1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
|
/******************************************************************************
File: $Id: gdeveprn.h,v 1.23 2001/04/30 05:15:51 Martin Rel $
Contents: Header file for the abstract ghostscript device 'eprn'
Author: Martin Lottermoser, Greifswaldstrasse 28, 38124 Braunschweig,
Germany; e-mail: Martin.Lottermoser@t-online.de.
*******************************************************************************
* *
* Copyright (C) 2000, 2001 by Martin Lottermoser *
* All rights reserved *
* *
*******************************************************************************
The 'eprn' device
*****************
In developing my hpdj/pcl3 driver for PCL 3+ I had to implement a lot of
functionality which was logically independent of PCL. This indicated that the
functionality offered by ghostscript's 'prn' device was insufficient and
should be extended, leading to this "extended prn device".
Functionality
=============
The "eprn" device offers the following services to derived devices:
- A simple but still flexible rendering model. A derived device defines
printer capability descriptions listing the supported rendering parameters,
lets the eprn device handle the user's rendering requests, and then just
fetches the pixels.
- A PostScript-conforming initialization of default user space with respect
to landscape orientation and support for the standard page device parameter
"LeadingEdge".
- Recognition of media sizes from the document and checking of supported
sizes based on printer descriptions
- Flexible handling of size-specific hardware margins
- Counting of pages printed across gs invocations by means of page count
files
Rendering Model
===============
The "eprn" device parameterizes the printer's rendering capabilities as
follows:
- process colour model (Gray, RGB, CMY, CMY+K, CMYK)
- resolution in horizontal and vertical directions
- number of intensity levels per colorant, chosen independently for black
and non-black (RGB or CMY) colorants.
In addition, the rendering process as implemented in this driver is
parameterized by:
- method for rendering intensities (printer, halftones or error diffusion)
These parameters are specified by the user. The device checks whether the
printer supports the requested combination and, if it does, sets
ghostscript's internal data structures accordingly.
The derived device can obtain the resulting pixels by successively calling
eprn_get_planes() from the page printing procedure.
Device Coordinates
==================
"Pixmap device space" is the coordinate system used by the "prn" device for
generating a pixmap and implicit in the API for accessing it (e.g.,
gdev_prn_copy_scan_lines()). In identifying the directions "left", "bottom",
"right" and "top" I'm assuming that the x axis is pointing to the right and
the y axis downwards. This is not concerned with the orientation of device
space on a sheet printed but is merely a definition of what, e.g., "down"
means for the eprn device: it is defined as "towards increasing prn y values".
This makes the code more readable for the case where the real device
coordinate system (on the sheet) has just this orientation. Too bad for the
others :-).
Terms like "width" and "height" are also defined with respect to this
interpretation, i.e., "width" is an extension in x direction.
Note that names and interpretations of some of ghostscript's standard
device structure fields (like 'width', 'height') are also based on this
convention although this is not explicitly stated. This does however not
apply to all parameters: for example, HWMargins[] and MediaSize[] are to be
interpreted in default user space (see gx_default_clip_box()).
One key assumption of the eprn device is that the top edge of pixmap device
space is the edge closest to and parallel with the medium's leading edge.
It is the responsibility of the derived device to ensure this. Usually
it means that raster lines have to be printed in the order of ascending y.
(The eprn device will work if the derived device violates this condition, but
the meaning of user-visible properties of the device would change.)
The device sets up the device coordinate system such that the device space
origin is the top left corner of the imageable area where "top" and "left"
refer to you holding the sheet with the printed side towards you and the
leading edge at the top. Units and directions are identical with pixmap
device space.
Page Descriptions
=================
When a PostScript document requests a particular page size by specifying its
width and height in default user space the eprn device combines this
information with certain conditions imposed by the derived device and looks
for a matching page description entry in the printer's capability
description. The following information from such an entry is needed for
correctly setting up the relation between default user space and device space:
- default orientation of the sheet in pixmap device space
(MS_TRANSVERSE_FLAG; set iff the sheet has width > height in pixmap
device space)
- hardware margins
This part is interpreted by the eprn device.
In addition, a page description entry may contain a number of flags
indicating special conditions under which this entry is to be selected or
carrying information on how to configure the printer. The flags are those
defined by mediasize.h (except that MS_TRANSVERSE_FLAG and MS_ROTATED_FLAG
may not be used for this purpose), their interpretation is up to the derived
device which must request them or to which they will become visible when the
entry is selected.
