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#include "qsgtexturemanager.h"

#include <QImage>

#include <qgl.h>
#include <qhash.h>

QSGTexture::QSGTexture()
    : m_status(Null)
    , m_texture_id(0)
    , m_ref_count(0)
    , m_has_alpha(false)
    , m_owns_texture(true)
    , m_has_mipmaps(false)
{
}



QSGTexture::~QSGTexture()
{
    if (m_owns_texture)
        glDeleteTextures(1, (GLuint *) &m_texture_id);
}



void QSGTexture::setStatus(Status s)
{
    m_status = s;
    Q_ASSERT(s != Ready || (m_texture_id > 0 && !m_texture_size.isEmpty()));
    emit statusChanged(s);
}



struct QSGTextureCacheKey {
    quint64 cacheKey;

    bool operator==(const QSGTextureCacheKey &other) const {
        return other.cacheKey == cacheKey;
    }
};


uint qHash(const QSGTextureCacheKey &key)
{
    return (key.cacheKey >> 32) ^ uint(key.cacheKey);
}

class QSGTextureManagerPrivate
{
public:
    QHash<QSGTextureCacheKey, QSGTexture *> cache;
};



QSGTextureManager::QSGTextureManager()
    : d(new QSGTextureManagerPrivate)
{
}



QImage QSGTextureManager::swizzleBGGRAToRGBA(const QImage &image)
{
    QImage img = image.copy();
    const int width = img.width();
    const int height = img.height();
    for (int i = 0; i < height; ++i) {
        uint *p = (uint *) img.scanLine(i);
        for (int x = 0; x < width; ++x)
            p[x] = ((p[x] << 16) & 0xff0000) | ((p[x] >> 16) & 0xff) | (p[x] & 0xff00ff00);
    }
    return img;
}



QSGTextureRef QSGTextureManager::upload(const QImage &image)
{
    QSGTextureCacheKey key = { image.cacheKey() };
    QSGTexture *texture = d->cache.value(key);
    if (texture)
        return QSGTextureRef(texture);

    GLuint id;
    glGenTextures(1, &id);
    glBindTexture(GL_TEXTURE_2D, id);

#ifdef QT_OPENGL_ES
    QImage i = swizzleBGRAToRGBA(image);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, i.width(), i.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, i.constBits());
#else
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, image.width(), image.height(), 0, GL_BGRA, GL_UNSIGNED_BYTE, image.constBits());
#endif

    texture = new QSGTexture;
    texture->setTextureId(id);
    texture->setTextureSize(image.size());
    texture->setAlphaChannel(image.hasAlphaChannel());
    texture->setStatus(QSGTexture::Ready);

    d->cache.insert(key, texture);

    QSGTextureRef ref(texture);
    return ref;
}



QSGTextureRef QSGTextureManager::requestUpload(const QImage &image,
                                               const QObject *listener,
                                               const char *slot)
{
    QSGTextureRef texture = upload(image);
    return texture;
}