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[reactos.git] / reactos / sdk / include / reactos / libs / libjpeg / transupp.h
1 /*
2 * transupp.h
3 *
4 * Copyright (C) 1997-2013, Thomas G. Lane, Guido Vollbeding.
5 * This file is part of the Independent JPEG Group's software.
6 * For conditions of distribution and use, see the accompanying README file.
7 *
8 * This file contains declarations for image transformation routines and
9 * other utility code used by the jpegtran sample application. These are
10 * NOT part of the core JPEG library. But we keep these routines separate
11 * from jpegtran.c to ease the task of maintaining jpegtran-like programs
12 * that have other user interfaces.
13 *
14 * NOTE: all the routines declared here have very specific requirements
15 * about when they are to be executed during the reading and writing of the
16 * source and destination files. See the comments in transupp.c, or see
17 * jpegtran.c for an example of correct usage.
18 */
19
20 /* If you happen not to want the image transform support, disable it here */
21 #ifndef TRANSFORMS_SUPPORTED
22 #define TRANSFORMS_SUPPORTED 1 /* 0 disables transform code */
23 #endif
24
25 /*
26 * Although rotating and flipping data expressed as DCT coefficients is not
27 * hard, there is an asymmetry in the JPEG format specification for images
28 * whose dimensions aren't multiples of the iMCU size. The right and bottom
29 * image edges are padded out to the next iMCU boundary with junk data; but
30 * no padding is possible at the top and left edges. If we were to flip
31 * the whole image including the pad data, then pad garbage would become
32 * visible at the top and/or left, and real pixels would disappear into the
33 * pad margins --- perhaps permanently, since encoders & decoders may not
34 * bother to preserve DCT blocks that appear to be completely outside the
35 * nominal image area. So, we have to exclude any partial iMCUs from the
36 * basic transformation.
37 *
38 * Transpose is the only transformation that can handle partial iMCUs at the
39 * right and bottom edges completely cleanly. flip_h can flip partial iMCUs
40 * at the bottom, but leaves any partial iMCUs at the right edge untouched.
41 * Similarly flip_v leaves any partial iMCUs at the bottom edge untouched.
42 * The other transforms are defined as combinations of these basic transforms
43 * and process edge blocks in a way that preserves the equivalence.
44 *
45 * The "trim" option causes untransformable partial iMCUs to be dropped;
46 * this is not strictly lossless, but it usually gives the best-looking
47 * result for odd-size images. Note that when this option is active,
48 * the expected mathematical equivalences between the transforms may not hold.
49 * (For example, -rot 270 -trim trims only the bottom edge, but -rot 90 -trim
50 * followed by -rot 180 -trim trims both edges.)
51 *
52 * We also offer a lossless-crop option, which discards data outside a given
53 * image region but losslessly preserves what is inside. Like the rotate and
54 * flip transforms, lossless crop is restricted by the current JPEG format: the
55 * upper left corner of the selected region must fall on an iMCU boundary. If
56 * this does not hold for the given crop parameters, we silently move the upper
57 * left corner up and/or left to make it so, simultaneously increasing the
58 * region dimensions to keep the lower right crop corner unchanged. (Thus, the
59 * output image covers at least the requested region, but may cover more.)
60 * The adjustment of the region dimensions may be optionally disabled.
61 *
62 * A complementary lossless-wipe option is provided to discard (gray out) data
63 * inside a given image region while losslessly preserving what is outside.
64 *
65 * We also provide a lossless-resize option, which is kind of a lossless-crop
66 * operation in the DCT coefficient block domain - it discards higher-order
67 * coefficients and losslessly preserves lower-order coefficients of a
68 * sub-block.
69 *
70 * Rotate/flip transform, resize, and crop can be requested together in a
71 * single invocation. The crop is applied last --- that is, the crop region
72 * is specified in terms of the destination image after transform/resize.
73 *
74 * We also offer a "force to grayscale" option, which simply discards the
75 * chrominance channels of a YCbCr image. This is lossless in the sense that
76 * the luminance channel is preserved exactly. It's not the same kind of
77 * thing as the rotate/flip transformations, but it's convenient to handle it
78 * as part of this package, mainly because the transformation routines have to
79 * be aware of the option to know how many components to work on.
80 */
81
82
83 /* Short forms of external names for systems with brain-damaged linkers. */
84
85 #ifdef NEED_SHORT_EXTERNAL_NAMES
86 #define jtransform_parse_crop_spec jTrParCrop
87 #define jtransform_request_workspace jTrRequest
88 #define jtransform_adjust_parameters jTrAdjust
89 #define jtransform_execute_transform jTrExec
90 #define jtransform_perfect_transform jTrPerfect
91 #define jcopy_markers_setup jCMrkSetup
92 #define jcopy_markers_execute jCMrkExec
93 #endif /* NEED_SHORT_EXTERNAL_NAMES */
94
95
96 /*
97 * Codes for supported types of image transformations.
