imageresponseprovider.cpp Example File

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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), m_texture(0)
          {
              setAutoDelete(false);
          }

          QQuickTextureFactory *textureFactory() const
          {
              return m_texture;
          }

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

          QString m_id;
          QSize m_requestedSize;
          QQuickTextureFactory *m_texture;
  };

  class AsyncImageProvider : public QQuickAsyncImageProvider
  {
  public:
      QQuickImageResponse *requestImageResponse(const QString &id, const QSize &requestedSize)
      {
          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)
      {
          Q_UNUSED(uri);
      }

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

  };

  #include "imageresponseprovider.moc"