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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/*
* GThumb
*
* Copyright (C) 2001, 2002 The Free Software Foundation, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
/* based upon file transupp.h from the libjpeg package, original copyright
* note follows:
*
* 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.
*/
/*
* Codes for supported types of image transformations.
*/
#ifdef HAVE_LIBJPEG
#ifndef TRANSUPP_H
#define TRANSUPP_H
#include <jpeglib.h>
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;
/* Request any required workspace */
void jtransform_request_workspace (j_decompress_ptr srcinfo,
jpeg_transform_info *info);
/* Adjust output image parameters */
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 */
void jtransform_execute_transformation (j_decompress_ptr srcinfo,
j_compress_ptr dstinfo,
jvirt_barray_ptr *src_coef_arrays,
jpeg_transform_info *info);
/*
* 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 */
void jcopy_markers_setup (j_decompress_ptr srcinfo,
JCOPY_OPTION option);
/* Copy markers saved in the given source object to the destination object */
void jcopy_markers_execute (j_decompress_ptr srcinfo,
j_compress_ptr dstinfo,
JCOPY_OPTION option);
#endif /* TRANSUPP_H */
#endif /* HAVE_LIBJPEG */
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