The eprn device takes the following items as the request to be matched with a
page description entry in the printer's capability description:
- the media size of the document and, if set, the "LeadingEdge" page device
parameter
- a pattern of desired (not necessarily *required*) flags
- an ordered list of optional flags
Media size and LeadingEdge are set via PostScript or the command line, the
flags can be set by the derived device through its device structure instance
or by calling eprn_set_media_flags(). The optional flags when combined with
the bitwise OR effectively define a mask of bits which may be ignored when
checking whether an entry matches the desired flags. The order of optional
flags is from most to least desirable to ignore.
The complete request is compared to the list of page descriptions as follows:
1. If the media size, irrespective of flags, cannot be matched at 5 bp
tolerance, the request fails with an error message to standard error.
2. Otherwise a shortened list containing all entries having a matching
size is compiled, at least conceptually. If the device supports custom
page sizes, they are listed at the end. This is the "base list".
3. If LeadingEdge is not null, the MS_TRANSVERSE_FLAG is set or cleared
accordingly in the pattern of desired flags. This flag is also always
added to the front of the list of optional flags.
4. A mask of flags to be ignored is set to zero.
5. The base list is searched for an entry agreeing with the desired flags
except possibly for those in the ignore mask.
6. If no such entry is found, the next flag in the list of optional flags is
added to the ignore mask and execution continues with step 5. If there is
no such flag, the request fails and the flag mismatch reporting function
is called (see below).
7. If a matching entry is found the list of optional flags is processed
backwards starting with the flag before the last one added to the ignore
mask. For each such flag an attempt is made to remove it from the mask.
If there still is at least one matching entry in the base list the flag
remains cleared, otherwise it is put back into the mask.
8. Finally, the first entry matching the request mask and the current
ignore mask will be selected:
- its media code will be made available to the derived device in the
eprn device's 'code' field,
- the hardware margins will be set from the page description (unless the
user has explicitly specified a value for the ".HWMargins" page device
parameter),
- default user space will be configured based on sheet orientation
(transverse or not in device space) and page orientation (portrait or
landscape in default user space).
Because the error message in step 6 has to report a mismatch on the flags
and because the interpretation of the flags is fixed by the derived device,
an error message issued by the eprn device may not be particularly
illuminating to the user (the user will usually think in terms of the
interpretation the derived device associates with these flags). Therefore
issuing this error message can be delegated to a function ("flag mismatch
reporting function") specified by the derived device in its device structure
instance.
******************************************************************************/
#ifndef _gdeveprn_h /* Inclusion protection */
#define _gdeveprn_h
/*****************************************************************************/
/* Special Aladdin header, must be included before <sys/types.h> on some
platforms (e.g., FreeBSD). This necessity seems to be triggered for example
by <stdio.h>. */
#include "std.h"
/* Standard headers */
#include <stdio.h> /* for 'FILE' and 'size_t' */
/* Ghostscript headers */
#include "gdevprn.h"
/* This header is assumed to include a definition for 'bool' (stdpre.h). */
/* Other header files */
#include "mediasize.h"
/*****************************************************************************/
/* Types to describe supported page sizes and associated setup information.
All sizes are in bp and all orientations refer to pixmap device space.
*/
/* Discrete page sizes */
typedef struct {
ms_MediaCode code;
/* The media flags in 'code' identify the conditions under which the size
is supported ("required flags") and carry information needed in order
to adapt ghostscript or the printer to using this entry ("optional
flags"). The distinction between the two groups of flags is fixed by the
derived device when calling eprn_set_media_flags() except that special
rules apply to MS_TRANSVERSE_FLAG which is handled by eprn.
Setting MS_TRANSVERSE_FLAG indicates that media of this size are normally
fed such that width > height in pixmap device space, otherwise
width <= height is assumed.
Setting MS_ROTATED_FLAG is not permitted.
The interpretation of all other flags is up to the derived device.
*/
float left, bottom, right, top;
/* Hardware margins (non-negative) in bp */
} eprn_PageDescription;
/* Custom page sizes */
typedef struct {
/* The first two lines have the same meaning as for 'eprn_PageDescription'.
However, apart from flags, the 'code' field must be 'ms_CustomPageSize'.
