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Driver API

Header cups/driver.h
Library -lcupsdriver
See Also Programming: Introduction to CUPS Programming

Contents

Overview

The driver API provides common dithering, color conversion, and utility functions for CUPS drivers.

Functions

cupsCMYKDelete

Delete a color separation.

void cupsCMYKDelete (
    cups_cmyk_t *cmyk
);

Parameters

cmyk
Color separation

cupsCMYKDoBlack

Do a black separation...

void cupsCMYKDoBlack (
    const cups_cmyk_t *cmyk,
    const unsigned char *input,
    short *output,
    int num_pixels
);

Parameters

cmyk
Color separation
input
Input grayscale pixels
output
Output Device-N pixels
num_pixels
Number of pixels

cupsCMYKDoCMYK

Do a CMYK separation...

void cupsCMYKDoCMYK (
    const cups_cmyk_t *cmyk,
    const unsigned char *input,
    short *output,
    int num_pixels
);

Parameters

cmyk
Color separation
input
Input grayscale pixels
output
Output Device-N pixels
num_pixels
Number of pixels

cupsCMYKDoGray

Do a grayscale separation...

void cupsCMYKDoGray (
    const cups_cmyk_t *cmyk,
    const unsigned char *input,
    short *output,
    int num_pixels
);

Parameters

cmyk
Color separation
input
Input grayscale pixels
output
Output Device-N pixels
num_pixels
Number of pixels

cupsCMYKDoRGB

Do an sRGB separation...

void cupsCMYKDoRGB (
    const cups_cmyk_t *cmyk,
    const unsigned char *input,
    short *output,
    int num_pixels
);

Parameters

cmyk
Color separation
input
Input grayscale pixels
output
Output Device-N pixels
num_pixels
Number of pixels

cupsCMYKLoad

Load a CMYK color profile from PPD attributes.

cups_cmyk_t *cupsCMYKLoad (
    ppd_file_t *ppd,
    const char *colormodel,
    const char *media,
    const char *resolution
);

Parameters

ppd
PPD file
colormodel
ColorModel value
media
MediaType value
resolution
Resolution value

Return Value

CMYK color separation

cupsCMYKNew

Create a new CMYK color separation.

cups_cmyk_t *cupsCMYKNew (
    int num_channels
);

Parameters

num_channels
Number of color components

Return Value

New CMYK separation or NULL

cupsCMYKSetBlack

Set the transition range for CMY to black.

void cupsCMYKSetBlack (
    cups_cmyk_t *cmyk,
    float lower,
    float upper
);

Parameters

cmyk
CMYK color separation
lower
No black ink
upper
Only black ink

cupsCMYKSetCurve

Set a color transform curve using points.

void cupsCMYKSetCurve (
    cups_cmyk_t *cmyk,
    int channel,
    int num_xypoints,
    const float *xypoints
);

Parameters

cmyk
CMYK color separation
channel
Color channel
num_xypoints
Number of X,Y points
xypoints
X,Y points

cupsCMYKSetGamma

Set a color transform curve using gamma and density.

void cupsCMYKSetGamma (
    cups_cmyk_t *cmyk,
    int channel,
    float gamval,
    float density
);

Parameters

cmyk
CMYK color separation
channel
Ink channel
gamval
Gamma correction
density
Maximum density

cupsCMYKSetInkLimit

Set the limit on the amount of ink.

void cupsCMYKSetInkLimit (
    cups_cmyk_t *cmyk,
    float limit
);

Parameters

cmyk
CMYK color separation
limit
Limit of ink

cupsCMYKSetLtDk

Set light/dark ink transforms.

void cupsCMYKSetLtDk (
    cups_cmyk_t *cmyk,
    int channel,
    float light,
    float dark
);

Parameters

cmyk
CMYK color separation
channel
Dark ink channel (+1 for light)
light
Light ink only level
dark
Dark ink only level

cupsCheckBytes

Check to see if all bytes are zero.

int cupsCheckBytes (
    const unsigned char *bytes,
    int length
);

