source: trunk/src/opengl/qgl.cpp@ 754

/****************************************************************************
**
** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation ([email protected])
**
** This file is part of the QtOpenGL module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** 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 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** 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
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at [email protected].
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qapplication.h"
#include "qplatformdefs.h"
#include "qgl.h"
#include <qdebug.h>

#if defined(Q_WS_X11)
#include "private/qt_x11_p.h"
#include "private/qpixmap_x11_p.h"
#define INT32 dummy_INT32
#define INT8 dummy_INT8
#if !defined(QT_OPENGL_ES)
# include <GL/glx.h>
#endif
#undef INT32
#undef INT8
#include "qx11info_x11.h"
#elif defined(Q_WS_MAC)
# include <private/qt_mac_p.h>
#endif

#include <qdatetime.h>

#include <stdlib.h> // malloc

#include "qpixmap.h"
#include "qimage.h"
#include "qgl_p.h"

#if !defined(QT_OPENGL_ES_1) && !defined(QT_OPENGL_ES_1_CL)
#include "gl2paintengineex/qpaintengineex_opengl2_p.h"
#endif

#ifndef QT_OPENGL_ES_2
#include <private/qpaintengine_opengl_p.h>
#endif

#ifdef Q_WS_QWS
#include <private/qglwindowsurface_qws_p.h>
#endif

#include <qglpixelbuffer.h>
#include <qglframebufferobject.h>

#include <private/qimage_p.h>
#include <private/qpixmapdata_p.h>
#include <private/qpixmapdata_gl_p.h>
#include <private/qglpixelbuffer_p.h>
#include <private/qwindowsurface_gl_p.h>
#include <private/qimagepixmapcleanuphooks_p.h>
#include "qcolormap.h"
#include "qfile.h"
#include "qlibrary.h"


QT_BEGIN_NAMESPACE

#ifdef QT_OPENGL_ES_1_CL
#include "qgl_cl_p.h"
#endif


#if defined(Q_WS_X11) || defined(Q_WS_MAC) || defined(Q_WS_QWS)
QGLExtensionFuncs QGLContextPrivate::qt_extensionFuncs;
#endif

struct QGLThreadContext {
    QGLContext *context;
};

static QThreadStorage<QGLThreadContext *> qgl_context_storage;

Q_GLOBAL_STATIC(QGLFormat, qgl_default_format)

class QGLDefaultOverlayFormat: public QGLFormat
{
public:
    inline QGLDefaultOverlayFormat()
    {
        setOption(QGL::FormatOption(0xffff << 16)); // turn off all options
        setOption(QGL::DirectRendering);
        setPlane(1);
    }
};
Q_GLOBAL_STATIC(QGLDefaultOverlayFormat, defaultOverlayFormatInstance)

Q_GLOBAL_STATIC(QGLSignalProxy, theSignalProxy)
QGLSignalProxy *QGLSignalProxy::instance()
{
    return theSignalProxy();
}


class QGLEngineSelector
{
public:
    QGLEngineSelector() : engineType(QPaintEngine::MaxUser)
    {
    }

    void setPreferredPaintEngine(QPaintEngine::Type type) {
        if (type == QPaintEngine::OpenGL || type == QPaintEngine::OpenGL2)
            engineType = type;
    }

    QPaintEngine::Type preferredPaintEngine() {
#ifdef Q_WS_MAC
        // The ATI X1600 driver for Mac OS X does not support return
        // values from functions in GLSL. Since working around this in
        // the GL2 engine would require a big, ugly rewrite, we're
        // falling back to the GL 1 engine..
        static bool mac_x1600_check_done = false;
        if (!mac_x1600_check_done) {
            QGLTemporaryContext *tmp = 0;
            if (!QGLContext::currentContext())
                tmp = new QGLTemporaryContext();
            if (strstr((char *) glGetString(GL_RENDERER), "X1600"))
                engineType = QPaintEngine::OpenGL;
            if (tmp)
                delete tmp;
            mac_x1600_check_done = true;
        }
#endif
        if (engineType == QPaintEngine::MaxUser) {
            // No user-set engine - use the defaults
#if defined(QT_OPENGL_ES_2)
            engineType = QPaintEngine::OpenGL2;
#else
            // We can't do this in the constructor for this object because it
            // needs to be called *before* the QApplication constructor.
            // Also check for the FragmentShader extension in conjunction with
            // the 2.0 version flag, to cover the case where we export the display
            // from an old GL 1.1 server to a GL 2.x client. In that case we can't
            // use GL 2.0.
            if ((QGLFormat::openGLVersionFlags() & QGLFormat::OpenGL_Version_2_0)
                && (QGLExtensions::glExtensions() & QGLExtensions::FragmentShader)
                && qgetenv("QT_GL_USE_OPENGL1ENGINE").isEmpty())
                engineType = QPaintEngine::OpenGL2;
            else
                engineType = QPaintEngine::OpenGL;
#endif
        }
        return engineType;
    }

private:
    QPaintEngine::Type engineType;
};

Q_GLOBAL_STATIC(QGLEngineSelector, qgl_engine_selector)


bool qt_gl_preferGL2Engine()
{
    return qgl_engine_selector()->preferredPaintEngine() == QPaintEngine::OpenGL2;
}


/*!
    \namespace QGL
    \inmodule QtOpenGL

    \brief The QGL namespace specifies miscellaneous identifiers used
    in the Qt OpenGL module.

    \ingroup painting-3D
*/

/*!
    \enum QGL::FormatOption

    This enum specifies the format options that can be used to configure an OpenGL
    context. These are set using QGLFormat::setOption().

    \value DoubleBuffer      Specifies the use of double buffering.
    \value DepthBuffer       Enables the use of a depth buffer.
    \value Rgba              Specifies that the context should use RGBA as its pixel format.
    \value AlphaChannel      Enables the use of an alpha channel.
    \value AccumBuffer       Enables the use of an accumulation buffer.
    \value StencilBuffer     Enables the use of a stencil buffer.
    \value StereoBuffers     Enables the use of a stereo buffers for use with visualization hardware.
    \value DirectRendering   Specifies that the context is used for direct rendering to a display.
    \value HasOverlay        Enables the use of an overlay.
    \value SampleBuffers     Enables the use of sample buffers.
    \value SingleBuffer      Specifies the use of a single buffer, as opposed to double buffers.
    \value NoDepthBuffer     Disables the use of a depth buffer.
    \value ColorIndex        Specifies that the context should use a color index as its pixel format.
    \value NoAlphaChannel    Disables the use of an alpha channel.
    \value NoAccumBuffer     Disables the use of an accumulation buffer.
    \value NoStencilBuffer   Disables the use of a stencil buffer.
    \value NoStereoBuffers   Disables the use of stereo buffers.
    \value IndirectRendering Specifies that the context is used for indirect rendering to a buffer.
    \value NoOverlay         Disables the use of an overlay.
    \value NoSampleBuffers   Disables the use of sample buffers.

