tor-browser

decode.h (70762B)

---

/* Copyright (c) the JPEG XL Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style
* license that can be found in the LICENSE file.
*/

/** @addtogroup libjxl_decoder
* @{
* @file decode.h
* @brief Decoding API for JPEG XL.
*/

#ifndef JXL_DECODE_H_
#define JXL_DECODE_H_

#include <jxl/cms_interface.h>
#include <jxl/codestream_header.h>
#include <jxl/color_encoding.h>
#include <jxl/jxl_export.h>
#include <jxl/memory_manager.h>
#include <jxl/parallel_runner.h>
#include <jxl/types.h>
#include <jxl/version.h>  // TODO(eustas): remove before v1.0
#include <stddef.h>
#include <stdint.h>

#ifdef __cplusplus
extern "C" {
#endif

/**
* Decoder library version.
*
* @return the decoder library version as an integer:
* MAJOR_VERSION * 1000000 + MINOR_VERSION * 1000 + PATCH_VERSION. For example,
* version 1.2.3 would return 1002003.
*/
JXL_EXPORT uint32_t JxlDecoderVersion(void);

/** The result of @ref JxlSignatureCheck.
*/
typedef enum {
 /** Not enough bytes were passed to determine if a valid signature was found.
  */
 JXL_SIG_NOT_ENOUGH_BYTES = 0,

 /** No valid JPEG XL header was found. */
 JXL_SIG_INVALID = 1,

 /** A valid JPEG XL codestream signature was found, that is a JPEG XL image
  * without container.
  */
 JXL_SIG_CODESTREAM = 2,

 /** A valid container signature was found, that is a JPEG XL image embedded
  * in a box format container.
  */
 JXL_SIG_CONTAINER = 3,
} JxlSignature;

/**
* JPEG XL signature identification.
*
* Checks if the passed buffer contains a valid JPEG XL signature. The passed @p
* buf of size
* @p size doesn't need to be a full image, only the beginning of the file.
*
* @return a flag indicating if a JPEG XL signature was found and what type.
*  - ::JXL_SIG_NOT_ENOUGH_BYTES if not enough bytes were passed to
*    determine if a valid signature is there.
*  - ::JXL_SIG_INVALID if no valid signature found for JPEG XL decoding.
*  - ::JXL_SIG_CODESTREAM if a valid JPEG XL codestream signature was
*    found.
*  - ::JXL_SIG_CONTAINER if a valid JPEG XL container signature was found.
*/
JXL_EXPORT JxlSignature JxlSignatureCheck(const uint8_t* buf, size_t len);

/**
* Opaque structure that holds the JPEG XL decoder.
*
* Allocated and initialized with @ref JxlDecoderCreate().
* Cleaned up and deallocated with @ref JxlDecoderDestroy().
*/
typedef struct JxlDecoderStruct JxlDecoder;

/**
* Creates an instance of @ref JxlDecoder and initializes it.
*
* @p memory_manager will be used for all the library dynamic allocations made
* from this instance. The parameter may be NULL, in which case the default
* allocator will be used. See jxl/memory_manager.h for details.
*
* @param memory_manager custom allocator function. It may be NULL. The memory
*        manager will be copied internally.
* @return @c NULL if the instance can not be allocated or initialized
* @return pointer to initialized @ref JxlDecoder otherwise
*/
JXL_EXPORT JxlDecoder* JxlDecoderCreate(const JxlMemoryManager* memory_manager);

/**
* Re-initializes a @ref JxlDecoder instance, so it can be re-used for decoding
* another image. All state and settings are reset as if the object was
* newly created with @ref JxlDecoderCreate, but the memory manager is kept.
*
* @param dec instance to be re-initialized.
*/
JXL_EXPORT void JxlDecoderReset(JxlDecoder* dec);

/**
* Deinitializes and frees @ref JxlDecoder instance.
*
* @param dec instance to be cleaned up and deallocated.
*/
JXL_EXPORT void JxlDecoderDestroy(JxlDecoder* dec);

/**
* Return value for @ref JxlDecoderProcessInput.
* The values from ::JXL_DEC_BASIC_INFO onwards are optional informative
* events that can be subscribed to, they are never returned if they
* have not been registered with @ref JxlDecoderSubscribeEvents.
*/
typedef enum {
 /** Function call finished successfully, or decoding is finished and there is
  * nothing more to be done.
  *
  * Note that @ref JxlDecoderProcessInput will return ::JXL_DEC_SUCCESS if
  * all events that were registered with @ref JxlDecoderSubscribeEvents were
  * processed, even before the end of the JPEG XL codestream.
  *
  * In this case, the return value @ref JxlDecoderReleaseInput will be the same
  * as it was at the last signaled event. E.g. if ::JXL_DEC_FULL_IMAGE was
  * subscribed to, then all bytes from the end of the JPEG XL codestream
  * (including possible boxes needed for jpeg reconstruction) will be returned
  * as unprocessed.
  */
 JXL_DEC_SUCCESS = 0,

 /** An error occurred, for example invalid input file or out of memory.
  * TODO(lode): add function to get error information from decoder.
  */
 JXL_DEC_ERROR = 1,

 /** The decoder needs more input bytes to continue. Before the next @ref
  * JxlDecoderProcessInput call, more input data must be set, by calling @ref
  * JxlDecoderReleaseInput (if input was set previously) and then calling @ref
  * JxlDecoderSetInput. @ref JxlDecoderReleaseInput returns how many bytes
  * are not yet processed, before a next call to @ref JxlDecoderProcessInput
  * all unprocessed bytes must be provided again (the address need not match,
  * but the contents must), and more bytes must be concatenated after the
  * unprocessed bytes.
  * In most cases, @ref JxlDecoderReleaseInput will return no unprocessed bytes
  * at this event, the only exceptions are if the previously set input ended
  * within (a) the raw codestream signature, (b) the signature box, (c) a box
  * header, or (d) the first 4 bytes of a `brob`, `ftyp`, or `jxlp` box. In any
  * of these cases the number of unprocessed bytes is less than 20.
  */
 JXL_DEC_NEED_MORE_INPUT = 2,

 /** The decoder is able to decode a preview image and requests setting a
  * preview output buffer using @ref JxlDecoderSetPreviewOutBuffer. This occurs
  * if ::JXL_DEC_PREVIEW_IMAGE is requested and it is possible to decode a
  * preview image from the codestream and the preview out buffer was not yet
  * set. There is maximum one preview image in a codestream.
  * In this case, @ref JxlDecoderReleaseInput will return all bytes from the
  * end of the frame header (including ToC) of the preview frame as
  * unprocessed.
  */
 JXL_DEC_NEED_PREVIEW_OUT_BUFFER = 3,

 /** The decoder requests an output buffer to store the full resolution image,
  * which can be set with @ref JxlDecoderSetImageOutBuffer or with @ref
  * JxlDecoderSetImageOutCallback. This event re-occurs for new frames if
  * there are multiple animation frames and requires setting an output again.
  * In this case, @ref JxlDecoderReleaseInput will return all bytes from the
  * end of the frame header (including ToC) as unprocessed.
  */
 JXL_DEC_NEED_IMAGE_OUT_BUFFER = 5,

 /** The JPEG reconstruction buffer is too small for reconstructed JPEG
  * codestream to fit. @ref JxlDecoderSetJPEGBuffer must be called again to
  * make room for remaining bytes. This event may occur multiple times
  * after ::JXL_DEC_JPEG_RECONSTRUCTION.
  */
 JXL_DEC_JPEG_NEED_MORE_OUTPUT = 6,

 /** The box contents output buffer is too small. @ref JxlDecoderSetBoxBuffer
  * must be called again to make room for remaining bytes. This event may occur
  * multiple times after ::JXL_DEC_BOX.
  */
 JXL_DEC_BOX_NEED_MORE_OUTPUT = 7,

 /** Informative event by @ref JxlDecoderProcessInput
  * "JxlDecoderProcessInput": Basic information such as image dimensions and
  * extra channels. This event occurs max once per image.
  * In this case, @ref JxlDecoderReleaseInput will return all bytes from the
  * end of the basic info as unprocessed (including the last byte of basic info
  * if it did not end on a byte boundary).
  */
 JXL_DEC_BASIC_INFO = 0x40,

