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Generating Outlines in OpenGL

, 7 Oct 2004
Using multi-pass techniques to generate outlines in OpenGL.
 * jmorecfg.h
 * Copyright (C) 1991-1997, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 * This file contains additional configuration options that customize the
 * JPEG software for special applications or support machine-dependent
 * optimizations.  Most users will not need to touch this file.

 * Define BITS_IN_JSAMPLE as either
 *   8   for 8-bit sample values (the usual setting)
 *   12  for 12-bit sample values
 * Only 8 and 12 are legal data precisions for lossy JPEG according to the
 * JPEG standard, and the IJG code does not support anything else!
 * We do not support run-time selection of data precision, sorry.

#define BITS_IN_JSAMPLE  8	/* use 8 or 12 */

 * Maximum number of components (color channels) allowed in JPEG image.
 * To meet the letter of the JPEG spec, set this to 255.  However, darn
 * few applications need more than 4 channels (maybe 5 for CMYK + alpha
 * mask).  We recommend 10 as a reasonable compromise; use 4 if you are
 * really short on memory.  (Each allowed component costs a hundred or so
 * bytes of storage, whether actually used in an image or not.)

#define MAX_COMPONENTS  10	/* maximum number of image components */

 * Basic data types.
 * You may need to change these if you have a machine with unusual data
 * type sizes; for example, "char" not 8 bits, "short" not 16 bits,
 * or "long" not 32 bits.  We don't care whether "int" is 16 or 32 bits,
 * but it had better be at least 16.

/* Representation of a single sample (pixel element value).
 * We frequently allocate large arrays of these, so it's important to keep
 * them small.  But if you have memory to burn and access to char or short
 * arrays is very slow on your hardware, you might want to change these.

/* JSAMPLE should be the smallest type that will hold the values 0..255.
 * You can use a signed char by having GETJSAMPLE mask it with 0xFF.


typedef unsigned char JSAMPLE;
#define GETJSAMPLE(value)  ((int) (value))

#else /* not HAVE_UNSIGNED_CHAR */

typedef char JSAMPLE;
#define GETJSAMPLE(value)  ((int) (value))
#define GETJSAMPLE(value)  ((int) (value) & 0xFF)
#endif /* CHAR_IS_UNSIGNED */


#define MAXJSAMPLE	255

#endif /* BITS_IN_JSAMPLE == 8 */

/* JSAMPLE should be the smallest type that will hold the values 0..4095.
 * On nearly all machines "short" will do nicely.

typedef short JSAMPLE;
#define GETJSAMPLE(value)  ((int) (value))

#define MAXJSAMPLE	4095
#define CENTERJSAMPLE	2048

#endif /* BITS_IN_JSAMPLE == 12 */

/* Representation of a DCT frequency coefficient.
 * This should be a signed value of at least 16 bits; "short" is usually OK.
 * Again, we allocate large arrays of these, but you can change to int
 * if you have memory to burn and "short" is really slow.

typedef short JCOEF;

/* Compressed datastreams are represented as arrays of JOCTET.
 * These must be EXACTLY 8 bits wide, at least once they are written to
 * external storage.  Note that when using the stdio data source/destination
 * managers, this is also the data type passed to fread/fwrite.


typedef unsigned char JOCTET;
#define GETJOCTET(value)  (value)

#else /* not HAVE_UNSIGNED_CHAR */

typedef char JOCTET;
#define GETJOCTET(value)  (value)
#define GETJOCTET(value)  ((value) & 0xFF)
#endif /* CHAR_IS_UNSIGNED */


/* These typedefs are used for various table entries and so forth.
 * They must be at least as wide as specified; but making them too big
 * won't cost a huge amount of memory, so we don't provide special
 * extraction code like we did for JSAMPLE.  (In other words, these
 * typedefs live at a different point on the speed/space tradeoff curve.)

