/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the plugins of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL21$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see http://www.qt.io/terms-conditions. For further
** information use the contact form at http://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 or version 3 as published by the Free
** Software Foundation and appearing in the file LICENSE.LGPLv21 and
** LICENSE.LGPLv3 included in the packaging of this file. Please review the
** following information to ensure the GNU Lesser General Public License
** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** As a special exception, The Qt Company gives you certain additional
** rights. These rights are described in The Qt Company LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qiosbackingstore.h"
#include "qioswindow.h"

#include <QtGui/QOpenGLContext>
#include <QtGui/QOpenGLPaintDevice>

#include <QtDebug>

QIOSBackingStore::QIOSBackingStore(QWindow *window)
    : QPlatformBackingStore(window)
    , m_context(new QOpenGLContext)
    , m_device(0)
{
    QSurfaceFormat fmt = window->requestedFormat();
    fmt.setDepthBufferSize(16);
    fmt.setStencilBufferSize(8);

    // Needed to prevent QOpenGLContext::makeCurrent() from failing
    window->setSurfaceType(QSurface::OpenGLSurface);

    m_context->setFormat(fmt);
    m_context->setScreen(window->screen());
    m_context->create();
}

QIOSBackingStore::~QIOSBackingStore()
{
    delete m_context;
    delete m_device;
}

void QIOSBackingStore::beginPaint(const QRegion &)
{
    m_context->makeCurrent(window());
}

QPaintDevice *QIOSBackingStore::paintDevice()
{
    if (!m_device)
        m_device = new QOpenGLPaintDevice;

    // Keep paint device size and device pixel ratio in sync with window
    qreal devicePixelRatio = window()->devicePixelRatio();
    m_device->setSize(window()->size() * devicePixelRatio);
    m_device->setDevicePixelRatio(devicePixelRatio);

    return m_device;
}

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

    if (window != this->window()) {
        // We skip flushing raster-based child windows, to avoid the extra cost of copying from the
        // parent FBO into the child FBO. Since the child is already drawn inside the parent FBO, it
        // will become visible when flushing the parent. The only case we end up not supporting is if
        // the child window overlaps a sibling window that's draws using a separate QOpenGLContext.
        return;
    }

    m_context->makeCurrent(window);
    m_context->swapBuffers(window);
}

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

    // Resizing the backing store would in our case mean resizing the QWindow,
    // as we cheat and use an QOpenGLPaintDevice that we target at the window.
    // That's probably not what the user intended, so we ignore resizes of the
    // backing store and always keep the paint device's size in sync with the
    // window size in beginPaint().

    if (size != window()->size() && !window()->inherits("QWidgetWindow"))
        qWarning() << "QIOSBackingStore needs to have the same size as its window";
}

QT_END_NAMESPACE