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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 6417 | ashmew2 | 1 | /* |
| 2 | * transupp.h |
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| 3 | * |
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| 4 | * Copyright (C) 1997, Thomas G. Lane. |
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| 5 | * This file is part of the Independent JPEG Group's software. |
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| 6 | * For conditions of distribution and use, see the accompanying README file. |
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| 7 | * |
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| 8 | * This file contains declarations for image transformation routines and |
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| 9 | * other utility code used by the jpegtran sample application. These are |
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| 10 | * NOT part of the core JPEG library. But we keep these routines separate |
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| 11 | * from jpegtran.c to ease the task of maintaining jpegtran-like programs |
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| 12 | * that have other user interfaces. |
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| 13 | * |
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| 14 | * NOTE: all the routines declared here have very specific requirements |
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| 15 | * about when they are to be executed during the reading and writing of the |
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| 16 | * source and destination files. See the comments in transupp.c, or see |
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| 17 | * jpegtran.c for an example of correct usage. |
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| 18 | */ |
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| 19 | |||
| 20 | /* If you happen not to want the image transform support, disable it here */ |
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| 21 | #ifndef TRANSFORMS_SUPPORTED |
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| 22 | #define TRANSFORMS_SUPPORTED 1 /* 0 disables transform code */ |
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| 23 | #endif |
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| 24 | |||
| 25 | /* Short forms of external names for systems with brain-damaged linkers. */ |
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| 26 | |||
| 27 | #ifdef NEED_SHORT_EXTERNAL_NAMES |
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| 28 | #define jtransform_request_workspace jTrRequest |
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| 29 | #define jtransform_adjust_parameters jTrAdjust |
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| 30 | #define jtransform_execute_transformation jTrExec |
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| 31 | #define jcopy_markers_setup jCMrkSetup |
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| 32 | #define jcopy_markers_execute jCMrkExec |
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| 33 | #endif /* NEED_SHORT_EXTERNAL_NAMES */ |
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| 34 | |||
| 35 | |||
| 36 | /* |
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| 37 | * Codes for supported types of image transformations. |
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| 38 | */ |
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| 39 | |||
| 40 | typedef enum { |
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| 41 | JXFORM_NONE, /* no transformation */ |
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| 42 | JXFORM_FLIP_H, /* horizontal flip */ |
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| 43 | JXFORM_FLIP_V, /* vertical flip */ |
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| 44 | JXFORM_TRANSPOSE, /* transpose across UL-to-LR axis */ |
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| 45 | JXFORM_TRANSVERSE, /* transpose across UR-to-LL axis */ |
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| 46 | JXFORM_ROT_90, /* 90-degree clockwise rotation */ |
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| 47 | JXFORM_ROT_180, /* 180-degree rotation */ |
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| 48 | JXFORM_ROT_270 /* 270-degree clockwise (or 90 ccw) */ |
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| 49 | } JXFORM_CODE; |
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| 50 | |||
| 51 | /* |
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| 52 | * Although rotating and flipping data expressed as DCT coefficients is not |
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| 53 | * hard, there is an asymmetry in the JPEG format specification for images |
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| 54 | * whose dimensions aren't multiples of the iMCU size. The right and bottom |
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| 55 | * image edges are padded out to the next iMCU boundary with junk data; but |
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| 56 | * no padding is possible at the top and left edges. If we were to flip |
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| 57 | * the whole image including the pad data, then pad garbage would become |
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| 58 | * visible at the top and/or left, and real pixels would disappear into the |
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| 59 | * pad margins --- perhaps permanently, since encoders & decoders may not |
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| 60 | * bother to preserve DCT blocks that appear to be completely outside the |
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| 61 | * nominal image area. So, we have to exclude any partial iMCUs from the |
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| 62 | * basic transformation. |
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| 63 | * |
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| 64 | * Transpose is the only transformation that can handle partial iMCUs at the |
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| 65 | * right and bottom edges completely cleanly. flip_h can flip partial iMCUs |
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| 66 | * at the bottom, but leaves any partial iMCUs at the right edge untouched. |