*/
ms_MediaCode code;
float left, bottom, right, top;
float width_min, width_max, height_min, height_max;
/* Permissible range in bp for width and height when a sheet's dimension is
given such that width <= height. */
} eprn_CustomPageDescription;
/*
Here follows an example of using "eprn_PageDescription". It describes a
printer supporting A4 and US Letter, the first with 5 mm margins, the latter
with 0.2 inches:
const eprn_PageDescription page_description[] = {
{ms_A4, 5*BP_PER_MM, 5*BP_PER_MM, 5*BP_PER_MM, 5*BP_PER_MM},
{ms_Letter, 0.2*BP_PER_IN, 0.2*BP_PER_IN, 0.2*BP_PER_IN, 0.2*BP_PER_IN},
{ms_none, 0, 0, 0, 0}
};
The last entry is a sentinel value which will be required later.
******************************************************************************/
/* Types to describe supported combinations of resolutions, process colour
models and intensity levels per colorant
These types often contain pointers to lists terminated with a sentinel
value. As these are usually static data, this makes it easier to share data
between printer descriptions.
*/
/* Process colour models */
typedef enum {
eprn_DeviceGray,
eprn_DeviceRGB,
eprn_DeviceCMY,
eprn_DeviceCMY_plus_K,
/* 'eprn_DeviceCMY_plus_K' is a process colour model using the CMYK
colorants but never mixing black with one of the others. The underlying
native colour space is 'DeviceRGB'. */
eprn_DeviceCMYK
} eprn_ColourModel;
/* Horizontal and vertical resolutions w.r.t. pixmap device space */
typedef struct {
float h, v;
} eprn_Resolution;
/* Range for the number of intensity levels */
typedef struct {
unsigned short from, to; /* both inclusive */
} eprn_IntensityLevels;
/* Combined resolutions and intensities. Any combination of the listed
resolutions and the listed intensity levels is permitted. */
typedef struct {
const eprn_Resolution *resolutions;
/* either NULL (all resolutions are accepted) or a list terminated with
a {0.0, 0.0} entry */
const eprn_IntensityLevels *levels;
/* non-NULL; this list is terminated with {0, 0}. The variable is a list in
order to permit easier specification of discrete levels. */
} eprn_ResLev;
/* A complete instance of a rendering capability entry */
typedef struct {
eprn_ColourModel colour_model;
/* A value of 'eprn_DeviceCMYK' implies the capability for
'eprn_DeviceCMY_plus_K' because the difference is realized in this driver
and is not part of the printer's capabilities.
In contrast, 'eprn_DeviceCMY_plus_K' or 'eprn_DeviceCMYK' do *not* imply
the capability for CMY or Gray! This is because we assume that
'colour_model' corresponds to particular hardware settings for the
printer.
*/
const eprn_ResLev *info[2];
/* Supported resolutions and intensities indexed by colorant. The first
entry refers to black except for eprn_DeviceRGB and eprn_DeviceCMY when
it describes the three non-black colorants. The second entry is ignored
unless both black and non-black colorants are used in which case it can
either refer to the latter or be NULL to indicate that the black entry
applies also to the non-black colorants.
Any non-null info[] points to a list terminated with a {NULL, NULL} entry.
Only values for those colorants described by different (non-NULL) 'info'
entries in an instance of this type can be chosen independently. Hence at
most black can have values different from those of the other colorants.
*/
} eprn_ColourInfo;
/*
As an example application of these types, consider a bilevel device
supporting 600 ppi monochrome printing:
const eprn_Resolution sixhundred[] = { {600, 600}, {0, 0}};
const eprn_IntensityLevels bilevel[] = { {2, 2}, {0, 0}};
const eprn_ResLev rl_600_2[] = { {sixhundred, bilevel}, {NULL, NULL}};
const eprn_ColourInfo mono_600_2[] = {
{eprn_DeviceGray, {rl_600_2, NULL}},
{eprn_DeviceGray, {NULL, NULL}}
};
******************************************************************************/
/* Printer capability description */
typedef struct {
const char *name;
/* This string is used in error messages generated by the device. It should
describe the printer, not a gs device. In selecting an appropriate value
imagine a statement like "... is not supported by the <name>" or "The
<name> does not support ...".
