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#include "qglsubsurface.h"

QT_BEGIN_NAMESPACE

/*!
    \class QGLSubsurface
    \brief The QGLSubsurface class represents a sub-surface of another OpenGL drawing surface.
    \since 4.8
    \ingroup qt3d
    \ingroup qt3d::painting
*/

class QGLSubsurfacePrivate
{
public:
    QGLSubsurfacePrivate() : surface(0) {}
    QGLSubsurfacePrivate(QGLAbstractSurface *surf, const QRect &rgn)
        : surface(surf), region(rgn) {}

    QGLAbstractSurface *surface;
    QRect region;
};

/*!
    Constructs a new subsurface.  This constructor should be followed
    by calls to setSurface() and setRegion().
*/
QGLSubsurface::QGLSubsurface()
    : QGLAbstractSurface(QGLAbstractSurface::Subsurface)
    , d_ptr(new QGLSubsurfacePrivate)
{
}

/*!
    Constructs a new subsurface that occupies \a region within
    \a surface.  The \a region has its origin at the top-left
    of \a surface.
*/
QGLSubsurface::QGLSubsurface
        (QGLAbstractSurface *surface, const QRect &region)
    : QGLAbstractSurface(QGLAbstractSurface::Subsurface)
    , d_ptr(new QGLSubsurfacePrivate(surface, region))
{
}

/*!
    Destroys this subsurface.
*/
QGLSubsurface::~QGLSubsurface()
{
}

/*!
    Returns the surface behind this subsurface, or null if the
    surface has not been set.

    \sa setSurface(), region()
*/
QGLAbstractSurface *QGLSubsurface::surface() const
{
    Q_D(const QGLSubsurface);
    return d->surface;
}

/*!
    Sets the \a surface behind this subsurface.

    \sa surface(), setRegion()
*/
void QGLSubsurface::setSurface(QGLAbstractSurface *surface)
{
    Q_D(QGLSubsurface);
    d->surface = surface;
}

/*!
    Returns the region within surface() that is occupied by this
    subsurface, relative to the viewportRect() of surface().
    The origin is at the top-left of surface().

    \sa setRegion(), surface()
*/
QRect QGLSubsurface::region() const
{
    Q_D(const QGLSubsurface);
    return d->region;
}

/*!
    Sets the \a region within surface() that is occupied by this
    subsurface, relative to the viewportRect() of surface().
    The origin is at the top-left of surface().

    \sa region(), setSurface()
*/
void QGLSubsurface::setRegion(const QRect &region)
{
    Q_D(QGLSubsurface);
    d->region = region;
}

/*!
    \reimp
*/
QPaintDevice *QGLSubsurface::device() const
{
    Q_D(const QGLSubsurface);
    if (d->surface)
        return d->surface->device();
    else
        return 0;
}

/*!
    \reimp
*/
bool QGLSubsurface::activate(QGLAbstractSurface *prevSurface)
{
    Q_D(QGLSubsurface);
    if (d->surface)
        return d->surface->activate(prevSurface);
    else
        return false;
}

/*!
    \reimp
*/
void QGLSubsurface::deactivate(QGLAbstractSurface *nextSurface)
{
    Q_D(QGLSubsurface);
    if (d->surface)
        d->surface->deactivate(nextSurface);
}

/*!
    \reimp
*/
QRect QGLSubsurface::viewportGL() const
{
    Q_D(const QGLSubsurface);
    if (d->surface) {
        // The underlying surface's viewportGL() has its origin
        // at the bottom-left, whereas d->region has its origin
        // at the top-left.  Flip the sub-region and adjust.
        QRect rect = d->surface->viewportGL();
        return QRect(rect.x() + d->region.x(),
                     rect.y() + rect.height() -
                        (d->region.y() + d->region.height()),
                     d->region.width(), d->region.height());
    } else {
        // Don't know the actual height of the surrounding surface,
        // so the best we can do is assume the region is bottom-aligned.
        return QRect(d->region.x(), 0, d->region.width(), d->region.height());
    }
}

QT_END_NAMESPACE