Parameters

bytes
Bytes to check
length
Number of bytes to check

Return Value

1 if they match

cupsCheckValue

Check to see if all bytes match the given value.

int cupsCheckValue (
    const unsigned char *bytes,
    int length,
    const unsigned char value
);

Parameters

bytes
Bytes to check
length
Number of bytes to check
value
Value to check

Return Value

1 if they match

cupsDitherDelete

Free a dithering buffer.

void cupsDitherDelete (
    cups_dither_t *d
);

Parameters

d
Dithering buffer

Discussion

Returns 0 on success, -1 on failure.

cupsDitherLine

Dither a line of pixels...

void cupsDitherLine (
    cups_dither_t *d,
    const cups_lut_t *lut,
    const short *data,
    int num_channels,
    unsigned char *p
);

Parameters

d
Dither data
lut
Lookup table
data
Separation data
num_channels
Number of components
p
Pixels

cupsDitherNew

Create an error-diffusion dithering buffer.

cups_dither_t *cupsDitherNew (
    int width
);

Parameters

width
Width of output in pixels

Return Value

New state array

cupsFindAttr

Find a PPD attribute based on the colormodel, media, and resolution.

ppd_attr_t *cupsFindAttr (
    ppd_file_t *ppd,
    const char *name,
    const char *colormodel,
    const char *media,
    const char *resolution,
    char *spec,
    int specsize
);

Parameters

ppd
PPD file
name
Attribute name
colormodel
Color model
media
Media type
resolution
Resolution
spec
Final selection string
specsize
Size of string buffer

Return Value

Matching attribute or NULL

cupsLutDelete

Free the memory used by a lookup table.

void cupsLutDelete (
    cups_lut_t *lut
);

Parameters

lut
Lookup table to free

cupsLutLoad

Load a LUT from a PPD file.

cups_lut_t *cupsLutLoad (
    ppd_file_t *ppd,
    const char *colormodel,
    const char *media,
    const char *resolution,
    const char *ink
);

Parameters

ppd
PPD file
colormodel
Color model
media
Media type
resolution
Resolution
ink
Ink name

Return Value

New lookup table

cupsLutNew

Make a lookup table from a list of pixel values.

cups_lut_t *cupsLutNew (
    int num_values,
    const float *values
);

Parameters

num_values
Number of values
values
Lookup table values

Return Value

New lookup table

Discussion

Returns a pointer to the lookup table on success, NULL on failure.

cupsPackHorizontal

Pack pixels horizontally...

void cupsPackHorizontal (
    const unsigned char *ipixels,
    unsigned char *obytes,
    int width,
    const unsigned char clearto,
    const int step
);

Parameters

ipixels
Input pixels
obytes
Output bytes
width
Number of pixels
clearto
Initial value of bytes
step
Step value between pixels

cupsPackHorizontal2

Pack 2-bit pixels horizontally...

void cupsPackHorizontal2 (
    const unsigned char *ipixels,
    unsigned char *obytes,
    int width,
    const int step
);

Parameters

ipixels
Input pixels
obytes
Output bytes
width
Number of pixels
step
Stepping value

cupsPackHorizontalBit

Pack pixels horizontally by bit...

void cupsPackHorizontalBit (
    const unsigned char *ipixels,
    unsigned char *obytes,
    int width,
    const unsigned char clearto,
    const unsigned char bit
);

Parameters

ipixels
Input pixels
obytes
Output bytes
width
Number of pixels
clearto
Initial value of bytes
bit
Bit to check

cupsPackVertical

Pack pixels vertically...

void cupsPackVertical (
    const unsigned char *ipixels,
    unsigned char *obytes,
    int width,
    const unsigned char bit,
    const int step
);

Parameters

ipixels
Input pixels
obytes
Output bytes
width
Number of input pixels
bit
Output bit
step
Number of bytes between columns

cupsRGBDelete

Delete a color separation.

void cupsRGBDelete (
    cups_rgb_t *rgbptr
);

Parameters

rgbptr
Color separation

cupsRGBDoGray

Do a grayscale separation...

