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src/Source/LibJPEG/jpeglib.h  view on Meta::CPAN

   * Values from 1 to 16 are supported.
   * Note that different components may receive different DCT scalings.
   */
  int DCT_h_scaled_size;
  int DCT_v_scaled_size;
  /* The downsampled dimensions are the component's actual, unpadded number
   * of samples at the main buffer (preprocessing/compression interface);
   * DCT scaling is included, so
   * downsampled_width =
   *   ceil(image_width * Hi/Hmax * DCT_h_scaled_size/block_size)
   * and similarly for height.
   */
  JDIMENSION downsampled_width;	 /* actual width in samples */
  JDIMENSION downsampled_height; /* actual height in samples */
  /* For decompression, in cases where some of the components will be
   * ignored (eg grayscale output from YCbCr image), we can skip most
   * computations for the unused components.
   * For compression, some of the components will need further quantization
   * scale by factor of 2 after DCT (eg BG_YCC output from normal RGB input).
   * The field is first set TRUE for decompression, FALSE for compression
   * in initial_setup, and then adapted in color conversion setup.
   */
  boolean component_needed;

  /* These values are computed before starting a scan of the component. */
  /* The decompressor output side may not use these variables. */
  int MCU_width;		/* number of blocks per MCU, horizontally */
  int MCU_height;		/* number of blocks per MCU, vertically */
  int MCU_blocks;		/* MCU_width * MCU_height */
  int MCU_sample_width;	/* MCU width in samples: MCU_width * DCT_h_scaled_size */
  int last_col_width;		/* # of non-dummy blocks across in last MCU */
  int last_row_height;		/* # of non-dummy blocks down in last MCU */

  /* Saved quantization table for component; NULL if none yet saved.
   * See jdinput.c comments about the need for this information.
   * This field is currently used only for decompression.
   */
  JQUANT_TBL * quant_table;

  /* Private per-component storage for DCT or IDCT subsystem. */
  void * dct_table;
} jpeg_component_info;


/* The script for encoding a multiple-scan file is an array of these: */

typedef struct {
  int comps_in_scan;		/* number of components encoded in this scan */
  int component_index[MAX_COMPS_IN_SCAN]; /* their SOF/comp_info[] indexes */
  int Ss, Se;			/* progressive JPEG spectral selection parms */
  int Ah, Al;			/* progressive JPEG successive approx. parms */
} jpeg_scan_info;

/* The decompressor can save APPn and COM markers in a list of these: */

typedef struct jpeg_marker_struct FAR * jpeg_saved_marker_ptr;

struct jpeg_marker_struct {
  jpeg_saved_marker_ptr next;	/* next in list, or NULL */
  UINT8 marker;			/* marker code: JPEG_COM, or JPEG_APP0+n */
  unsigned int original_length;	/* # bytes of data in the file */
  unsigned int data_length;	/* # bytes of data saved at data[] */
  JOCTET FAR * data;		/* the data contained in the marker */
  /* the marker length word is not counted in data_length or original_length */
};

/* Known color spaces. */

typedef enum {
	JCS_UNKNOWN,		/* error/unspecified */
	JCS_GRAYSCALE,		/* monochrome */
	JCS_RGB,		/* red/green/blue, standard RGB (sRGB) */
	JCS_YCbCr,		/* Y/Cb/Cr (also known as YUV), standard YCC */
	JCS_CMYK,		/* C/M/Y/K */
	JCS_YCCK,		/* Y/Cb/Cr/K */
	JCS_BG_RGB,		/* big gamut red/green/blue, bg-sRGB */
	JCS_BG_YCC		/* big gamut Y/Cb/Cr, bg-sYCC */
} J_COLOR_SPACE;

/* Supported color transforms. */

typedef enum {
	JCT_NONE           = 0,
	JCT_SUBTRACT_GREEN = 1
} J_COLOR_TRANSFORM;

/* DCT/IDCT algorithm options. */

typedef enum {
	JDCT_ISLOW,		/* slow but accurate integer algorithm */
	JDCT_IFAST,		/* faster, less accurate integer method */
	JDCT_FLOAT		/* floating-point: accurate, fast on fast HW */
} J_DCT_METHOD;

#ifndef JDCT_DEFAULT		/* may be overridden in jconfig.h */
#define JDCT_DEFAULT  JDCT_ISLOW
#endif
#ifndef JDCT_FASTEST		/* may be overridden in jconfig.h */
#define JDCT_FASTEST  JDCT_IFAST
#endif

/* Dithering options for decompression. */

typedef enum {
	JDITHER_NONE,		/* no dithering */
	JDITHER_ORDERED,	/* simple ordered dither */
	JDITHER_FS		/* Floyd-Steinberg error diffusion dither */
} J_DITHER_MODE;


/* Common fields between JPEG compression and decompression master structs. */

#define jpeg_common_fields \
  struct jpeg_error_mgr * err;	/* Error handler module */\
  struct jpeg_memory_mgr * mem;	/* Memory manager module */\
  struct jpeg_progress_mgr * progress; /* Progress monitor, or NULL if none */\
  void * client_data;		/* Available for use by application */\
  boolean is_decompressor;	/* So common code can tell which is which */\
  int global_state		/* For checking call sequence validity */

/* Routines that are to be used by both halves of the library are declared
 * to receive a pointer to this structure.  There are no actual instances of
 * jpeg_common_struct, only of jpeg_compress_struct and jpeg_decompress_struct.
 */