/*

 * transupp.h

 *

 * Copyright (C) 1997-2009, Thomas G. Lane, Guido Vollbeding.

 * 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

/*

 * 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.)

 *

 * 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.

 */

/* Short forms of external names for systems with brain-damaged linkers. */

#ifdef NEED_SHORT_EXTERNAL_NAMES

#define jtransform_parse_crop_spec	jTrParCrop

#define jtransform_request_workspace	jTrRequest

#define jtransform_adjust_parameters	jTrAdjust

#define jtransform_execute_transform	jTrExec

#define jtransform_perfect_transform	jTrPerfect

#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;

/*

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

 * positive, or negative.  (Negative width or height makes no sense, though.)

 */

typedef enum {

	JCROP_UNSET,

	JCROP_POS,

	JCROP_NEG

} 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 */

  /* 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;

  JDIMENSION crop_height;	/* Height of selected region */

  JCROP_CODE crop_height_set;

  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

	JPP((jpeg_transform_info *info, const char *spec));

/* Request any required workspace */

EXTERN(boolean) 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_transform

	JPP((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

	JPP((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 */

} 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));