/* * 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));