98 */
99
100 typedef enum {
101 JXFORM_NONE, /* no transformation */
102 JXFORM_FLIP_H, /* horizontal flip */
103 JXFORM_FLIP_V, /* vertical flip */
104 JXFORM_TRANSPOSE, /* transpose across UL-to-LR axis */
105 JXFORM_TRANSVERSE, /* transpose across UR-to-LL axis */
106 JXFORM_ROT_90, /* 90-degree clockwise rotation */
107 JXFORM_ROT_180, /* 180-degree rotation */
108 JXFORM_ROT_270, /* 270-degree clockwise (or 90 ccw) */
109 JXFORM_WIPE /* wipe */
110 } JXFORM_CODE;
111
112 /*
113 * Codes for crop parameters, which can individually be unspecified,
114 * positive or negative for xoffset or yoffset,
115 * positive or forced for width or height.
116 */
117
118 typedef enum {
119 JCROP_UNSET,
120 JCROP_POS,
121 JCROP_NEG,
122 JCROP_FORCE
123 } JCROP_CODE;
124
125 /*
126 * Transform parameters struct.
127 * NB: application must not change any elements of this struct after
128 * calling jtransform_request_workspace.
129 */
130
131 typedef struct {
132 /* Options: set by caller */
133 JXFORM_CODE transform; /* image transform operator */
134 boolean perfect; /* if TRUE, fail if partial MCUs are requested */
135 boolean trim; /* if TRUE, trim partial MCUs as needed */
136 boolean force_grayscale; /* if TRUE, convert color image to grayscale */
137 boolean crop; /* if TRUE, crop or wipe source image */
138
139 /* Crop parameters: application need not set these unless crop is TRUE.
140 * These can be filled in by jtransform_parse_crop_spec().
141 */
142 JDIMENSION crop_width; /* Width of selected region */
143 JCROP_CODE crop_width_set; /* (forced disables adjustment) */
144 JDIMENSION crop_height; /* Height of selected region */
145 JCROP_CODE crop_height_set; /* (forced disables adjustment) */
146 JDIMENSION crop_xoffset; /* X offset of selected region */
147 JCROP_CODE crop_xoffset_set; /* (negative measures from right edge) */
148 JDIMENSION crop_yoffset; /* Y offset of selected region */
149 JCROP_CODE crop_yoffset_set; /* (negative measures from bottom edge) */
150
151 /* Internal workspace: caller should not touch these */
152 int num_components; /* # of components in workspace */
153 jvirt_barray_ptr * workspace_coef_arrays; /* workspace for transformations */
154 JDIMENSION output_width; /* cropped destination dimensions */
155 JDIMENSION output_height;
156 JDIMENSION x_crop_offset; /* destination crop offsets measured in iMCUs */
157 JDIMENSION y_crop_offset;
158 JDIMENSION drop_width; /* drop/wipe dimensions measured in iMCUs */
159 JDIMENSION drop_height;
160 int iMCU_sample_width; /* destination iMCU size */
161 int iMCU_sample_height;
162 } jpeg_transform_info;
163
164
165 #if TRANSFORMS_SUPPORTED
166
167 /* Parse a crop specification (written in X11 geometry style) */
168 EXTERN(boolean) jtransform_parse_crop_spec
169 JPP((jpeg_transform_info *info, const char *spec));
170 /* Request any required workspace */
171 EXTERN(boolean) jtransform_request_workspace
172 JPP((j_decompress_ptr srcinfo, jpeg_transform_info *info));
173 /* Adjust output image parameters */
174 EXTERN(jvirt_barray_ptr *) jtransform_adjust_parameters
175 JPP((j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
176 jvirt_barray_ptr *src_coef_arrays,
177 jpeg_transform_info *info));
178 /* Execute the actual transformation, if any */
179 EXTERN(void) jtransform_execute_transform
180 JPP((j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
181 jvirt_barray_ptr *src_coef_arrays,
182 jpeg_transform_info *info));
183 /* Determine whether lossless transformation is perfectly
184 * possible for a specified image and transformation.
185 */
186 EXTERN(boolean) jtransform_perfect_transform
187 JPP((JDIMENSION image_width, JDIMENSION image_height,
188 int MCU_width, int MCU_height,
189 JXFORM_CODE transform));
190
191 /* jtransform_execute_transform used to be called
192 * jtransform_execute_transformation, but some compilers complain about
193 * routine names that long. This macro is here to avoid breaking any
194 * old source code that uses the original name...
195 */
196 #define jtransform_execute_transformation jtransform_execute_transform
197
198 #endif /* TRANSFORMS_SUPPORTED */
199
200
201 /*
202 * Support for copying optional markers from source to destination file.
203 */
204
205 typedef enum {
206 JCOPYOPT_NONE, /* copy no optional markers */
207 JCOPYOPT_COMMENTS, /* copy only comment (COM) markers */
208 JCOPYOPT_ALL /* copy all optional markers */
209 } JCOPY_OPTION;
210
211 #define JCOPYOPT_DEFAULT JCOPYOPT_COMMENTS /* recommended default */
212
213 /* Setup decompression object to save desired markers in memory */
214 EXTERN(void) jcopy_markers_setup
215 JPP((j_decompress_ptr srcinfo, JCOPY_OPTION option));
216 /* Copy markers saved in the given source object to the destination object */
217 EXTERN(void) jcopy_markers_execute
218 JPP((j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
219 JCOPY_OPTION option));