sane-apple - SANE backend for Apple flatbed scanners
DESCRIPTION
The
sane-apple
library implements a SANE (Scanner Access Now Easy) backend that
provides access to Apple flatbed scanners. At present, the following
scanners are supported from this backend:
--------------- ----- ------------------ ------
AppleScanner 4bit 16 Shades of Gray
OneScanner 8bit 256 Shades of Gray
ColorOneScanner 24bit RGB color 3-pass
Where
special
is either the path-name for the special device that corresponds to a
SCSI scanner. For SCSI
scanners, the special device name must be a generic SCSI device or a
symlink to such a device. Under Linux, such a device name could be
/dev/sga
or
/dev/sge,
for example. See sane-scsi(5) for details.
CONFIGURATION
The
apple.conf
file is a list of options and device names that correspond to Apple
scanners. Empty lines and lines starting with a hash mark (#) are
ignored. See sane-scsi(5) on details of what constitutes a valid
device name.
Options come in two flavors: global and positional ones. Global
options apply to all devices managed by the backend, whereas positional
options apply just to the most recently mentioned device. Note that
this means that the order in which the options appear matters!
SCSI ADAPTER TIPS
SCSI scanners are typically delivered with an ISA SCSI adapter.
Unfortunately, that adapter is not worth much since it is not
interrupt driven. It is sometimes possible to get the supplied card
to work, but without an interrupt line, scanning will put so much load on
the system that it becomes almost unusable for other tasks.
FILES
/etc/sane.d/apple.conf
The backend configuration file (see also description of
SANE_CONFIG_DIR
below).
/usr/lib/sane/libsane-apple.a
The static library implementing this backend.
/usr/lib/sane/libsane-apple.so
The shared library implementing this backend (present on systems that
support dynamic loading).
ENVIRONMENT
SANE_CONFIG_DIR
This environment variable is list of directories where SANE looks
for the configuration file. Under UNIX directory names are
separated by a colon (`:'), under OS/2 by a semi-colon (`;').
If SANE_CONFIG_DIR is not set, SANE defaults to
searching the current working directory (".") and then /etc/sane.d.
If the value of $SANE_CONFIG_DIR ends with the separator
character, the default directories are searched after the directory list.
For example, setting
SANE_CONFIG_DIR
to "/tmp/config:" would result in directories "tmp/config", ".", and
"/etc/sane.d" being searched (in that order).
SANE_DEBUG_APPLE
Controls the debug level. A value of 255 prints
all debug output. Smaller values reduce verbosity. Requires a
library compiled with debug support.
CURRENT STATUS
The apple backend is now in version 0.3 (Tue Jul 21 1998). Since
I only have the AppleScanner and not the other models (OneScanner,
ColorOneScanner) I can only develop/test for the AppleScanner effectively.
However with this release I almost completed the gui part of all scanners.
Most of the functionality is there. At least OneScanner should scan
at the AppleScanner's compatible modes (LineArt, HalfTone, Gray16). My
personal belief is that with a slight touch of debugging the OneScanner
could be actually usable. The ColorOneScanner needs more work. AppleScanner
is of course almost fully supported.
MISSING FUNCTIONALITY
Currently all three models lack upload/download support.
AppleScanner
Cannot up/download a halftone pattern.
OneScanner
Cannot up/download halftone patterns or calibration vectors.
ColorOneScanner
Cannot up/download halftone patterns, calibration vectors,
custom Color Correction Tables (CCT) and of course custom gamma tables.
Park/UnPark (OneScanner, ColorOneScanner)
The above functionalities are missing because I don't
have the hardware to experiment on. Another reason is my lack
of understanding as to how or if the SANE API provide means
to describe any array type besides gamma.
UNSUPPORTED FEATURES
The following "features" will never be supported, at least while I maintain
the sane-apple backend.
NoHome (AppleScanner)
The scanner lamp stays on and the carriage assembly remains where it stops
at the end of the scan. After two minutes, if the scanner does not receive
another SCAN command, the lamp goes off and the carriage returns to the home
position.
