source: trunk/src/openvg/qvgimagepool.cpp

/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtOpenVG 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 qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qvgimagepool_p.h"
#include "qpixmapdata_vg_p.h"

QT_BEGIN_NAMESPACE

static QVGImagePool *qt_vg_image_pool = 0;

class QVGImagePoolPrivate
{
public:
    QVGImagePoolPrivate() : lruFirst(0), lruLast(0) {}

    QVGPixmapData *lruFirst;
    QVGPixmapData *lruLast;
};

QVGImagePool::QVGImagePool()
    : d_ptr(new QVGImagePoolPrivate())
{
}

QVGImagePool::~QVGImagePool()
{
}

QVGImagePool *QVGImagePool::instance()
{
    if (!qt_vg_image_pool)
        qt_vg_image_pool = new QVGImagePool();
    return qt_vg_image_pool;
}

void QVGImagePool::setImagePool(QVGImagePool *pool)
{
    if (qt_vg_image_pool != pool)
        delete qt_vg_image_pool;
    qt_vg_image_pool = pool;
}

VGImage QVGImagePool::createTemporaryImage(VGImageFormat format,
                                           VGint width, VGint height,
                                           VGbitfield allowedQuality,
                                           QVGPixmapData *keepData)
{
    VGImage image;
    do {
        image = vgCreateImage(format, width, height, allowedQuality);
        if (image != VG_INVALID_HANDLE)
            return image;
    } while (reclaimSpace(format, width, height, keepData));
    qWarning("QVGImagePool: cannot reclaim sufficient space for a %dx%d temporary image",
             width, height);
    return VG_INVALID_HANDLE;
}

VGImage QVGImagePool::createImageForPixmap(VGImageFormat format,
                                           VGint width, VGint height,
                                           VGbitfield allowedQuality,
                                           QVGPixmapData *data)
{
    VGImage image;
    do {
        image = vgCreateImage(format, width, height, allowedQuality);
        if (image != VG_INVALID_HANDLE) {
            if (data)
                moveToHeadOfLRU(data);
            return image;
        }
    } while (reclaimSpace(format, width, height, data));
    qWarning("QVGImagePool: cannot reclaim sufficient space for a %dx%d pixmap",
             width, height);
    return VG_INVALID_HANDLE;
}

VGImage QVGImagePool::createPermanentImage(VGImageFormat format,
                                           VGint width, VGint height,
                                           VGbitfield allowedQuality)
{
    VGImage image;
    do {
        image = vgCreateImage(format, width, height, allowedQuality);
        if (image != VG_INVALID_HANDLE)
            return image;
    } while (reclaimSpace(format, width, height, 0));
    qWarning("QVGImagePool: cannot reclaim sufficient space for a %dx%d image",
             width, height);
    return VG_INVALID_HANDLE;
}

void QVGImagePool::releaseImage(QVGPixmapData *data, VGImage image)
{
    // Very simple strategy at the moment: just destroy the image.
    if (data)
        removeFromLRU(data);
    vgDestroyImage(image);
}

void QVGImagePool::useImage(QVGPixmapData *data)
{
    moveToHeadOfLRU(data);
}

void QVGImagePool::detachImage(QVGPixmapData *data)
{
    removeFromLRU(data);
}

bool QVGImagePool::reclaimSpace(VGImageFormat format,
                                VGint width, VGint height,
                                QVGPixmapData *data)
{
    Q_UNUSED(format);   // For future use in picking the best image to eject.
    Q_UNUSED(width);
    Q_UNUSED(height);

    bool succeeded = false;
    bool wasInLRU = false;
    if (data) {
        wasInLRU = data->inLRU;
        moveToHeadOfLRU(data);
    }

    QVGPixmapData *lrudata = pixmapLRU();
    if (lrudata && lrudata != data) {
        lrudata->reclaimImages();
        succeeded = true;
    }

    if (data && !wasInLRU)
        removeFromLRU(data);

    return succeeded;
}

void QVGImagePool::hibernate()
{
    // Nothing to do here at the moment since the pool does not
    // retain VGImage's after they have been released.
}

void QVGImagePool::moveToHeadOfLRU(QVGPixmapData *data)
{
    Q_D(QVGImagePool);
    if (data->inLRU) {
        if (!data->prevLRU)
            return;     // Already at the head of the list.
        removeFromLRU(data);
    }
    data->inLRU = true;
    data->nextLRU = d->lruFirst;
    data->prevLRU = 0;
    if (d->lruFirst)
        d->lruFirst->prevLRU = data;
    else
        d->lruLast = data;
    d->lruFirst = data;
}

void QVGImagePool::removeFromLRU(QVGPixmapData *data)
{
    Q_D(QVGImagePool);
    if (!data->inLRU)
        return;
    if (data->nextLRU)
        data->nextLRU->prevLRU = data->prevLRU;
    else
        d->lruLast = data->prevLRU;
    if (data->prevLRU)
        data->prevLRU->nextLRU = data->nextLRU;
    else
        d->lruFirst = data->nextLRU;
    data->inLRU = false;
}

QVGPixmapData *QVGImagePool::pixmapLRU()
{
    Q_D(QVGImagePool);
    return d->lruLast;
}

QT_END_NAMESPACE