width() << r.y();
        verts << r.x() << r.y();
        verts << r.x() << r.y() + r.height();
        verts << r.x() << r.y() + r.height();
        verts << r.x() + r.width() << r.y() + r.height();
        verts << r.x() + r.width() << r.y();
    }
    vbo->setData(verts.count() / 2, 2, verts.data(), NULL);
    vbo->render(GL_TRIANGLES);
    if (ShaderManager::instance()->isValid()) {
        ShaderManager::instance()->popShader();
    }
    glDisable(GL_BLEND);
}

void ShowPaintEffect::paintXrender()
{
#ifdef KWIN_HAVE_XRENDER_COMPOSITING
    XRenderColor col;
    float alpha = 0.2;
    const QColor& color = colors[ color_index ];
    col.alpha = int(alpha * 0xffff);
    col.red = int(alpha * 0xffff * color.red() / 255);
    col.green = int(alpha * 0xffff * color.green() / 255);
    col.blue = int(alpha * 0xffff * color.blue() / 255);
    foreach (const QRect & r, painted.rects())
    XRenderFillRectangle(display(), PictOpOver, effects->xrenderBufferPicture(),
                         &col, r.x(), r.y(), r.width(), r.height());
#endif
}

} // namespace