Ubuntu Manpage: sane-test - SANE backend for testing frontends

NAME

       sane-test - SANE backend for testing frontends

DESCRIPTION

       The  sane-test  library  implements a SANE (Scanner Access Now Easy) backend that allows testing the SANE
       installation and SANE frontends.  It provides access to a (nearly) unlimited number of  virtual  devices.
       There  is  no  support for real scanners or cameras.  However, the backend simulates scanning and setting
       options.

       The idea is not only to find bugs in frontends but also to show  all  capabilities  of  SANE.   Therefore
       sane-test implements functions and options that are not (or seldom) found in other backends.

       The  backend is commented out in /etc/sane.d/dll.conf, so either the comment character must be removed or
       the backend must be called explicitly.  E.g.  scanimage -d test or xscanimage test.

SCAN MODE OPTIONS

Option mode selects the scan mode (Gray or Color).

Option depth determines the number of bits per sample (1. 8, or 16). Keep in mind, that this value
refers to the sample, not the pixel. So depth=16 results in 48 bits per pixel in color mode. The most
usual combinations are mode=Gray, depth=1 for lineart, mode=Gray, depth=8 for gray and mode=Color,
depth=8 for color mode. The combination of color and 1-bit mode is quite obscure (8 colors) but allowed
in the SANE standard. However, the meaning of bits is not defined. Currently 1 = high intensity and 0 =
low intensity is used.

Setting option hand-scanner results in the test-backend behaving like a hand-scanner. Hand-scanners do
not know the image height a priori. Instead, they return a height of -1. Setting this option allows one
to test whether a frontend can handle this correctly. This option also enables a fixed width of 11 cm.

Setting option three-pass simulates a three-pass scanner. Older color scanners needed to scan the image
once per color (red/green/blue) to get the full image. Therefore, in this mode three single frames are
transmitted in color mode.

Option three-pass-order provides support for changing the order of the three frames (see option three-
pass above). A frontend should support all orders.

Option resolution sets the resolution of the image in dots per inch.

Option source can be used to simulate an Automatic Document Feeder (ADF). After 10 scans, the ADF will be
"empty".

SPECIAL OPTIONS

Option test-picture allows one to set the image that's returned to the frontend. While "Solid white" and
"Solid black" are quite obvious, the other options need some more explanation. Color patterns are used
to determine if all modes and their colors are represented correctly by the frontend. The grid should
look like the same in every mode and resolution. A table of all the test pictures can be found at:
http://www.meier-geinitz.de/sane/test-backend/test-pictures.html.

If option invert-endianness is set, the upper and lower bytes of image data in 16 bit modes are
exchanged. This option can be used to test the 16 bit modes of frontends, e.g. if the frontend uses the
correct endianness.

If option read-limit is set, the maximum amount of data transferred with each call to sane_read() is
limited.

Option read-limit-size sets the limit for option read-limit. A low limit slows down scanning. It can be
used to detect errors in frontend that occur because of wrong assumptions on the size of the buffer or
timing problems.

Option read-delay enables delaying data to the frontend.

Option read-delay-duration selects the number of microseconds the backends waits after each transfer of a
buffer. This option is useful to find timing-related bugs, especially if used over the network.

If option read-return-value is different from "Default", the selected status will be returned by every
call to sane_read(). This is useful to test the frontend's handling of the SANE statuses.

If option ppl-loss is different from 0, it determines the number of pixels that are "lost" at the end of
each line. That means, lines are padded with unused data.

Option fuzzy-parameters selects that fuzzy (inexact) parameters are returned as long as the scan hasn't
been started. This option can be used to test if the frontend uses the parameters it got before the
start of the scan (which it shouldn't).

Option non-blocking determines if non-blocking IO for sane_read() should be used if supported by the
frontend.

If option select-fd is set, the backend offers a select filedescriptor for detecting if sane_read() will
return data.

If option enable-test-options is set, a fairly big list of options for testing the various SANE option
types is enabled.

Option print-options can be used to print a list of all options to standard error.

GEOMETRY OPTIONS

       Option tl-x determines the top-left x position of the scan area.

       Option tl-y determines the top-left y position of the scan area.

       Option br-x determines the bottom-right x position of the scan area.

       Option br-y determines the bottom-right y position of the scan area.

BOOL TEST OPTIONS

       There  are  6  bool test options in total.  Each option is numbered.  (3/6) means: this is option 3 of 6.
       The numbering scheme is intended for easier detection of options not displayed by the  frontend  (because
       of missing support or bugs).

       Option bool-soft-select-soft-detect (1/6) is a bool test option that has soft select and soft detect (and
       advanced) capabilities.  That's just a normal bool option.