/* UINT8 must hold at least the values 0..255. */

typedef unsigned char UINT8;
#else /* not HAVE_UNSIGNED_CHAR */
typedef char UINT8;
#else /* not CHAR_IS_UNSIGNED */
typedef short UINT8;
#endif /* CHAR_IS_UNSIGNED */

/* UINT16 must hold at least the values 0..65535. */

typedef unsigned short UINT16;
#else /* not HAVE_UNSIGNED_SHORT */
typedef unsigned int UINT16;

/* INT16 must hold at least the values -32768..32767. */

#ifndef XMD_H			/* X11/xmd.h correctly defines INT16 */
typedef short INT16;

/* INT32 must hold at least signed 32-bit values. */

//#ifndef XMD_H			/* X11/xmd.h correctly defines INT32 */
//typedef long INT32;

/* Datatype used for image dimensions.  The JPEG standard only supports
 * images up to 64K*64K due to 16-bit fields in SOF markers.  Therefore
 * "unsigned int" is sufficient on all machines.  However, if you need to
 * handle larger images and you don't mind deviating from the spec, you
 * can change this datatype.

typedef unsigned int JDIMENSION;

#define JPEG_MAX_DIMENSION  65500L  /* a tad under 64K to prevent overflows */

/* These macros are used in all function definitions and extern declarations.
 * You could modify them if you need to change function linkage conventions;
 * in particular, you'll need to do that to make the library a Windows DLL.
 * Another application is to make all functions global for use with debuggers
 * or code profilers that require it.

/* a function called through method pointers: */
#define METHODDEF(type)		static type
/* a function used only in its module: */
#define LOCAL(type)		static type
/* a function referenced thru EXTERNs: */
#define GLOBAL(type)		type
/* a reference to a GLOBAL function: */
#define EXTERN(type)		extern type

/* This macro is used to declare a "method", that is, a function pointer.
 * We want to supply prototype parameters if the compiler can cope.
 * Note that the arglist parameter must be parenthesized!
 * Again, you can customize this if you need special linkage keywords.

#define JMETHOD(type,methodname,arglist)  type (*methodname) arglist
#define JMETHOD(type,methodname,arglist)  type (*methodname) ()

/* Here is the pseudo-keyword for declaring pointers that must be "far"
 * on 80x86 machines.  Most of the specialized coding for 80x86 is handled
 * by just saying "FAR *" where such a pointer is needed.  In a few places
 * explicit coding is needed; see uses of the NEED_FAR_POINTERS symbol.

 * On a few systems, type boolean and/or its values FALSE, TRUE may appear
 * in standard header files.  Or you may have conflicts with application-
 * specific header files that you want to include together with these files.
 * Defining HAVE_BOOLEAN before including jpeglib.h should make it work.

typedef int boolean;
#ifndef FALSE			/* in case these macros already exist */
#define FALSE	0		/* values of boolean */
#ifndef TRUE
#define TRUE	1

 * The remaining options affect code selection within the JPEG library,
 * but they don't need to be visible to most applications using the library.
 * To minimize application namespace pollution, the symbols won't be
 * defined unless JPEG_INTERNALS or JPEG_INTERNAL_OPTIONS has been defined.



 * These defines indicate whether to include various optional functions.
 * Undefining some of these symbols will produce a smaller but less capable
 * library.  Note that you can leave certain source files out of the
 * compilation/linking process if you've #undef'd the corresponding symbols.
 * (You may HAVE to do that if your compiler doesn't like null source files.)

/* Arithmetic coding is unsupported for legal reasons.  Complaints to IBM. */

/* Capability options common to encoder and decoder: */

#define DCT_ISLOW_SUPPORTED	/* slow but accurate integer algorithm */
#define DCT_IFAST_SUPPORTED	/* faster, less accurate integer method */
#define DCT_FLOAT_SUPPORTED	/* floating-point: accurate, fast on fast HW */

/* Encoder capability options: */

#undef  C_ARITH_CODING_SUPPORTED    /* Arithmetic coding back end? */
#define C_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
#define C_PROGRESSIVE_SUPPORTED	    /* Progressive JPEG? (Requires MULTISCAN)*/
#define ENTROPY_OPT_SUPPORTED	    /* Optimization of entropy coding parms? */
/* Note: if you selected 12-bit data precision, it is dangerous to turn off
 * ENTROPY_OPT_SUPPORTED.  The standard Huffman tables are only good for 8-bit
 * precision, so jchuff.c normally uses entropy optimization to compute
 * usable tables for higher precision.  If you don't want to do optimization,
 * you'll have to supply different default Huffman tables.
 * The exact same statements apply for progressive JPEG: the default tables
 * don't work for progressive mode.  (This may get fixed, however.)
#define INPUT_SMOOTHING_SUPPORTED   /* Input image smoothing option? */

