[sane-devel] GSOC idea - develope sane-generic backend

Robert Ancell robert.ancell at canonical.com
Fri Mar 26 01:23:40 UTC 2010

Hi all,

One thing I've noticed developing simple-scan is a lot of the SANE 
backends implement the same functionality.  For example managing the 
table of options.  It would be nice if there was a generic sane driver 
that the others could derive from, e.g.

static SANEGenericDriver *driver;

static void connect(SANEGenericDriver *driver)
     // Do USB connection

static void start_page(SANEGenericDriver *driver)
     // Do USB config
     // using sgd_get_resolution(driver) etc

static void read(SANEGenericDriver *driver)
    // Do USB read data

static void end_page(SANEGenericDriver *driver)
     // Do USB config

static void disconnect(SANEGenericDriver *driver)
     // Clean up USB connection

void init()
     SANE_Int resultions[] = {75, 150, 300, 600};

     driver = sgd_new ("plustek");

     sgd_set_color_mode (driver, true);
     sgd_set_supported_resolutions (driver, resolutions, 4);
     sgd_add_custom_option_int (driver, "toggle");

     sgd_set_connect (driver, connect);
     sgd_set_start_page (driver, start_page);
     sgd_set_read (driver, read);
     sgd_set_end_page (driver, end_page);
     sgd_set_disconnect (driver, disconnect);


/* Generates:
void sane_init()

Advantages of this approach:
  - Less code duplication
  - Easier driver development (driver doesn't have to maintain 
configuration table etc)
  - SANEGenericDriver always correctly implements SANE interface:
    - Validates inputs
    - Uses names defined in saneopts.h
    - Can handle corner cases better, e.g. sane_cancel being called at 
unexpected times
  - Can change SANE interface easier

This seems like a good project for a summer of code student to perform, 
would anyone be interested in being a mentor?


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