 /** Informative event by @ref JxlDecoderProcessInput
  * "JxlDecoderProcessInput": Color encoding or ICC profile from the
  * codestream header. This event occurs max once per image and always later
  * than ::JXL_DEC_BASIC_INFO and earlier than any pixel data.
  * In this case, @ref JxlDecoderReleaseInput will return all bytes from the
  * end of the image header (which is the start of the first frame) as
  * unprocessed.
  */
 JXL_DEC_COLOR_ENCODING = 0x100,

 /** Informative event by @ref JxlDecoderProcessInput
  * "JxlDecoderProcessInput": Preview image, a small frame, decoded. This
  * event can only happen if the image has a preview frame encoded. This event
  * occurs max once for the codestream and always later than @ref
  * JXL_DEC_COLOR_ENCODING and before ::JXL_DEC_FRAME.
  * In this case, @ref JxlDecoderReleaseInput will return all bytes from the
  * end of the preview frame as unprocessed.
  */
 JXL_DEC_PREVIEW_IMAGE = 0x200,

 /** Informative event by @ref JxlDecoderProcessInput
  * "JxlDecoderProcessInput": Beginning of a frame. @ref
  * JxlDecoderGetFrameHeader can be used at this point. A note on frames:
  * a JPEG XL image can have internal frames that are not intended to be
  * displayed (e.g. used for compositing a final frame), but this only returns
  * displayed frames, unless @ref JxlDecoderSetCoalescing was set to @ref
  * JXL_FALSE "JXL_FALSE": in that case, the individual layers are returned,
  * without blending. Note that even when coalescing is disabled, only frames
  * of type kRegularFrame are returned; frames of type kReferenceOnly
  * and kLfFrame are always for internal purposes only and cannot be accessed.
  * A displayed frame either has an animation duration or is the only or last
  * frame in the image. This event occurs max once per displayed frame, always
  * later than ::JXL_DEC_COLOR_ENCODING, and always earlier than any pixel
  * data. While JPEG XL supports encoding a single frame as the composition of
  * multiple internal sub-frames also called frames, this event is not
  * indicated for the internal frames. In this case, @ref
  * JxlDecoderReleaseInput will return all bytes from the end of the frame
  * header (including ToC) as unprocessed.
  */
 JXL_DEC_FRAME = 0x400,

 /** Informative event by @ref JxlDecoderProcessInput
  * "JxlDecoderProcessInput": full frame (or layer, in case coalescing is
  * disabled) is decoded. @ref JxlDecoderSetImageOutBuffer must be used after
  * getting the basic image information to be able to get the image pixels, if
  * not this return status only indicates we're past this point in the
  * codestream. This event occurs max once per frame.
  * In this case, @ref JxlDecoderReleaseInput will return all bytes from the
  * end of the frame (or if ::JXL_DEC_JPEG_RECONSTRUCTION is subscribed to,
  * from the end of the last box that is needed for jpeg reconstruction) as
  * unprocessed.
  */
 JXL_DEC_FULL_IMAGE = 0x1000,

 /** Informative event by @ref JxlDecoderProcessInput
  * "JxlDecoderProcessInput": JPEG reconstruction data decoded. @ref
  * JxlDecoderSetJPEGBuffer may be used to set a JPEG reconstruction buffer
  * after getting the JPEG reconstruction data. If a JPEG reconstruction buffer
  * is set a byte stream identical to the JPEG codestream used to encode the
  * image will be written to the JPEG reconstruction buffer instead of pixels
  * to the image out buffer. This event occurs max once per image and always
  * before ::JXL_DEC_FULL_IMAGE.
  * In this case, @ref JxlDecoderReleaseInput will return all bytes from the
  * end of the `jbrd` box as unprocessed.
  */
 JXL_DEC_JPEG_RECONSTRUCTION = 0x2000,

 /** Informative event by @ref JxlDecoderProcessInput
  * "JxlDecoderProcessInput": The header of a box of the container format
  * (BMFF) is decoded. The following API functions related to boxes can be used
  * after this event:
  *  - @ref JxlDecoderSetBoxBuffer and @ref JxlDecoderReleaseBoxBuffer
  *    "JxlDecoderReleaseBoxBuffer": set and release a buffer to get the box
  *    data.
  *  - @ref JxlDecoderGetBoxType get the 4-character box typename.
  *  - @ref JxlDecoderGetBoxSizeRaw get the size of the box as it appears in
  *    the container file, not decompressed.
  *  - @ref JxlDecoderSetDecompressBoxes to configure whether to get the box
  *    data decompressed, or possibly compressed.
  *
  * Boxes can be compressed. This is so when their box type is
  * "brob". In that case, they have an underlying decompressed box
  * type and decompressed data. @ref JxlDecoderSetDecompressBoxes allows
  * configuring which data to get. Decompressing requires
  * Brotli. @ref JxlDecoderGetBoxType has a flag to get the compressed box
  * type, which can be "brob", or the decompressed box type. If a box
  * is not compressed (its compressed type is not "brob"), then
  * the output decompressed box type and data is independent of what
  * setting is configured.
  *
  * The buffer set with @ref JxlDecoderSetBoxBuffer must be set again for each
  * next box to be obtained, or can be left unset to skip outputting this box.
  * The output buffer contains the full box data when the
  * ::JXL_DEC_BOX_COMPLETE (if subscribed to) or subsequent ::JXL_DEC_SUCCESS
  * or ::JXL_DEC_BOX event occurs. ::JXL_DEC_BOX occurs for all boxes,
  * including non-metadata boxes such as the signature box or codestream boxes.
  * To check whether the box is a metadata type for respectively EXIF, XMP or
  * JUMBF, use @ref JxlDecoderGetBoxType and check for types "Exif", "xml " and
  * "jumb" respectively.
  *
  * In this case, @ref JxlDecoderReleaseInput will return all bytes from the
  * start of the box header as unprocessed.
  */
 JXL_DEC_BOX = 0x4000,

 /** Informative event by @ref JxlDecoderProcessInput
  * "JxlDecoderProcessInput": a progressive step in decoding the frame is
  * reached. When calling @ref JxlDecoderFlushImage at this point, the flushed
  * image will correspond exactly to this point in decoding, and not yet
  * contain partial results (such as partially more fine detail) of a next
  * step. By default, this event will trigger maximum once per frame, when a
  * 8x8th resolution (DC) image is ready (the image data is still returned at
  * full resolution, giving upscaled DC). Use @ref
  * JxlDecoderSetProgressiveDetail to configure more fine-grainedness. The
  * event is not guaranteed to trigger, not all images have progressive steps
  * or DC encoded.
  * In this case, @ref JxlDecoderReleaseInput will return all bytes from the
  * end of the section that was needed to produce this progressive event as
  * unprocessed.
  */
 JXL_DEC_FRAME_PROGRESSION = 0x8000,

 /** The box being decoded is now complete. This is only emitted if a buffer
  * was set for the box.
  */
 JXL_DEC_BOX_COMPLETE = 0x10000,
} JxlDecoderStatus;

/** Types of progressive detail.
* Setting a progressive detail with value N implies all progressive details
* with smaller or equal value. Currently only the following level of
* progressive detail is implemented:
*  - @ref kDC (which implies kFrames)
*  - @ref kLastPasses (which implies @ref kDC and @ref kFrames)
*  - @ref kPasses (which implies @ref kLastPasses, kDC and @ref kFrames)
*/
typedef enum {
 /**
  * after completed kRegularFrames
  */
 kFrames = 0,
 /**
  * after completed DC (1:8)
  */
 kDC = 1,
 /**
  * after completed AC passes that are the last pass for their resolution
  * target.
  */
 kLastPasses = 2,
 /**
  * after completed AC passes that are not the last pass for their resolution
  * target.
  */
 kPasses = 3,
 /**
  * during DC frame when lower resolution are completed (1:32, 1:16)
  */
 kDCProgressive = 4,
 /**
  * after completed groups
  */
 kDCGroups = 5,
 /**
  * after completed groups
  */
 kGroups = 6,
} JxlProgressiveDetail;