    \sa {Sample Buffers Example}
*/

/*!
   \fn void QGL::setPreferredPaintEngine(QPaintEngine::Type engineType)

   \since 4.6

   Sets the preferred OpenGL paint engine that is used to draw onto
   QGLWidget, QGLPixelBuffer and QGLFramebufferObject targets with QPainter
   in Qt.

   The \a engineType parameter specifies which of the GL engines to
   use. Only \c QPaintEngine::OpenGL and \c QPaintEngine::OpenGL2 are
   valid parameters to this function. All other values are ignored.

   By default, the \c QPaintEngine::OpenGL2 engine is used if GL/GLES
   version 2.0 is available, otherwise \c QPaintEngine::OpenGL is
   used.

   \warning This function must be called before the QApplication
   constructor is called.
*/
void QGL::setPreferredPaintEngine(QPaintEngine::Type engineType)
{
    qgl_engine_selector()->setPreferredPaintEngine(engineType);
}


/*****************************************************************************
  QGLFormat implementation
 *****************************************************************************/


/*!
    \class QGLFormat
    \brief The QGLFormat class specifies the display format of an OpenGL
    rendering context.

    \ingroup painting-3D

    A display format has several characteristics:
    \list
    \i \link setDoubleBuffer() Double or single buffering.\endlink
    \i \link setDepth() Depth buffer.\endlink
    \i \link setRgba() RGBA or color index mode.\endlink
    \i \link setAlpha() Alpha channel.\endlink
    \i \link setAccum() Accumulation buffer.\endlink
    \i \link setStencil() Stencil buffer.\endlink
    \i \link setStereo() Stereo buffers.\endlink
    \i \link setDirectRendering() Direct rendering.\endlink
    \i \link setOverlay() Presence of an overlay.\endlink
    \i \link setPlane() Plane of an overlay.\endlink
    \i \link setSampleBuffers() Multisample buffers.\endlink
    \endlist

    You can also specify preferred bit depths for the color buffer,
    depth buffer, alpha buffer, accumulation buffer and the stencil
    buffer with the functions: setRedBufferSize(), setGreenBufferSize(),
    setBlueBufferSize(), setDepthBufferSize(), setAlphaBufferSize(),
    setAccumBufferSize() and setStencilBufferSize().

    Note that even if you specify that you prefer a 32 bit depth
    buffer (e.g. with setDepthBufferSize(32)), the format that is
    chosen may not have a 32 bit depth buffer, even if there is a
    format available with a 32 bit depth buffer. The main reason for
    this is how the system dependant picking algorithms work on the
    different platforms, and some format options may have higher
    precedence than others.

    You create and tell a QGLFormat object what rendering options you
    want from an OpenGL rendering context.

    OpenGL drivers or accelerated hardware may or may not support
    advanced features such as alpha channel or stereographic viewing.
    If you request some features that the driver/hardware does not
    provide when you create a QGLWidget, you will get a rendering
    context with the nearest subset of features.

    There are different ways to define the display characteristics of
    a rendering context. One is to create a QGLFormat and make it the
    default for the entire application:
    \snippet doc/src/snippets/code/src_opengl_qgl.cpp 0

    Or you can specify the desired format when creating an object of
    your QGLWidget subclass:
    \snippet doc/src/snippets/code/src_opengl_qgl.cpp 1

    After the widget has been created, you can find out which of the
    requested features the system was able to provide:
    \snippet doc/src/snippets/code/src_opengl_qgl.cpp 2

    \legalese
        OpenGL is a trademark of Silicon Graphics, Inc. in the
        United States and other countries.
    \endlegalese

    \sa QGLContext, QGLWidget
*/

#ifndef QT_OPENGL_ES

static inline void transform_point(GLdouble out[4], const GLdouble m[16], const GLdouble in[4])
{
#define M(row,col)  m[col*4+row]
    out[0] =
        M(0, 0) * in[0] + M(0, 1) * in[1] + M(0, 2) * in[2] + M(0, 3) * in[3];
    out[1] =
        M(1, 0) * in[0] + M(1, 1) * in[1] + M(1, 2) * in[2] + M(1, 3) * in[3];
    out[2] =
        M(2, 0) * in[0] + M(2, 1) * in[1] + M(2, 2) * in[2] + M(2, 3) * in[3];
    out[3] =
        M(3, 0) * in[0] + M(3, 1) * in[1] + M(3, 2) * in[2] + M(3, 3) * in[3];
#undef M
}

static inline GLint qgluProject(GLdouble objx, GLdouble objy, GLdouble objz,
           const GLdouble model[16], const GLdouble proj[16],
           const GLint viewport[4],
           GLdouble * winx, GLdouble * winy, GLdouble * winz)
{
   GLdouble in[4], out[4];

   in[0] = objx;
   in[1] = objy;
   in[2] = objz;
   in[3] = 1.0;
   transform_point(out, model, in);
   transform_point(in, proj, out);

   if (in[3] == 0.0)
      return GL_FALSE;

   in[0] /= in[3];
   in[1] /= in[3];
   in[2] /= in[3];

   *winx = viewport[0] + (1 + in[0]) * viewport[2] / 2;
   *winy = viewport[1] + (1 + in[1]) * viewport[3] / 2;

   *winz = (1 + in[2]) / 2;
   return GL_TRUE;
}

#endif // !QT_OPENGL_ES

/*!
    Constructs a QGLFormat object with the following default settings:
    \list
    \i \link setDoubleBuffer() Double buffer:\endlink Enabled.
    \i \link setDepth() Depth buffer:\endlink Enabled.
    \i \link setRgba() RGBA:\endlink Enabled (i.e., color index disabled).
    \i \link setAlpha() Alpha channel:\endlink Disabled.
    \i \link setAccum() Accumulator buffer:\endlink Disabled.
    \i \link setStencil() Stencil buffer:\endlink Enabled.
    \i \link setStereo() Stereo:\endlink Disabled.
    \i \link setDirectRendering() Direct rendering:\endlink Enabled.
    \i \link setOverlay() Overlay:\endlink Disabled.
    \i \link setPlane() Plane:\endlink 0 (i.e., normal plane).
    \i \link setSampleBuffers() Multisample buffers:\endlink Disabled.
    \endlist
*/

QGLFormat::QGLFormat()
{
    d = new QGLFormatPrivate;
}


/*!
    Creates a QGLFormat object that is a copy of the current
    defaultFormat().

    If \a options is not 0, the default format is modified by the
    specified format options. The \a options parameter should be
    QGL::FormatOption values OR'ed together.

    This constructor makes it easy to specify a certain desired format
    in classes derived from QGLWidget, for example:
    \snippet doc/src/snippets/code/src_opengl_qgl.cpp 3

    Note that there are QGL::FormatOption values to turn format settings
    both on and off, e.g. QGL::DepthBuffer and QGL::NoDepthBuffer,
    QGL::DirectRendering and QGL::IndirectRendering, etc.

    The \a plane parameter defaults to 0 and is the plane which this
    format should be associated with. Not all OpenGL implementations
    supports overlay/underlay rendering planes.

