/****************************************************************************
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** This file is part of the plugins of the Qt Toolkit.
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** ensure the GNU Lesser General Public License version 2.1 requirements
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** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
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****************************************************************************/

#include "qeglfsbackingstore.h"
#include "qeglfscompositor.h"
#include "qeglfscursor.h"
#include "qeglfswindow.h"
#include "qeglfscontext.h"

#include <QtGui/QOpenGLPaintDevice>
#include <QtGui/QOpenGLShaderProgram>

QT_BEGIN_NAMESPACE

QEglFSBackingStore::QEglFSBackingStore(QWindow *window)
    : QPlatformBackingStore(window),
      m_window(static_cast<QEglFSWindow *>(window->handle())),
      m_texture(0)
{
    m_window->setBackingStore(this);
}

QPaintDevice *QEglFSBackingStore::paintDevice()
{
    return &m_image;
}

void QEglFSBackingStore::updateTexture()
{
    glBindTexture(GL_TEXTURE_2D, m_texture);

    if (!m_dirty.isNull()) {
        QRegion fixed;
        QRect imageRect = m_image.rect();
        m_dirty |= imageRect;

        foreach (const QRect &rect, m_dirty.rects()) {
            // intersect with image rect to be sure
            QRect r = imageRect & rect;

            // if the rect is wide enough it's cheaper to just
            // extend it instead of doing an image copy
            if (r.width() >= imageRect.width() / 2) {
                r.setX(0);
                r.setWidth(imageRect.width());
            }

            fixed |= r;
        }

        foreach (const QRect &rect, fixed.rects()) {
            // if the sub-rect is full-width we can pass the image data directly to
            // OpenGL instead of copying, since there's no gap between scanlines
            if (rect.width() == imageRect.width()) {
                glTexSubImage2D(GL_TEXTURE_2D, 0, 0, rect.y(), rect.width(), rect.height(), GL_RGBA, GL_UNSIGNED_BYTE,
                                m_image.constScanLine(rect.y()));
            } else {
                glTexSubImage2D(GL_TEXTURE_2D, 0, rect.x(), rect.y(), rect.width(), rect.height(), GL_RGBA, GL_UNSIGNED_BYTE,
                    m_image.copy(rect).constBits());
            }
        }

        m_dirty = QRegion();
    }
}

void QEglFSBackingStore::flush(QWindow *window, const QRegion &region, const QPoint &offset)
{
    Q_UNUSED(window);
    Q_UNUSED(region);
    Q_UNUSED(offset);

#ifdef QEGL_EXTRA_DEBUG
    qWarning("QEglBackingStore::flush %p", window);
#endif

    QEglFSWindow *rootWin = m_window->screen()->rootWindow();
    if (!rootWin)
        return;

    m_window->create();
    rootWin->screen()->rootContext()->makeCurrent(rootWin->window());
    updateTexture();
    QEglFSCompositor::instance()->schedule(rootWin->screen());
}

void QEglFSBackingStore::beginPaint(const QRegion &rgn)
{
    m_dirty |= rgn;
}

void QEglFSBackingStore::resize(const QSize &size, const QRegion &staticContents)
{
    Q_UNUSED(staticContents);

    QEglFSWindow *rootWin = m_window->screen()->rootWindow();
    if (!rootWin)
        return;

    m_image = QImage(size, QImage::Format_RGB32);
    m_window->create();

    rootWin->screen()->rootContext()->makeCurrent(rootWin->window());

    if (m_texture)
        glDeleteTextures(1, &m_texture);

    glGenTextures(1, &m_texture);
    glBindTexture(GL_TEXTURE_2D, m_texture);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, size.width(), size.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
}

QT_END_NAMESPACE