source: trunk/src/opengl/qglpixelbuffer.cpp@ 365

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/*!
    \class QGLPixelBuffer
    \brief The QGLPixelBuffer class encapsulates an OpenGL pbuffer.
    \since 4.1

    \ingroup multimedia

    Rendering into a pbuffer is normally done using full hardware
    acceleration. This can be significantly faster than rendering
    into a QPixmap.

    There are three approaches to using this class:

    \list 1
    \o \bold{We can draw into the pbuffer and convert it to a QImage
       using toImage().} This is normally much faster than calling
       QGLWidget::renderPixmap().

    \o \bold{We can draw into the pbuffer and copy the contents into
       an OpenGL texture using updateDynamicTexture().} This allows
       us to create dynamic textures and works on all systems
       with pbuffer support.

    \o \bold{On systems that support it, we can bind the pbuffer to
       an OpenGL texture.} The texture is then updated automatically
       when the pbuffer contents change, eliminating the need for
       additional copy operations. This is supported only on Windows
       and Mac OS X systems that provide the \c render_texture
       extension.
    \endlist

    Pbuffers are provided by the OpenGL \c pbuffer extension; call
    hasOpenGLPbuffer() to find out if the system provides pbuffers.

    \sa {opengl/pbuffers}{Pbuffers Example}
*/


#include <qglpixelbuffer.h>
#include <private/qglpixelbuffer_p.h>
#include <qimage.h>

#if !defined(QT_OPENGL_ES_2)
#include <private/qpaintengine_opengl_p.h>
#endif

QT_BEGIN_NAMESPACE

#if !defined(QT_OPENGL_ES_2)
extern void qgl_cleanup_glyph_cache(QGLContext *);
#else
void qgl_cleanup_glyph_cache(QGLContext *) {}
#endif

extern QImage qt_gl_read_framebuffer(const QSize&, bool, bool);

void QGLPixelBufferPrivate::common_init(const QSize &size, const QGLFormat &format, QGLWidget *shareWidget)
{
    Q_Q(QGLPixelBuffer);
    if(init(size, format, shareWidget)) {
        req_size = size;
        req_format = format;
        req_shareWidget = shareWidget;
        invalid = false;
        qctx = new QGLContext(format);
        qctx->d_func()->sharing = (shareWidget != 0);
        if (shareWidget != 0 && shareWidget->d_func()->glcx)
            qgl_share_reg()->addShare(qctx, shareWidget->d_func()->glcx);

        qctx->d_func()->paintDevice = q;
        qctx->d_func()->valid = true;
#if defined(Q_WS_WIN) && !defined(QT_OPENGL_ES)
        qctx->d_func()->dc = dc;
        qctx->d_func()->rc = ctx;
#elif (defined(Q_WS_X11) && !defined(QT_OPENGL_ES))
        qctx->d_func()->cx = ctx;
        qctx->d_func()->pbuf = (void *) pbuf;
        qctx->d_func()->vi = 0;
#elif defined(Q_WS_MAC)
        qctx->d_func()->cx = ctx;
        qctx->d_func()->vi = 0;
#elif defined(QT_OPENGL_ES)
        qctx->d_func()->eglContext = ctx;
#endif
    }
}

/*!
    Constructs an OpenGL pbuffer of the given \a size. If no \a
    format is specified, the \l{QGLFormat::defaultFormat()}{default
    format} is used. If the \a shareWidget parameter points to a
    valid QGLWidget, the pbuffer will share its context with \a
    shareWidget.

    If you intend to bind this pbuffer as a dynamic texture, the width
    and height components of \c size must be powers of two (e.g., 512
    x 128).

    \sa size(), format()
*/
QGLPixelBuffer::QGLPixelBuffer(const QSize &size, const QGLFormat &format, QGLWidget *shareWidget)
    : d_ptr(new QGLPixelBufferPrivate(this))
{
    Q_D(QGLPixelBuffer);
    d->common_init(size, format, shareWidget);
}


/*! \overload

    Constructs an OpenGL pbuffer with the \a width and \a height. If
    no \a format is specified, the
    \l{QGLFormat::defaultFormat()}{default format} is used. If the \a
    shareWidget parameter points to a valid QGLWidget, the pbuffer
    will share its context with \a shareWidget.

    If you intend to bind this pbuffer as a dynamic texture, the width
    and height components of \c size must be powers of two (e.g., 512
    x 128).

    \sa size(), format()
*/
QGLPixelBuffer::QGLPixelBuffer(int width, int height, const QGLFormat &format, QGLWidget *shareWidget)
    : d_ptr(new QGLPixelBufferPrivate(this))
{
    Q_D(QGLPixelBuffer);
    d->common_init(QSize(width, height), format, shareWidget);
}


/*! \fn QGLPixelBuffer::~QGLPixelBuffer()

    Destroys the pbuffer and frees any allocated resources.
*/
QGLPixelBuffer::~QGLPixelBuffer()
{
    Q_D(QGLPixelBuffer);

    // defined in qpaintengine_opengl.cpp
    QGLContext *current = const_cast<QGLContext *>(QGLContext::currentContext());
    if (current != d->qctx)
        makeCurrent();
    qgl_cleanup_glyph_cache(d->qctx);
    d->cleanup();
    delete d->qctx;
    if (current && current != d->qctx)
        current->makeCurrent();
    delete d_ptr;
}

/*! \fn bool QGLPixelBuffer::makeCurrent()

    Makes this pbuffer the current OpenGL rendering context. Returns
    true on success; otherwise returns false.

    \sa QGLContext::makeCurrent(), doneCurrent()
*/

bool QGLPixelBuffer::makeCurrent()
{
    Q_D(QGLPixelBuffer);
    if (d->invalid)
        return false;
    d->qctx->makeCurrent();
    return true;
}

/*! \fn bool QGLPixelBuffer::doneCurrent()

    Makes no context the current OpenGL context. Returns true on
    success; otherwise returns false.
*/

bool QGLPixelBuffer::doneCurrent()
{
    Q_D(QGLPixelBuffer);
    if (d->invalid)
        return false;
    d->qctx->doneCurrent();
    return true;
}

/*!
    Generates and binds a 2D GL texture that is the same size as the
    pbuffer, and returns the texture's ID. This can be used in
    conjunction with bindToDynamicTexture() and
    updateDynamicTexture().

    \sa size()
*/

#if (defined(Q_WS_X11) || defined(Q_WS_WIN)) && !defined(QT_OPENGL_ES)
GLuint QGLPixelBuffer::generateDynamicTexture() const
{
    Q_D(const QGLPixelBuffer);
    GLuint texture;
    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, d->req_size.width(), d->req_size.height(), 0, GL_RGBA, GL_FLOAT, 0);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    return texture;
}
#endif