/* 
 * transupp.h 
 * 
 * Copyright (C) 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)); 
