Coverage Report

Created: 2024-05-04 01:11

/src/libjpeg-turbo.main/transupp.h
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/*
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 * transupp.h
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 *
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 * This file was part of the Independent JPEG Group's software:
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 * Copyright (C) 1997-2019, Thomas G. Lane, Guido Vollbeding.
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 * libjpeg-turbo Modifications:
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 * Copyright (C) 2017, 2021, D. R. Commander.
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 * For conditions of distribution and use, see the accompanying README.ijg
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 * file.
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 *
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 * This file contains declarations for image transformation routines and
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 * other utility code used by the jpegtran sample application.  These are
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 * NOT part of the core JPEG library.  But we keep these routines separate
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 * from jpegtran.c to ease the task of maintaining jpegtran-like programs
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 * that have other user interfaces.
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 *
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 * NOTE: all the routines declared here have very specific requirements
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 * about when they are to be executed during the reading and writing of the
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 * source and destination files.  See the comments in transupp.c, or see
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 * jpegtran.c for an example of correct usage.
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 */
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/* If you happen not to want the image transform support, disable it here */
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#ifndef TRANSFORMS_SUPPORTED
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#define TRANSFORMS_SUPPORTED  1         /* 0 disables transform code */
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#endif
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/*
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 * Although rotating and flipping data expressed as DCT coefficients is not
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 * hard, there is an asymmetry in the JPEG format specification for images
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 * whose dimensions aren't multiples of the iMCU size.  The right and bottom
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 * image edges are padded out to the next iMCU boundary with junk data; but
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 * no padding is possible at the top and left edges.  If we were to flip
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 * the whole image including the pad data, then pad garbage would become
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 * visible at the top and/or left, and real pixels would disappear into the
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 * pad margins --- perhaps permanently, since encoders & decoders may not
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 * bother to preserve DCT blocks that appear to be completely outside the
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 * nominal image area.  So, we have to exclude any partial iMCUs from the
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 * basic transformation.
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 *
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 * Transpose is the only transformation that can handle partial iMCUs at the
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 * right and bottom edges completely cleanly.  flip_h can flip partial iMCUs
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 * at the bottom, but leaves any partial iMCUs at the right edge untouched.
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 * Similarly flip_v leaves any partial iMCUs at the bottom edge untouched.
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 * The other transforms are defined as combinations of these basic transforms
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 * and process edge blocks in a way that preserves the equivalence.
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 *
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 * The "trim" option causes untransformable partial iMCUs to be dropped;
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 * this is not strictly lossless, but it usually gives the best-looking
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 * result for odd-size images.  Note that when this option is active,
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 * the expected mathematical equivalences between the transforms may not hold.
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 * (For example, -rot 270 -trim trims only the bottom edge, but -rot 90 -trim
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 * followed by -rot 180 -trim trims both edges.)
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 *
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 * We also offer a lossless-crop option, which discards data outside a given
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 * image region but losslessly preserves what is inside.  Like the rotate and
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 * flip transforms, lossless crop is restricted by the JPEG format: the upper
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 * left corner of the selected region must fall on an iMCU boundary.  If this
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 * does not hold for the given crop parameters, we silently move the upper left
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 * corner up and/or left to make it so, simultaneously increasing the region
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 * dimensions to keep the lower right crop corner unchanged.  (Thus, the
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 * output image covers at least the requested region, but may cover more.)
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 * The adjustment of the region dimensions may be optionally disabled.
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 *
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 * A complementary lossless wipe option is provided to discard (gray out) data
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 * inside a given image region while losslessly preserving what is outside.
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 * A lossless drop option is also provided, which allows another JPEG image to
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 * be inserted ("dropped") into the source image data at a given position,
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 * replacing the existing image data at that position.  Both the source image
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 * and the drop image must have the same subsampling level.  It is best if they
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 * also have the same quantization (quality.)  Otherwise, the quantization of
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 * the output image will be adapted to accommodate the higher of the source
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 * image quality and the drop image quality.  The trim option can be used with
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 * the drop option to requantize the drop image to match the source image.
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 *
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 * We also provide a lossless-resize option, which is kind of a lossless-crop
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 * operation in the DCT coefficient block domain - it discards higher-order
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 * coefficients and losslessly preserves lower-order coefficients of a
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 * sub-block.
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 *
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 * Rotate/flip transform, resize, and crop can be requested together in a
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 * single invocation.  The crop is applied last --- that is, the crop region
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 * is specified in terms of the destination image after transform/resize.
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 *
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 * We also offer a "force to grayscale" option, which simply discards the
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 * chrominance channels of a YCbCr image.  This is lossless in the sense that
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 * the luminance channel is preserved exactly.  It's not the same kind of
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 * thing as the rotate/flip transformations, but it's convenient to handle it
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 * as part of this package, mainly because the transformation routines have to
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 * be aware of the option to know how many components to work on.
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 */
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/*
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 * Codes for supported types of image transformations.
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 */
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typedef enum {
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  JXFORM_NONE,            /* no transformation */
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  JXFORM_FLIP_H,          /* horizontal flip */
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  JXFORM_FLIP_V,          /* vertical flip */
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  JXFORM_TRANSPOSE,       /* transpose across UL-to-LR axis */
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  JXFORM_TRANSVERSE,      /* transpose across UR-to-LL axis */
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  JXFORM_ROT_90,          /* 90-degree clockwise rotation */
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  JXFORM_ROT_180,         /* 180-degree rotation */
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  JXFORM_ROT_270,         /* 270-degree clockwise (or 90 ccw) */
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  JXFORM_WIPE,            /* wipe */
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  JXFORM_DROP             /* drop */
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} JXFORM_CODE;
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/*
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 * Codes for crop parameters, which can individually be unspecified,
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 * positive or negative for xoffset or yoffset,
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 * positive or force or reflect for width or height.
