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#include "qdeclarativeimageprovider.h"

QT_BEGIN_NAMESPACE

class QDeclarativeImageProviderPrivate

{

public:

    QDeclarativeImageProvider::ImageType type;

};

/*!

    \class QDeclarativeImageProvider

    \since 4.7

    \brief The QDeclarativeImageProvider class provides an interface for supporting pixmaps and threaded image requests in QML.

    QDeclarativeImageProvider is used to provide advanced image loading features

    in QML applications. It allows images in QML to be:

    \list

    \o Loaded using QPixmaps rather than actual image files

    \endlist

    To specify that an image should be loaded by an image provider, use the

    \bold {"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 QDeclarativeEngine::addImageProvider().

    \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 examples/declarative/cppextensions/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 examples/declarative/cppextensions/imageprovider/imageprovider.cpp 0

    \codeline

    \snippet examples/declarative/cppextensions/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[]) 

    {

        ...

        QDeclarativeEngine engine;

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

        ...

    }

    \endcode

    \image imageprovider.png

    A complete example is available in Qt's 

    \l {declarative/cppextensions/imageprovider}{examples/declarative/cppextensions/imageprovider}

    directory. Note the example registers the provider via a \l{QDeclarativeExtensionPlugin}{plugin}

    instead of registering it in the application \c main() function as shown above.

    \section2 Asynchronous image loading

    Image providers that support QImage loading automatically include support

    for asychronous loading of images. To enable asynchronous loading for an

    \l Image source, set \l Image::asynchronous to \c true. 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.

    Asynchronous loading is not supported for image providers that provide

    QPixmap rather than QImage values, as pixmaps can only be created in the

    main thread. In this case, if \l {Image::}{asynchronous} is set to 

    \c true, the value is ignored and the image is loaded

    synchronously.

    \sa QDeclarativeEngine::addImageProvider()

*/

/*!

    \enum QDeclarativeImageProvider::ImageType

    Defines the type of image supported by this image provider.

    \value Image The Image Provider provides QImage images. The 

        requestImage() method will be called for all image requests.

    \value Pixmap The Image Provider provides QPixmap images. The 

        requestPixmap() method will be called for all image requests.

*/

/*!

    Creates an image provider that will provide images of the given \a type.

*/

QDeclarativeImageProvider::QDeclarativeImageProvider(ImageType type)

    : d(new QDeclarativeImageProviderPrivate)

{

    d->type = type;

}

/*!

*/

QDeclarativeImageProvider::~QDeclarativeImageProvider()

{

    delete d;

}

/*!

    Returns the image type supported by this provider.

*/

QDeclarativeImageProvider::ImageType QDeclarativeImageProvider::imageType() const

{

    return d->type;

}

/*!

    Implement this method to return the image with \a id. The default 

    implementation returns an empty image.

    The \a requestedSize corresponds to the \l {Image::sourceSize} requested by

    an Image element. 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 image

    elements that should be automatically sized to the loaded image.

    \note this method may be called by multiple threads, so ensure the

    implementation of this method is reentrant.

*/

QImage QDeclarativeImageProvider::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 requestedSize corresponds to the \l {Image::sourceSize} requested by

    an Image element. 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 image

    elements that should be automatically sized to the loaded image.

*/

QPixmap QDeclarativeImageProvider::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();

}

QT_END_NAMESPACE