File indexing completed on 2025-07-13 04:19:52

 // SPDX-FileCopyrightText: Lukas Sommer <sommerluk@gmail.com>
 // SPDX-License-Identifier: BSD-2-Clause OR MIT
 
 #ifndef ASYNCIMAGERENDERCALLBACK_H
 #define ASYNCIMAGERENDERCALLBACK_H
 
 #include <qglobal.h>
 #include <qmetatype.h>
 
 class QImage;
 class QVariant;
 
 namespace PerceptualColor
 {
 /** @internal
  *
  * @brief Interface for @ref AsyncImageRenderThread::pointerToRenderFunction
  * to make callbacks. */
 class AsyncImageRenderCallback
 {
 public:
     virtual ~AsyncImageRenderCallback() noexcept;
 
     /** @brief Describes the interlacing state of an image.
      *
      * This enum is <em>not</em> declared to the meta-object system.
      *
      * This type is declared as type to Qt’s type system via
      * <tt>Q_DECLARE_METATYPE</tt>. Depending on your use case (for
      * example if you want to use for <em>queued</em> signal-slot connections),
      * you might consider calling <tt>qRegisterMetaType()</tt> for
      * this type, once you have a QApplication object. */
     // Q_ENUM can only be used within classes that have the Q_OBJECT macro,
     // which this class template does not have, because we want to avoid
     // conflicts when doing multiple inheritance with this class.
     // Tough the Qt documentation allows using Q_ENUM with Q_GADGET instead
     // of Q_OBJECT, in practice it does not work: It compiles without warnings
     // or errors, but the meta type is nevertheless not registered and
     // not available for signals and slots. Therefore, we do not use Q_ENUM
     // here.
     enum class InterlacingState {
         Intermediate, /**< The image represents
             an intermediate interlacing result. */
         Final /**< The image represents the final image in full quality.
             No further interlacing passes will happen. */
     };
 
     /** @brief Deliver the result of an interlacing pass of
      * the <em>rendering</em> operation.
      *
      * This function is thread-safe.
      *
      * @param image The image
      * @param parameters The parameters of the image
      * @param state The interlacing state of the image. A render function
      * must first return zero or more images with intermediate state. After
      * that, it must return exactly one image with final state (unless it
      * was aborted). After that, it must not return any more images. */
     virtual void deliverInterlacingPass(const QImage &image, const QVariant &parameters, const InterlacingState state) = 0;
 
     /** @brief If the render function should abort.
      *
      * This function is thread-safe.
      *
      * @returns <tt>true</tt> if the render function should abort and
      * return. <tt>false</tt> otherwise. */
     [[nodiscard]] virtual bool shouldAbort() const = 0;
 
 protected:
     AsyncImageRenderCallback() = default;
 
 private:
     Q_DISABLE_COPY(AsyncImageRenderCallback)
 };
 
 } // namespace PerceptualColor
 
 Q_DECLARE_METATYPE(PerceptualColor::AsyncImageRenderCallback::InterlacingState)
 
 #endif // ASYNCIMAGERENDERCALLBACK_H