SAP ABAP: Capturing CHECK BOX event in FM REUSE_ALV_GRID_DISPLAY / Cell Editing

Requirement: Show total number of rows selected as message whenever a user
    click on a check box column in REUSE_ALV_GRID_DISPLAY.

To accomplish this, we have to use EVENTS in REUSE_ALV_GRID_DISPLAY to capture changes made by the user.

In data declaration:
Data: gt_events  TYPE slis_t_event,
        wa_events  TYPE slis_alv_event.
*/------------------------------------------------------------------------
 FORM display_alv_report.
*/------------------------------------------------------------------------
gd_repid = sy-repid.
Refresh: gt_events.

wa_events-name = 'CALLER_EXIT'.
wa_events-form = 'CALLER_EXIT'.
APPEND wa_events TO gt_events.
wa_events-name = 'DATA_CHANGED'.
wa_events-form = 'DATA_CHANGED'.
APPEND wa_events TO gt_events.

CALL FUNCTION 'REUSE_ALV_GRID_DISPLAY'
     EXPORTING
          i_callback_program       = l_repid
          I_CALLBACK_PF_STATUS_SET = 'SET_PF_STATUS'
          I_CALLBACK_USER_COMMAND  = 'USER_COMMAND'
          is_layout                = wa_layout
          it_events                = gt_events
          it_fieldcat              = lt_fieldcat[]
          i_default                = 'X'
          i_save                    = 'A'
     TABLES
          t_outtab                 = i_Output
     EXCEPTIONS
          program_error            = 1
          OTHERS                   = 2.
If sy-subrc <> 0.
   Message 'Error in ALV report display' type 'E'.
Endif.
ENDFORM.               "End of DISPLAY_ALV_REPORT
*/======================================================================


*/---------------------------------------------------------------------
FORM data_changed USING ir_data_changed TYPE REF TO cl_alv_changed_data_protocol.
*/---------------------------------------------------------------------
**// This module will be called every time changes made on the 'TAG' column.
**// If in the register_edit_event you use the MC_EVT_MODIFIED, any field
**// that has an EDIT mode will call this module whenever changes been made without capturing the ENTER event.

DATA ls_modi TYPE lvc_s_modi.
* Check each modification:
LOOP AT ir_data_changed->mt_mod_cells INTO ls_modi.
     CASE ls_modi-fieldname.
          WHEN 'TAG'.
*              break-point.
              Read table i_Output Index ls_modi-row_id.
              Check sy-subrc eq 0.
              If i_Output-tag eq 'X'.
                  gTagCtr = gTagCtr - 1.
              Else.
                  gTagCtr = gTagCtr + 1.
              Endif.
              Perform Mess_Info Using gTagCtr.
        ENDCASE.
ENDLOOP.
ENDFORM.                    "End of data_changed
*/=====================================================================

*/--------------------------------------------------------------------
  FORM Mess_Info Using gTagCtr.
*/--------------------------------------------------------------------
Data: cCtr(5) type c.
Data: Mess type string.
cCtr = gTagCtr.
Concatenate 'Total rows selected (' cCtr ')'
             Into Mess Separated by Space.
Message Mess Type 'S' Display Like 'I'.
ENDFORM.                    "End of Mess_Info
*/=====================================================================

*/---------------------------------------------------------------------
 FORM caller_exit USING is_data TYPE slis_data_caller_exit.
*/---------------------------------------------------------------------
**//This module will be fired up before displaying the ALV report.
DATA: lr_alv TYPE REF TO cl_gui_alv_grid.
CALL FUNCTION 'GET_GLOBALS_FROM_SLVC_FULLSCR'
     IMPORTING
        e_grid = lr_alv.
CALL METHOD lr_alv->register_edit_event
     EXPORTING
          i_event_id = cl_gui_alv_grid=>mc_evt_modified.
ENDFORM.       "End of CALLER_EXIT
*/=====================================================
Sample output displaying total number of rows selected in REAL TIME.

 




 
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