/* Decoder capability options: */

#undef  D_ARITH_CODING_SUPPORTED    /* Arithmetic coding back end? */
#define D_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
#define D_PROGRESSIVE_SUPPORTED	    /* Progressive JPEG? (Requires MULTISCAN)*/
#define SAVE_MARKERS_SUPPORTED	    /* jpeg_save_markers() needed? */
#define BLOCK_SMOOTHING_SUPPORTED   /* Block smoothing? (Progressive only) */
#define IDCT_SCALING_SUPPORTED	    /* Output rescaling via IDCT? */
#undef  UPSAMPLE_SCALING_SUPPORTED  /* Output rescaling at upsample stage? */
#define UPSAMPLE_MERGING_SUPPORTED  /* Fast path for sloppy upsampling? */
#define QUANT_1PASS_SUPPORTED	    /* 1-pass color quantization? */
#define QUANT_2PASS_SUPPORTED	    /* 2-pass color quantization? */

/* more capability options later, no doubt */

 * Ordering of RGB data in scanlines passed to or from the application.
 * If your application wants to deal with data in the order B,G,R, just
 * change these macros.  You can also deal with formats such as R,G,B,X
 * (one extra byte per pixel) by changing RGB_PIXELSIZE.  Note that changing
 * the offsets will also change the order in which colormap data is organized.
 * 1. The sample applications cjpeg,djpeg do NOT support modified RGB formats.
 * 2. These macros only affect RGB<=>YCbCr color conversion, so they are not
 *    useful if you are using JPEG color spaces other than YCbCr or grayscale.
 * 3. The color quantizer modules will not behave desirably if RGB_PIXELSIZE
 *    is not 3 (they don't understand about dummy color components!).  So you
 *    can't use color quantization if you change that value.

#define RGB_RED		0	/* Offset of Red in an RGB scanline element */
#define RGB_GREEN	1	/* Offset of Green */
#define RGB_BLUE	2	/* Offset of Blue */
#define RGB_PIXELSIZE	3	/* JSAMPLEs per RGB scanline element */

/* Definitions for speed-related optimizations. */

/* If your compiler supports inline functions, define INLINE
 * as the inline keyword; otherwise define it as empty.

#ifndef INLINE
#ifdef __GNUC__			/* for instance, GNU C knows about inline */
#define INLINE __inline__
#ifndef INLINE
#define INLINE			/* default is to define it as empty */

/* On some machines (notably 68000 series) "int" is 32 bits, but multiplying
 * two 16-bit shorts is faster than multiplying two ints.  Define MULTIPLIER
 * as short on such a machine.  MULTIPLIER must be at least 16 bits wide.

#define MULTIPLIER  int		/* type for fastest integer multiply */

/* FAST_FLOAT should be either float or double, whichever is done faster
 * by your compiler.  (Note that this type is only used in the floating point
 * DCT routines, so it only matters if you've defined DCT_FLOAT_SUPPORTED.)
 * Typically, float is faster in ANSI C compilers, while double is faster in
 * pre-ANSI compilers (because they insist on converting to double anyway).
 * The code below therefore chooses float if we have ANSI-style prototypes.

#ifndef FAST_FLOAT
#define FAST_FLOAT  float
#define FAST_FLOAT  double


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About the Author

Dave Handley
Web Developer
United Kingdom United Kingdom
I started programming on 8 bit machines as a teenager, writing my first compiled programming language before I was 16. I went on to study Engineering and Computer Science at Oxford University, getting a first and the University Prize for the best results in Computer Science. Since then I have worked in a variety of roles, involving systems management and development management on a wide variety of platforms. Now I manage a software development company producing CAD software for Windows using C++.

My 3 favourite reference books are: Design Patterns, Gamma et al; The C++ Standard Library, Josuttis; and Computer Graphics, Foley et al.

Outside computers, I am also the drummer in a band, The Unbelievers and we have just released our first album. I am a pretty good juggler and close up magician, and in my more insane past, I have cycled from Spain to Eastern Turkey, and cycled across the Namib desert.

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