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| 67 | * Similarly flip_v leaves any partial iMCUs at the bottom edge untouched. |
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| 68 | * The other transforms are defined as combinations of these basic transforms |
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| 69 | * and process edge blocks in a way that preserves the equivalence. |
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| 70 | * |
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| 71 | * The "trim" option causes untransformable partial iMCUs to be dropped; |
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| 72 | * this is not strictly lossless, but it usually gives the best-looking |
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| 73 | * result for odd-size images. Note that when this option is active, |
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| 74 | * the expected mathematical equivalences between the transforms may not hold. |
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| 75 | * (For example, -rot 270 -trim trims only the bottom edge, but -rot 90 -trim |
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| 76 | * followed by -rot 180 -trim trims both edges.) |
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| 77 | * |
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| 78 | * We also offer a "force to grayscale" option, which simply discards the |
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| 79 | * chrominance channels of a YCbCr image. This is lossless in the sense that |
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| 80 | * the luminance channel is preserved exactly. It's not the same kind of |
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| 81 | * thing as the rotate/flip transformations, but it's convenient to handle it |
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| 82 | * as part of this package, mainly because the transformation routines have to |
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| 83 | * be aware of the option to know how many components to work on. |
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| 84 | */ |
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| 85 | |||
| 86 | typedef struct { |
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| 87 | /* Options: set by caller */ |
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| 88 | JXFORM_CODE transform; /* image transform operator */ |
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| 89 | boolean trim; /* if TRUE, trim partial MCUs as needed */ |
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| 90 | boolean force_grayscale; /* if TRUE, convert color image to grayscale */ |
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| 91 | |||
| 92 | /* Internal workspace: caller should not touch these */ |
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| 93 | int num_components; /* # of components in workspace */ |
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| 94 | jvirt_barray_ptr * workspace_coef_arrays; /* workspace for transformations */ |
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| 95 | } jpeg_transform_info; |
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| 96 | |||
| 97 | |||
| 98 | #if TRANSFORMS_SUPPORTED |
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| 99 | |||
| 100 | /* Request any required workspace */ |
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| 101 | EXTERN(void) jtransform_request_workspace |
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| 102 | JPP((j_decompress_ptr srcinfo, jpeg_transform_info *info)); |
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| 103 | /* Adjust output image parameters */ |
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| 104 | EXTERN(jvirt_barray_ptr *) jtransform_adjust_parameters |
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| 105 | JPP((j_decompress_ptr srcinfo, j_compress_ptr dstinfo, |
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| 106 | jvirt_barray_ptr *src_coef_arrays, |
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| 107 | jpeg_transform_info *info)); |
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| 108 | /* Execute the actual transformation, if any */ |
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| 109 | EXTERN(void) jtransform_execute_transformation |
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| 110 | JPP((j_decompress_ptr srcinfo, j_compress_ptr dstinfo, |
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| 111 | jvirt_barray_ptr *src_coef_arrays, |
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| 112 | jpeg_transform_info *info)); |
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| 113 | |||
| 114 | #endif /* TRANSFORMS_SUPPORTED */ |
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| 115 | |||
| 116 | |||
| 117 | /* |
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| 118 | * Support for copying optional markers from source to destination file. |
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| 119 | */ |
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| 120 | |||
| 121 | typedef enum { |
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| 122 | JCOPYOPT_NONE, /* copy no optional markers */ |
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| 123 | JCOPYOPT_COMMENTS, /* copy only comment (COM) markers */ |
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| 124 | JCOPYOPT_ALL /* copy all optional markers */ |
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| 125 | } JCOPY_OPTION; |
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| 126 | |||
| 127 | #define JCOPYOPT_DEFAULT JCOPYOPT_COMMENTS /* recommended default */ |
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| 128 | |||
| 129 | /* Setup decompression object to save desired markers in memory */ |
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| 130 | EXTERN(void) jcopy_markers_setup |
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| 131 | JPP((j_decompress_ptr srcinfo, JCOPY_OPTION option)); |
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| 132 | /* Copy markers saved in the given source object to the destination object */ |
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| 133 | EXTERN(void) jcopy_markers_execute |
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| 134 | JPP((j_decompress_ptr srcinfo, j_compress_ptr dstinfo, |
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| 135 | JCOPY_OPTION option)); |