Compression (AppleScanner)
The Scanner can compress data with CCITT Group III one dimensional algorithm
(fax) and the Skip White Line algorithm.
Multiple Windows (AppleScanner)
AppleScanner may support multiple windows. It would be a cool feature
and a challenge for me to code if it could intermix different options
for different windows (scan areas). This way it could scan a document
in LineArt mode but the figures in it in Gray and at a different resolution.
Unfortunately this is impossible.
Scan Direction (OneScanner)
It controls the scan direction. (?)
Status/Reset Button (OneScanner)
This option controls the status of the button on the OneScanner model. You can
also reset the button status by software.
BUGS
SANE backend bugs are divided in two classes. We have
GUI
bugs and
scanner specific
bugs.
We know we have a GUI bug when a parameter is not showing up when it
should (active) or vice versa. Finding out which parameters are active
across various Apple modes and models from the documentation
ftp://ftpdev.info.apple.com/devworld/Technical_Documentation/Peripherals_Documentation/
is an interesting exercise. I may have missed some dependencies. For example
of the threshold parameter the Apple Scanners Programming Guide says
nothing. I had to assume it is valid only in LineArt mode.
Scanner specific bugs are mostly due to mandatory round-offs in order to
scan. In the documentation in one place states that the width of the
scan area should be a byte multiple. In another place it says that the
width of the scan area should be an even byte multiple. Go figure...
Other sources of bugs are due to scsi communication, scsi connects and
disconnects. However the classical bugs are still there. So you may
encounter buffer overruns, null pointers, memory corruption and
SANE
API violations.
SIGSEGV on SliceBars
When you try to modify the scan area from the slice bar you have a nice
little cute core dump. I don't know why. If you select the scan area from
the preview window or by hand typing the numbers everything is fine. The
SIGSEGV happens deep in gtk library (gdk). I really cannot debug it.
Options too much
It is possible, especially for the ColorOneScanner, for the backend's
options panel to extend beyond your screen. It happens with mine
and I am running my X Server at 1024x768. What can I say? Try smaller
fonts in the X server, or virtual screens.
Weird SCSI behaviour
I am quoting David Myers Here...
>> OS: FreeBSD 2.2.6
>> CC: egcs-1.02
Just wanted to follow up on this... I recently changed my SCSI card from
the Adaptec 2940UW to a dual-channel Symbios 786 chipset. When I started up
SANE with your driver, I managed to scan line art drawings okay, but Gray16
scans led to a stream of SCSI error messages on the console, ultimately
hanging with a message saying the scanner wasn't releasing the SCSI bus.
This may be that the Symbios is simply less tolerant of ancient
hardware, or may be bugs in your driver or in SANE itself...
DEBUG
If you encounter a GUI bug please set the environmental variable
SANE_DEBUG_APPLE to 255 and rerun the exact sequence of keystrokes
and menu selections to reproduce it. Then send me a report with the
log attached.
If you have an Apple Macintosh with the AppleScanners driver installed,
reporting to me which options are grayed out (inactive) in what modes
would be very helpful.
If you want to offer some help but you don't have a scanner, or you
don't have the model you would like to help with, or you are
a SANE developer and you just want to take a look at how the apple backend
looks like, goto to apple.h and #define the NEUTRALIZE_BACKEND
macro. You can select the scanner model through the APPLE_MODEL_SELECT
macro. Available options are APPLESCANNER, ONESCANNER, COLORONESCANNER.
If you encounter a SCSI bus error or trimmed and/or displaced images please
set the environment variable SANE_DEBUG_SANEI_SCSI to 255 before sending me
the report.
TODO
Non Blocking Support
Make sane-apple a non blocking backend. Properly support
sane_set_io_mode
and
sane_get_select_fd
Scan
Make scanning possible for all models in all supported modes.
The sane-apple backend was written not entirely from scratch by
Milon Firikis. It is mostly based on the mustek backend from
David Mosberger and Andreas Czechanowski