/** Rewinds decoder to the beginning. The same input must be given again from
* the beginning of the file and the decoder will emit events from the beginning
* again. When rewinding (as opposed to @ref JxlDecoderReset), the decoder can
* keep state about the image, which it can use to skip to a requested frame
* more efficiently with @ref JxlDecoderSkipFrames. Settings such as parallel
* runner or subscribed events are kept. After rewind, @ref
* JxlDecoderSubscribeEvents can be used again, and it is feasible to leave out
* events that were already handled before, such as ::JXL_DEC_BASIC_INFO
* and ::JXL_DEC_COLOR_ENCODING, since they will provide the same information
* as before.
* The difference to @ref JxlDecoderReset is that some state is kept, namely
* settings set by a call to
*  - @ref JxlDecoderSetCoalescing,
*  - @ref JxlDecoderSetDesiredIntensityTarget,
*  - @ref JxlDecoderSetDecompressBoxes,
*  - @ref JxlDecoderSetKeepOrientation,
*  - @ref JxlDecoderSetUnpremultiplyAlpha,
*  - @ref JxlDecoderSetParallelRunner,
*  - @ref JxlDecoderSetRenderSpotcolors, and
*  - @ref JxlDecoderSubscribeEvents.
*
* @param dec decoder object
*/
JXL_EXPORT void JxlDecoderRewind(JxlDecoder* dec);

/** Makes the decoder skip the next `amount` frames. It still needs to process
* the input, but will not output the frame events. It can be more efficient
* when skipping frames, and even more so when using this after @ref
* JxlDecoderRewind. If the decoder is already processing a frame (could
* have emitted ::JXL_DEC_FRAME but not yet ::JXL_DEC_FULL_IMAGE), it
* starts skipping from the next frame. If the amount is larger than the amount
* of frames remaining in the image, all remaining frames are skipped. Calling
* this function multiple times adds the amount to skip to the already existing
* amount.
*
* A frame here is defined as a frame that without skipping emits events such
* as ::JXL_DEC_FRAME and ::JXL_DEC_FULL_IMAGE, frames that are internal
* to the file format but are not rendered as part of an animation, or are not
* the final still frame of a still image, are not counted.
*
* @param dec decoder object
* @param amount the amount of frames to skip
*/
JXL_EXPORT void JxlDecoderSkipFrames(JxlDecoder* dec, size_t amount);

/**
* Skips processing the current frame. Can be called after frame processing
* already started, signaled by a ::JXL_DEC_NEED_IMAGE_OUT_BUFFER event,
* but before the corresponding ::JXL_DEC_FULL_IMAGE event. The next signaled
* event will be another ::JXL_DEC_FRAME, or ::JXL_DEC_SUCCESS if there
* are no more frames. If pixel data is required from the already processed part
* of the frame, @ref JxlDecoderFlushImage must be called before this.
*
* @param dec decoder object
* @return ::JXL_DEC_SUCCESS if there is a frame to skip, and @ref
*     JXL_DEC_ERROR if the function was not called during frame processing.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderSkipCurrentFrame(JxlDecoder* dec);

/**
* Set the parallel runner for multithreading. May only be set before starting
* decoding.
*
* @param dec decoder object
* @param parallel_runner function pointer to runner for multithreading. It may
*     be NULL to use the default, single-threaded, runner. A multithreaded
*     runner should be set to reach fast performance.
* @param parallel_runner_opaque opaque pointer for parallel_runner.
* @return ::JXL_DEC_SUCCESS if the runner was set, ::JXL_DEC_ERROR
*     otherwise (the previous runner remains set).
*/
JXL_EXPORT JxlDecoderStatus
JxlDecoderSetParallelRunner(JxlDecoder* dec, JxlParallelRunner parallel_runner,
                           void* parallel_runner_opaque);

/**
* Returns a hint indicating how many more bytes the decoder is expected to
* need to make @ref JxlDecoderGetBasicInfo available after the next @ref
* JxlDecoderProcessInput call. This is a suggested large enough value for
* the amount of bytes to provide in the next @ref JxlDecoderSetInput call, but
* it is not guaranteed to be an upper bound nor a lower bound. This number does
* not include bytes that have already been released from the input. Can be used
* before the first @ref JxlDecoderProcessInput call, and is correct the first
* time in most cases. If not, @ref JxlDecoderSizeHintBasicInfo can be called
* again to get an updated hint.
*
* @param dec decoder object
* @return the size hint in bytes if the basic info is not yet fully decoded.
* @return 0 when the basic info is already available.
*/
JXL_EXPORT size_t JxlDecoderSizeHintBasicInfo(const JxlDecoder* dec);

/** Select for which informative events, i.e. ::JXL_DEC_BASIC_INFO, etc., the
* decoder should return with a status. It is not required to subscribe to any
* events, data can still be requested from the decoder as soon as it available.
* By default, the decoder is subscribed to no events (events_wanted == 0), and
* the decoder will then only return when it cannot continue because it needs
* more input data or more output buffer. This function may only be be called
* before using @ref JxlDecoderProcessInput.
*
* @param dec decoder object
* @param events_wanted bitfield of desired events.
* @return ::JXL_DEC_SUCCESS if no error, ::JXL_DEC_ERROR otherwise.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderSubscribeEvents(JxlDecoder* dec,
                                                     int events_wanted);

/** Enables or disables preserving of as-in-bitstream pixeldata
* orientation. Some images are encoded with an Orientation tag
* indicating that the decoder must perform a rotation and/or
* mirroring to the encoded image data.
*
*  - If skip_reorientation is ::JXL_FALSE (the default): the decoder
*    will apply the transformation from the orientation setting, hence
*    rendering the image according to its specified intent. When
*    producing a @ref JxlBasicInfo, the decoder will always set the
*    orientation field to JXL_ORIENT_IDENTITY (matching the returned
*    pixel data) and also align xsize and ysize so that they correspond
*    to the width and the height of the returned pixel data.
*  - If skip_reorientation is ::JXL_TRUE "JXL_TRUE": the decoder will skip
*    applying the transformation from the orientation setting, returning
*    the image in the as-in-bitstream pixeldata orientation.
*    This may be faster to decode since the decoder doesn't have to apply the
*    transformation, but can cause wrong display of the image if the
*    orientation tag is not correctly taken into account by the user.
*
* By default, this option is disabled, and the returned pixel data is
* re-oriented according to the image's Orientation setting.
*
* This function must be called at the beginning, before decoding is performed.
*
* @see JxlBasicInfo for the orientation field, and @ref JxlOrientation for the
* possible values.
*
* @param dec decoder object
* @param skip_reorientation JXL_TRUE to enable, JXL_FALSE to disable.
* @return ::JXL_DEC_SUCCESS if no error, ::JXL_DEC_ERROR otherwise.
*/
JXL_EXPORT JxlDecoderStatus
JxlDecoderSetKeepOrientation(JxlDecoder* dec, JXL_BOOL skip_reorientation);

/**
* Enables or disables preserving of associated alpha channels. If
* unpremul_alpha is set to ::JXL_FALSE then for associated alpha channel,
* the pixel data is returned with premultiplied colors. If it is set to @ref
* JXL_TRUE, The colors will be unpremultiplied based on the alpha channel. This
* function has no effect if the image does not have an associated alpha
* channel.
*
* By default, this option is disabled, and the returned pixel data "as is".
*
* This function must be called at the beginning, before decoding is performed.
*
* @param dec decoder object
* @param unpremul_alpha JXL_TRUE to enable, JXL_FALSE to disable.
* @return ::JXL_DEC_SUCCESS if no error, ::JXL_DEC_ERROR otherwise.
*/
JXL_EXPORT JxlDecoderStatus
JxlDecoderSetUnpremultiplyAlpha(JxlDecoder* dec, JXL_BOOL unpremul_alpha);

/** Enables or disables rendering spot colors. By default, spot colors
* are rendered, which is OK for viewing the decoded image. If render_spotcolors
* is ::JXL_FALSE, then spot colors are not rendered, and have to be
* retrieved separately using @ref JxlDecoderSetExtraChannelBuffer. This is
* useful for e.g. printing applications.
*
* @param dec decoder object
* @param render_spotcolors JXL_TRUE to enable (default), JXL_FALSE to disable.
* @return ::JXL_DEC_SUCCESS if no error, ::JXL_DEC_ERROR otherwise.
*/
JXL_EXPORT JxlDecoderStatus
JxlDecoderSetRenderSpotcolors(JxlDecoder* dec, JXL_BOOL render_spotcolors);

/** Enables or disables coalescing of zero-duration frames. By default, frames
* are returned with coalescing enabled, i.e. all frames have the image
* dimensions, and are blended if needed. When coalescing is disabled, frames
* can have arbitrary dimensions, a non-zero crop offset, and blending is not
* performed. For display, coalescing is recommended. For loading a multi-layer
* still image as separate layers (as opposed to the merged image), coalescing
* has to be disabled.
*
* @param dec decoder object
* @param coalescing JXL_TRUE to enable coalescing (default), JXL_FALSE to
*     disable it.
* @return ::JXL_DEC_SUCCESS if no error, ::JXL_DEC_ERROR otherwise.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderSetCoalescing(JxlDecoder* dec,
                                                   JXL_BOOL coalescing);