*/
/* Media sizes and hardware margins */
const eprn_PageDescription *sizes;
/* List of supported discrete media sizes and associated hardware margins,
terminated by an entry with 'code' == ms_none. This must always be
non-NULL. */
const eprn_CustomPageDescription *custom;
/* This may be NULL, in which case the printer does not support custom
page sizes. Otherwise it is a list of entries, terminated with an entry
having 0.0 for 'width_max'. */
float bottom_increment;
/* Change of bottom hardware margin when not printing in DeviceGray,
specified in bp. This correction is ignored if the bottom margin is
exactly zero.
Some HP DeskJets have a larger hardware margin at the bottom for the
colour cartridge but this is not the case for banner printing. */
/* Colour capabilities */
const eprn_ColourInfo *colour_info;
/* List of supported colour models, resolutions and intensity levels.
This must always be non-NULL and terminated with an entry having NULL as
'info[0]'. There must be at least one 'eprn_ColourInfo' entry permitting
identical resolution for all colorants.
*/
} eprn_PrinterDescription;
/*
To continue our series of examples, here is a complete printer description:
const eprn_PrinterDescription description = {
"Wrzlbrnf printer", page_description, NULL, 0, mono_600_2
};
******************************************************************************/
/* Intensity rendering methods */
typedef enum {
eprn_IR_printer,
eprn_IR_halftones,
eprn_IR_FloydSteinberg
} eprn_IR;
/*****************************************************************************/
/* Unsigned 8-bit values (should really be 'uint8_t') */
typedef unsigned char eprn_Octet;
/* Octet strings */
typedef struct {
eprn_Octet *str;
int length; /* zero or the length in 'eprn_Octet' instances of the area
filled starting at '*str' */
} eprn_OctetString;
/* Type for flag mismatch reporting function */
struct s_eprn_Device;
/* The preceding statement is needed in order to establish a forward
declaration for "struct s_eprn_Device" at file scope. */
typedef void (*eprn_FlagMismatchReporter)(const struct s_eprn_Device *dev,
bool no_match);
/* A function of this kind will be called if the requested media flags cannot
be satisfied by the printer although the size itself is supported for some
(unspecified) set of flags. The parameter 'no_match' indicates whether the
printer supports the set of required flags for some size or not at all
(this is intended to be useful in the case of flags denoting printer
capabilities). The requested set of media selection flags is available in
'dev->eprn.desired_flags' and 'dev->eprn.optional_flags' (MS_ROTATED_FLAG
will never be set).
The function must write an error message.
*/
/*****************************************************************************/
/* The eprn device variables. These are deliberately defined as a structure
and not as usual in ghostscript as a macro body to be inserted into a
structure because I want to have namespace isolation for these fields.
A derived device may read any of these parameters but should never change
them directly. The only exception is 'soft_tumble'.
*/
typedef struct s_eprn_Device {
/* Capabilities */
const eprn_PrinterDescription *cap;
/* non-NULL. The data pointed to may not change unless this is immediately
followed by a call to eprn_init_device(). */
char *media_file;
/* gs_malloc()-allocated media configuration file name.
Non-NULL if 'media_overrides' is non-NULL. */
eprn_PageDescription *media_overrides;
/* A list of supported media dimensions and corresponding hardware margins.
This is usually NULL, meaning that 'cap->sizes' and 'cap->custom' should
be used.
If non-NULL, 'media_overrides' must be terminated with an entry having
'code' == ms_none. If this field is non-NULL, only the sizes listed here
will be supported. The device will support custom page sizes only if
'cap->custom' is not NULL and 'media_overrides' contains an entry for
'ms_CustomPageSize'.
The pointer refers to gs_malloc()-allocated storage.
*/
/* Page setup */
const ms_Flag *flag_desc;
/* Description of the additional flags the derived device understands. This
can be NULL or a list terminated with an entry having 'code' equal to
'ms_none'. */
ms_MediaCode
desired_flags;
const ms_MediaCode
*optional_flags; /* may be NULL; terminated with 'ms_none'. */
eprn_FlagMismatchReporter fmr; /* may be NULL */
ms_MediaCode code;
/* Page size and other media attributes determined based on printer
capabilities. A value of 'ms_none' indicates that the page description
entry to be used has not (yet) been successfully identified and that
therefore some of the other fields in this structure are not valid. */
/* Coordinates */
int default_orientation;
/* Direction of the positive y axis of default default user space (the
requested PageSize had width <= height) as seen from pixmap device space:
0 up
1 left
2 down
3 right
Hence the value is the number of +90 degrees rotations necessary to
obtain the "up" direction of default default user space (positive y axis)
from the "up" direction of pixmap device space (negative y axis).
