--******************************************************************************
--*                                                                            *
--*  File:        Chime.lua                             Revision:  1.0         *
--*                                                                            *
--*  Contents:    a simple digital chime                                       *
--*                                                                            *
--*  Creation:    04.03.2002                   Last Modification:  04.03.2002  *
--*                                                                            *
--*  Platform:    IBM-compatible PC running Windows 98SE                       *
--*                                                                            *
--*  Environment: Lua 4.0, TkLua 4.0                                           *
--*                                                                            *
--*  Author:      Andreas Rozek           Phone:  ++49 (711) 6770682           *
--*               Kirschblütenweg 15      Fax:    -                            *
--*             D-70569 Stuttgart         EMail:  Andreas.Rozek@T-Online.De    *
--*               Germany                                                      *
--*                                                                            *
--*  URL:         http://www.Andreas-Rozek.de/                                 *
--*                                                                            *
--*  Copyright:   the software is published under the "GNU Lesser General Pub- *
--*               lic  License" (see "http://www.fsf.org/copyleft/lesser.html" *
--*               for additional information)                                  *
--*                                                                            *
--*  Comments:    (none)                                                       *
--*                                                                            *
--******************************************************************************

--**** global constants and variables ****

  HourTensView, HourUnitsView     = nil;                      -- shows the hours
  ColonView                       = nil;               -- shows a blinking colon
  MinuteTensView, MinuteUnitsView = nil;                    -- shows the minutes

  AlarmCheck = nil;                 -- allows to switch the audible alarm on/off
  StatusBar  = nil;                           -- shows the actual program status

  SevenSegmentDigit = {                      -- list of all seven-segment images
    "./SevenSegment_1.gif","./SevenSegment_2.gif","./SevenSegment_3.gif",
    "./SevenSegment_4.gif","./SevenSegment_5.gif","./SevenSegment_6.gif",
    "./SevenSegment_7.gif","./SevenSegment_8.gif","./SevenSegment_9.gif";
    [0]="./SevenSegment_0.gif"
  };
  SevenSegmentColon = {                              -- list of all colon images
    [0]="./SevenSegment_noColon.gif", [1]="./SevenSegment_Colon.gif"
  };

  oldHours, oldMinutes = nil;         -- used to detect significant time changes

--**** local constants and variables ****

  local Icon     = "Chime.gif";-- specifying the file name is already sufficient
  local Title    = "Chime";
  local Subtitle = "a simple digital chime";

--******************************************************************************
--*                                                                            *
--* processTick                                         processes a timer tick *
--*                                                                            *
--******************************************************************************

  function processTick (required)
    local a,b,hours,minutes,seconds = strfind(date(),"(%d*)%:(%d*)%:(%d*)$");

    ColonView.image=SevenSegmentColon[mod(seconds,2)];

    required = required or ((hours ~= oldHours) or (minutes ~= oldMinutes));
    if required then
      showTime(hours,minutes);
      updateUserInterface(hours,minutes);

      oldHours,oldMinutes = hours,minutes;
    end;
  end;

--******************************************************************************
--*                                                                            *
--* showTime                                          displays the actual time *
--*                                                                            *
--******************************************************************************

  function showTime (hours,minutes)
       HourTensView.image=SevenSegmentDigit[floor(hours/10)];
      HourUnitsView.image=SevenSegmentDigit[mod(hours,10)];
     MinuteTensView.image=SevenSegmentDigit[floor(minutes/10)];
    MinuteUnitsView.image=SevenSegmentDigit[mod(minutes,10)];
  end;