/**
* Decodes JPEG XL file using the available bytes. Requires input has been
* set with @ref JxlDecoderSetInput. After @ref JxlDecoderProcessInput, input
* can optionally be released with @ref JxlDecoderReleaseInput and then set
* again to next bytes in the stream. @ref JxlDecoderReleaseInput returns how
* many bytes are not yet processed, before a next call to @ref
* JxlDecoderProcessInput all unprocessed bytes must be provided again (the
* address need not match, but the contents must), and more bytes may be
* concatenated after the unprocessed bytes.
*
* The returned status indicates whether the decoder needs more input bytes, or
* more output buffer for a certain type of output data. No matter what the
* returned status is (other than ::JXL_DEC_ERROR), new information, such
* as @ref JxlDecoderGetBasicInfo, may have become available after this call.
* When the return value is not ::JXL_DEC_ERROR or ::JXL_DEC_SUCCESS, the
* decoding requires more @ref JxlDecoderProcessInput calls to continue.
*
* @param dec decoder object
* @return ::JXL_DEC_SUCCESS when decoding finished and all events handled.
*     If you still have more unprocessed input data anyway, then you can still
*     continue by using @ref JxlDecoderSetInput and calling @ref
*     JxlDecoderProcessInput again, similar to handling @ref
*     JXL_DEC_NEED_MORE_INPUT. ::JXL_DEC_SUCCESS can occur instead of @ref
*     JXL_DEC_NEED_MORE_INPUT when, for example, the input data ended right at
*     the boundary of a box of the container format, all essential codestream
*     boxes were already decoded, but extra metadata boxes are still present in
*     the next data. @ref JxlDecoderProcessInput cannot return success if all
*     codestream boxes have not been seen yet.
* @return ::JXL_DEC_ERROR when decoding failed, e.g. invalid codestream.
*     TODO(lode): document the input data mechanism
* @return ::JXL_DEC_NEED_MORE_INPUT when more input data is necessary.
* @return ::JXL_DEC_BASIC_INFO when basic info such as image dimensions is
*     available and this informative event is subscribed to.
* @return ::JXL_DEC_COLOR_ENCODING when color profile information is
*     available and this informative event is subscribed to.
* @return ::JXL_DEC_PREVIEW_IMAGE when preview pixel information is
*     available and output in the preview buffer.
* @return ::JXL_DEC_FULL_IMAGE when all pixel information at highest detail
*     is available and has been output in the pixel buffer.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderProcessInput(JxlDecoder* dec);

/**
* Sets input data for @ref JxlDecoderProcessInput. The data is owned by the
* caller and may be used by the decoder until @ref JxlDecoderReleaseInput is
* called or the decoder is destroyed or reset so must be kept alive until then.
* Cannot be called if @ref JxlDecoderSetInput was already called and @ref
* JxlDecoderReleaseInput was not yet called, and cannot be called after @ref
* JxlDecoderCloseInput indicating the end of input was called.
*
* @param dec decoder object
* @param data pointer to next bytes to read from
* @param size amount of bytes available starting from data
* @return ::JXL_DEC_ERROR if input was already set without releasing or @ref
*     JxlDecoderCloseInput was already called, ::JXL_DEC_SUCCESS otherwise.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderSetInput(JxlDecoder* dec,
                                              const uint8_t* data,
                                              size_t size);

/**
* Releases input which was provided with @ref JxlDecoderSetInput. Between @ref
* JxlDecoderProcessInput and @ref JxlDecoderReleaseInput, the user may not
* alter the data in the buffer. Calling @ref JxlDecoderReleaseInput is required
* whenever any input is already set and new input needs to be added with @ref
* JxlDecoderSetInput, but is not required before @ref JxlDecoderDestroy or @ref
* JxlDecoderReset. Calling @ref JxlDecoderReleaseInput when no input is set is
* not an error and returns `0`.
*
* @param dec decoder object
* @return The amount of bytes the decoder has not yet processed that are still
*     remaining in the data set by @ref JxlDecoderSetInput, or `0` if no input
* is set or @ref JxlDecoderReleaseInput was already called. For a next call to
* @ref JxlDecoderProcessInput, the buffer must start with these unprocessed
* bytes. From this value it is possible to infer the position of certain JPEG
* XL codestream elements (e.g. end of headers, frame start/end). See the
* documentation of individual values of @ref JxlDecoderStatus for more
* information.
*/
JXL_EXPORT size_t JxlDecoderReleaseInput(JxlDecoder* dec);

/**
* Marks the input as finished, indicates that no more @ref JxlDecoderSetInput
* will be called. This function allows the decoder to determine correctly if it
* should return success, need more input or error in certain cases. For
* backwards compatibility with a previous version of the API, using this
* function is optional when not using the ::JXL_DEC_BOX event (the decoder
* is able to determine the end of the image frames without marking the end),
* but using this function is required when using ::JXL_DEC_BOX for getting
* metadata box contents. This function does not replace @ref
* JxlDecoderReleaseInput, that function should still be called if its return
* value is needed.
*
* @ref JxlDecoderCloseInput should be called as soon as all known input bytes
* are set (e.g. at the beginning when not streaming but setting all input
* at once), before the final @ref JxlDecoderProcessInput calls.
*
* @param dec decoder object
*/
JXL_EXPORT void JxlDecoderCloseInput(JxlDecoder* dec);

/**
* Outputs the basic image information, such as image dimensions, bit depth and
* all other JxlBasicInfo fields, if available.
*
* @param dec decoder object
* @param info struct to copy the information into, or NULL to only check
*     whether the information is available through the return value.
* @return ::JXL_DEC_SUCCESS if the value is available, @ref
*     JXL_DEC_NEED_MORE_INPUT if not yet available, ::JXL_DEC_ERROR
*     in case of other error conditions.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderGetBasicInfo(const JxlDecoder* dec,
                                                  JxlBasicInfo* info);

/**
* Outputs information for extra channel at the given index. The index must be
* smaller than num_extra_channels in the associated @ref JxlBasicInfo.
*
* @param dec decoder object
* @param index index of the extra channel to query.
* @param info struct to copy the information into, or NULL to only check
*     whether the information is available through the return value.
* @return ::JXL_DEC_SUCCESS if the value is available, @ref
*     JXL_DEC_NEED_MORE_INPUT if not yet available, ::JXL_DEC_ERROR
*     in case of other error conditions.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderGetExtraChannelInfo(
   const JxlDecoder* dec, size_t index, JxlExtraChannelInfo* info);

/**
* Outputs name for extra channel at the given index in UTF-8. The index must be
* smaller than `num_extra_channels` in the associated @ref JxlBasicInfo. The
* buffer for name must have at least `name_length + 1` bytes allocated, gotten
* from the associated @ref JxlExtraChannelInfo.
*
* @param dec decoder object
* @param index index of the extra channel to query.
* @param name buffer to copy the name into
* @param size size of the name buffer in bytes
* @return ::JXL_DEC_SUCCESS if the value is available, @ref
*     JXL_DEC_NEED_MORE_INPUT if not yet available, ::JXL_DEC_ERROR
*     in case of other error conditions.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderGetExtraChannelName(const JxlDecoder* dec,
                                                         size_t index,
                                                         char* name,
                                                         size_t size);

/** Defines which color profile to get: the profile from the codestream
* metadata header, which represents the color profile of the original image,
* or the color profile from the pixel data produced by the decoder. Both are
* the same if the JxlBasicInfo has uses_original_profile set.
*/
typedef enum {
 /** Get the color profile of the original image from the metadata.
  */
 JXL_COLOR_PROFILE_TARGET_ORIGINAL = 0,

 /** Get the color profile of the pixel data the decoder outputs. */
 JXL_COLOR_PROFILE_TARGET_DATA = 1,
} JxlColorProfileTarget;

