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#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);

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

    m_context->makeCurrent(window());

    QIOSWindow *iosWindow = static_cast<QIOSWindow *>(window()->handle());
    static_cast<QOpenGLPaintDevice *>(paintDevice())->setSize(window()->size() * iosWindow->devicePixelRatio());
}

QPaintDevice *QIOSBackingStore::paintDevice()
{
    if (!m_device) {
        QIOSWindow *iosWindow = static_cast<QIOSWindow *>(window()->handle());
        QOpenGLPaintDevice *openGLDevice = new QOpenGLPaintDevice(window()->size() * iosWindow->devicePixelRatio());
        openGLDevice->setDevicePixelRatio(iosWindow->devicePixelRatio());
        m_device = openGLDevice;
    }

    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->swapBuffers(window);
}

void QIOSBackingStore::endPaint()
{
    // Calling makeDone() on the context here would be an option,
    // but is not needed, and would actually add some overhead.
}

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())
        qWarning() << "QIOSBackingStore needs to have the same size as its window";
}

QT_END_NAMESPACE