Suggestions for changes for sane-api-2

(x = already included into sane2.tex)

 - SANE_FRAME_*:

x  - SANE_FRAME_RAW, formatdesc="red:8,green:8,blue:8", replaces old SANE_FRAME_* types

x  - SANE_FRAME_MIME, formatdesc=MIME-desciptor, only one frame/image, arbitary data 
     this allows transmission of e.g. jpeg, tiff and any other data format

x  - SANE_FRAME_GRAY/RGB/RED/GREEN/BLUE only allowed for sane-1 backends. 


 - parameter.flags

x  - compatible to sane-1

x  - adds more_images, new_page, front/backside info, 28 more flags available

x  - dpi_x, dpi_y, proposed_filename, formatdesc, channels_per_image

x  - 32 bytes for future extension (set to 0)


 - define the following well known options:

x  - BIT_DEPTH = Word_List with bits/sample

x  - GAMMA_VECTOR, and GAMMA_VECTOR_[RGB]

x  - RESOLUTION or (X_RESOLUTION and Y_RESOLUTION)

x  - scanmode COLOR, GRAY, LINEART (for frontend defaults, e.g. for fax => Gray)

x  - scansource FLATBED/DOCUMENTFEEDER/TRANSPARENCY

x  - ANALOG_GAMMA

x  - HIGHLIGHT

x  - SHADOW

x  - THRESHOLD

x  - LAMP_CONTROL

x  - Scanner button options and protocol

   - set focus position FOCUS_POS_X, FOCUS_POS_Y

   - SANE_CAP_ADVANCED for a group

   - SANE_CAP_ALWAYS_SETTABLE ??? (xcam/quickcam?)

x- add to SANE_Device
   - email_backend_author (string)
   - device_location (string)
   - comment (string)
   - reserved_string (string)
   - version_code (integer)
   - backend_capability_flags (integer)
   - reserved_int (integer)

x- define recommended file formats for internationalization
   in sane_i18n definition files:
   *.po, default translation tables: *.(g)mo

x- sane_open does return sane_device:
   A frontend may decide not to call sane_get_devices
   because it already knows which device shall be
   opened. In this case it does not get any information
   about the device (vendor, model, ...). So it makes
   sense to return the SANE_Device in sane_open

!- saned or a stand alone "turn lamp off deamon" should get
   an internal timer to turn off the lamp of some scanners.
   This has to be defined closer.
   May be it is necessary to find out how long a scanner
   has not been used. For this saned needs a function
   like sane_get_offline_time()...

!- define a way how multiple scanareas can be handled
   before the scanning is started

!- define return value of sane_init - also necessary for SANE1

!- define bit order of 1 bit modes  - also necessary for SANE1

!- implementation note for select_fd  - also necessary for SANE1

!- all texts and translations: UTF-8 format
   (this is used in KDE and gtk+-2.x)
   may be UTF-8 should be forced as SANE_Char format.

!- download backend translation and documentation:
   The Download function does not care about the file
   format, this propably also has to be defined in the sane standard.
   - sane_download_backend_file(filename). The backend
     has to load the file from a fixed directory. The path
     to the directory has to contain the backend name,
     e.g: /usr/local/share/sane/sane-umax/
     The frontend can not change the directory due to security!!!

!- let backend display a frontend-info or -selection (ok/cancel)
   dialog-box (e.g. "Calibration in progress: wait 10/9/8/... seconds")
   this has to be done with a callback, eg.:
     sane_frontend_dialog_display(**window, text, ok_text, cancel_text, backend_dialog_callback_function)
     sane_frontend_dialog_close(window)
   the frontend function has to be implemented in a way that the backend
   can change the text. 
   A good place to define the callback functions could be sane_init,
   where already the authorization_callback is defined.

!- give backend the chance to tell the frontend while/after scan
   that the options have changed (e.g. film scanner reduces
   number of available images): 
   may be a flag (comparable to int *i in sane_control_option)

-- add sane_get_device_info function that allows the frontend
   to ask for information about all involved backends and meta backends
   that are used.
   is this still needed with version_code in sane_device?

-- sane_extended_call() and sane_extended_callback() ?
   I don`t like this because it makes it too simple
   to add proprietary functions that are not defined
   in the sane standard

!- define what parts in a option_descriptor may be changed after
   it has been set up and passed to the frontend

?- add #define SANE_OPTION_IS_GETTABLE(cap)   (((cap) & (SANE_CAP_SOFT_DETECT | SANE_CAP_INACTIVE)) == SANE_CAP_SOFT_DETECT)

x- define endianess for SANE_FRAME_RAW