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#include "qquickimageprovider.h"

QT_BEGIN_NAMESPACE

class QQuickImageProviderPrivate
{
public:
    QQuickImageProvider::ImageType type;
    QQuickImageProvider::Flags flags;
};

/*!
    \class QQuickTextureFactory
    \since QtQuick 2.0
    \brief The QQuickTextureFactory class provides an interface for loading custom textures from QML.
    \inmodule QtQuick

    The purpose of the texture factory is to provide a placeholder for a image
    data that can be converted into an OpenGL texture.

    Creating a texture directly is not possible as there is rarely an OpenGL context
    available in the thread that is responsible for loading the image data.
*/

/*!
    Constructs a texture factory. Since QQuickTextureFactory is abstract, it
    cannot be instantiated directly.
*/

QQuickTextureFactory::QQuickTextureFactory()
{
}

/*!
    Destroys the texture factory.
*/

QQuickTextureFactory::~QQuickTextureFactory()
{
}

/*!
    \fn int QQuickTextureFactory::textureByteCount() const

    Returns the number of bytes of memory the texture consumes.
*/

/*!
    \fn QImage QQuickTextureFactory::image() const

    Returns an image version of this texture.

    The lifespan of the returned image is unknown, so the implementation should
    return a self contained QImage, not make use of the QImage(uchar *, ...)
    constructor.

    This function is not commonly used and is expected to be slow.
 */

QImage QQuickTextureFactory::image() const
{
    return QImage();
}


/*!
    \fn QSGTexture *QQuickTextureFactory::createTexture(QQuickWindow *window) const

    This function is called on the scene graph rendering thread to create a QSGTexture
    instance from the factory. \a window provides the context which this texture is
    created in.

    QML will internally cache the returned texture as needed. Each call to this
    function should return a unique instance.

    The OpenGL context used for rendering is bound when this function is called.
 */

/*!
    \fn QSize QQuickTextureFactory::textureSize() const

    Returns the size of the texture. This function will be called from arbitrary threads
    and should not rely on an OpenGL context bound.
 */


/*!
    \class QQuickImageProvider
    \since QtQuick 2.0
    \inmodule QtQuick
    \brief The QQuickImageProvider class provides an interface for supporting pixmaps and threaded image requests in QML.

    QQuickImageProvider is used to provide advanced image loading features
    in QML applications. It allows images in QML to be:

    \list
    \li Loaded using QPixmaps rather than actual image files
    \li Loaded asynchronously in a separate thread
    \endlist

    To specify that an image should be loaded by an image provider, use the
    \b {"image:"} scheme for the URL source of the image, followed by the
    identifiers of the image provider and the requested image. For example:

    \qml
    Image { source: "image://myimageprovider/image.png" }
    \endqml

    This specifies that the image should be loaded by the image provider named 
    "myimageprovider", and the image to be loaded is named "image.png". The QML engine 
    invokes the appropriate image provider according to the providers that have
    been registered through QQmlEngine::addImageProvider().

    Note that the identifiers are case-insensitive, but the rest of the URL will be passed on with
    preserved case. For example, the below snippet would still specify that the image is loaded by the
    image provider named "myimageprovider", but it would request a different image than the above snippet
    ("Image.png" instead of "image.png").
    \qml
    Image { source: "image://MyImageProvider/Image.png" }
    \endqml

    If you want the rest of the URL to be case insensitive, you will have to take care
    of that yourself inside your image provider.

    \section2 An example

    Here are two images. Their \c source values indicate they should be loaded by
    an image provider named "colors", and the images to be loaded are "yellow"
    and "red", respectively:

    \snippet quick/imageprovider/imageprovider-example.qml 0

    When these images are loaded by QML, it looks for a matching image provider
    and calls its requestImage() or requestPixmap() method (depending on its
    imageType()) to load the image. The method is called with the \c id 
    parameter set to "yellow" for the first image, and "red" for the second.

    Here is an image provider implementation that can load the images 
    requested by the above QML. This implementation dynamically 
    generates QPixmap images that are filled with the requested color:

    \snippet quick/imageprovider/imageprovider.cpp 0
    \codeline
    \snippet quick/imageprovider/imageprovider.cpp 1

    To make this provider accessible to QML, it is registered with the QML engine
    with a "colors" identifier:

    \code
    int main(int argc, char *argv[]) 
    {
        ...

        QQmlEngine engine;
        engine->addImageProvider(QLatin1String("colors"), new ColorPixmapProvider);

        ...
    }
    \endcode

    Now the images can be successfully loaded in QML:

    \image imageprovider.png

    A complete example is available in Qt's 
    \l {qml/imageprovider}{examples/qml/imageprovider}
    directory. Note the example registers the provider via a \l{QQmlExtensionPlugin}{plugin}
    instead of registering it in the application \c main() function as shown above.


    \section2 Asynchronous image loading

    Image providers that support QImage or Texture loading automatically include support
    for asychronous loading of images. To enable asynchronous loading for an
    image source, set the \c asynchronous property to \c true for the relevant
    \l Image, \l BorderImage or \l AnimatedImage object. When this is enabled, 
    the image request to the provider is run in a low priority thread,
    allowing image loading to be executed in the background, and reducing the
    performance impact on the user interface.