The values 0 and 2 imply that the medium has width <= height in pixmap
device space, 1 and 3 imply height <= width. */
bool leading_edge_set;
/* True iff someone set the 'LeadingEdge' page device parameter. In this
case its value is stored in 'default_orientation'. The values permitted
for 'default_orientation' and their interpretation are chosen such that
this gives the desired result.
If this value is false, the device will select a value for
'default_orientation' based on the MS_TRANSVERSE_FLAG in 'code'. */
float
right_shift,
down_shift;
/* Seen from pixmap device space, the top left corner of the sheet is at
(-right_shift, -down_shift). Both values are in bp and represent
hardware margins, i.e., the origin of pixmap device space is a corner
of the sheet's imageable area.
These parameters are logically superfluous and could be derived from
'HWMargins[]' and possibly other data (like 'default_orientation'),
provided one knows what the reference system for 'HWMargins[]' is.
This is not documented but it seems to be default user space. In order
to have values with a reliable interpretation and because the data are
originally given in pixmap device space anyway I have introduced these
variables. */
bool keep_margins;
/* True iff margin information should be taken from 'HWMargins[]' instead
of from the printer description. */
bool soft_tumble;
/* If this field is set, every second page will have its default user
coordinate system rotated by 180 degrees. */
dev_proc_fillpage((*orig_fillpage));
/* Colour */
eprn_ColourModel
colour_model; /* Colour model selected */
unsigned int
black_levels, /* Number of intensity levels for black colorant */
non_black_levels; /* Number of intensity levels for non-black colorants */
eprn_IR
intensity_rendering; /* method to use */
/* Page counting and other spooler support */
char
*pagecount_file; /* gs_malloc()-allocated name of page count file.
May be NULL. */
bool
CUPS_accounting, /* Send CUPS page accounting messages. */
CUPS_messages; /* Add CUPS message prefixes to error messages and
warnings. */
/* Support for the standard page device parameter "MediaPosition" */
bool media_position_set;
int media_position;
/* Internal parameters. These have reliable values only after a successful
call to eprn_open(). */
unsigned int
bits_per_colorant; /* Number of bits per colorant used in 'gx_color_index'
values. Constant while the device is open. */
eprn_OctetString
scan_line, /* 'str' is gs_malloc()-allocated */
next_scan_line; /* 'str' is gs_malloc()-allocated. Non-null only for
Floyd-Steinberg error diffusion. */
unsigned int
octets_per_line, /* Constant while the device is open. */
output_planes; /* Constant while the device is open. */
int next_y; /* During a call to eprn_output_page(), the device y
coordinate for the next scan line to fetch from the "prn" device. For
eprn_IR_FloydSteinberg, the next scan line to return is actually already
present in 'next_scan_line' with its device coordinate being "next_y - 1",
unless 'next_y' is zero in which case we have finished. */
gs_gstate * pgs;
} eprn_Eprn;
/* Macro for device structure type definitions. Note that in contrast to
gx_prn_device_common this macro does include the inherited attributes. */
#define gx_eprn_device_common \
gx_device_common; /* Attributes common to all devices */ \
gx_prn_device_common; /* Attributes for all printers */ \
eprn_Eprn eprn
/* Base type needed for casts */
typedef struct {
gx_eprn_device_common;
} eprn_Device;
#define private_st_device_EPRN(eprn_enum, eprn_reloc) \
gs_private_st_composite(st_eprn_Device, eprn_Device, \
"eprn_Device", eprn_enum, eprn_reloc);
/* Macro for initializing device structure instances (device prototypes)
This macro corresponds to the prn_device*() macros which are used when
basing a device directly on the prn device.
