File indexing completed on 2025-01-19 03:55:52

 /*
  * transupp.h
  *
  * SPDX-FileCopyrightText: 1997, Thomas G. Lane.
  * This file is part of the Independent JPEG Group's software.
  * For conditions of distribution and use, see the accompanying README 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
 
 /* Short forms of external names for systems with brain-damaged linkers. */
 
 #ifdef NEED_SHORT_EXTERNAL_NAMES
 #define jtransform_request_workspace        jTrRequest
 #define jtransform_adjust_parameters        jTrAdjust
 #define jtransform_execute_transformation   jTrExec
 #define jcopy_markers_setup         jCMrkSetup
 #define jcopy_markers_execute           jCMrkExec
 #endif /* NEED_SHORT_EXTERNAL_NAMES */
 
 
 /*
  * 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;
 
 /*
  * 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 "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.
  */
 
 typedef struct {
   /* Options: set by caller */
   JXFORM_CODE transform;    /* image transform operator */
   boolean trim;         /* if TRUE, trim partial MCUs as needed */
   boolean force_grayscale;  /* if TRUE, convert color image to grayscale */
 
   /* Internal workspace: caller should not touch these */
   int num_components;       /* # of components in workspace */
   jvirt_barray_ptr * workspace_coef_arrays; /* workspace for transformations */
 } jpeg_transform_info;
 
 
 #if TRANSFORMS_SUPPORTED
 
 /* Request any required workspace */
 EXTERN(void) jtransform_request_workspace
     JPP((j_decompress_ptr srcinfo, jpeg_transform_info *info));
 /* Adjust output image parameters */
 EXTERN(jvirt_barray_ptr *) jtransform_adjust_parameters
     JPP((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_transformation
     JPP((j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
          jvirt_barray_ptr *src_coef_arrays,
          jpeg_transform_info *info));
 
 #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 */
 } JCOPY_OPTION;
 
 #define JCOPYOPT_DEFAULT  JCOPYOPT_COMMENTS /* recommended default */
 
 /* Setup decompression object to save desired markers in memory */
 EXTERN(void) jcopy_markers_setup
     JPP((j_decompress_ptr srcinfo, JCOPY_OPTION option));
 /* Copy markers saved in the given source object to the destination object */
 EXTERN(void) jcopy_markers_execute
     JPP((j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
          JCOPY_OPTION option));