File: transupp.h

package info (click to toggle)
fbi 2.10-3
  • links: PTS
  • area: main
  • in suites: bullseye, buster, sid
  • size: 1,780 kB
  • sloc: ansic: 22,994; sh: 120; perl: 12; makefile: 6
file content (220 lines) | stat: -rw-r--r-- 9,768 bytes parent folder | download | duplicates (14)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
/*
 * transupp.h
 *
 * Copyright (C) 1997-2011, 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.)
 * The adjustment of the region dimensions may be optionally disabled.
 *
 * 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 for xoffset or yoffset,
 * positive or forced for width or height.
 */

typedef enum {
        JCROP_UNSET,
        JCROP_POS,
        JCROP_NEG,
        JCROP_FORCE
} 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 */
  boolean slow_hflip;  /* For best performance, the JXFORM_FLIP_H transform
                          normally modifies the source coefficients in place.
                          Setting this to TRUE will instead use a slower,
                          double-buffered algorithm, which leaves the source
                          coefficients in tact (necessary if other transformed
                          images must be generated from the same set of
                          coefficients. */

  /* 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;	/* (forced disables adjustment) */
  JDIMENSION crop_height;	/* Height of selected region */
  JCROP_CODE crop_height_set;	/* (forced disables adjustment) */
  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));