/*

 * transupp.h

 *

 * This file was part of the Independent JPEG Group's software:

 * Copyright (C) 1997-2011, Thomas G. Lane, Guido Vollbeding.

 * libjpeg-turbo Modifications:

 * Copyright (C) 2017, D. R. Commander.

 * For conditions of distribution and use, see the accompanying README.ijg

 * file.

 *

 * This file contains declarations for image transformation routines and

 * other utility code used by the jpegtran sample application.  These are

 * NOT part of the core JPEG library.  But we keep these routines separate

 * from jpegtran.c to ease the task of maintaining jpegtran-like programs

 * that have other user interfaces.

 *

 * NOTE: all the routines declared here have very specific requirements

 * about when they are to be executed during the reading and writing of the

 * source and destination files.  See the comments in transupp.c, or see

 * jpegtran.c for an example of correct usage.

 */

/* If you happen not to want the image transform support, disable it here */

#ifndef TRANSFORMS_SUPPORTED

#define TRANSFORMS_SUPPORTED  1         /* 0 disables transform code */

#endif

/*

 * Although rotating and flipping data expressed as DCT coefficients is not

 * hard, there is an asymmetry in the JPEG format specification for images

 * whose dimensions aren't multiples of the iMCU size.  The right and bottom

 * image edges are padded out to the next iMCU boundary with junk data; but

 * no padding is possible at the top and left edges.  If we were to flip

 * the whole image including the pad data, then pad garbage would become

 * visible at the top and/or left, and real pixels would disappear into the

 * pad margins --- perhaps permanently, since encoders & decoders may not

 * bother to preserve DCT blocks that appear to be completely outside the

 * nominal image area.  So, we have to exclude any partial iMCUs from the

 * basic transformation.

 *

 * Transpose is the only transformation that can handle partial iMCUs at the

 * right and bottom edges completely cleanly.  flip_h can flip partial iMCUs

 * at the bottom, but leaves any partial iMCUs at the right edge untouched.

 * Similarly flip_v leaves any partial iMCUs at the bottom edge untouched.

 * The other transforms are defined as combinations of these basic transforms

 * and process edge blocks in a way that preserves the equivalence.

 *

 * The "trim" option causes untransformable partial iMCUs to be dropped;

 * this is not strictly lossless, but it usually gives the best-looking

 * result for odd-size images.  Note that when this option is active,

 * the expected mathematical equivalences between the transforms may not hold.

 * (For example, -rot 270 -trim trims only the bottom edge, but -rot 90 -trim

 * followed by -rot 180 -trim trims both edges.)

 *

 * We also offer a lossless-crop option, which discards data outside a given

 * image region but losslessly preserves what is inside.  Like the rotate and

 * flip transforms, lossless crop is restricted by the JPEG format: the upper

 * left corner of the selected region must fall on an iMCU boundary.  If this

 * does not hold for the given crop parameters, we silently move the upper left

 * corner up and/or left to make it so, simultaneously increasing the region

 * dimensions to keep the lower right crop corner unchanged.  (Thus, the

 * output image covers at least the requested region, but may cover more.)

 * The adjustment of the region dimensions may be optionally disabled.

 *

 * We also provide a lossless-resize option, which is kind of a lossless-crop

 * operation in the DCT coefficient block domain - it discards higher-order

 * coefficients and losslessly preserves lower-order coefficients of a

 * sub-block.

 *

 * Rotate/flip transform, resize, and crop can be requested together in a

 * single invocation.  The crop is applied last --- that is, the crop region

 * is specified in terms of the destination image after transform/resize.

 *

 * We also offer a "force to grayscale" option, which simply discards the

 * chrominance channels of a YCbCr image.  This is lossless in the sense that

 * the luminance channel is preserved exactly.  It's not the same kind of

 * thing as the rotate/flip transformations, but it's convenient to handle it

 * as part of this package, mainly because the transformation routines have to

 * be aware of the option to know how many components to work on.

 */

/*

 * Codes for supported types of image transformations.

 */

typedef enum {

  JXFORM_NONE,            /* no transformation */

  JXFORM_FLIP_H,          /* horizontal flip */

  JXFORM_FLIP_V,          /* vertical flip */

  JXFORM_TRANSPOSE,       /* transpose across UL-to-LR axis */

  JXFORM_TRANSVERSE,      /* transpose across UR-to-LL axis */

  JXFORM_ROT_90,          /* 90-degree clockwise rotation */

  JXFORM_ROT_180,         /* 180-degree rotation */

  JXFORM_ROT_270          /* 270-degree clockwise (or 90 ccw) */

} JXFORM_CODE;

/*

 * Codes for crop parameters, which can individually be unspecified,

 * positive or negative for xoffset or yoffset,

 * positive or forced for width or height.