    \sa defaultFormat(), setOption(), setPlane()
*/

QGLFormat::QGLFormat(QGL::FormatOptions options, int plane)
{
    d = new QGLFormatPrivate;
    QGL::FormatOptions newOpts = options;
    d->opts = defaultFormat().d->opts;
    d->opts |= (newOpts & 0xffff);
    d->opts &= ~(newOpts >> 16);
    d->pln = plane;
}

/*!
    \internal
*/
void QGLFormat::detach()
{
    if (d->ref != 1) {
        QGLFormatPrivate *newd = new QGLFormatPrivate(d);
        if (!d->ref.deref())
            delete d;
        d = newd;
    }
}

/*!
    Constructs a copy of \a other.
*/

QGLFormat::QGLFormat(const QGLFormat &other)
{
    d = other.d;
    d->ref.ref();
}

/*!
    Assigns \a other to this object.
*/

QGLFormat &QGLFormat::operator=(const QGLFormat &other)
{
    if (d != other.d) {
        other.d->ref.ref();
        if (!d->ref.deref())
            delete d;
        d = other.d;
    }
    return *this;
}

/*!
    Destroys the QGLFormat.
*/
QGLFormat::~QGLFormat()
{
    if (!d->ref.deref())
        delete d;
}

/*!
    \fn bool QGLFormat::doubleBuffer() const

    Returns true if double buffering is enabled; otherwise returns
    false. Double buffering is enabled by default.

    \sa setDoubleBuffer()
*/

/*!
    If \a enable is true sets double buffering; otherwise sets single
    buffering.

    Double buffering is enabled by default.

    Double buffering is a technique where graphics are rendered on an
    off-screen buffer and not directly to the screen. When the drawing
    has been completed, the program calls a swapBuffers() function to
    exchange the screen contents with the buffer. The result is
    flicker-free drawing and often better performance.

    \sa doubleBuffer(), QGLContext::swapBuffers(),
    QGLWidget::swapBuffers()
*/

void QGLFormat::setDoubleBuffer(bool enable)
{
    setOption(enable ? QGL::DoubleBuffer : QGL::SingleBuffer);
}


/*!
    \fn bool QGLFormat::depth() const

    Returns true if the depth buffer is enabled; otherwise returns
    false. The depth buffer is enabled by default.

    \sa setDepth(), setDepthBufferSize()
*/

/*!
    If \a enable is true enables the depth buffer; otherwise disables
    the depth buffer.

    The depth buffer is enabled by default.

    The purpose of a depth buffer (or Z-buffering) is to remove hidden
    surfaces. Pixels are assigned Z values based on the distance to
    the viewer. A pixel with a high Z value is closer to the viewer
    than a pixel with a low Z value. This information is used to
    decide whether to draw a pixel or not.

    \sa depth(), setDepthBufferSize()
*/

void QGLFormat::setDepth(bool enable)
{
    setOption(enable ? QGL::DepthBuffer : QGL::NoDepthBuffer);
}


/*!
    \fn bool QGLFormat::rgba() const

    Returns true if RGBA color mode is set. Returns false if color
    index mode is set. The default color mode is RGBA.

    \sa setRgba()
*/

/*!
    If \a enable is true sets RGBA mode. If \a enable is false sets
    color index mode.

    The default color mode is RGBA.

    RGBA is the preferred mode for most OpenGL applications. In RGBA
    color mode you specify colors as red + green + blue + alpha
    quadruplets.

    In color index mode you specify an index into a color lookup
    table.

    \sa rgba()
*/

void QGLFormat::setRgba(bool enable)
{
    setOption(enable ? QGL::Rgba : QGL::ColorIndex);
}


/*!
    \fn bool QGLFormat::alpha() const

    Returns true if the alpha buffer in the framebuffer is enabled;
    otherwise returns false. The alpha buffer is disabled by default.

    \sa setAlpha(), setAlphaBufferSize()
*/

/*!
    If \a enable is true enables the alpha buffer; otherwise disables
    the alpha buffer.

    The alpha buffer is disabled by default.

    The alpha buffer is typically used for implementing transparency
    or translucency. The A in RGBA specifies the transparency of a
    pixel.

    \sa alpha(), setAlphaBufferSize()
*/

void QGLFormat::setAlpha(bool enable)
{
    setOption(enable ? QGL::AlphaChannel : QGL::NoAlphaChannel);
}


/*!
    \fn bool QGLFormat::accum() const

    Returns true if the accumulation buffer is enabled; otherwise
    returns false. The accumulation buffer is disabled by default.

    \sa setAccum(), setAccumBufferSize()
*/

/*!
    If \a enable is true enables the accumulation buffer; otherwise
    disables the accumulation buffer.

    The accumulation buffer is disabled by default.

    The accumulation buffer is used to create blur effects and
    multiple exposures.

    \sa accum(), setAccumBufferSize()
*/

void QGLFormat::setAccum(bool enable)
{
    setOption(enable ? QGL::AccumBuffer : QGL::NoAccumBuffer);
}


/*!
    \fn bool QGLFormat::stencil() const

    Returns true if the stencil buffer is enabled; otherwise returns
    false. The stencil buffer is enabled by default.

    \sa setStencil(), setStencilBufferSize()
*/

/*!
    If \a enable is true enables the stencil buffer; otherwise
    disables the stencil buffer.

    The stencil buffer is enabled by default.

    The stencil buffer masks certain parts of the drawing area so that
    masked parts are not drawn on.

    \sa stencil(), setStencilBufferSize()
*/

void QGLFormat::setStencil(bool enable)
{
    setOption(enable ? QGL::StencilBuffer: QGL::NoStencilBuffer);
}


/*!
    \fn bool QGLFormat::stereo() const

    Returns true if stereo buffering is enabled; otherwise returns
    false. Stereo buffering is disabled by default.

    \sa setStereo()
*/

/*!
    If \a enable is true enables stereo buffering; otherwise disables
    stereo buffering.

    Stereo buffering is disabled by default.

    Stereo buffering provides extra color buffers to generate left-eye
    and right-eye images.

    \sa stereo()
*/

void QGLFormat::setStereo(bool enable)
{
    setOption(enable ? QGL::StereoBuffers : QGL::NoStereoBuffers);
}


/*!
    \fn bool QGLFormat::directRendering() const

    Returns true if direct rendering is enabled; otherwise returns
    false.

    Direct rendering is enabled by default.

    \sa setDirectRendering()
*/

/*!
    If \a enable is true enables direct rendering; otherwise disables
    direct rendering.

    Direct rendering is enabled by default.

    Enabling this option will make OpenGL bypass the underlying window
    system and render directly from hardware to the screen, if this is
    supported by the system.

    \sa directRendering()
*/

void QGLFormat::setDirectRendering(bool enable)
{
    setOption(enable ? QGL::DirectRendering : QGL::IndirectRendering);
}

/*!
    \fn bool QGLFormat::sampleBuffers() const

    Returns true if multisample buffer support is enabled; otherwise
    returns false.

    The multisample buffer is disabled by default.

    \sa setSampleBuffers()
*/

/*!
    If \a enable is true, a GL context with multisample buffer support
    is picked; otherwise ignored.