/**
* Outputs the color profile as JPEG XL encoded structured data, if available.
* This is an alternative to an ICC Profile, which can represent a more limited
* amount of color spaces, but represents them exactly through enum values.
*
* It is often possible to use @ref JxlDecoderGetColorAsICCProfile as an
* alternative anyway. The following scenarios are possible:
*  - The JPEG XL image has an attached ICC Profile, in that case, the encoded
*    structured data is not available and this function will return an error
*    status. @ref JxlDecoderGetColorAsICCProfile should be called instead.
*  - The JPEG XL image has an encoded structured color profile, and it
*    represents an RGB or grayscale color space. This function will return it.
*    You can still use @ref JxlDecoderGetColorAsICCProfile as well as an
*    alternative if desired, though depending on which RGB color space is
*    represented, the ICC profile may be a close approximation. It is also not
*    always feasible to deduce from an ICC profile which named color space it
*    exactly represents, if any, as it can represent any arbitrary space.
*    HDR color spaces such as those using PQ and HLG are also potentially
*    problematic, in that: while ICC profiles can encode a transfer function
*    that happens to approximate those of PQ and HLG (HLG for only one given
*    system gamma at a time, and necessitating a 3D LUT if gamma is to be
*    different from `1`), they cannot (before ICCv4.4) semantically signal that
*    this is the color space that they represent. Therefore, they will
*    typically not actually be interpreted as representing an HDR color space.
*    This is especially detrimental to PQ which will then be interpreted as if
*    the maximum signal value represented SDR white instead of 10000 cd/m^2,
*    meaning that the image will be displayed two orders of magnitude (5-7 EV)
*    too dim.
*  - The JPEG XL image has an encoded structured color profile, and it
*    indicates an unknown or xyb color space. In that case, @ref
*    JxlDecoderGetColorAsICCProfile is not available.
*
* When rendering an image on a system where ICC-based color management is used,
* @ref JxlDecoderGetColorAsICCProfile should generally be used first as it will
* return a ready-to-use profile (with the aforementioned caveat about HDR).
* When knowledge about the nominal color space is desired if available, @ref
* JxlDecoderGetColorAsEncodedProfile should be used first.
*
* @param dec decoder object
* @param target whether to get the original color profile from the metadata
*     or the color profile of the decoded pixels.
* @param color_encoding struct to copy the information into, or NULL to only
*     check whether the information is available through the return value.
* @return ::JXL_DEC_SUCCESS if the data is available and returned, @ref
*     JXL_DEC_NEED_MORE_INPUT if not yet available, ::JXL_DEC_ERROR in
*     case the encoded structured color profile does not exist in the
*     codestream.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderGetColorAsEncodedProfile(
   const JxlDecoder* dec, JxlColorProfileTarget target,
   JxlColorEncoding* color_encoding);

/**
* Outputs the size in bytes of the ICC profile returned by @ref
* JxlDecoderGetColorAsICCProfile, if available, or indicates there is none
* available. In most cases, the image will have an ICC profile available, but
* if it does not, @ref JxlDecoderGetColorAsEncodedProfile must be used instead.
*
* @see JxlDecoderGetColorAsEncodedProfile for more information. The ICC
* profile is either the exact ICC profile attached to the codestream metadata,
* or a close approximation generated from JPEG XL encoded structured data,
* depending of what is encoded in the codestream.
*
* @param dec decoder object
* @param target whether to get the original color profile from the metadata
*     or the color profile of the decoded pixels.
* @param size variable to output the size into, or NULL to only check the
*     return status.
* @return ::JXL_DEC_SUCCESS if the ICC profile is available, @ref
*     JXL_DEC_NEED_MORE_INPUT if the decoder has not yet received enough
*     input data to determine whether an ICC profile is available or what its
*     size is, ::JXL_DEC_ERROR in case the ICC profile is not available and
*     cannot be generated.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderGetICCProfileSize(
   const JxlDecoder* dec, JxlColorProfileTarget target, size_t* size);

/**
* Outputs ICC profile if available. The profile is only available if @ref
* JxlDecoderGetICCProfileSize returns success. The output buffer must have
* at least as many bytes as given by @ref JxlDecoderGetICCProfileSize.
*
* @param dec decoder object
* @param target whether to get the original color profile from the metadata
*     or the color profile of the decoded pixels.
* @param icc_profile buffer to copy the ICC profile into
* @param size size of the icc_profile buffer in bytes
* @return ::JXL_DEC_SUCCESS if the profile was successfully returned,
*     ::JXL_DEC_NEED_MORE_INPUT if not yet available, @ref
*     JXL_DEC_ERROR if the profile doesn't exist or the output size is not
*     large enough.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderGetColorAsICCProfile(
   const JxlDecoder* dec, JxlColorProfileTarget target, uint8_t* icc_profile,
   size_t size);

/** Sets the desired output color profile of the decoded image by calling
* @ref JxlDecoderSetOutputColorProfile, passing on @c color_encoding and
* setting @c icc_data to NULL. See @ref JxlDecoderSetOutputColorProfile for
* details.
*
* @param dec decoder object
* @param color_encoding the default color encoding to set
* @return ::JXL_DEC_SUCCESS if the preference was set successfully, @ref
*     JXL_DEC_ERROR otherwise.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderSetPreferredColorProfile(
   JxlDecoder* dec, const JxlColorEncoding* color_encoding);

/** Requests that the decoder perform tone mapping to the peak display luminance
* passed as @c desired_intensity_target, if appropriate.
* @note This is provided for convenience and the exact tone mapping that is
* performed is not meant to be considered authoritative in any way. It may
* change from version to version.
* @param dec decoder object
* @param desired_intensity_target the intended target peak luminance
* @return ::JXL_DEC_SUCCESS if the preference was set successfully, @ref
* JXL_DEC_ERROR otherwise.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderSetDesiredIntensityTarget(
   JxlDecoder* dec, float desired_intensity_target);

/**
* Sets the desired output color profile of the decoded image either from a
* color encoding or an ICC profile. Valid calls of this function have either @c
* color_encoding or @c icc_data set to NULL and @c icc_size must be `0` if and
* only if @c icc_data is NULL.
*
* Depending on whether a color management system (CMS) has been set the
* behavior is as follows:
*
* If a color management system (CMS) has been set with @ref JxlDecoderSetCms,
* and the CMS supports output to the desired color encoding or ICC profile,
* then it will provide the output in that color encoding or ICC profile. If the
* desired color encoding or the ICC is not supported, then an error will be
* returned.
*
* If no CMS has been set with @ref JxlDecoderSetCms, there are two cases:
*
* (1) Calling this function with a color encoding will convert XYB images to
* the desired color encoding. In this case, if the requested color encoding has
* a narrower gamut, or the white points differ, then the resulting image can
* have significant color distortion. Non-XYB images will not be converted to
* the desired color space.
*
* (2) Calling this function with an ICC profile will result in an error.
*
* If called with an ICC profile (after a call to @ref JxlDecoderSetCms), the
* ICC profile has to be a valid RGB or grayscale color profile.
*
* Can only be set after the ::JXL_DEC_COLOR_ENCODING event occurred and
* before any other event occurred, and should be used before getting
* ::JXL_COLOR_PROFILE_TARGET_DATA.
*
* This function must not be called before @ref JxlDecoderSetCms.
*
* @param dec decoder object
* @param color_encoding the output color encoding
* @param icc_data bytes of the icc profile
* @param icc_size size of the icc profile in bytes
* @return ::JXL_DEC_SUCCESS if the color profile was set successfully, @ref
*     JXL_DEC_ERROR otherwise.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderSetOutputColorProfile(
   JxlDecoder* dec, const JxlColorEncoding* color_encoding,
   const uint8_t* icc_data, size_t icc_size);

/**
* Sets the color management system (CMS) that will be used for color
* conversion (if applicable) during decoding. May only be set before starting
* decoding and must not be called after @ref JxlDecoderSetOutputColorProfile.
*
* See @ref JxlDecoderSetOutputColorProfile for how color conversions are done
* depending on whether or not a CMS has been set with @ref JxlDecoderSetCms.
*
* @param dec decoder object.
* @param cms structure representing a CMS implementation. See @ref
* JxlCmsInterface for more details.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderSetCms(JxlDecoder* dec,
                                            JxlCmsInterface cms);
// TODO(firsching): add a function JxlDecoderSetDefaultCms() for setting a
// default in case libjxl is build with a CMS.