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 */
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typedef enum {
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  JCROP_UNSET,
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  JCROP_POS,
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  JCROP_NEG,
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  JCROP_FORCE,
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  JCROP_REFLECT
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} JCROP_CODE;
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/*
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 * Transform parameters struct.
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 * NB: application must not change any elements of this struct after
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 * calling jtransform_request_workspace.
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 */
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typedef struct {
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  /* Options: set by caller */
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  JXFORM_CODE transform;        /* image transform operator */
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  boolean perfect;              /* if TRUE, fail if partial MCUs are requested */
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  boolean trim;                 /* if TRUE, trim partial MCUs as needed */
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  boolean force_grayscale;      /* if TRUE, convert color image to grayscale */
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  boolean crop;                 /* if TRUE, crop or wipe source image, or drop */
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  boolean slow_hflip;  /* For best performance, the JXFORM_FLIP_H transform
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                          normally modifies the source coefficients in place.
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                          Setting this to TRUE will instead use a slower,
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                          double-buffered algorithm, which leaves the source
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                          coefficients in tact (necessary if other transformed
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                          images must be generated from the same set of
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                          coefficients. */
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  /* Crop parameters: application need not set these unless crop is TRUE.
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   * These can be filled in by jtransform_parse_crop_spec().
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   */
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  JDIMENSION crop_width;        /* Width of selected region */
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  JCROP_CODE crop_width_set;    /* (force-disables adjustment) */
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  JDIMENSION crop_height;       /* Height of selected region */
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  JCROP_CODE crop_height_set;   /* (force-disables adjustment) */
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  JDIMENSION crop_xoffset;      /* X offset of selected region */
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  JCROP_CODE crop_xoffset_set;  /* (negative measures from right edge) */
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  JDIMENSION crop_yoffset;      /* Y offset of selected region */
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  JCROP_CODE crop_yoffset_set;  /* (negative measures from bottom edge) */
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  /* Drop parameters: set by caller for drop request */
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  j_decompress_ptr drop_ptr;
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  jvirt_barray_ptr *drop_coef_arrays;
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  /* Internal workspace: caller should not touch these */
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  int num_components;           /* # of components in workspace */
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  jvirt_barray_ptr *workspace_coef_arrays; /* workspace for transformations */
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  JDIMENSION output_width;      /* cropped destination dimensions */
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  JDIMENSION output_height;
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  JDIMENSION x_crop_offset;     /* destination crop offsets measured in iMCUs */
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  JDIMENSION y_crop_offset;
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  JDIMENSION drop_width;        /* drop/wipe dimensions measured in iMCUs */
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  JDIMENSION drop_height;
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  int iMCU_sample_width;        /* destination iMCU size */
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  int iMCU_sample_height;
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} jpeg_transform_info;
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#if TRANSFORMS_SUPPORTED
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/* Parse a crop specification (written in X11 geometry style) */
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EXTERN(boolean) jtransform_parse_crop_spec(jpeg_transform_info *info,
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                                           const char *spec);
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/* Request any required workspace */
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EXTERN(boolean) jtransform_request_workspace(j_decompress_ptr srcinfo,
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                                             jpeg_transform_info *info);
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/* Adjust output image parameters */
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EXTERN(jvirt_barray_ptr *) jtransform_adjust_parameters
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  (j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
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   jvirt_barray_ptr *src_coef_arrays, jpeg_transform_info *info);
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/* Execute the actual transformation, if any */
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EXTERN(void) jtransform_execute_transform(j_decompress_ptr srcinfo,
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                                          j_compress_ptr dstinfo,
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                                          jvirt_barray_ptr *src_coef_arrays,
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                                          jpeg_transform_info *info);
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/* Determine whether lossless transformation is perfectly
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 * possible for a specified image and transformation.
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 */
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EXTERN(boolean) jtransform_perfect_transform(JDIMENSION image_width,
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                                             JDIMENSION image_height,
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                                             int MCU_width, int MCU_height,
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                                             JXFORM_CODE transform);
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/* jtransform_execute_transform used to be called
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 * jtransform_execute_transformation, but some compilers complain about
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 * routine names that long.  This macro is here to avoid breaking any
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 * old source code that uses the original name...
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 */
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0
#define jtransform_execute_transformation       jtransform_execute_transform
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#endif /* TRANSFORMS_SUPPORTED */
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/*
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 * Support for copying optional markers from source to destination file.
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 */
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typedef enum {
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  JCOPYOPT_NONE,           /* copy no optional markers */
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  JCOPYOPT_COMMENTS,       /* copy only comment (COM) markers */
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  JCOPYOPT_ALL,            /* copy all optional markers */
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  JCOPYOPT_ALL_EXCEPT_ICC, /* copy all optional markers except APP2 */
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  JCOPYOPT_ICC             /* copy only ICC profile (APP2) markers */
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} JCOPY_OPTION;
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#define JCOPYOPT_DEFAULT  JCOPYOPT_COMMENTS     /* recommended default */
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/* Setup decompression object to save desired markers in memory */
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EXTERN(void) jcopy_markers_setup(j_decompress_ptr srcinfo,
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                                 JCOPY_OPTION option);
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/* Copy markers saved in the given source object to the destination object */
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EXTERN(void) jcopy_markers_execute(j_decompress_ptr srcinfo,
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                                   j_compress_ptr dstinfo,
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                                   JCOPY_OPTION option);