       Option bool-hard-select-soft-detect (2/6) is a bool test option that has hard select and soft detect (and
       advanced)  capabilities.   That  means  the  option can't be set by the frontend but by the user (e.g. by
       pressing a button at the device).

       Option bool-hard-select (3/6) is a bool test option that has hard  select  (and  advanced)  capabilities.
       That  means  the  option  can't  be set by the frontend but by the user (e.g. by pressing a button at the
       device) and can't be read by the frontend.

       Option bool-soft-detect (4/6) is a bool test option that has soft  detect  (and  advanced)  capabilities.
       That means the option is read-only.

       Option  bool-soft-select-soft-detect-emulated  (5/6)  is  a  Bool  test option that has soft select, soft
       detect, and emulated (and advanced) capabilities.

       Option bool-soft-select-soft-detect-auto (6/6) is a Bool test option that has soft select,  soft  detect,
       and automatic (and advanced) capabilities.  This option can be automatically set by the backend.

INT TEST OPTIONS

       There are 7 int test options in total.

       Option int (1/7) is an int test option with no unit and no constraint set.

       Option  int-constraint-range  (2/7)  is  an  int  test  option  with unit pixel and constraint range set.
       Minimum is 4, maximum 192, and quant is 2.

       Option int-constraint-word-list (3/7) is an int test option with unit bits and constraint word list set.

       Option int-constraint-array (4/7) is an int  test  option  with  unit  mm  and  using  an  array  without
       constraints.

       Option  int-constraint-array-constraint-range (5/7) is an int test option with unit mm and using an array
       with a range constraint.  Minimum is 4, maximum 192, and quant is 2.

       Option int-constraint-array-constraint-word-list (6/7) is an int test option with unit percent and  using
       an array or word list constraint.

       Option  int-inexact  (7/7)  is  an  int  test option that increments the requested value and returns flag
       SANE_INFO_INEXACT.

FIXED TEST OPTIONS

       There are 3 fixed test options in total.

       Option fixed (1/3) is a fixed test option with no unit and no constraint set.

       Option fixed-constraint-range (2/3) is a fixed test option with unit  microsecond  and  constraint  range
       set. Minimum is -42.17, maximum 32767.9999, and quant is 2.0.

       Option fixed-constraint-word-list (3/3) is a fixed test option with no unit and constraint word list set.

STRING TEST OPTIONS

       There are 3 string test options in total.

       Option string (1/3) is a string test option without constraint.

       Option string-constraint-string-list (2/3) is a string test option with string list constraint.

       Option  string-constraint-long-string-list  (3/3)  is  a  string test option with string list constraint.
       Contains some more entries...

BUTTON TEST OPTION

       Option button (1/1) is a Button test option. Prints some text...

FILES

       /etc/sane.d/test.conf
              The backend configuration file (see also description of SANE_CONFIG_DIR below). The initial values
              of most of the basic SANE options can be configured in this file. A template  containing  all  the
              default  values  is provided together with this backend. One of the more interesting values may be
              number_of_devices.  It can be used to check the frontend's ability to show a long list of devices.
              The config values concerning resolution and geometry can be useful to test  the  handling  of  big
              file sizes.

       /usr/lib/x86_64-linux-gnu/sane/libsane-test.a
              The static library implementing this backend.

       /usr/lib/x86_64-linux-gnu/sane/libsane-test.so
              The shared library implementing this backend (present on systems that support dynamic loading).

ENVIRONMENT

       SANE_CONFIG_DIR
              This  environment  variable  specifies  the list of directories that may contain the configuration
              file.  On *NIX systems, the directories are separated by a  colon  (`:'),  under  OS/2,  they  are
              separated  by a semi-colon (`;').  If this variable is not set, the configuration file is searched
              in two default directories: first, the current working directory (".") and  then  in  /etc/sane.d.
              If  the  value  of  the environment variable ends with the directory separator character, then the
              default directories are searched after the explicitly specified directories.  For example, setting
              SANE_CONFIG_DIR to "/tmp/config:" would result in directories tmp/config, ., and /etc/sane.d being
              searched (in this order).

       SANE_DEBUG_TEST
              If the library was compiled with debug support enabled, this  environment  variable  controls  the
              debug level for this backend.  Higher debug levels increase the verbosity of the output.

              Example: export SANE_DEBUG_TEST=4

AUTHOR

       Henning Meier-Geinitz <henning@meier-geinitz.de>

BUGS

       - config file values aren't tested for correctness

                                                   14 Jul 2008                                      sane-test(5)