    To force asynchronous image loading, even for image sources that do not
    have the \c asynchronous property set to \c true, you may pass the
    \c QQuickImageProvider::ForceAsynchronousImageLoading flag to the image
    provider constructor. This ensures that all image requests for the
    provider are handled in a separate thread.

    Asynchronous loading for image providers that provide QPixmap is only supported
    in platforms that have the ThreadedPixmaps feature, in platforms where
    pixmaps can only be created in the main thread (i.e. ThreadedPixmaps is not supported)
    if \l {Image::}{asynchronous} is set to \c true, the value is ignored
    and the image is loaded synchronously.


    \section2 Image caching

    Images returned by a QQuickImageProvider are automatically cached,
    similar to any image loaded by the QML engine. When an image with a
    "image://" prefix is loaded from cache, requestImage() and requestPixmap()
    will not be called for the relevant image provider. If an image should always
    be fetched from the image provider, and should not be cached at all, set the
    \c cache property to \c false for the relevant \l Image, \l BorderImage or
    \l AnimatedImage object.

    The QtQuick 1 version of this class is named QDeclarativeImageProvider.

    \sa QQmlEngine::addImageProvider()
*/

/*!
    Creates an image provider that will provide images of the given \a type and
    behave according to the given \a flags.
*/
QQuickImageProvider::QQuickImageProvider(ImageType type, Flags flags)
    : d(new QQuickImageProviderPrivate)
{
    d->type = type;
    d->flags = flags;
}

/*!
    Destroys the QQuickImageProvider

    \note The destructor of your derived class need to be thread safe.
*/
QQuickImageProvider::~QQuickImageProvider()
{
    delete d;
}

/*!
    Returns the image type supported by this provider.
*/
QQuickImageProvider::ImageType QQuickImageProvider::imageType() const
{
    return d->type;
}

/*!
    Returns the flags set for this provider.
*/
QQuickImageProvider::Flags QQuickImageProvider::flags() const
{
    return d->flags;
}

/*!
    Implement this method to return the image with \a id. The default 
    implementation returns an empty image.

    The \a id is the requested image source, with the "image:" scheme and
    provider identifier removed. For example, if the image \l{Image::}{source}
    was "image://myprovider/icons/home", the given \a id would be "icons/home".

    The \a requestedSize corresponds to the \l {Image::sourceSize} requested by
    an Image item. If \a requestedSize is a valid size, the image
    returned should be of that size.

    In all cases, \a size must be set to the original size of the image. This
    is used to set the \l {Item::}{width} and \l {Item::}{height} of the
    relevant \l Image if these values have not been set explicitly.

    \note this method may be called by multiple threads, so ensure the
    implementation of this method is reentrant.
*/
QImage QQuickImageProvider::requestImage(const QString &id, QSize *size, const QSize& requestedSize)
{
    Q_UNUSED(id);
    Q_UNUSED(size);
    Q_UNUSED(requestedSize);
    if (d->type == Image)
        qWarning("ImageProvider supports Image type but has not implemented requestImage()");
    return QImage();
}

/*!
    Implement this method to return the pixmap with \a id. The default
    implementation returns an empty pixmap.

    The \a id is the requested image source, with the "image:" scheme and
    provider identifier removed. For example, if the image \l{Image::}{source}
    was "image://myprovider/icons/home", the given \a id would be "icons/home".

    The \a requestedSize corresponds to the \l {Image::sourceSize} requested by
    an Image item. If \a requestedSize is a valid size, the image
    returned should be of that size.

    In all cases, \a size must be set to the original size of the image. This
    is used to set the \l {Item::}{width} and \l {Item::}{height} of the
    relevant \l Image if these values have not been set explicitly.

    \note this method may be called by multiple threads, so ensure the
    implementation of this method is reentrant.
*/
QPixmap QQuickImageProvider::requestPixmap(const QString &id, QSize *size, const QSize& requestedSize)
{
    Q_UNUSED(id);
    Q_UNUSED(size);
    Q_UNUSED(requestedSize);
    if (d->type == Pixmap)
        qWarning("ImageProvider supports Pixmap type but has not implemented requestPixmap()");
    return QPixmap();
}


/*!
    Implement this method to return the texture with \a id. The default
    implementation returns 0.

    The \a id is the requested image source, with the "image:" scheme and
    provider identifier removed. For example, if the image \l{Image::}{source}
    was "image://myprovider/icons/home", the given \a id would be "icons/home".

    The \a requestedSize corresponds to the \l {Image::sourceSize} requested by
    an Image item. If \a requestedSize is a valid size, the image
    returned should be of that size.

    In all cases, \a size must be set to the original size of the image. This
    is used to set the \l {Item::}{width} and \l {Item::}{height} of the
    relevant \l Image if these values have not been set explicitly.

    \note this method may be called by multiple threads, so ensure the
    implementation of this method is reentrant.
*/

QQuickTextureFactory *QQuickImageProvider::requestTexture(const QString &id, QSize *size, const QSize &requestedSize)
{
    Q_UNUSED(id);
    Q_UNUSED(size);
    Q_UNUSED(requestedSize);
    if (d->type == Texture)
        qWarning("ImageProvider supports Texture type but has not implemented requestTexture()");
    return 0;
}

QT_END_NAMESPACE