    \sa sampleBuffers(), setSamples(), samples()
*/
void QGLFormat::setSampleBuffers(bool enable)
{
    setOption(enable ? QGL::SampleBuffers : QGL::NoSampleBuffers);
}

/*!
    Returns the number of samples per pixel when multisampling is
    enabled. By default, the highest number of samples that is
    available is used.

    \sa setSampleBuffers(), sampleBuffers(), setSamples()
*/
int QGLFormat::samples() const
{
   return d->numSamples;
}

/*!
    Set the preferred number of samples per pixel when multisampling
    is enabled to \a numSamples. By default, the highest number of
    samples available is used.

    \sa setSampleBuffers(), sampleBuffers(), samples()
*/
void QGLFormat::setSamples(int numSamples)
{
    detach();
    if (numSamples < 0) {
        qWarning("QGLFormat::setSamples: Cannot have negative number of samples per pixel %d", numSamples);
        return;
    }
    d->numSamples = numSamples;
}

/*!
    \since 4.2

    Set the preferred swap interval. This can be used to sync the GL
    drawing into a system window to the vertical refresh of the screen.
    Setting an \a interval value of 0 will turn the vertical refresh syncing
    off, any value higher than 0 will turn the vertical syncing on.

    Under Windows and under X11, where the \c{WGL_EXT_swap_control}
    and \c{GLX_SGI_video_sync} extensions are used, the \a interval
    parameter can be used to set the minimum number of video frames
    that are displayed before a buffer swap will occur. In effect,
    setting the \a interval to 10, means there will be 10 vertical
    retraces between every buffer swap.

    Under Windows the \c{WGL_EXT_swap_control} extension has to be present,
    and under X11 the \c{GLX_SGI_video_sync} extension has to be present.
*/
void QGLFormat::setSwapInterval(int interval)
{
    detach();
    d->swapInterval = interval;
}

/*!
    \since 4.2

    Returns the currently set swap interval. -1 is returned if setting
    the swap interval isn't supported in the system GL implementation.
*/
int QGLFormat::swapInterval() const
{
    return d->swapInterval;
}

/*!
    \fn bool QGLFormat::hasOverlay() const

    Returns true if overlay plane is enabled; otherwise returns false.

    Overlay is disabled by default.

    \sa setOverlay()
*/

/*!
    If \a enable is true enables an overlay plane; otherwise disables
    the overlay plane.

    Enabling the overlay plane will cause QGLWidget to create an
    additional context in an overlay plane. See the QGLWidget
    documentation for further information.

    \sa hasOverlay()
*/

void QGLFormat::setOverlay(bool enable)
{
    setOption(enable ? QGL::HasOverlay : QGL::NoOverlay);
}

/*!
    Returns the plane of this format. The default for normal formats
    is 0, which means the normal plane. The default for overlay
    formats is 1, which is the first overlay plane.

    \sa setPlane(), defaultOverlayFormat()
*/
int QGLFormat::plane() const
{
    return d->pln;
}

/*!
    Sets the requested plane to \a plane. 0 is the normal plane, 1 is
    the first overlay plane, 2 is the second overlay plane, etc.; -1,
    -2, etc. are underlay planes.

    Note that in contrast to other format specifications, the plane
    specifications will be matched exactly. This means that if you
    specify a plane that the underlying OpenGL system cannot provide,
    an \link QGLWidget::isValid() invalid\endlink QGLWidget will be
    created.

    \sa plane()
*/
void QGLFormat::setPlane(int plane)
{
    detach();
    d->pln = plane;
}

/*!
    Sets the format option to \a opt.

    \sa testOption()
*/

void QGLFormat::setOption(QGL::FormatOptions opt)
{
    detach();
    if (opt & 0xffff)
        d->opts |= opt;
    else
       d->opts &= ~(opt >> 16);
}



/*!
    Returns true if format option \a opt is set; otherwise returns false.

    \sa setOption()
*/

bool QGLFormat::testOption(QGL::FormatOptions opt) const
{
    if (opt & 0xffff)
       return (d->opts & opt) != 0;
    else
       return (d->opts & (opt >> 16)) == 0;
}

/*!
    Set the minimum depth buffer size to \a size.

    \sa depthBufferSize(), setDepth(), depth()
*/
void QGLFormat::setDepthBufferSize(int size)
{
    detach();
    if (size < 0) {
        qWarning("QGLFormat::setDepthBufferSize: Cannot set negative depth buffer size %d", size);
        return;
    }
    d->depthSize = size;
}

/*!
    Returns the depth buffer size.

    \sa depth(), setDepth(), setDepthBufferSize()
*/
int QGLFormat::depthBufferSize() const
{
   return d->depthSize;
}

/*!
    \since 4.2

    Set the preferred red buffer size to \a size.

    \sa setGreenBufferSize(), setBlueBufferSize(), setAlphaBufferSize()
*/
void QGLFormat::setRedBufferSize(int size)
{
    detach();
    if (size < 0) {
        qWarning("QGLFormat::setRedBufferSize: Cannot set negative red buffer size %d", size);
        return;
    }
    d->redSize = size;
}

/*!
    \since 4.2

    Returns the red buffer size.

    \sa setRedBufferSize()
*/
int QGLFormat::redBufferSize() const
{
   return d->redSize;
}

/*!
    \since 4.2

    Set the preferred green buffer size to \a size.

    \sa setRedBufferSize(), setBlueBufferSize(), setAlphaBufferSize()
*/
void QGLFormat::setGreenBufferSize(int size)
{
    detach();
    if (size < 0) {
        qWarning("QGLFormat::setGreenBufferSize: Cannot set negative green buffer size %d", size);
        return;
    }
    d->greenSize = size;
}

/*!
    \since 4.2

    Returns the green buffer size.

    \sa setGreenBufferSize()
*/
int QGLFormat::greenBufferSize() const
{
   return d->greenSize;
}

/*!
    \since 4.2

    Set the preferred blue buffer size to \a size.

    \sa setRedBufferSize(), setGreenBufferSize(), setAlphaBufferSize()
*/
void QGLFormat::setBlueBufferSize(int size)
{
    detach();
    if (size < 0) {
        qWarning("QGLFormat::setBlueBufferSize: Cannot set negative blue buffer size %d", size);
        return;
    }
    d->blueSize = size;
}

/*!
    \since 4.2

    Returns the blue buffer size.

    \sa setBlueBufferSize()
*/
int QGLFormat::blueBufferSize() const
{
   return d->blueSize;
}

/*!
    Set the preferred alpha buffer size to \a size.
    This function implicitly enables the alpha channel.

    \sa setRedBufferSize(), setGreenBufferSize(), alphaBufferSize()
*/
void QGLFormat::setAlphaBufferSize(int size)
{
    detach();
    if (size < 0) {
        qWarning("QGLFormat::setAlphaBufferSize: Cannot set negative alpha buffer size %d", size);
        return;
    }
    d->alphaSize = size;
    setOption(QGL::AlphaChannel);
}

/*!
    Returns the alpha buffer size.

