Scanning: Scanner object, driver Interface, etc.

[michaelrsweet]

In order to support multi-function devices and standalone scanners, PAPPL should provide APIs, interfaces, and objects for scanning, with the goal of providing IPP Scan and/or eSCL protocol endpoints (eSCL is used for AirPrint and Mopria, IPP Scan is a published but otherwise unused standard that has the needed semantics/data elements) that can be linked to a printer object and/or used separately.

Specific sub-tasks:

• Implement pappl_scanner_t object based on pappl_printer_t (adapted to the needs of scanning - 90% duplication here)
• Update pappl_job_t object to support print or scan jobs (add a pointer to pappl_scanner_t)
• Implement pappl_sc_driver_data_t structure based on pappl_pr_driver_data_t, with corresponding callback functions using the pappl_sc_ prefix. For the purposes of PAPPL scanning, do not support vendor options.
• Implement pappl_sc_options_t structure based on pappl_pr_options_t. For the purposes of PAPPL scanning, do not support vendor options.
• Add scanner.h header with public API and scanner-private.h header with private API using appropriately-named header guard macros. These can be patterned after the corresponding printer headers.
• Add scanner.c file that provides the scanner object constructor and destructor.
• Add scanner-accessors.c file that provides the scanner object accessor (get/set) functions, patterned on printer-accessors.c
• Add scanner-driver.c file that provides the scan driver interfaces and attributes, patterned on printer-driver.c.
• Add scanner-webif.c file that provides scan-specific web pages.
• Add job-scan.c file that provides scan job processing functions.
• Add papplPrinterSetScanner API to set the scanner associated with a printer
• Add papplSystemSetScannerDrivers API to set the list of scanner drivers, callback, etc.
• Add pappl_sc_autoadd_cb_t, pappl_sc_create_cb_t, pappl_sc_driver_cb_t, and pappl_scanner_cb_t callbacks to system.h.

Need to think about how to auto-associate scanners in printers.

[Kappuccino111]

@michaelrsweet @tillkamppeter new PR opened : #349

Commit 7190a0b solves:

• Implement pappl_scanner_t object based on pappl_printer_t (adapted to the needs of scanning - 90% duplication here)
• Implement pappl_sc_driver_data_t structure based on pappl_pr_driver_data_t, with corresponding callback functions using the pappl_sc_ prefix. For the purposes of PAPPL scanning, do not support vendor options.
• Implement pappl_sc_options_t structure based on pappl_pr_options_t. For the purposes of PAPPL scanning, do not support vendor options.
• Add scanner.h header with public API and scanner-private.h header with private API using appropriately-named header guard macros. These can be patterned after the corresponding printer headers.

Please review the above in detail.

[Kappuccino111]

Commit e24d9e3 marks this as done

• Update pappl_job_t object to support print or scan jobs (add a pointer to pappl_scanner_t)

[Kappuccino111]

Commit 317300f marks this as done

• Add scanner-accessors.c file that provides the scanner object accessor (get/set) functions, patterned on printer-accessors.c