/**
* Returns the minimum size in bytes of the preview image output pixel buffer
* for the given format. This is the buffer for @ref
* JxlDecoderSetPreviewOutBuffer. Requires the preview header information is
* available in the decoder.
*
* @param dec decoder object
* @param format format of pixels
* @param size output value, buffer size in bytes
* @return ::JXL_DEC_SUCCESS on success, ::JXL_DEC_ERROR on error, such as
*     information not available yet.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderPreviewOutBufferSize(
   const JxlDecoder* dec, const JxlPixelFormat* format, size_t* size);

/**
* Sets the buffer to write the low-resolution preview image
* to. The size of the buffer must be at least as large as given by @ref
* JxlDecoderPreviewOutBufferSize. The buffer follows the format described
* by @ref JxlPixelFormat. The preview image dimensions are given by the
* @ref JxlPreviewHeader. The buffer is owned by the caller.
*
* @param dec decoder object
* @param format format of pixels. Object owned by user and its contents are
*     copied internally.
* @param buffer buffer type to output the pixel data to
* @param size size of buffer in bytes
* @return ::JXL_DEC_SUCCESS on success, ::JXL_DEC_ERROR on error, such as
*     size too small.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderSetPreviewOutBuffer(
   JxlDecoder* dec, const JxlPixelFormat* format, void* buffer, size_t size);

/**
* Outputs the information from the frame, such as duration when have_animation.
* This function can be called when ::JXL_DEC_FRAME occurred for the current
* frame, even when have_animation in the JxlBasicInfo is JXL_FALSE.
*
* @param dec decoder object
* @param header struct to copy the information into, or NULL to only check
*     whether the information is available through the return value.
* @return ::JXL_DEC_SUCCESS if the value is available, @ref
*     JXL_DEC_NEED_MORE_INPUT if not yet available, ::JXL_DEC_ERROR in
*     case of other error conditions.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderGetFrameHeader(const JxlDecoder* dec,
                                                    JxlFrameHeader* header);

/**
* Outputs name for the current frame. The buffer for name must have at least
* `name_length + 1` bytes allocated, gotten from the associated JxlFrameHeader.
*
* @param dec decoder object
* @param name buffer to copy the name into
* @param size size of the name buffer in bytes, including zero termination
*    character, so this must be at least @ref JxlFrameHeader.name_length + 1.
* @return ::JXL_DEC_SUCCESS if the value is available, @ref
*     JXL_DEC_NEED_MORE_INPUT if not yet available, ::JXL_DEC_ERROR in
*     case of other error conditions.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderGetFrameName(const JxlDecoder* dec,
                                                  char* name, size_t size);

/**
* Outputs the blend information for the current frame for a specific extra
* channel. This function can be called once the ::JXL_DEC_FRAME event occurred
* for the current frame, even if the `have_animation` field in the @ref
* JxlBasicInfo is @ref JXL_FALSE. This information is only useful if coalescing
* is disabled; otherwise the decoder will have performed blending already.
*
* @param dec decoder object
* @param index the index of the extra channel
* @param blend_info struct to copy the information into
* @return ::JXL_DEC_SUCCESS on success, ::JXL_DEC_ERROR on error
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderGetExtraChannelBlendInfo(
   const JxlDecoder* dec, size_t index, JxlBlendInfo* blend_info);

/**
* Returns the minimum size in bytes of the image output pixel buffer for the
* given format. This is the buffer for @ref JxlDecoderSetImageOutBuffer.
* Requires that the basic image information is available in the decoder in the
* case of coalescing enabled (default). In case coalescing is disabled, this
* can only be called after the ::JXL_DEC_FRAME event occurs. In that case,
* it will return the size required to store the possibly cropped frame (which
* can be larger or smaller than the image dimensions).
*
* @param dec decoder object
* @param format format of the pixels.
* @param size output value, buffer size in bytes
* @return ::JXL_DEC_SUCCESS on success, ::JXL_DEC_ERROR on error, such as
*     information not available yet.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderImageOutBufferSize(
   const JxlDecoder* dec, const JxlPixelFormat* format, size_t* size);

/**
* Sets the buffer to write the full resolution image to. This can be set when
* the ::JXL_DEC_FRAME event occurs, must be set when the @ref
* JXL_DEC_NEED_IMAGE_OUT_BUFFER event occurs, and applies only for the
* current frame. The size of the buffer must be at least as large as given
* by @ref JxlDecoderImageOutBufferSize. The buffer follows the format described
* by @ref JxlPixelFormat. The buffer is owned by the caller.
*
* @param dec decoder object
* @param format format of the pixels. Object owned by user and its contents
*     are copied internally.
* @param buffer buffer type to output the pixel data to
* @param size size of buffer in bytes
* @return ::JXL_DEC_SUCCESS on success, ::JXL_DEC_ERROR on error, such as
*     size too small.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderSetImageOutBuffer(
   JxlDecoder* dec, const JxlPixelFormat* format, void* buffer, size_t size);

/**
* Function type for @ref JxlDecoderSetImageOutCallback.
*
* The callback may be called simultaneously by different threads when using a
* threaded parallel runner, on different pixels.
*
* @param opaque optional user data, as given to @ref
*     JxlDecoderSetImageOutCallback.
* @param x horizontal position of leftmost pixel of the pixel data.
* @param y vertical position of the pixel data.
* @param num_pixels amount of pixels included in the pixel data, horizontally.
*     This is not the same as xsize of the full image, it may be smaller.
* @param pixels pixel data as a horizontal stripe, in the format passed to @ref
*     JxlDecoderSetImageOutCallback. The memory is not owned by the user, and
*     is only valid during the time the callback is running.
*/
typedef void (*JxlImageOutCallback)(void* opaque, size_t x, size_t y,
                                   size_t num_pixels, const void* pixels);

/**
* Initialization callback for @ref JxlDecoderSetMultithreadedImageOutCallback.
*
* @param init_opaque optional user data, as given to @ref
*     JxlDecoderSetMultithreadedImageOutCallback.
* @param num_threads maximum number of threads that will call the @c run
*     callback concurrently.
* @param num_pixels_per_thread maximum number of pixels that will be passed in
*     one call to @c run.
* @return a pointer to data that will be passed to the @c run callback, or
*     @c NULL if initialization failed.
*/
typedef void* (*JxlImageOutInitCallback)(void* init_opaque, size_t num_threads,
                                        size_t num_pixels_per_thread);

/**
* Worker callback for @ref JxlDecoderSetMultithreadedImageOutCallback.
*
* @param run_opaque user data returned by the @c init callback.
* @param thread_id number in `[0, num_threads)` identifying the thread of the
*     current invocation of the callback.
* @param x horizontal position of the first (leftmost) pixel of the pixel data.
* @param y vertical position of the pixel data.
* @param num_pixels number of pixels in the pixel data. May be less than the
*     full @c xsize of the image, and will be at most equal to the @c
*     num_pixels_per_thread that was passed to @c init.
* @param pixels pixel data as a horizontal stripe, in the format passed to @ref
*     JxlDecoderSetMultithreadedImageOutCallback. The data pointed to
*     remains owned by the caller and is only guaranteed to outlive the current
*     callback invocation.
*/
typedef void (*JxlImageOutRunCallback)(void* run_opaque, size_t thread_id,
                                      size_t x, size_t y, size_t num_pixels,
                                      const void* pixels);

/**
* Destruction callback for @ref JxlDecoderSetMultithreadedImageOutCallback,
* called after all invocations of the @c run callback to perform any
* appropriate clean-up of the @c run_opaque data returned by @c init.
*
* @param run_opaque user data returned by the @c init callback.
*/
typedef void (*JxlImageOutDestroyCallback)(void* run_opaque);

/**
* Sets pixel output callback. This is an alternative to @ref
* JxlDecoderSetImageOutBuffer. This can be set when the ::JXL_DEC_FRAME
* event occurs, must be set when the ::JXL_DEC_NEED_IMAGE_OUT_BUFFER event
* occurs, and applies only for the current frame. Only one of @ref
* JxlDecoderSetImageOutBuffer or @ref JxlDecoderSetImageOutCallback may be used
* for the same frame, not both at the same time.
*
* The callback will be called multiple times, to receive the image
* data in small chunks. The callback receives a horizontal stripe of pixel
* data, `1` pixel high, xsize pixels wide, called a scanline. The xsize here is
* not the same as the full image width, the scanline may be a partial section,
* and xsize may differ between calls. The user can then process and/or copy the
* partial scanline to an image buffer. The callback may be called
* simultaneously by different threads when using a threaded parallel runner, on
* different pixels.
*
* If @ref JxlDecoderFlushImage is not used, then each pixel will be visited
* exactly once by the different callback calls, during processing with one or
* more @ref JxlDecoderProcessInput calls. These pixels are decoded to full
* detail, they are not part of a lower resolution or lower quality progressive
* pass, but the final pass.
*
* If @ref JxlDecoderFlushImage is used, then in addition each pixel will be
* visited zero or one times during the blocking @ref JxlDecoderFlushImage call.
* Pixels visited as a result of @ref JxlDecoderFlushImage may represent a lower
* resolution or lower quality intermediate progressive pass of the image. Any
* visited pixel will be of a quality at least as good or better than previous
* visits of this pixel. A pixel may be visited zero times if it cannot be
* decoded yet or if it was already decoded to full precision (this behavior is
* not guaranteed).
*
* @param dec decoder object
* @param format format of the pixels. Object owned by user; its contents are
*     copied internally.
* @param callback the callback function receiving partial scanlines of pixel
*     data.
* @param opaque optional user data, which will be passed on to the callback,
*     may be NULL.
* @return ::JXL_DEC_SUCCESS on success, ::JXL_DEC_ERROR on error, such
*     as @ref JxlDecoderSetImageOutBuffer already set.
*/
JXL_EXPORT JxlDecoderStatus
JxlDecoderSetImageOutCallback(JxlDecoder* dec, const JxlPixelFormat* format,
                             JxlImageOutCallback callback, void* opaque);

