Display traffic light icon on ALV grid report

*&-----------------------------------------------*
*& Report  ZDISPLAY_TRAFFIC                      *
*&                                               *
*&-----------------------------------------------*
REPORT  zdisplay_traffic.
TABLES:     ekko.
type-pools: slis.                                 "ALV Declarations
*Data Declaration
*----------------
TYPES: BEGIN OF t_ekko,
  ebeln TYPE ekpo-ebeln,
  ebelp TYPE ekpo-ebelp,
  statu TYPE ekpo-statu,
  aedat TYPE ekpo-aedat,
  matnr TYPE ekpo-matnr,
  menge TYPE ekpo-menge,
  meins TYPE ekpo-meins,
  netpr TYPE ekpo-netpr,
  peinh TYPE ekpo-peinh,
  TRAFFIC(4) type c,
 END OF t_ekko.
DATA: it_ekko TYPE STANDARD TABLE OF t_ekko INITIAL SIZE 0,
      wa_ekko TYPE t_ekko.
*ALV data declarations
data: fieldcatalog type slis_t_fieldcat_alv with header line,
      gd_tab_group type slis_t_sp_group_alv,
      gd_layout    type slis_layout_alv,
      gd_repid     like sy-repid.
************************************************************************
*Start-of-selection.
START-OF-SELECTION.
perform data_retrieval.
perform build_fieldcatalog.
perform build_layout.
perform display_alv_report.
*&---------------------------------------------------------------------*
*&      Form  BUILD_FIELDCATALOG
*&---------------------------------------------------------------------*
*       Build Fieldcatalog for ALV Report
*----------------------------------------------------------------------*
form build_fieldcatalog.
  fieldcatalog-fieldname   = 'EBELN'.
  fieldcatalog-seltext_m   = 'Purchase Order'.
  fieldcatalog-col_pos     = 0.
  fieldcatalog-outputlen   = 10.
  fieldcatalog-emphasize   = 'X'.
  fieldcatalog-key         = 'X'.
*  fieldcatalog-do_sum      = 'X'.
*  fieldcatalog-no_zero     = 'X'.
  append fieldcatalog to fieldcatalog.
  clear  fieldcatalog.
  fieldcatalog-fieldname   = 'EBELP'.
  fieldcatalog-seltext_m   = 'PO Item'.
  fieldcatalog-col_pos     = 1.
  append fieldcatalog to fieldcatalog.
  clear  fieldcatalog.
  fieldcatalog-fieldname   = 'AEDAT'.
  fieldcatalog-seltext_m   = 'Item change date'.
  fieldcatalog-col_pos     = 3.
  append fieldcatalog to fieldcatalog.
  clear  fieldcatalog.
  fieldcatalog-fieldname   = 'MATNR'.
  fieldcatalog-seltext_m   = 'Material Number'.
  fieldcatalog-col_pos     = 4.
  append fieldcatalog to fieldcatalog.
  clear  fieldcatalog.
  fieldcatalog-fieldname   = 'MENGE'.
  fieldcatalog-seltext_m   = 'PO quantity'.
  fieldcatalog-col_pos     = 5.
  append fieldcatalog to fieldcatalog.
  clear  fieldcatalog.
  fieldcatalog-fieldname   = 'MEINS'.
  fieldcatalog-seltext_m   = 'Order Unit'.
  fieldcatalog-col_pos     = 6.
  append fieldcatalog to fieldcatalog.
  clear  fieldcatalog.
  fieldcatalog-fieldname   = 'NETPR'.
  fieldcatalog-seltext_m   = 'Net Price'.
  fieldcatalog-col_pos     = 7.
  fieldcatalog-outputlen   = 15.
  fieldcatalog-do_sum      = 'X'.        "Display column total
  fieldcatalog-datatype     = 'CURR'.
  append fieldcatalog to fieldcatalog.
  clear  fieldcatalog.
  fieldcatalog-fieldname   = 'PEINH'.
  fieldcatalog-seltext_m   = 'Price Unit'.
  fieldcatalog-col_pos     = 8.
  append fieldcatalog to fieldcatalog.
  clear  fieldcatalog.
    fieldcatalog-fieldname   = 'TRAFFIC'.
  fieldcatalog-seltext_m   = 'Traffic'.
  fieldcatalog-col_pos     = 9.
  append fieldcatalog to fieldcatalog.
  clear  fieldcatalog.
endform.                    " BUILD_FIELDCATALOG
*&---------------------------------------------------------------------*
*&      Form  BUILD_LAYOUT
*&---------------------------------------------------------------------*
*       Build layout for ALV grid report
*----------------------------------------------------------------------*
form build_layout.
  gd_layout-no_input          = 'X'.
  gd_layout-colwidth_optimize = 'X'.
  gd_layout-totals_text       = 'Totals'(201).
endform.                    " BUILD_LAYOUT
*&---------------------------------------------------------------------*
*&      Form  DISPLAY_ALV_REPORT
*&---------------------------------------------------------------------*
*       Display report using ALV grid
*----------------------------------------------------------------------*
form display_alv_report.
  gd_repid = sy-repid.
  call function 'REUSE_ALV_GRID_DISPLAY'
       exporting
            i_callback_program      = gd_repid
            is_layout               = gd_layout
            it_fieldcat             = fieldcatalog[]
            i_save                  = 'X'
       tables
            t_outtab                = it_ekko
       exceptions
            program_error           = 1
            others                  = 2.
  if sy-subrc <> 0.
  endif.
endform.                    " DISPLAY_ALV_REPORT
*&---------------------------------------------------------------------*
*&      Form  DATA_RETRIEVAL
*&---------------------------------------------------------------------*
*       Retrieve data form EKPO table and populate itab it_ekko
*----------------------------------------------------------------------*
form data_retrieval.
data: ld_count type i.
select ebeln ebelp statu aedat matnr menge meins netpr peinh
 up to 10 rows
  from ekpo
  into table it_ekko.
  clear: ld_count.
  loop at it_ekko into wa_ekko.
    ld_count = ld_count + 1.
     case  ld_count.
       when 1.
         wa_ekko-traffic = '@08@'. "green traffic light
       when 2.
         wa_ekko-traffic = '@09@'. "Yellow traffic light
       when 3.
         wa_ekko-traffic = '@0A@'. "red traffic light
         clear: ld_count.
     endcase.
     MODIFY it_ekko from wa_ekko.
  endloop.
endform.                    " DATA_RETRIEVAL