 */

typedef enum {

  JCROP_UNSET,

  JCROP_POS,

  JCROP_NEG,

  JCROP_FORCE

} JCROP_CODE;

/*

 * Transform parameters struct.

 * NB: application must not change any elements of this struct after

 * calling jtransform_request_workspace.

 */

typedef struct {

  /* Options: set by caller */

  JXFORM_CODE transform;        /* image transform operator */

  boolean perfect;              /* if TRUE, fail if partial MCUs are requested */

  boolean trim;                 /* if TRUE, trim partial MCUs as needed */

  boolean force_grayscale;      /* if TRUE, convert color image to grayscale */

  boolean crop;                 /* if TRUE, crop source image */

  boolean slow_hflip;  /* For best performance, the JXFORM_FLIP_H transform

                          normally modifies the source coefficients in place.

                          Setting this to TRUE will instead use a slower,

                          double-buffered algorithm, which leaves the source

                          coefficients in tact (necessary if other transformed

                          images must be generated from the same set of

                          coefficients. */

  /* Crop parameters: application need not set these unless crop is TRUE.

   * These can be filled in by jtransform_parse_crop_spec().

   */

  JDIMENSION crop_width;        /* Width of selected region */

  JCROP_CODE crop_width_set;    /* (forced disables adjustment) */

  JDIMENSION crop_height;       /* Height of selected region */

  JCROP_CODE crop_height_set;   /* (forced disables adjustment) */

  JDIMENSION crop_xoffset;      /* X offset of selected region */

  JCROP_CODE crop_xoffset_set;  /* (negative measures from right edge) */

  JDIMENSION crop_yoffset;      /* Y offset of selected region */

  JCROP_CODE crop_yoffset_set;  /* (negative measures from bottom edge) */

  /* Internal workspace: caller should not touch these */

  int num_components;           /* # of components in workspace */

  jvirt_barray_ptr *workspace_coef_arrays; /* workspace for transformations */

  JDIMENSION output_width;      /* cropped destination dimensions */

  JDIMENSION output_height;

  JDIMENSION x_crop_offset;     /* destination crop offsets measured in iMCUs */

  JDIMENSION y_crop_offset;

  int iMCU_sample_width;        /* destination iMCU size */

  int iMCU_sample_height;

} jpeg_transform_info;

#if TRANSFORMS_SUPPORTED

/* Parse a crop specification (written in X11 geometry style) */

EXTERN(boolean) jtransform_parse_crop_spec(jpeg_transform_info *info,

                                           const char *spec);

/* Request any required workspace */

EXTERN(boolean) jtransform_request_workspace(j_decompress_ptr srcinfo,

                                             jpeg_transform_info *info);

/* Adjust output image parameters */

EXTERN(jvirt_barray_ptr *) jtransform_adjust_parameters

  (j_decompress_ptr srcinfo, j_compress_ptr dstinfo,

   jvirt_barray_ptr *src_coef_arrays, jpeg_transform_info *info);

/* Execute the actual transformation, if any */

EXTERN(void) jtransform_execute_transform(j_decompress_ptr srcinfo,

                                          j_compress_ptr dstinfo,

                                          jvirt_barray_ptr *src_coef_arrays,

                                          jpeg_transform_info *info);

/* Determine whether lossless transformation is perfectly

 * possible for a specified image and transformation.

 */

EXTERN(boolean) jtransform_perfect_transform(JDIMENSION image_width,

                                             JDIMENSION image_height,

                                             int MCU_width, int MCU_height,

                                             JXFORM_CODE transform);

/* jtransform_execute_transform used to be called

 * jtransform_execute_transformation, but some compilers complain about

 * routine names that long.  This macro is here to avoid breaking any

 * old source code that uses the original name...

 */

#define jtransform_execute_transformation       jtransform_execute_transform

#endif /* TRANSFORMS_SUPPORTED */

/*

 * Support for copying optional markers from source to destination file.

 */

typedef enum {

  JCOPYOPT_NONE,          /* copy no optional markers */

  JCOPYOPT_COMMENTS,      /* copy only comment (COM) markers */

  JCOPYOPT_ALL,           /* copy all optional markers */

  JCOPYOPT_ALL_EXCEPT_ICC /* copy all optional markers except APP2 */

} JCOPY_OPTION;

#define JCOPYOPT_DEFAULT  JCOPYOPT_COMMENTS     /* recommended default */

/* Setup decompression object to save desired markers in memory */

EXTERN(void) jcopy_markers_setup(j_decompress_ptr srcinfo,

                                 JCOPY_OPTION option);

/* Copy markers saved in the given source object to the destination object */

EXTERN(void) jcopy_markers_execute(j_decompress_ptr srcinfo,

                                   j_compress_ptr dstinfo,

                                   JCOPY_OPTION option);