/** Similar to @ref JxlDecoderSetImageOutCallback except that the callback is
* allowed an initialization phase during which it is informed of how many
* threads will call it concurrently, and those calls are further informed of
* which thread they are occurring in.
*
* @param dec decoder object
* @param format format of the pixels. Object owned by user; its contents are
*     copied internally.
* @param init_callback initialization callback.
* @param run_callback the callback function receiving partial scanlines of
*     pixel data.
* @param destroy_callback clean-up callback invoked after all calls to @c
*     run_callback. May be NULL if no clean-up is necessary.
* @param init_opaque optional user data passed to @c init_callback, may be NULL
*     (unlike the return value from @c init_callback which may only be NULL if
*     initialization failed).
* @return ::JXL_DEC_SUCCESS on success, ::JXL_DEC_ERROR on error, such
*     as @ref JxlDecoderSetImageOutBuffer having already been called.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderSetMultithreadedImageOutCallback(
   JxlDecoder* dec, const JxlPixelFormat* format,
   JxlImageOutInitCallback init_callback, JxlImageOutRunCallback run_callback,
   JxlImageOutDestroyCallback destroy_callback, void* init_opaque);

/**
* Returns the minimum size in bytes of an extra channel pixel buffer for the
* given format. This is the buffer for @ref JxlDecoderSetExtraChannelBuffer.
* Requires the basic image information is available in the decoder.
*
* @param dec decoder object
* @param format format of the pixels. The num_channels value is ignored and is
*     always treated to be `1`.
* @param size output value, buffer size in bytes
* @param index which extra channel to get, matching the index used in @ref
*     JxlDecoderGetExtraChannelInfo. Must be smaller than num_extra_channels in
*     the associated @ref JxlBasicInfo.
* @return ::JXL_DEC_SUCCESS on success, ::JXL_DEC_ERROR on error, such as
*     information not available yet or invalid index.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderExtraChannelBufferSize(
   const JxlDecoder* dec, const JxlPixelFormat* format, size_t* size,
   uint32_t index);

/**
* Sets the buffer to write an extra channel to. This can be set when
* the ::JXL_DEC_FRAME or ::JXL_DEC_NEED_IMAGE_OUT_BUFFER event occurs,
* and applies only for the current frame. The size of the buffer must be at
* least as large as given by @ref JxlDecoderExtraChannelBufferSize. The buffer
* follows the format described by @ref JxlPixelFormat, but where num_channels
* is `1`. The buffer is owned by the caller. The amount of extra channels is
* given by the num_extra_channels field in the associated @ref JxlBasicInfo,
* and the information of individual extra channels can be queried with @ref
* JxlDecoderGetExtraChannelInfo. To get multiple extra channels, this function
* must be called multiple times, once for each wanted index. Not all images
* have extra channels. The alpha channel is an extra channel and can be gotten
* as part of the color channels when using an RGBA pixel buffer with @ref
* JxlDecoderSetImageOutBuffer, but additionally also can be gotten
* separately as extra channel. The color channels themselves cannot be gotten
* this way.
*
*
* @param dec decoder object
* @param format format of the pixels. Object owned by user and its contents
*     are copied internally. The num_channels value is ignored and is always
*     treated to be `1`.
* @param buffer buffer type to output the pixel data to
* @param size size of buffer in bytes
* @param index which extra channel to get, matching the index used in @ref
*     JxlDecoderGetExtraChannelInfo. Must be smaller than num_extra_channels in
*     the associated @ref JxlBasicInfo.
* @return ::JXL_DEC_SUCCESS on success, ::JXL_DEC_ERROR on error, such as
*     size too small or invalid index.
*/
JXL_EXPORT JxlDecoderStatus
JxlDecoderSetExtraChannelBuffer(JxlDecoder* dec, const JxlPixelFormat* format,
                               void* buffer, size_t size, uint32_t index);

/**
* Sets output buffer for reconstructed JPEG codestream.
*
* The data is owned by the caller and may be used by the decoder until @ref
* JxlDecoderReleaseJPEGBuffer is called or the decoder is destroyed or
* reset so must be kept alive until then.
*
* If a JPEG buffer was set before and released with @ref
* JxlDecoderReleaseJPEGBuffer, bytes that the decoder has already output
* should not be included, only the remaining bytes output must be set.
*
* @param dec decoder object
* @param data pointer to next bytes to write to
* @param size amount of bytes available starting from data
* @return ::JXL_DEC_ERROR if output buffer was already set and @ref
*     JxlDecoderReleaseJPEGBuffer was not called on it, ::JXL_DEC_SUCCESS
*     otherwise
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderSetJPEGBuffer(JxlDecoder* dec,
                                                   uint8_t* data, size_t size);

/**
* Releases buffer which was provided with @ref JxlDecoderSetJPEGBuffer.
*
* Calling @ref JxlDecoderReleaseJPEGBuffer is required whenever
* a buffer is already set and a new buffer needs to be added with @ref
* JxlDecoderSetJPEGBuffer, but is not required before @ref
* JxlDecoderDestroy or @ref JxlDecoderReset.
*
* Calling @ref JxlDecoderReleaseJPEGBuffer when no buffer is set is
* not an error and returns `0`.
*
* @param dec decoder object
* @return the amount of bytes the decoder has not yet written to of the data
*     set by @ref JxlDecoderSetJPEGBuffer, or `0` if no buffer is set or @ref
*     JxlDecoderReleaseJPEGBuffer was already called.
*/
JXL_EXPORT size_t JxlDecoderReleaseJPEGBuffer(JxlDecoder* dec);

/**
* Sets output buffer for box output codestream.
*
* The data is owned by the caller and may be used by the decoder until @ref
* JxlDecoderReleaseBoxBuffer is called or the decoder is destroyed or
* reset so must be kept alive until then.
*
* If for the current box a box buffer was set before and released with @ref
* JxlDecoderReleaseBoxBuffer, bytes that the decoder has already output
* should not be included, only the remaining bytes output must be set.
*
* The @ref JxlDecoderReleaseBoxBuffer must be used at the next ::JXL_DEC_BOX
* event or final ::JXL_DEC_SUCCESS event to compute the size of the output
* box bytes.
*
* @param dec decoder object
* @param data pointer to next bytes to write to
* @param size amount of bytes available starting from data
* @return ::JXL_DEC_ERROR if output buffer was already set and @ref
*     JxlDecoderReleaseBoxBuffer was not called on it, ::JXL_DEC_SUCCESS
*     otherwise
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderSetBoxBuffer(JxlDecoder* dec,
                                                  uint8_t* data, size_t size);

/**
* Releases buffer which was provided with @ref JxlDecoderSetBoxBuffer.
*
* Calling @ref JxlDecoderReleaseBoxBuffer is required whenever
* a buffer is already set and a new buffer needs to be added with @ref
* JxlDecoderSetBoxBuffer, but is not required before @ref
* JxlDecoderDestroy or @ref JxlDecoderReset.
*
* Calling @ref JxlDecoderReleaseBoxBuffer when no buffer is set is
* not an error and returns `0`.
*
* @param dec decoder object
* @return the amount of bytes the decoder has not yet written to of the data
*     set by @ref JxlDecoderSetBoxBuffer, or `0` if no buffer is set or @ref
*     JxlDecoderReleaseBoxBuffer was already called.
*/
JXL_EXPORT size_t JxlDecoderReleaseBoxBuffer(JxlDecoder* dec);

