BBC BASIC Programmers' Reference

by Richard Russell, September 2010

A significant difference between a List View and a List Box is that the former allows you to select multiple items whereas the latter only allows you to select a single item. This complicates somewhat the issue of discovering which item(s) is/are selected.

With a List Box you can simply send the LB_GETCURSEL message:

      SYS "SendMessage", hListBox%, LB_GETCURSEL, 0, 0 TO sel%

where sel% is set to the index of the current selection (or -1 if no item is selected).

With a List View you can optionally discover how many items are selected as follows:

      SYS "SendMessage", hListView%, LVM_GETSELECTEDCOUNT, 0, 0 TO nsel%

where nsel% is set to the number of selected items.

To find which item(s) is/are selected you can send the List View the LVM_GETNEXTITEM message:

      iStart% = -1
      SYS "SendMessage", hListView%, LVM_GETNEXTITEM, iStart%, LVNI_SELECTED TO index%

where index% is set to the index of the first item selected (or to -1 if no items are selected).

To discover which other items (if any) are selected send the message repeatedly with iStart% set to the index previously returned, until index% is -1:

      iStart% = -1
      REPEAT
        SYS "SendMessage", hListView%, LVM_GETNEXTITEM, iStart%, LVNI_SELECTED TO index%
        IF index% <> -1 THEN PROC_do_something(index%)
        iStart% = index%
      UNTIL index% = -1

Use the Windows Constants utility or API Viewer to discover the values of the constants.