imageresponseprovider.cpp Example File | Qt Quick 5.12.8

- Qt 5.12
- Qt Quick
- C++ Extensions: Image Response Provider Example
- imageresponseprovider.cpp Example File
- Qt 5.12.8 Reference Documentation

# imageresponseprovider.cpp Example File

imageresponseprovider/imageresponseprovider.cpp

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     #include <qqmlextensionplugin.h>

     #include <qqmlengine.h>
     #include <qquickimageprovider.h>
     #include <QDebug>
     #include <QImage>
     #include <QThreadPool>

     class AsyncImageResponse : public QQuickImageResponse, public QRunnable
     {
         public:
             AsyncImageResponse(const QString &id, const QSize &requestedSize)
              : m_id(id), m_requestedSize(requestedSize)
             {
                 setAutoDelete(false);
             }

             QQuickTextureFactory *textureFactory() const override
             {
                 return QQuickTextureFactory::textureFactoryForImage(m_image);
             }

             void run() override
             {
                 m_image = QImage(50, 50, QImage::Format_RGB32);
                 if (m_id == "slow") {
                     qDebug() << "Slow, red, sleeping for 5 seconds";
                     QThread::sleep(5);
                     m_image.fill(Qt::red);
                 } else {
                     qDebug() << "Fast, blue, sleeping for 1 second";
                     QThread::sleep(1);
                     m_image.fill(Qt::blue);
                 }
                 if (m_requestedSize.isValid())
                     m_image = m_image.scaled(m_requestedSize);

                 emit finished();
             }

             QString m_id;
             QSize m_requestedSize;
             QImage m_image;
     };

     class AsyncImageProvider : public QQuickAsyncImageProvider
     {
     public:
         QQuickImageResponse *requestImageResponse(const QString &id, const QSize &requestedSize) override
         {
             AsyncImageResponse *response = new AsyncImageResponse(id, requestedSize);
             pool.start(response);
             return response;
         }

     private:
         QThreadPool pool;
     };

     class ImageProviderExtensionPlugin : public QQmlExtensionPlugin
     {
         Q_OBJECT
         Q_PLUGIN_METADATA(IID QQmlExtensionInterface_iid)
     public:
         void registerTypes(const char *uri) override
         {
             Q_UNUSED(uri);
         }

         void initializeEngine(QQmlEngine *engine, const char *uri) override
         {
             Q_UNUSED(uri);
             engine->addImageProvider("async", new AsyncImageProvider);
         }

     };

     #include "imageresponseprovider.moc"