| /* |
| * transupp.h |
| * |
| * This file was part of the Independent JPEG Group's software: |
| * Copyright (C) 1997-2011, Thomas G. Lane, Guido Vollbeding. |
| * libjpeg-turbo Modifications: |
| * Copyright (C) 2017, D. R. Commander. |
| * For conditions of distribution and use, see the accompanying README.ijg |
| * 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. |
| */ |
| |
| |
| /* |
| * 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(jpeg_transform_info *info, |
| const char *spec); |
| /* Request any required workspace */ |
| EXTERN(boolean) jtransform_request_workspace(j_decompress_ptr srcinfo, |
| jpeg_transform_info *info); |
| /* Adjust output image parameters */ |
| EXTERN(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 */ |
| EXTERN(void) jtransform_execute_transform(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(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 */ |
| JCOPYOPT_ALL_EXCEPT_ICC /* copy all optional markers except APP2 */ |
| } JCOPY_OPTION; |
| |
| #define JCOPYOPT_DEFAULT JCOPYOPT_COMMENTS /* recommended default */ |
| |
| /* Setup decompression object to save desired markers in memory */ |
| EXTERN(void) jcopy_markers_setup(j_decompress_ptr srcinfo, |
| JCOPY_OPTION option); |
| /* Copy markers saved in the given source object to the destination object */ |
| EXTERN(void) jcopy_markers_execute(j_decompress_ptr srcinfo, |
| j_compress_ptr dstinfo, |
| JCOPY_OPTION option); |