The parameters are:
dtype: identifier of the device structure type
procs: pointer to static device procedure table
(const gx_device_procs *, not NULL)
dname: name of the device (const char *, not NULL)
xdpi: horizontal resolution in ppi (float, positive)
ydpi: vertical resolution in ppi (float, positive)
print_page: page printing procedure to be called by
gdev_prn_output_page(), not NULL
cap: pointer to printer capability description
(const eprn_PrinterDescription *, not NULL, the description may
not change until immediately before the next call to
eprn_init_device())
flag_desc description of the non-standard flags the derived device
accepts (const ms_Flag *, may be NULL, otherwise terminated
with an entry having 'ms_none' for 'code')
desired pattern of desired media flags (ms_MediaCode)
optional NULL or a list of optional media flags (const ms_MediaCode *)
terminated with an 'ms_none' value
fmr NULL or pointer to a flag mismatch reporting function
(eprn_FlagMismatchReporter)
All storage referred to by pointers remains under the control of the
derived device and should not be modified during the lifetime of the
device unless explicitly permitted.
This macro assumes that it is dealing with a printer supporting at least
DeviceGray with 2 intensity levels and the page size described by
(DEFAULT_WIDTH_10THS, DEFAULT_HEIGHT_10THS), usually US Letter or ISO A4.
This is also the initial state. If a derived device wishes to use another
initial state, it should define its own macro.
*/
#define eprn_device_initdata(dtype, procs, dname, xdpi, ydpi, print_page, cap, flag_desc, desired, optional, fmr) \
prn_device_std_body( \
dtype, \
procs, \
dname, \
DEFAULT_WIDTH_10THS, \
DEFAULT_HEIGHT_10THS, \
xdpi, ydpi, \
0.0, 0.0, 0.0, 0.0, /* margins */ \
1, /* color_info.depth */ \
print_page), \
{ \
cap, /* cap */ \
NULL, /* media_file */ \
NULL, /* media_overrides */ \
flag_desc, /* flag_desc */ \
desired, /* desired_flags */ \
optional, /* optional_flags */ \
fmr, /* fmr */ \
ms_none, /* code */ \
0, /* default_orientation */\
false, /* leading_edge_set */ \
0.0, /* right_shift */ \
0.0, /* down_shift */ \
false, /* keep_margins */ \
false, /* soft_tumble */ \
NULL, /* orig_fillpage */ \
eprn_DeviceGray, /* colour_model */ \
2, /* black_levels */ \
0, /* non_black_levels */ \
eprn_IR_halftones, /* intensity_rendering */ \
NULL, /* pagecount_file */ \
false, /* CUPS_accounting */ \
false, /* CUPS_messages */ \
false, /* media_position_set */\
0, /* media_position */ \
0, /* bits_per_colorant */ \
{NULL, 0}, /* scan_line */ \
{NULL, 0}, /* next_scan_line */ \
0, /* octets_per_line */ \
0, /* output_planes */ \
0, /* next_y */ \
NULL /* pgs */ \
}
/* For the calling conventions of the following functions consult the comments
preceding each function's implementation. */
/* Initialize the eprn device for another printer model */
extern void eprn_init_device(eprn_Device *dev,
const eprn_PrinterDescription *desc);
/* Modify the information on supported media sizes and associated hardware
margins by reading new values from a file */
extern int eprn_set_media_data(eprn_Device *dev, const char *media_file,
size_t length);
/* Set media flags */
extern void eprn_set_media_flags(eprn_Device *dev, ms_MediaCode desired,
const ms_MediaCode *optional);
/*****************************************************************************/
/* Device procedures */
extern dev_proc_open_device(eprn_open_device);
extern dev_proc_get_initial_matrix(eprn_get_initial_matrix);
extern dev_proc_output_page(eprn_output_page);
extern dev_proc_close_device(eprn_close_device);
extern dev_proc_map_rgb_color(eprn_map_rgb_color_for_RGB);
extern dev_proc_map_rgb_color(eprn_map_rgb_color_for_RGB_flex);
extern dev_proc_map_rgb_color(eprn_map_rgb_color_for_RGB_max);
extern dev_proc_map_rgb_color(eprn_map_rgb_color_for_CMY_or_K);
extern dev_proc_map_rgb_color(eprn_map_rgb_color_for_CMY_or_K_flex);
extern dev_proc_map_rgb_color(eprn_map_rgb_color_for_CMY_or_K_max);
extern dev_proc_map_color_rgb(eprn_map_color_rgb);
extern dev_proc_get_params(eprn_get_params);
extern dev_proc_put_params(eprn_put_params);
extern dev_proc_map_cmyk_color(eprn_map_cmyk_color);
extern dev_proc_map_cmyk_color(eprn_map_cmyk_color_flex);
extern dev_proc_map_cmyk_color(eprn_map_cmyk_color_max);
extern dev_proc_map_cmyk_color(eprn_map_cmyk_color_glob);
extern dev_proc_fillpage(eprn_fillpage);
/* Macro for initializing device procedure tables
This macro corresponds to the macro prn_params_procs() which is used when
basing a device directly on the prn device.
