How to change a cell value periodically in libreoffice calc? - macros

Question

The title says it all...
For example, if I want to have a cell which displays the current time and auto updates minute by minute (well, I think we call that a clock), how do I do it?
Is there a simple function implemented already or should I create a macro and assign it to a specific event?
EDIT: Following the provided answer by #Jim K, I want to be more clear about what I want. The "clock" example above was here to make it simple to understand, but what I really want is in the title: a cell value which changes periodically, be it a string, a number, a date...

Answer 1

First enter =NOW() in a cell, and format the number by going to Format -> Cells.
Next, this Basic macro (from here) recalculates every minute. Go to Tools -> Customize and assign it to the Open Document event.
Sub RecalculatePeriodically
Const secs = 60
On Error Goto ErrorHandler
Do While True
Wait(1000 * secs)
ThisComponent.calculateAll()
Loop
ErrorHandler:
'Document was probably closed
End Sub
However, this crashes when exiting LibreOffice. So instead, use the following threaded Python macro (like here). Assign keep_recalculating_thread to the Open Document event.
import time
from threading import Thread
import uno
def keep_recalculating_thread(action_event=None):
t = Thread(target = keep_recalculating)
t.start()
def keep_recalculating():
oDoc = XSCRIPTCONTEXT.getDocument()
while hasattr(oDoc, 'calculateAll'):
oDoc.calculateAll()
time.sleep(60)
g_exportedScripts = keep_recalculating_thread,
Another idea is at https://ask.libreoffice.org/en/question/5327/how-can-i-run-a-macro-at-regular-time-interval/, although it requires linking to another file which seems cumbersome.
EDIT:
Maybe you are looking for something like this? Test it by starting with a blank spreadsheet and entering 1 in cell A1.
def keep_changing_cell(action_event=None):
t = Thread(target = keep_changing_thread)
t.start()
def keep_changing_thread():
oDoc = XSCRIPTCONTEXT.getDocument()
oSheet = oDoc.CurrentController.ActiveSheet
COLUMN_A = 0
FIRST_ROW = 0
oCell = oSheet.getCellByPosition(COLUMN_A, FIRST_ROW)
while hasattr(oDoc, 'calculateAll'):
oCell.setValue(oCell.getValue() + 1)
time.sleep(2)

Answer 2

tl;dr
Is there a simple function implemented already
No.
From LibreOffice and fairly recent:
(I don't know a 'clock' property applying to cells.)
There are simple ways to obtain the time, for example given suitable formatting, with date:
=NOW()
or Ctrl+;
Or, for example, without date:
=MOD(NOW(),1)
The first and last will update, but only when the sheet is recalculated.
For a cell that ticks away (eg second by second) I believe you will need a script.