test2/source/blender/compositor/cached_resources/COM_cached_image.hh

/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

#pragma once

#include <cstdint>
#include <memory>
#include <string>

#include "BLI_map.hh"

#include "GPU_texture.hh"

#include "DNA_image_types.h"

#include "RE_pipeline.h"

#include "COM_cached_resource.hh"
#include "COM_result.hh"

namespace blender::compositor {

class Context;

/* ------------------------------------------------------------------------------------------------
 * Cached Image Key.
 */
class CachedImageKey {
 public:
  ImageUser image_user;
  std::string pass_name;

  CachedImageKey(ImageUser image_user, std::string pass_name);

  uint64_t hash() const;
};

bool operator==(const CachedImageKey &a, const CachedImageKey &b);

/* -------------------------------------------------------------------------------------------------
 * Cached Image.
 *
 * A cached resource that computes and caches a result containing the contents of the image with
 * the given image user. */
class CachedImage : public CachedResource {
 public:
  Result result;

 private:
  /* For GPU, the result wraps an external GPU texture that is generated by the IMB module and
   * stored in this member to be freed when the cached resource is deleted. */
  GPUTexture *texture_ = nullptr;

 public:
  CachedImage(Context &context, Image *image, ImageUser *image_user, const char *pass_name);

  ~CachedImage();

 private:
  /* Populates the meta data of the image. */
  void populate_meta_data(const RenderResult *render_result, const ImageUser &image_user);
};

/* ------------------------------------------------------------------------------------------------
 * Cached Image Container.
 */
class CachedImageContainer : CachedResourceContainer {
 private:
  Map<std::string, Map<CachedImageKey, std::unique_ptr<CachedImage>>> map_;

  /* A map that stores the update counts of the images at the moment they were cached. */
  Map<std::string, uint64_t> update_counts_;

 public:
  void reset() override;

  /* Check if the given image has changed since it was cached, and if so, invalidate its cache
   * entry. Then, check if there is an available CachedImage cached resource with the given image
   * user and pass_name in the container, if one exists, return it, otherwise, return a newly
   * created one and add it to the container. In both cases, tag the cached resource as needed to
   * keep it cached for the next evaluation. */
  Result get(Context &context, Image *image, const ImageUser *image_user, const char *pass_name);
};

}  // namespace blender::compositor