text: /*
   * transupp.h
   *
   * This file was part of the Independent JPEG Group's software:
   * Copyright (C) 1997-2011, Thomas G. Lane, Guido Vollbeding.
   * It was modified by The libjpeg-turbo Project to include only code relevant
   * to libjpeg-turbo.
   * 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.
   */
  
  #ifdef __cplusplus
  #ifndef DONT_USE_EXTERN_C
  extern "C" {
  #endif
  #endif
  
  /* 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 */
  } 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);
  
  #ifdef __cplusplus
  #ifndef DONT_USE_EXTERN_C
  }
  #endif
  #endif
  