    \sa alpha(), setAlpha(), setAlphaBufferSize()
*/
int QGLFormat::alphaBufferSize() const
{
   return d->alphaSize;
}

/*!
    Set the preferred accumulation buffer size, where \a size is the
    bit depth for each RGBA component.

    \sa accum(), setAccum(), accumBufferSize()
*/
void QGLFormat::setAccumBufferSize(int size)
{
    detach();
    if (size < 0) {
        qWarning("QGLFormat::setAccumBufferSize: Cannot set negative accumulate buffer size %d", size);
        return;
    }
    d->accumSize = size;
}

/*!
    Returns the accumulation buffer size.

    \sa setAccumBufferSize(), accum(), setAccum()
*/
int QGLFormat::accumBufferSize() const
{
   return d->accumSize;
}

/*!
    Set the preferred stencil buffer size to \a size.

    \sa stencilBufferSize(), setStencil(), stencil()
*/
void QGLFormat::setStencilBufferSize(int size)
{
    detach();
    if (size < 0) {
        qWarning("QGLFormat::setStencilBufferSize: Cannot set negative stencil buffer size %d", size);
        return;
    }
    d->stencilSize = size;
}

/*!
    Returns the stencil buffer size.

    \sa stencil(), setStencil(), setStencilBufferSize()
*/
int QGLFormat::stencilBufferSize() const
{
   return d->stencilSize;
}

/*!
    \fn bool QGLFormat::hasOpenGL()

    Returns true if the window system has any OpenGL support;
    otherwise returns false.

    \warning This function must not be called until the QApplication
    object has been created.
*/



/*!
    \fn bool QGLFormat::hasOpenGLOverlays()

    Returns true if the window system supports OpenGL overlays;
    otherwise returns false.

    \warning This function must not be called until the QApplication
    object has been created.
*/

QGLFormat::OpenGLVersionFlags Q_AUTOTEST_EXPORT qOpenGLVersionFlagsFromString(const QString &versionString)
{
    QGLFormat::OpenGLVersionFlags versionFlags = QGLFormat::OpenGL_Version_None;

    if (versionString.startsWith(QLatin1String("OpenGL ES"))) {
        QStringList parts = versionString.split(QLatin1Char(' '));
        if (parts.size() >= 3) {
            if (parts[2].startsWith(QLatin1String("1."))) {
                if (parts[1].endsWith(QLatin1String("-CM"))) {
                    versionFlags |= QGLFormat::OpenGL_ES_Common_Version_1_0 |
                                    QGLFormat::OpenGL_ES_CommonLite_Version_1_0;
                    if (parts[2].startsWith(QLatin1String("1.1")))
                        versionFlags |= QGLFormat::OpenGL_ES_Common_Version_1_1 |
                                        QGLFormat::OpenGL_ES_CommonLite_Version_1_1;
                }
                else {
                    // Not -CM, must be CL, CommonLite
                    versionFlags |= QGLFormat::OpenGL_ES_CommonLite_Version_1_0;
                    if (parts[2].startsWith(QLatin1String("1.1")))
                        versionFlags |= QGLFormat::OpenGL_ES_CommonLite_Version_1_1;
                }
            }
            else {
                // OpenGL ES version 2.0 or higher
                versionFlags |= QGLFormat::OpenGL_ES_Version_2_0;
            }
        }
        else {
            // if < 3 parts to the name, it is an unrecognised OpenGL ES
            qWarning("Unrecognised OpenGL ES version");
        }
    }
    else {
        // not ES, regular OpenGL, the version numbers are first in the string
        if (versionString.startsWith(QLatin1String("1."))) {
            switch (versionString[2].toAscii()) {
            case '5':
                versionFlags |= QGLFormat::OpenGL_Version_1_5;
            case '4':
                versionFlags |= QGLFormat::OpenGL_Version_1_4;
            case '3':
                versionFlags |= QGLFormat::OpenGL_Version_1_3;
            case '2':
                versionFlags |= QGLFormat::OpenGL_Version_1_2;
            case '1':
                versionFlags |= QGLFormat::OpenGL_Version_1_1;
            default:
                break;
            }
        }
        else if (versionString.startsWith(QLatin1String("2."))) {
            versionFlags |= QGLFormat::OpenGL_Version_1_1 |
                            QGLFormat::OpenGL_Version_1_2 |
                            QGLFormat::OpenGL_Version_1_3 |
                            QGLFormat::OpenGL_Version_1_4 |
                            QGLFormat::OpenGL_Version_1_5 |
                            QGLFormat::OpenGL_Version_2_0;
            QString minorVersion = versionString.section(QLatin1Char(' '), 0, 0).section(QLatin1Char('.'), 1, 1);
            if (minorVersion == QChar(QLatin1Char('1')))
                versionFlags |= QGLFormat::OpenGL_Version_2_1;
        }
        else if (versionString.startsWith(QLatin1String("3."))) {
         versionFlags |= QGLFormat::OpenGL_Version_1_1 |
                         QGLFormat::OpenGL_Version_1_2 |
                         QGLFormat::OpenGL_Version_1_3 |
                         QGLFormat::OpenGL_Version_1_4 |
                         QGLFormat::OpenGL_Version_1_5 |
                         QGLFormat::OpenGL_Version_2_0 |
                         QGLFormat::OpenGL_Version_2_1 |
                         QGLFormat::OpenGL_Version_3_0;
        }
        else
            qWarning("Unrecognised OpenGL version");
    }
    return versionFlags;
}

/*!
    \enum QGLFormat::OpenGLVersionFlag
    \since 4.2

    This enum describes the various OpenGL versions that are
    recognized by Qt. Use the QGLFormat::openGLVersionFlags() function
    to identify which versions that are supported at runtime.

    \value OpenGL_Version_None  If no OpenGL is present or if no OpenGL context is current.

    \value OpenGL_Version_1_1  OpenGL version 1.1 or higher is present.

    \value OpenGL_Version_1_2  OpenGL version 1.2 or higher is present.

    \value OpenGL_Version_1_3  OpenGL version 1.3 or higher is present.

    \value OpenGL_Version_1_4  OpenGL version 1.4 or higher is present.

    \value OpenGL_Version_1_5  OpenGL version 1.5 or higher is present.

    \value OpenGL_Version_2_0  OpenGL version 2.0 or higher is present.
    Note that version 2.0 supports all the functionality of version 1.5.

    \value OpenGL_Version_2_1  OpenGL version 2.1 or higher is present.

    \value OpenGL_Version_3_0  OpenGL version 3.0 or higher is present.

    \value OpenGL_ES_CommonLite_Version_1_0  OpenGL ES version 1.0 Common Lite or higher is present.

    \value OpenGL_ES_Common_Version_1_0  OpenGL ES version 1.0 Common or higher is present.
    The Common profile supports all the features of Common Lite.

    \value OpenGL_ES_CommonLite_Version_1_1  OpenGL ES version 1.1 Common Lite or higher is present.

