BBC BASIC Programmers' Reference

by Richard Russell, April 2011

A List View control has built-in support for tooltips, but this feature requires your program to respond to the LVN_EX_INFOTIP notification, and in BBC BASIC for Windows that is only possible using assembler code.

The program listed below uses an alternative technique that doesn't require assembler code. The position of the mouse cursor is constantly monitored, and when it moves over the List View control a tooltip is displayed. As shown, the displayed message depends only on what item (row) the mouse is hovering over, but it could easily be adapted so the message is specific to the subitem (column) as well.

The code requires v4.70 of the Windows Common Controls, so won't work on versions of Windows prior to XP. It is also necessary to ensure that the Use Windows XP visual styles option is selected if the program is compiled.

      REM. List View with tooltips, Richard Russell, 02-Apr-2011

      REM. Install libraries:
      INSTALL @lib$+"WINLIB5"

      nColumns% = 5

      REM!WC Windows constants:
      LVCF_FMT = 1
      LVCF_SUBITEM = 8
      LVCF_TEXT = 4
      LVCF_WIDTH = 2
      LVIF_PARAM = 4
      LVIF_STATE = 8
      LVIF_TEXT = 1
      LVM_GETITEMRECT = 4110
      LVM_GETTOOLTIPS = 4174
      LVM_INSERTCOLUMN = 4123
      LVM_INSERTITEM = 4103
      LVM_SETITEMTEXT = 4142
      LVM_SUBITEMHITTEST = 4153
      LVS_REPORT = 1
      TTM_ADDTOOL = &404
      TTM_NEWTOOLRECT = &406
      TTM_UPDATETIPTEXT = &40C

      ON ERROR SYS "MessageBox", @hwnd%, REPORT$, 0, 48 : PROCcleanup : QUIT
      ON CLOSE PROCcleanup : QUIT

      REM. Declare and initialise structures:
      DIM pt{x%,y%}, rc{l%,t%,r%,b%}
      DIM ti{cbSize%, uFlags%, hwnd%, uId%, rect{} = rc{}, hinst%, lpszText%}
      DIM lvh{pt{} = pt{}, flags%, iItem%, iSubItem%, iGroup%}
      DIM lvc{mask%, fmt%, cx%, pszText%, cchTextMax%, iSubItem%}
      DIM lvi{mask%, iItem%, iSubItem%, state%, stateMask%, pszText%, \
      \       cchTextMax%, iImage%, lParam%}
      lvc.mask% = LVCF_WIDTH OR LVCF_SUBITEM OR LVCF_FMT OR LVCF_TEXT
      lvi.mask% = LVIF_TEXT OR LVIF_STATE OR LVIF_PARAM

      REM. Create list view control:
      SYS "InitCommonControls"
      dx% =  @vdu.tr%
      dy% =  @vdu.tb%
      hwndLV% = FN_createwindow("SysListView32", "", 0, 0, dx%, dy%, 0, LVS_REPORT, 0)
      FOR col% = 0 TO nColumns%-1
        title$ = "Column " + STR$col% + " header" + CHR$0
        lvc.cx%         = dx% DIV nColumns%
        lvc.pszText%    = !^title$
        lvc.cchTextMax% = LEN(title$)
        lvc.iSubItem%   = col%
        SYS "SendMessage", hwndLV%, LVM_INSERTCOLUMN, col%, lvc{}
      NEXT
      SYS "SendMessage", hwndLV%, LVM_GETTOOLTIPS, 0, 0 TO hwndTT%
      ti.cbSize% = DIM(ti{})
      ti.hwnd% = hwndLV%
      SYS "SendMessage", hwndTT%, TTM_ADDTOOL, 0, ti{}

      REM. Populate list view control:
      FOR item% = 0 TO 10
        FOR col% = 0 TO nColumns%
          text$ = "Item " + STR$item% + " column " + STR$col% + CHR$0
          lvi.iItem%      = item%
          lvi.iSubItem%   = col%
          lvi.pszText%    = !^text$
          lvi.cchTextMax% = LEN(text$)
          IF col% THEN
            SYS "SendMessage", hwndLV%, LVM_SETITEMTEXT, item%, lvi{}
          ELSE
            SYS "SendMessage", hwndLV%, LVM_INSERTITEM, item%, lvi{}
          ENDIF
        NEXT col%
      NEXT item%

      REM. Polling loop, monitoring mouse position:
      oldx% = -1
      oldy% = -1
      REPEAT
        WAIT 1
        SYS "GetCursorPos", pt{}
        SYS "ScreenToClient", hwndLV%, pt{}
        IF pt.x%<>oldx% OR pt.y%<>oldy% THEN
          oldx% = pt.x%
          oldy% = pt.y%
          PROCtooltip(pt.x%, pt.y%)
        ENDIF
      UNTIL FALSE

      DEF PROCtooltip(x%, y%)
      LOCAL tip$
      lvh.pt.x% = x%
      lvh.pt.y% = y%
      SYS "SendMessage", hwndLV%, LVM_SUBITEMHITTEST, 0, lvh{}
      IF lvh.iItem% >= 0 THEN
        SYS "SendMessage", hwndLV%, LVM_GETITEMRECT, lvh.iItem%, rc{}
        tip$ = "Tooltip for item " + STR$(lvh.iItem%) + CHR$0
        ti.lpszText% = !^tip$
        ti.rect.l% = rc.l%
        ti.rect.r% = rc.r%
        ti.rect.t% = rc.t%
        ti.rect.b% = rc.b%
        SYS "SendMessage", hwndTT%, TTM_UPDATETIPTEXT, 0, ti{}
        SYS "SendMessage", hwndTT%, TTM_NEWTOOLRECT, 0, ti{}
      ENDIF
      ENDPROC

      DEF PROCcleanup
      hwndLV% += 0 : IF hwndLV% PROC_closewindow(hwndLV%) : hwndLV% = 0
      ENDPROC