#include <optional>
#include "BKE_image.hh"
#include "BKE_image_partial_update.hh"
#include "DNA_image_types.h"
#include "IMB_imbuf_types.hh"
#include "BLI_bit_vector.hh"
#include "BLI_listbase.h"
#include "BLI_vector.hh"

Classes
struct	blender::bke::image::partial_update::PartialUpdateUserImpl

struct	blender::bke::image::partial_update::TileChangeset
	Dirty chunks of an ImageTile. More...

struct	blender::bke::image::partial_update::Changeset
	Changeset keeping track of changes for an image. More...

struct	blender::bke::image::partial_update::PartialUpdateRegisterImpl
	Partial update changes stored inside the image runtime. More...

Namespaces
namespace	blender

namespace	blender::bke

namespace	blender::bke::image

namespace	blender::bke::image::partial_update

Typedefs
using	blender::bke::image::partial_update::ChangesetID = int64_t

Functions
static int	blender::bke::image::partial_update::chunk_number_for_pixel (int pixel_offset)
	get the chunk number for the give pixel coordinate.

static PartialUpdateUser *	blender::bke::image::partial_update::wrap (PartialUpdateUserImpl *user)

static PartialUpdateUserImpl *	blender::bke::image::partial_update::unwrap (PartialUpdateUser *user)

static PartialUpdateRegister *	blender::bke::image::partial_update::wrap (PartialUpdateRegisterImpl *partial_update_register)

static PartialUpdateRegisterImpl *	blender::bke::image::partial_update::unwrap (PartialUpdateRegister *partial_update_register)

static PartialUpdateRegister *	blender::bke::image::partial_update::image_partial_update_register_ensure (Image *image)

ePartialUpdateCollectResult	blender::bke::image::partial_update::BKE_image_partial_update_collect_changes (Image image, PartialUpdateUser user)
	collect the partial update since the last request.

ePartialUpdateIterResult	blender::bke::image::partial_update::BKE_image_partial_update_get_next_change (PartialUpdateUser user, PartialUpdateRegion r_region)

PartialUpdateUser *	BKE_image_partial_update_create (const Image *image)
	Create a new PartialUpdateUser. An Object that contains data to use partial updates.

void	BKE_image_partial_update_free (PartialUpdateUser *user)
	free a partial update user.

void	BKE_image_partial_update_register_free (Image *image)

void	BKE_image_partial_update_mark_region (Image image, const ImageTile image_tile, const ImBuf image_buffer, const rcti updated_region)
	Mark a region of the image to update.

void	BKE_image_partial_update_mark_full_update (Image *image)
	Mark the whole image to be updated.

Variables
constexpr int	blender::bke::image::partial_update::CHUNK_SIZE = 256
	Size of chunks to track changes.

constexpr int	blender::bke::image::partial_update::MAX_HISTORY_LEN = 4
	Max number of changesets to keep in history.

constexpr ChangesetID	blender::bke::image::partial_update::UnknownChangesetID = -1

Detailed Description

To reduce the overhead of image processing this file contains a mechanism to detect areas of the image that are changed. These areas are organized in chunks. Changes that happen over time are organized in changesets.

A common use case is to update #GPUTexture for drawing where only that part is uploaded that only changed.

Usage:

Image *image = ...;
ImBuf *image_buffer = ...;
 
// Partial_update_user should be kept for the whole session where the changes needs to be
// tracked. Keep this instance alive as long as you need to track image changes.
 
PartialUpdateUser *partial_update_user = BKE_image_partial_update_create(image);
 
...
 
switch (BKE_image_partial_update_collect_changes(image, image_buffer))
{
case ePartialUpdateCollectResult::FullUpdateNeeded:
 // Unable to do partial updates. Perform a full update.
 break;
case ePartialUpdateCollectResult::PartialChangesDetected:
 PartialUpdateRegion change;
 while (BKE_image_partial_update_get_next_change(partial_update_user, &change) ==
        ePartialUpdateIterResult::ChangeAvailable){
 // Do something with the change.
 }
 case ePartialUpdateCollectResult::NoChangesDetected:
   break;
}
 
...
 
// Free partial_update_user.
BKE_image_partial_update_free(partial_update_user);