source: trunk/src/opengl/qpixmapdata_gl.cpp@ 1023

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#include "qpixmap.h"
#include "qglframebufferobject.h"

#include <private/qpaintengine_raster_p.h>

#include "qpixmapdata_gl_p.h"

#include <private/qgl_p.h>
#include <private/qdrawhelper_p.h>
#include <private/qimage_p.h>

#include <private/qpaintengineex_opengl2_p.h>

#include <qdesktopwidget.h>
#include <qfile.h>
#include <qimagereader.h>

QT_BEGIN_NAMESPACE

extern QGLWidget* qt_gl_share_widget();

/*!
    \class QGLFramebufferObjectPool
    \since 4.6

    \brief The QGLFramebufferObject class provides a pool of framebuffer
    objects for offscreen rendering purposes.

    When requesting an FBO of a given size and format, an FBO of the same
    format and a size at least as big as the requested size will be returned.

    \internal
*/

static inline int areaDiff(const QSize &size, const QGLFramebufferObject *fbo)
{
    return qAbs(size.width() * size.height() - fbo->width() * fbo->height());
}

extern int qt_next_power_of_two(int v);

static inline QSize maybeRoundToNextPowerOfTwo(const QSize &sz)
{
#ifdef QT_OPENGL_ES_2
    QSize rounded(qt_next_power_of_two(sz.width()), qt_next_power_of_two(sz.height()));
    if (rounded.width() * rounded.height() < 1.20 * sz.width() * sz.height())
        return rounded;
#endif
    return sz;
}


QGLFramebufferObject *QGLFramebufferObjectPool::acquire(const QSize &requestSize, const QGLFramebufferObjectFormat &requestFormat, bool strictSize)
{
    QGLFramebufferObject *chosen = 0;
    QGLFramebufferObject *candidate = 0;
    for (int i = 0; !chosen && i < m_fbos.size(); ++i) {
        QGLFramebufferObject *fbo = m_fbos.at(i);

        if (strictSize) {
            if (fbo->size() == requestSize && fbo->format() == requestFormat) {
                chosen = fbo;
                break;
            } else {
                continue;
            }
        }

        if (fbo->format() == requestFormat) {
            // choose the fbo with a matching format and the closest size
            if (!candidate || areaDiff(requestSize, candidate) > areaDiff(requestSize, fbo))
                candidate = fbo;
        }

        if (candidate) {
            m_fbos.removeOne(candidate);

            const QSize fboSize = candidate->size();
            QSize sz = fboSize;

            if (sz.width() < requestSize.width())
                sz.setWidth(qMax(requestSize.width(), qRound(sz.width() * 1.5)));
            if (sz.height() < requestSize.height())
                sz.setHeight(qMax(requestSize.height(), qRound(sz.height() * 1.5)));

            // wasting too much space?
            if (sz.width() * sz.height() > requestSize.width() * requestSize.height() * 4)
                sz = requestSize;

            if (sz != fboSize) {
                delete candidate;
                candidate = new QGLFramebufferObject(maybeRoundToNextPowerOfTwo(sz), requestFormat);
            }

            chosen = candidate;
        }
    }

    if (!chosen) {
        if (strictSize)
            chosen = new QGLFramebufferObject(requestSize, requestFormat);
        else
            chosen = new QGLFramebufferObject(maybeRoundToNextPowerOfTwo(requestSize), requestFormat);
    }

    if (!chosen->isValid()) {
        delete chosen;
        chosen = 0;
    }

    return chosen;
}

void QGLFramebufferObjectPool::release(QGLFramebufferObject *fbo)
{
    if (fbo)
        m_fbos << fbo;
}


QPaintEngine* QGLPixmapGLPaintDevice::paintEngine() const
{
    return data->paintEngine();
}

void QGLPixmapGLPaintDevice::beginPaint()
{
    if (!data->isValid())
        return;

    // QGLPaintDevice::beginPaint will store the current binding and replace
    // it with m_thisFBO:
    m_thisFBO = data->m_renderFbo->handle();
    QGLPaintDevice::beginPaint();

    Q_ASSERT(data->paintEngine()->type() == QPaintEngine::OpenGL2);