ref: f99b9cae6a3dc5775a83b264d6041be8d5d416d6
dir: /sys/src/cmd/postscript/postmd/postmd.h/
/*
*
* An interval list used to map matrix elements into integers in the range 0 to
* 254 representing shades of gray on a PostScript printer. The list can be given
* using the -i option or can be set in the optional header that can preceed each
* matrix. The list should be a comma or space separated list that looks like,
*
* num1,num2, ... ,numn
*
* where each num is a floating point number. The list must be given in increasing
* numerical order. The n numbers in the list partion the real line into 2n+1
* regions given by,
*
* region1 element < num1
* region2 element = num1
* region3 element < num2
* region4 element = num3
* . .
* . .
* . .
* region2n element = numn
* region2n+1 element > numn
*
* Every number in a given region is mapped into an integer in the range 0 to 254
* and that number, when displayed on a PostScript printer using the image operator,
* prints as a square filled with a gray scale that reflects the integer that was
* chosen. 0 maps to black and 255 white (that's why 255 is normally omitted).
*
* The shades of gray chosen by the program are normally generated automatically,
* but can be reassigned using the -g option or by including a grayscale line in
* the optional header. The grayscale list is comma or space separated list of
* integers between 0 and 255 that's used to map individual regions into arbitray
* shade of gray, thus overriding the default choice made in the program. The list
* should look like,
*
* color1,color2, ... ,color2n+1
*
* where color1 applies to region1 and color2n+1 applies to region2n+1. If less
* than 2n+1 numbers are given the default assignments will be used for the missing
* regions. Each color must be an integer in the range 0 to 255.
*
* The default interval list is given below. The default grayscale maps 254 (almost
* white) into the first region and 0 (black) into the last.
*
*/
#define DFLTILIST "-1,0,1"
/*
*
* The active interval list is built from an interval string and stored in an array
* whose elements are of type Ilist.
*
*/
typedef struct {
double val; /* only valid in kind is ENDPOINT */
int color; /* gray scale color */
long count; /* statistics for each region */
} Ilist;
/*
*
* Non-integer function declarations.
*
*/
char *savestring();