    \value OpenGL_ES_Common_Version_1_1  OpenGL ES version 1.1 Common or higher is present.
    The Common profile supports all the features of Common Lite.

    \value OpenGL_ES_Version_2_0  OpenGL ES version 2.0 or higher is present.
    Note that OpenGL ES version 2.0 does not support all the features of OpenGL ES 1.x.
    So if OpenGL_ES_Version_2_0 is returned, none of the ES 1.x flags are returned.

    See also \l{http://www.opengl.org} for more information about the different
    revisions of OpenGL.

    \sa openGLVersionFlags()
*/

/*!
    \since 4.2

    Identifies, at runtime, which OpenGL versions that are supported
    by the current platform.

    Note that if OpenGL version 1.5 is supported, its predecessors
    (i.e., version 1.4 and lower) are also supported. To identify the
    support of a particular feature, like multi texturing, test for
    the version in which the feature was first introduced (i.e.,
    version 1.3 in the case of multi texturing) to adapt to the largest
    possible group of runtime platforms.

    This function needs a valid current OpenGL context to work;
    otherwise it will return OpenGL_Version_None.

    \sa hasOpenGL(), hasOpenGLOverlays()
*/
QGLFormat::OpenGLVersionFlags QGLFormat::openGLVersionFlags()
{
    static bool cachedDefault = false;
    static OpenGLVersionFlags defaultVersionFlags = OpenGL_Version_None;
    QGLContext *currentCtx = const_cast<QGLContext *>(QGLContext::currentContext());
    QGLTemporaryContext *tmpContext = 0;

    if (currentCtx && currentCtx->d_func()->version_flags_cached)
        return currentCtx->d_func()->version_flags;

    if (!currentCtx) {
        if (cachedDefault) {
            return defaultVersionFlags;
        } else {
            if (!hasOpenGL())
                return defaultVersionFlags;
            tmpContext = new QGLTemporaryContext;
            cachedDefault = true;
        }
    }

    QString versionString(QLatin1String(reinterpret_cast<const char*>(glGetString(GL_VERSION))));
    OpenGLVersionFlags versionFlags = qOpenGLVersionFlagsFromString(versionString);
    if (currentCtx) {
        currentCtx->d_func()->version_flags_cached = true;
        currentCtx->d_func()->version_flags = versionFlags;
    }
    if (tmpContext) {
        defaultVersionFlags = versionFlags;
        delete tmpContext;
    }

    return versionFlags;
}


/*!
    Returns the default QGLFormat for the application. All QGLWidget
    objects that are created use this format unless another format is
    specified, e.g. when they are constructed.

    If no special default format has been set using
    setDefaultFormat(), the default format is the same as that created
    with QGLFormat().

    \sa setDefaultFormat()
*/

QGLFormat QGLFormat::defaultFormat()
{
    return *qgl_default_format();
}

/*!
    Sets a new default QGLFormat for the application to \a f. For
    example, to set single buffering as the default instead of double
    buffering, your main() might contain code like this:
    \snippet doc/src/snippets/code/src_opengl_qgl.cpp 4

    \sa defaultFormat()
*/

void QGLFormat::setDefaultFormat(const QGLFormat &f)
{
    *qgl_default_format() = f;
}


/*!
    Returns the default QGLFormat for overlay contexts.

    The default overlay format is:
    \list
    \i \link setDoubleBuffer() Double buffer:\endlink Disabled.
    \i \link setDepth() Depth buffer:\endlink Disabled.
    \i \link setRgba() RGBA:\endlink Disabled (i.e., color index enabled).
    \i \link setAlpha() Alpha channel:\endlink Disabled.
    \i \link setAccum() Accumulator buffer:\endlink Disabled.
    \i \link setStencil() Stencil buffer:\endlink Disabled.
    \i \link setStereo() Stereo:\endlink Disabled.
    \i \link setDirectRendering() Direct rendering:\endlink Enabled.
    \i \link setOverlay() Overlay:\endlink Disabled.
    \i \link setSampleBuffers() Multisample buffers:\endlink Disabled.
    \i \link setPlane() Plane:\endlink 1 (i.e., first overlay plane).
    \endlist

    \sa setDefaultFormat()
*/

QGLFormat QGLFormat::defaultOverlayFormat()
{
    return *defaultOverlayFormatInstance();
}

/*!
    Sets a new default QGLFormat for overlay contexts to \a f. This
    format is used whenever a QGLWidget is created with a format that
    hasOverlay() enabled.

    For example, to get a double buffered overlay context (if
    available), use code like this:

    \snippet doc/src/snippets/code/src_opengl_qgl.cpp 5

    As usual, you can find out after widget creation whether the
    underlying OpenGL system was able to provide the requested
    specification:

    \snippet doc/src/snippets/code/src_opengl_qgl.cpp 6

    \sa defaultOverlayFormat()
*/

void QGLFormat::setDefaultOverlayFormat(const QGLFormat &f)
{
    QGLFormat *defaultFormat = defaultOverlayFormatInstance();
    *defaultFormat = f;
    // Make sure the user doesn't request that the overlays themselves
    // have overlays, since it is unlikely that the system supports
    // infinitely many planes...
    defaultFormat->setOverlay(false);
}


/*!
    Returns true if all the options of the two QGLFormat objects
    \a a and \a b are equal; otherwise returns false.

    \relates QGLFormat
*/

bool operator==(const QGLFormat& a, const QGLFormat& b)
{
    return (int) a.d->opts == (int) b.d->opts && a.d->pln == b.d->pln && a.d->alphaSize == b.d->alphaSize
        && a.d->accumSize == b.d->accumSize && a.d->stencilSize == b.d->stencilSize
        && a.d->depthSize == b.d->depthSize
        && a.d->redSize == b.d->redSize
        && a.d->greenSize == b.d->greenSize
        && a.d->blueSize == b.d->blueSize
        && a.d->numSamples == b.d->numSamples
        && a.d->swapInterval == b.d->swapInterval;
}


/*!
    Returns false if all the options of the two QGLFormat objects
    \a a and \a b are equal; otherwise returns true.