/**
* Configures whether to get boxes in raw mode or in decompressed mode. In raw
* mode, boxes are output as their bytes appear in the container file, which may
* be decompressed, or compressed if their type is "brob". In decompressed mode,
* "brob" boxes are decompressed with Brotli before outputting them. The size of
* the decompressed stream is not known before the decompression has already
* finished.
*
* The default mode is raw. This setting can only be changed before decoding, or
* directly after a ::JXL_DEC_BOX event, and is remembered until the decoder
* is reset or destroyed.
*
* Enabling decompressed mode requires Brotli support from the library.
*
* @param dec decoder object
* @param decompress ::JXL_TRUE to transparently decompress, ::JXL_FALSE
* to get boxes in raw mode.
* @return ::JXL_DEC_ERROR if decompressed mode is set and Brotli is not
*     available, ::JXL_DEC_SUCCESS otherwise.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderSetDecompressBoxes(JxlDecoder* dec,
                                                        JXL_BOOL decompress);

/**
* Outputs the type of the current box, after a ::JXL_DEC_BOX event occurred,
* as `4` characters without null termination character. In case of a compressed
* "brob" box, this will return "brob" if the decompressed argument is
* JXL_FALSE, or the underlying box type if the decompressed argument is
* JXL_TRUE.
*
* The following box types are currently described in ISO/IEC 18181-2:
*  - "Exif": a box with EXIF metadata.  Starts with a 4-byte tiff header offset
*    (big-endian uint32) that indicates the start of the actual EXIF data
*    (which starts with a tiff header). Usually the offset will be zero and the
*    EXIF data starts immediately after the offset field. The Exif orientation
*    should be ignored by applications; the JPEG XL codestream orientation
*    takes precedence and libjxl will by default apply the correct orientation
*    automatically (see @ref JxlDecoderSetKeepOrientation).
*  - "xml ": a box with XML data, in particular XMP metadata.
*  - "jumb": a JUMBF superbox (JPEG Universal Metadata Box Format, ISO/IEC
*    19566-5).
*  - "JXL ": mandatory signature box, must come first, `12` bytes long
* including the box header
*  - "ftyp": a second mandatory signature box, must come second, `20` bytes
* long including the box header
*  - "jxll": a JXL level box. This indicates if the codestream is level `5` or
*    level `10` compatible. If not present, it is level `5`. Level `10` allows
* more features such as very high image resolution and bit-depths above `16`
* bits per channel. Added automatically by the encoder when
*    @ref JxlEncoderSetCodestreamLevel is used
*  - "jxlc": a box with the image codestream, in case the codestream is not
*    split across multiple boxes. The codestream contains the JPEG XL image
*    itself, including the basic info such as image dimensions, ICC color
*    profile, and all the pixel data of all the image frames.
*  - "jxlp": a codestream box in case it is split across multiple boxes.
*    The contents are the same as in case of a jxlc box, when concatenated.
*  - "brob": a Brotli-compressed box, which otherwise represents an existing
*    type of box such as Exif or "xml ". When @ref JxlDecoderSetDecompressBoxes
*    is set to JXL_TRUE, these boxes will be transparently decompressed by the
*    decoder.
*  - "jxli": frame index box, can list the keyframes in case of a JPEG XL
*    animation allowing the decoder to jump to individual frames more
*    efficiently.
*  - "jbrd": JPEG reconstruction box, contains the information required to
*    byte-for-byte losslessly reconstruct a JPEG-1 image. The JPEG DCT
*    coefficients (pixel content) themselves as well as the ICC profile are
*    encoded in the JXL codestream (jxlc or jxlp) itself. EXIF, XMP and JUMBF
*    metadata is encoded in the corresponding boxes. The jbrd box itself
*    contains information such as the remaining app markers of the JPEG-1 file
*    and everything else required to fit the information together into the
*    exact original JPEG file.
*
* Other application-specific boxes can exist. Their typename should not begin
* with "jxl" or "JXL" or conflict with other existing typenames.
*
* The signature, jxl* and jbrd boxes are processed by the decoder and would
* typically be ignored by applications. The typical way to use this function is
* to check if an encountered box contains metadata that the application is
* interested in (e.g. EXIF or XMP metadata), in order to conditionally set a
* box buffer.
*
* @param dec decoder object
* @param type buffer to copy the type into
* @param decompressed which box type to get: JXL_FALSE to get the raw box type,
*     which can be "brob", JXL_TRUE, get the underlying box type.
* @return ::JXL_DEC_SUCCESS if the value is available, ::JXL_DEC_ERROR if
*     not, for example the JPEG XL file does not use the container format.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderGetBoxType(JxlDecoder* dec,
                                                JxlBoxType type,
                                                JXL_BOOL decompressed);

/**
* Returns the size of a box as it appears in the container file, after the @ref
* JXL_DEC_BOX event. This includes all the box headers.
*
* @param dec decoder object
* @param size raw size of the box in bytes
* @return ::JXL_DEC_ERROR if no box size is available, ::JXL_DEC_SUCCESS
*     otherwise.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderGetBoxSizeRaw(const JxlDecoder* dec,
                                                   uint64_t* size);

/**
* Returns the size of the contents of a box, after the @ref
* JXL_DEC_BOX event. This does not include any of the headers of the box. For
* compressed "brob" boxes, this is the size of the compressed content. Even
* when @ref JxlDecoderSetDecompressBoxes is enabled, the return value of
* function does not change, and the decompressed size is not known before it
* has already been decompressed and output.
*
* @param dec decoder object
* @param size size of the payload of the box in bytes
* @return @ref JXL_DEC_ERROR if no box size is available, @ref JXL_DEC_SUCCESS
*     otherwise.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderGetBoxSizeContents(const JxlDecoder* dec,
                                                        uint64_t* size);

/**
* Configures at which progressive steps in frame decoding these @ref
* JXL_DEC_FRAME_PROGRESSION event occurs. The default value for the level
* of detail if this function is never called is `kDC`.
*
* @param dec decoder object
* @param detail at which level of detail to trigger @ref
*     JXL_DEC_FRAME_PROGRESSION
* @return ::JXL_DEC_SUCCESS on success, ::JXL_DEC_ERROR on error, such as
*     an invalid value for the progressive detail.
*/
JXL_EXPORT JxlDecoderStatus
JxlDecoderSetProgressiveDetail(JxlDecoder* dec, JxlProgressiveDetail detail);

/**
* Returns the intended downsampling ratio for the progressive frame produced
* by @ref JxlDecoderFlushImage after the latest ::JXL_DEC_FRAME_PROGRESSION
* event.
*
* @param dec decoder object
* @return The intended downsampling ratio, can be `1`, `2`, `4` or `8`.
*/
JXL_EXPORT size_t JxlDecoderGetIntendedDownsamplingRatio(JxlDecoder* dec);

/**
* Outputs progressive step towards the decoded image so far when only partial
* input was received. If the flush was successful, the buffer set with @ref
* JxlDecoderSetImageOutBuffer will contain partial image data.
*
* Can be called when @ref JxlDecoderProcessInput returns @ref
* JXL_DEC_NEED_MORE_INPUT, after the ::JXL_DEC_FRAME event already occurred
* and before the ::JXL_DEC_FULL_IMAGE event occurred for a frame.
*
* @param dec decoder object
* @return ::JXL_DEC_SUCCESS if image data was flushed to the output buffer,
*     or ::JXL_DEC_ERROR when no flush was done, e.g. if not enough image
*     data was available yet even for flush, or no output buffer was set yet.
*     This error is not fatal, it only indicates no flushed image is available
*     right now. Regular decoding can still be performed.
*/
JXL_EXPORT JxlDecoderStatus JxlDecoderFlushImage(JxlDecoder* dec);

/**
* Sets the bit depth of the output buffer or callback.
*
* Can be called after @ref JxlDecoderSetImageOutBuffer or @ref
* JxlDecoderSetImageOutCallback. For float pixel data types, only the default
* ::JXL_BIT_DEPTH_FROM_PIXEL_FORMAT setting is supported.
*
* @param dec decoder object
* @param bit_depth the bit depth setting of the pixel output
* @return ::JXL_DEC_SUCCESS on success, ::JXL_DEC_ERROR on error, such as
*     incompatible custom bit depth and pixel data type.
*/
JXL_EXPORT JxlDecoderStatus
JxlDecoderSetImageOutBitDepth(JxlDecoder* dec, const JxlBitDepth* bit_depth);

#ifdef __cplusplus
}
#endif

#endif /* JXL_DECODE_H_ */

/** @}*/