If your device does not need all of the procedures in the argument list,
use the following defaults:
p_open: eprn_open_device
p_close: eprn_close_device
p_get_params: eprn_get_params
p_put_params: eprn_put_params
On the other hand, if your driver needs its own procedure in any of these
cases its code must also call the appropriate default routine.
*/
#define eprn_procs_initdata(p_open, p_close, p_get_params, p_put_params) \
p_open, /* open_device */ \
eprn_get_initial_matrix, /* get_initial_matrix */ \
NULL, /* sync_output */ \
eprn_output_page, /* output_page */ \
p_close, /* close_device */ \
eprn_map_rgb_color_for_CMY_or_K, /* map_rgb_color */ \
eprn_map_color_rgb, /* map_color_rgb */ \
NULL, /* fill_rectangle */ \
NULL, /* tile_rectangle */ \
NULL, /* copy_mono */ \
NULL, /* copy_color */ \
NULL, /* draw_line */ \
NULL, /* get_bits */ \
p_get_params, /* get_params */ \
p_put_params, /* put_params */ \
eprn_map_cmyk_color_glob, /* map_cmyk_color */ \
NULL, /* get_xfont_procs */ \
NULL, /* get_xfont_device */ \
NULL, /* map_rgb_alpha_color */ \
gx_page_device_get_page_device, /* get_page_device */ \
NULL, /* get_alpha_bits */ \
NULL, /* copy_alpha */ \
NULL, /* get_band */ \
NULL, /* copy_rop */ \
NULL, /* fill_path */ \
NULL, /* stroke_path */ \
NULL, /* fill_mask */ \
NULL, /* fill_trapezoid */ \
NULL, /* fill_parallelogram */ \
NULL, /* fill_triangle */ \
NULL, /* draw_thin_line */ \
NULL, /* begin_image */ \
NULL, /* image_data */ \
NULL, /* end_image */ \
NULL, /* strip_tile_rectangle */ \
NULL, /* strip_copy_rop */ \
NULL, /* get_clipping_box */ \
NULL, /* begin_typed_image */ \
NULL, /* get_bits_rectangle */ \
NULL, /* map_color_rgb_alpha */ \
NULL, /* create_compositor */ \
NULL, /* get_hardware_params */ \
NULL, /* text_begin */ \
NULL, /* finish_copydevice */ \
NULL, /* begin_transparency_group */ \
NULL, /* end_transparency_group */ \
NULL, /* begin_transparency_mask */ \
NULL, /* end_transparency_mask */ \
NULL, /* discard_transparency_layer */\
NULL, /* get_color_mapping_procs */ \
NULL, /* get_color_comp_index */ \
NULL, /* encode_color */ \
NULL, /* decode_color */ \
NULL, /* pattern_manage */ \
NULL, /* fill_rectangle_hl_color */ \
NULL, /* include_color_space */ \
NULL, /* fill_linear_color_scanline */\
NULL, /* fill_linear_color_trapezoid */ \
NULL, /* fill_linear_color_triangle */\
NULL, /* update_spot_equivalent_colors */\
NULL, /* ret_devn_params */ \
eprn_fillpage /* fillpage */
/* The remaining fields should be NULL. */
/*****************************************************************************/
/* Access to pixels
Of course, you could also use the prn interface to obtain pixel values.
This, however, requires information on how eprn interprets 'gx_color_index'
values (see eprnrend.c for a description) and bypasses all processing steps
(error diffusion and the clipping of null bytes) which happen in
eprn_get_planes().
*/
/* Number of bits and hence bit planes used to represent 'levels' intensity
levels in eprn_get_planes(). The return values are independent of the
device's state. */
extern unsigned int eprn_bits_for_levels(unsigned int levels);
/* Total number of bit planes written by eprn_get_planes().