    \relates QGLFormat
*/

bool operator!=(const QGLFormat& a, const QGLFormat& b)
{
    return !(a == b);
}

/*****************************************************************************
  QGLContext implementation
 *****************************************************************************/

QGLContextGroup::~QGLContextGroup()
{
    // Clear any remaining QGLSharedResourceGuard objects on the group.
    QGLSharedResourceGuard *guard = m_guards;
    while (guard != 0) {
        guard->m_group = 0;
        guard->m_id = 0;
        guard = guard->m_next;
    }
}

void QGLContextGroup::addGuard(QGLSharedResourceGuard *guard)
{
    if (m_guards)
        m_guards->m_prev = guard;
    guard->m_next = m_guards;
    guard->m_prev = 0;
    m_guards = guard;
}

void QGLContextGroup::removeGuard(QGLSharedResourceGuard *guard)
{
    if (guard->m_next)
        guard->m_next->m_prev = guard->m_prev;
    if (guard->m_prev)
        guard->m_prev->m_next = guard->m_next;
    else
        m_guards = guard->m_next;
}

const QGLContext *qt_gl_transfer_context(const QGLContext *ctx)
{
    if (!ctx)
        return 0;
    QList<const QGLContext *> shares
        (QGLContextPrivate::contextGroup(ctx)->shares());
    if (shares.size() >= 2)
        return (ctx == shares.at(0)) ? shares.at(1) : shares.at(0);
    else
        return 0;
}

QGLContextPrivate::~QGLContextPrivate()
{
    if (!group->m_refs.deref()) {
        Q_ASSERT(group->context() == q_ptr);
        delete group;
    }
}

void QGLContextPrivate::init(QPaintDevice *dev, const QGLFormat &format)
{
    Q_Q(QGLContext);
    glFormat = reqFormat = format;
    valid = false;
    q->setDevice(dev);
#if defined(Q_WS_X11)
    pbuf = 0;
    gpm = 0;
    vi = 0;
    screen = QX11Info::appScreen();
#endif
#if defined(Q_WS_WIN)
    dc = 0;
    win = 0;
    pixelFormatId = 0;
    cmap = 0;
    hbitmap = 0;
    hbitmap_hdc = 0;
#endif
#if defined(Q_WS_MAC)
#  ifndef QT_MAC_USE_COCOA
    update = false;
#  endif
    vi = 0;
#endif
#if defined(QT_OPENGL_ES)
    eglContext = 0;
    eglSurface = EGL_NO_SURFACE;
#endif
    fbo = 0;
    crWin = false;
    initDone = false;
    sharing = false;
    max_texture_size = -1;
    version_flags_cached = false;
    version_flags = QGLFormat::OpenGL_Version_None;
    extension_flags_cached = false;
    extension_flags = 0;
    current_fbo = 0;
    default_fbo = 0;
    active_engine = 0;
    for (int i = 0; i < QT_GL_VERTEX_ARRAY_TRACKED_COUNT; ++i)
        vertexAttributeArraysEnabledState[i] = false;
}

QGLContext* QGLContext::currentCtx = 0;

/*
   Read back the contents of the currently bound framebuffer, used in
   QGLWidget::grabFrameBuffer(), QGLPixelbuffer::toImage() and
   QGLFramebufferObject::toImage()
*/

static void convertFromGLImage(QImage &img, int w, int h, bool alpha_format, bool include_alpha)
{
    if (QSysInfo::ByteOrder == QSysInfo::BigEndian) {
        // OpenGL gives RGBA; Qt wants ARGB
        uint *p = (uint*)img.bits();
        uint *end = p + w*h;
        if (alpha_format && include_alpha) {
            while (p < end) {
                uint a = *p << 24;
                *p = (*p >> 8) | a;
                p++;
            }
        } else {
            // This is an old legacy fix for PowerPC based Macs, which
            // we shouldn't remove
            while (p < end) {
                *p = 0xff000000 | (*p>>8);
                ++p;
            }
        }
    } else {
        // OpenGL gives ABGR (i.e. RGBA backwards); Qt wants ARGB
        for (int y = 0; y < h; y++) {
            uint *q = (uint*)img.scanLine(y);
            for (int x=0; x < w; ++x) {
                const uint pixel = *q;
                *q = ((pixel << 16) & 0xff0000) | ((pixel >> 16) & 0xff) | (pixel & 0xff00ff00);
                q++;
            }
        }

    }
    img = img.mirrored();
}

QImage qt_gl_read_framebuffer(const QSize &size, bool alpha_format, bool include_alpha)
{
    QImage img(size, alpha_format ? QImage::Format_ARGB32 : QImage::Format_RGB32);
    int w = size.width();
    int h = size.height();
    glReadPixels(0, 0, w, h, GL_RGBA, GL_UNSIGNED_BYTE, img.bits());
    convertFromGLImage(img, w, h, alpha_format, include_alpha);
    return img;
}

QImage qt_gl_read_texture(const QSize &size, bool alpha_format, bool include_alpha)
{
    QImage img(size, alpha_format ? QImage::Format_ARGB32_Premultiplied : QImage::Format_RGB32);
    int w = size.width();
    int h = size.height();
#if !defined(QT_OPENGL_ES_2) && !defined(QT_OPENGL_ES_1) && !defined(QT_OPENGL_ES_1_CL)
    //### glGetTexImage not in GL ES 2.0, need to do something else here!
    glGetTexImage(GL_TEXTURE_2D, 0, GL_RGBA, GL_UNSIGNED_BYTE, img.bits());
#endif
    convertFromGLImage(img, w, h, alpha_format, include_alpha);
    return img;
}

// returns the highest number closest to v, which is a power of 2
// NB! assumes 32 bit ints
int qt_next_power_of_two(int v)
{
    v--;
    v |= v >> 1;
    v |= v >> 2;
    v |= v >> 4;
    v |= v >> 8;
    v |= v >> 16;
    ++v;
    return v;
}

typedef void (*_qt_pixmap_cleanup_hook_64)(qint64);
typedef void (*_qt_image_cleanup_hook_64)(qint64);

extern Q_GUI_EXPORT _qt_pixmap_cleanup_hook_64 qt_pixmap_cleanup_hook_64;
extern Q_GUI_EXPORT _qt_image_cleanup_hook_64 qt_image_cleanup_hook_64;

static QGLTextureCache *qt_gl_texture_cache = 0;

QGLTextureCache::QGLTextureCache()
    : m_cache(64*1024) // cache ~64 MB worth of textures - this is not accurate though
{
    Q_ASSERT(qt_gl_texture_cache == 0);
    qt_gl_texture_cache = this;

    QImagePixmapCleanupHooks::instance()->addPixmapDataModificationHook(cleanupTextures);
    QImagePixmapCleanupHooks::instance()->addPixmapDataDestructionHook(cleanupBeforePixmapDestruction);
    QImagePixmapCleanupHooks::instance()->addImageHook(imageCleanupHook);
}

QGLTextureCache::~QGLTextureCache()
{
    qt_gl_texture_cache = 0;

    QImagePixmapCleanupHooks::instance()->removePixmapDataModificationHook(cleanupTextures);
    QImagePixmapCleanupHooks::instance()->removePixmapDataDestructionHook(cleanupBeforePixmapDestruction);
    QImagePixmapCleanupHooks::instance()->removeImageHook(imageCleanupHook);
}

void QGLTextureCache::insert(QGLContext* ctx, qint64 key, QGLTexture* texture, int cost)
{
    if (m_cache.totalCost() + cost > m_cache.maxCost()) {
        // the cache is full - make an attempt to remove something
        const QList<qint64> keys = m_cache.keys();
        int i = 0;
        while (i < m_cache.count()
               && (m_cache.totalCost() + cost > m_cache.maxCost())) {
            QGLTexture *tex = m_cache.object(keys.at(i));
            if (tex->context == ctx)
                m_cache.remove(keys.at(i));
            ++i;
        }
    }
    m_cache.insert(key, texture, cost);
}

bool QGLTextureCache::remove(QGLContext* ctx, GLuint textureId)
{
    QList<qint64> keys = m_cache.keys();
    for (int i = 0; i < keys.size(); ++i) {
        QGLTexture *tex = m_cache.object(keys.at(i));
        if (tex->id == textureId && tex->context == ctx) {
            tex->options |= QGLContext::MemoryManagedBindOption; // forces a glDeleteTextures() call
            m_cache.remove(keys.at(i));
            return true;
        }
    }
    return false;
}

void QGLTextureCache::removeContextTextures(QGLContext* ctx)
{
    QList<qint64> keys = m_cache.keys();
    for (int i = 0; i < keys.size(); ++i) {
        const qint64 &key = keys.at(i);
        if (m_cache.object(key)->context == ctx)
            m_cache.remove(key);
    }
}

