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#include <qopenglpaintdevice.h>
#include <qpaintengine.h>
#include <qthreadstorage.h>

#include <private/qobject_p.h>
#include <private/qopenglcontext_p.h>
#include <private/qopenglframebufferobject_p.h>
#include <private/qopenglpaintengine_p.h>

// for qt_defaultDpiX/Y
#include <private/qfont_p.h>

#include <qopenglfunctions.h>

QT_BEGIN_NAMESPACE

/*!
    \class QOpenGLPaintDevice
    \brief The QOpenGLPaintDevice class enables painting to an OpenGL context using QPainter.
    \since 5.0
    \inmodule QtGui

    \ingroup painting-3D

    When painting to a QOpenGLPaintDevice using QPainter, the state of
    the current OpenGL context will be altered by the paint engine to reflect
    its needs.  Applications should not rely upon the OpenGL state being reset
    to its original conditions, particularly the current shader program,
    OpenGL viewport, texture units, and drawing modes.
*/

class QOpenGLPaintDevicePrivate
{
public:
    QOpenGLPaintDevicePrivate(const QSize &size);

    QSize size;
    QOpenGLContext *ctx;

    qreal dpmx;
    qreal dpmy;

    bool flipped;

    QPaintEngine *engine;
};

/*!
    Constructs a QOpenGLPaintDevice.

    The QOpenGLPaintDevice is only valid for the current context.

    \sa QOpenGLContext::currentContext()
*/
QOpenGLPaintDevice::QOpenGLPaintDevice()
    : d_ptr(new QOpenGLPaintDevicePrivate(QSize()))
{
}

/*!
    Constructs a QOpenGLPaintDevice with the given \a size.

    The QOpenGLPaintDevice is only valid for the current context.

    \sa QOpenGLContext::currentContext()
*/
QOpenGLPaintDevice::QOpenGLPaintDevice(const QSize &size)
    : d_ptr(new QOpenGLPaintDevicePrivate(size))
{
}

/*!
    Constructs a QOpenGLPaintDevice with the given \a width and \a height.

    The QOpenGLPaintDevice is only valid for the current context.

    \sa QOpenGLContext::currentContext()
*/
QOpenGLPaintDevice::QOpenGLPaintDevice(int width, int height)
    : d_ptr(new QOpenGLPaintDevicePrivate(QSize(width, height)))
{
}

/*!
    Destroys the QOpenGLPaintDevice.
*/

QOpenGLPaintDevice::~QOpenGLPaintDevice()
{
    delete d_ptr->engine;
}

/*!
    \fn int QOpenGLPaintDevice::devType() const
    \internal
    \reimp
*/

QOpenGLPaintDevicePrivate::QOpenGLPaintDevicePrivate(const QSize &sz)
    : size(sz)
    , ctx(QOpenGLContext::currentContext())
    , dpmx(qt_defaultDpiX() * 100. / 2.54)
    , dpmy(qt_defaultDpiY() * 100. / 2.54)
    , flipped(false)
    , engine(0)
{
}

class QOpenGLEngineThreadStorage
{
public:
    QPaintEngine *engine() {
        QPaintEngine *&localEngine = storage.localData();
        if (!localEngine)
            localEngine = new QOpenGL2PaintEngineEx;
        return localEngine;
    }

private:
    QThreadStorage<QPaintEngine *> storage;
};

Q_GLOBAL_STATIC(QOpenGLEngineThreadStorage, qt_opengl_engine)

/*!
    \reimp
*/

QPaintEngine *QOpenGLPaintDevice::paintEngine() const
{
    if (d_ptr->engine)
        return d_ptr->engine;

    QPaintEngine *engine = qt_opengl_engine()->engine();
    if (engine->isActive() && engine->paintDevice() != this) {
        d_ptr->engine = new QOpenGL2PaintEngineEx;
        return d_ptr->engine;
    }

    return engine;
}

/*!
    Returns the OpenGL context associated with the paint device.
*/

QOpenGLContext *QOpenGLPaintDevice::context() const
{
    return d_ptr->ctx;
}

/*!
    Returns the pixel size of the paint device.

    \sa setSize()
*/

QSize QOpenGLPaintDevice::size() const
{
    return d_ptr->size;
}

/*!
    Sets the pixel size of the paint device to \a size.

    \sa size()
*/

void QOpenGLPaintDevice::setSize(const QSize &size)
{
    d_ptr->size = size;
}

/*!
    \reimp
*/

int QOpenGLPaintDevice::metric(QPaintDevice::PaintDeviceMetric metric) const
{
    switch (metric) {
    case PdmWidth:
        return d_ptr->size.width();
    case PdmHeight:
        return d_ptr->size.height();
    case PdmDepth:
        return 32;
    case PdmWidthMM:
        return qRound(d_ptr->size.width() * 1000 / d_ptr->dpmx);
    case PdmHeightMM:
        return qRound(d_ptr->size.height() * 1000 / d_ptr->dpmy);
    case PdmNumColors:
        return 0;
    case PdmDpiX:
        return qRound(d_ptr->dpmx * 0.0254);
    case PdmDpiY:
        return qRound(d_ptr->dpmy * 0.0254);
    case PdmPhysicalDpiX:
        return qRound(d_ptr->dpmx * 0.0254);
    case PdmPhysicalDpiY:
        return qRound(d_ptr->dpmy * 0.0254);
    default:
        qWarning("QOpenGLPaintDevice::metric() - metric %d not known", metric);
        return 0;
    }
}

/*!
    Returns the number of pixels per meter horizontally.

    \sa setDotsPerMeterX()
*/

qreal QOpenGLPaintDevice::dotsPerMeterX() const
{
    return d_ptr->dpmx;
}

/*!
    Returns the number of pixels per meter vertically.

    \sa setDotsPerMeterY()
*/

qreal QOpenGLPaintDevice::dotsPerMeterY() const
{
    return d_ptr->dpmy;
}

/*!
    Sets the number of pixels per meter horizontally to \a dpmx.

    \sa dotsPerMeterX()
*/

void QOpenGLPaintDevice::setDotsPerMeterX(qreal dpmx)
{
    d_ptr->dpmx = dpmx;
}

/*!
    Sets the number of pixels per meter vertically to \a dpmy.

    \sa dotsPerMeterY()
*/

void QOpenGLPaintDevice::setDotsPerMeterY(qreal dpmy)
{
    d_ptr->dpmx = dpmy;
}

/*!
    Sets whether painting should be flipped around the Y-axis or not to \a flipped.

    \sa paintFlipped()
*/
void QOpenGLPaintDevice::setPaintFlipped(bool flipped)
{
    d_ptr->flipped = flipped;
}

/*!
    Returns true if painting is flipped around the Y-axis.

    \sa setPaintFlipped()
*/

bool QOpenGLPaintDevice::paintFlipped() const
{
    return d_ptr->flipped;
}

/*!
    This virtual method is provided as a callback to allow re-binding a
    target frame buffer object when different QOpenGLPaintDevice instances
    are issuing draw calls alternately on the same OpenGL context.

    QPainter::beginNativePainting will also trigger this method.
*/
void QOpenGLPaintDevice::ensureActiveTarget()
{
}

QT_END_NAMESPACE