void cupsRGBDoGray (
    cups_rgb_t *rgbptr,
    const unsigned char *input,
    unsigned char *output,
    int num_pixels
);

Parameters

rgbptr
Color separation
input
Input grayscale pixels
output
Output Device-N pixels
num_pixels
Number of pixels

cupsRGBDoRGB

Do a RGB separation...

void cupsRGBDoRGB (
    cups_rgb_t *rgbptr,
    const unsigned char *input,
    unsigned char *output,
    int num_pixels
);

Parameters

rgbptr
Color separation
input
Input RGB pixels
output
Output Device-N pixels
num_pixels
Number of pixels

cupsRGBLoad

Load a RGB color profile from a PPD file.

cups_rgb_t *cupsRGBLoad (
    ppd_file_t *ppd,
    const char *colormodel,
    const char *media,
    const char *resolution
);

Parameters

ppd
PPD file
colormodel
Color model
media
Media type
resolution
Resolution

Return Value

New color profile

cupsRGBNew

Create a new RGB color separation.

cups_rgb_t *cupsRGBNew (
    int num_samples,
    cups_sample_t *samples,
    int cube_size,
    int num_channels
);

Parameters

num_samples
Number of samples
samples
Samples
cube_size
Size of LUT cube
num_channels
Number of color components

Return Value

New color separation or NULL

Data Types

cups_cmyk_t

Simple CMYK lookup table

typedef struct cups_cmyk_s cups_cmyk_t;

cups_dither_t

Dithering State

typedef struct cups_dither_s cups_dither_t;

cups_lut_t

Lookup Table for Dithering

typedef struct cups_lut_s cups_lut_t;

cups_rgb_t

Color separation lookup table

typedef struct cups_rgb_s cups_rgb_t;

cups_sample_t

Color sample point

typedef struct cups_sample_s cups_sample_t;

Structures

cups_cmyk_s

Simple CMYK lookup table

struct cups_cmyk_s {
    unsigned char black_lut[256];
    short *channels[CUPS_MAX_CHAN];
    unsigned char color_lut[256];
    int ink_limit;
    int num_channels;
};

Members

black_lut[256]
Black generation LUT
channels[CUPS_MAX_CHAN]
Lookup tables
color_lut[256]
Color removal LUT
ink_limit
Ink limit
num_channels
Number of components

cups_dither_s

Dithering State

struct cups_dither_s {
    int errors[96];
    int row;
    int width;
};

Members

errors[96]
Error values
row
Current row
width
Width of buffer

cups_lut_s

Lookup Table for Dithering

struct cups_lut_s {
    int error;
    short intensity;
    short pixel;
};

Members

error
Error from desired value
intensity
Adjusted intensity
pixel
Output pixel value

cups_rgb_s

Color separation lookup table

struct cups_rgb_s {
    unsigned char black[CUPS_MAX_RGB];
    int cache_init;
    unsigned char ****colors;
    int cube_index[256];
    int cube_mult[256];
    int cube_size;
    int num_channels;
    unsigned char white[CUPS_MAX_RGB];
};

Members

black[CUPS_MAX_RGB]
Cached black (sRGB = 0,0,0)
cache_init
Are cached values initialized?
colors
4-D array of sample values
cube_index[256]
Index into cube for a given sRGB value
cube_mult[256]
Multiplier value for a given sRGB value
cube_size
Size of color cube (2-N) on a side
num_channels
Number of colors per sample
white[CUPS_MAX_RGB]
Cached white (sRGB = 255,255,255)

cups_sample_s

Color sample point

struct cups_sample_s {
    unsigned char colors[CUPS_MAX_RGB];
    unsigned char rgb[3];
};

Members

colors[CUPS_MAX_RGB]
Color values
rgb[3]
sRGB values

Variables

cups_scmy_lut[256]

sRGB gamma lookup table (inverted)

extern const unsigned char cups_scmy_lut[256];

cups_srgb_lut[256]

sRGB gamma lookup table

extern const unsigned char cups_srgb_lut[256];