QGLTextureCache* QGLTextureCache::instance()
{
    if (!qt_gl_texture_cache)
        qt_gl_texture_cache = new QGLTextureCache;

    return qt_gl_texture_cache;
}

/*
  a hook that removes textures from the cache when a pixmap/image
  is deref'ed
*/
void QGLTextureCache::imageCleanupHook(qint64 cacheKey)
{
    // ### remove when the GL texture cache becomes thread-safe
    if (qApp->thread() != QThread::currentThread())
        return;
    QGLTexture *texture = instance()->getTexture(cacheKey);
    if (texture && texture->options & QGLContext::MemoryManagedBindOption)
        instance()->remove(cacheKey);
}


void QGLTextureCache::cleanupTextures(QPixmapData* pmd)
{
    // ### remove when the GL texture cache becomes thread-safe
    if (qApp->thread() == QThread::currentThread()) {
        const qint64 cacheKey = pmd->cacheKey();
        QGLTexture *texture = instance()->getTexture(cacheKey);
        if (texture && texture->options & QGLContext::MemoryManagedBindOption)
            instance()->remove(cacheKey);
    }
}

void QGLTextureCache::cleanupBeforePixmapDestruction(QPixmapData* pmd)
{
    // Remove any bound textures first:
    cleanupTextures(pmd);
    Q_ASSERT(instance()->getTexture(pmd->cacheKey()) == 0);

#if defined(Q_WS_X11)
    if (pmd->classId() == QPixmapData::X11Class) {
        Q_ASSERT(pmd->ref == 0); // Make sure reference counting isn't broken
        QGLContextPrivate::destroyGlSurfaceForPixmap(pmd);
    }
#endif
}

void QGLTextureCache::deleteIfEmpty()
{
    if (instance()->size() == 0)
        delete instance();
}

// DDS format structure
struct DDSFormat {
    quint32 dwSize;
    quint32 dwFlags;
    quint32 dwHeight;
    quint32 dwWidth;
    quint32 dwLinearSize;
    quint32 dummy1;
    quint32 dwMipMapCount;
    quint32 dummy2[11];
    struct {
        quint32 dummy3[2];
        quint32 dwFourCC;
        quint32 dummy4[5];
    } ddsPixelFormat;
};

// compressed texture pixel formats
#define FOURCC_DXT1  0x31545844
#define FOURCC_DXT2  0x32545844
#define FOURCC_DXT3  0x33545844
#define FOURCC_DXT4  0x34545844
#define FOURCC_DXT5  0x35545844

#ifndef GL_COMPRESSED_RGB_S3TC_DXT1_EXT
#define GL_COMPRESSED_RGB_S3TC_DXT1_EXT   0x83F0
#define GL_COMPRESSED_RGBA_S3TC_DXT1_EXT  0x83F1
#define GL_COMPRESSED_RGBA_S3TC_DXT3_EXT  0x83F2
#define GL_COMPRESSED_RGBA_S3TC_DXT5_EXT  0x83F3
#endif

#ifndef GL_GENERATE_MIPMAP_SGIS
#define GL_GENERATE_MIPMAP_SGIS       0x8191
#define GL_GENERATE_MIPMAP_HINT_SGIS  0x8192
#endif

/*!
    \class QGLContext
    \brief The QGLContext class encapsulates an OpenGL rendering context.

    \ingroup painting-3D

    An OpenGL rendering context is a complete set of OpenGL state
    variables. The rendering context's \l {QGL::FormatOption} {format}
    is set in the constructor, but it can also be set later with
    setFormat(). The format options that are actually set are returned
    by format(); the options you asked for are returned by
    requestedFormat(). Note that after a QGLContext object has been
    constructed, the actual OpenGL context must be created by
    explicitly calling the \link create() create()\endlink
    function. The makeCurrent() function makes this context the
    current rendering context. You can make \e no context current
    using doneCurrent(). The reset() function will reset the context
    and make it invalid.

    You can examine properties of the context with, e.g. isValid(),
    isSharing(), initialized(), windowCreated() and
    overlayTransparentColor().

    If you're using double buffering you can swap the screen contents
    with the off-screen buffer using swapBuffers().

    Please note that QGLContext is not thread safe.
*/

/*!
    \enum QGLContext::BindOption
    \since 4.6

    A set of options to decide how to bind a texture using bindTexture().

    \value NoBindOption Don't do anything, pass the texture straight
    through.

    \value InvertedYBindOption Specifies that the texture should be flipped
    over the X axis so that the texture coordinate 0,0 corresponds to
    the top left corner. Inverting the texture implies a deep copy
    prior to upload.

    \value MipmapBindOption Specifies that bindTexture() should try
    to generate mipmaps.  If the GL implementation supports the \c
    GL_SGIS_generate_mipmap extension, mipmaps will be automatically
    generated for the texture. Mipmap generation is only supported for
    the \c GL_TEXTURE_2D target.

    \value PremultipliedAlphaBindOption Specifies that the image should be
    uploaded with premultiplied alpha and does a conversion accordingly.

    \value LinearFilteringBindOption Specifies that the texture filtering
    should be set to GL_LINEAR. Default is GL_NEAREST. If mipmap is
    also enabled, filtering will be set to GL_LINEAR_MIPMAP_LINEAR.

    \value DefaultBindOption In Qt 4.5 and earlier, bindTexture()
    would mirror the image and automatically generate mipmaps. This
    option helps preserve this default behavior.

    \omitvalue CanFlipNativePixmapBindOption Used by x11 from pixmap to choose
    wether or not it can bind the pixmap upside down or not.

    \omitvalue MemoryManagedBindOption Used by paint engines to
    indicate that the pixmap should be memory managed along side with
    the pixmap/image that it stems from, e.g. installing destruction
    hooks in them.

    \omitvalue InternalBindOption
*/

/*!
    \obsolete

    Constructs an OpenGL context for the given paint \a device, which
    can be a widget or a pixmap. The \a format specifies several
    display options for the context.

    If the underlying OpenGL/Window system cannot satisfy all the
    features requested in \a format, the nearest subset of features
    will be used. After creation, the format() method will return the
    actual format obtained.

    Note that after a QGLContext object has been constructed, \l
    create() must be called explicitly to create the actual OpenGL
    context. The context will be \l {isValid()}{invalid} if it was not
    possible to obtain a GL context at all.
*/