--******************************************************************************
--*                                                                            *
--* updateUserInterface       updates user interface according to actual state *
--*                                                                            *
--******************************************************************************

  function updateUserInterface (hours,minutes)
    if (AlarmCheck.current == 1) then                        -- alarm is enabled
      local AlarmTime = mod(minutes,30);
      if     (AlarmTime ==  0) then
        StatusBar.text = "(alarm is running)";
        tkeval("bell");                      -- a sound file would be preferable
        StatusBar.text = "";
      elseif (AlarmTime <= 23) then
        StatusBar.text = "next warning in "..(25-AlarmTime).." minutes";
      elseif (AlarmTime == 24) then
        StatusBar.text = "next warning in 1 minute";
      elseif (AlarmTime == 25) then
        StatusBar.text = "next alarm in 5 minutes";
        tkeval("bell");                      -- a sound file would be preferable
      elseif (AlarmTime <= 28) then
        StatusBar.text = "next alarm in "..(30-AlarmTime).." minutes";
      else
        StatusBar.text = "next alarm in 1 minute";
      end;
    else                                                    -- alarm is disabled
      StatusBar.text = "(alarm is disabled)";
    end;
  end;

--******************************************************************************
--*                                                                            *
--*                                main program                                *
--*                                                                            *
--******************************************************************************

--**** preload any seven-segment images ****

  for i=0,9 do
    local TkImage = tkeval("image create photo -file",SevenSegmentDigit[i]);
    SevenSegmentDigit[i] = TkImage[1];            -- looks strange, but works...
  end

  for i=0,1 do
    local TkImage = tkeval("image create photo -file",SevenSegmentColon[i]);
    SevenSegmentColon[i] = TkImage[1];            -- looks strange, but works...
  end

--**** define window components ****

  local IconLabel, TitleLabel, SubtitleLabel = nil;     -- title area components
  local UpperSeparator, LowerSeparator       = nil;         -- visual separators

  IconLabel       = tklabel{image=Icon, anchor="center", width=32, height=32};
  TitleLabel      = tklabel{Title;      anchor="e", font="-*-helvetica-bold-o-*--16"};
  SubtitleLabel   = tklabel{Subtitle;   anchor="e", font="-*-helvetica-bold-r-*--12"};
  UpperSeparator  = tkframe{relief="groove", borderwidth=2, height=2};

  HourTensView    = tklabel{image="./SevenSegment.gif"}; -- preloads dummy image
  HourUnitsView   = tklabel{image="./SevenSegment.gif"};                 -- dto.
  ColonView       = tklabel{image="./SevenSegment_noColon.gif"};
  MinuteTensView  = tklabel{image="./SevenSegment.gif"};                 -- dto.
  MinuteUnitsView = tklabel{image="./SevenSegment.gif"};                 -- dto.

  AlarmCheck      = tkcheckbutton{
                      "Audible Alarm"; anchor="w", font="-*-helvetica-medium-r-*--11",
                      command="processTick(1)"-- actually updates user interface
                    };

  LowerSeparator  = tkframe{relief="groove", borderwidth=2, height=2};
  StatusBar       = tklabel{""; anchor="w", font="-*-helvetica-medium-r-*--11"};

--**** construct application window ****

  local MainWindow = tkmain{
    tkframe{
      IconLabel,     {side="left"},
      TitleLabel,    {side="top", fill="x", expand=1},
      SubtitleLabel, {side="top", fill="x", expand=1}
    },              {side="top", fill="x", expand=1},
    UpperSeparator, {side="top", fill="x"},
    tkframe{
      HourTensView,    {side="left"},
      HourUnitsView,   {side="left"},
      ColonView,       {side="left"},
      MinuteTensView,  {side="left"},
      MinuteUnitsView, {side="left"}
    },              {side="top", anchor="center", pady=4},
    AlarmCheck,     {side="top", fill="x"},
    LowerSeparator, {side="top", fill="x"},
    StatusBar,      {side="top", fill="x"}
  };

--**** initialize user interface ****

  AlarmCheck.current = 1;                         -- activates the audible alarm
  processTick(1);            -- updates the display to reflect the current state

--**** display application window ****

  MainWindow:title(Title.." - "..Subtitle);
  MainWindow:show();                            -- also triggers a window layout
  MainWindow:resizable(0,0);                     -- disables window size changes
  MainWindow:raise();                   -- brings the window into the foreground

--**** start continous display ****

  tktimer(1000,function() processTick(); end);

--**** provide an explicit method to terminate this program! ****

  MainWindow:protocol("WM_DELETE_WINDOW", "print('done...'); tkexit()");