The value returned is reliable only after the eprn part of the device has
been successfully opened. The value remains constant while the device is
open and equals the sum of eprn_bits_for_levels() for all colorants. */
extern unsigned int eprn_number_of_bitplanes(eprn_Device *dev);
/* Maximal lengths, in terms of the number of 'eprn_Octet' instances, for each
bit plane returned by eprn_get_planes() for this device.
These values are reliable after the eprn part of the device has been
successfully opened and remain constant while the device is open.
The array 'lengths' must have at least the length returned by
eprn_number_of_bitplanes(). */
extern void eprn_number_of_octets(eprn_Device *dev, unsigned int lengths[]);
/* The following function may be called only from the page printing procedure
(see the macro eprn_device_initdata() above). For every invocation of that
procedure, the first call of this function returns the scan line with
device coordinate y = 0, subsequent invocations return the lines with the
y coordinate incremented by 1 for every call.
This function returns each scan line split into bit planes and stored into
the areas pointed to by the 'bitplanes' array. The order of colorants is
(K)(CMY) or RGB, where the parentheses indicate optional groups, depending
on the colour model. Within each colorant, bit planes are stored from least
to most significant. The number of bit planes per colorant is given by
eprn_bits_for_levels(levels) where 'levels' is the number of intensity
levels for this colorant.
If the bit planes for a particular colorant result in the value zero for a
certain pixel, this indicates a complete absence of that colorant for this
pixel. The highest possible value is one less than the number of intensity
levels for that colorant.
The 'str' entries in the 'bitplanes' array must be non-NULL and point to
storage areas of a length sufficient to hold the number of octets as
returned by eprn_number_of_octets(). The 'length' entries will be set such
that there will be no trailing zero octets in the octet strings returned.
Bits are stored in an octet from most to least signicant bit (left to
right). If a bit plane does not fill an integral number of octets the last
octet will be filled on the right as if there were additional white pixels.
This function returns zero if there was a scan line to be fetched and a
non-zero value otherwise.
*/
extern int eprn_get_planes(eprn_Device *dev, eprn_OctetString bitplanes[]);
/*****************************************************************************/
/* Auxiliary types and functions for parameter processing */
/* Type to describe an association between a string and an integer */
typedef struct {
const char *name;
int value;
} eprn_StringAndInt;
/* Routines on 'eprn_StringAndInt' arrays
These are used to map names to integers and vice versa. It is possible to
have several names for the same value. The first name given in the array
for a particular 'value' is the canonical name for this value, i.e. the one
returned by the eprn_get_string() routine.
The arrays must be terminated by entries with a NULL pointer for 'name'.
*/
struct gs_param_string_s; /* Forward declaration */
extern int eprn_get_string(int in_value, const eprn_StringAndInt *table,
struct gs_param_string_s *out_value);
extern int eprn_get_int(const struct gs_param_string_s *in_value,
const eprn_StringAndInt *table, int *out_value);
/*****************************************************************************/
/* CUPS message prefixes */
#define CUPS_ERRPREF "ERROR: "
#define CUPS_WARNPREF "WARNING: "
/*****************************************************************************/
/* Selection character for tracing */
#ifndef EPRN_TRACE_CHAR
#define EPRN_TRACE_CHAR '_'
#endif /* !EPRN_TRACE_CHAR */
/* Debugging function */
struct gs_param_list_s;
extern void eprn_dump_parameter_list(struct gs_param_list_s *plist);
/* Internal data structures */
extern const eprn_StringAndInt eprn_colour_model_list[];
/* Internal functions */
extern int eprn_set_page_layout(eprn_Device *dev);
extern int eprn_check_colour_info(const eprn_ColourInfo *list,
eprn_ColourModel *model, float *hres, float *vres,
unsigned int *black_levels, unsigned int *non_black_levels);
extern int eprn_fetch_scan_line(eprn_Device *dev, eprn_OctetString *line);
extern void eprn_finalize(bool is_RGB, unsigned int non_black_levels,
int planes, eprn_OctetString *plane, eprn_Octet **ptr, int pixels);
extern void eprn_split_FS(eprn_OctetString *line, eprn_OctetString *next_line,
int max_octets, eprn_ColourModel colour_model, unsigned int black_levels,
unsigned int non_black_levels, eprn_OctetString bitplanes[]);
/*****************************************************************************/
#endif /* Inclusion protection */
|