In LibreOffice Calc, how do I change through LibreOffice Basic the value of a cell with an event listener set to it without crashing the program? - event-listener

Question

I am trying to create two tables which mirror changes made to any of them to one another automatically.
To that end, I added event listeners which are triggered when the cells of these tables are edited by the user.
Unfortunately, editing one of the tables causes LibreOffice to crash, even though the changes are indeed reflected correctly, as seen upon reopening the file.
I thought the crash might be due to a never-ending circular reference, but it still crashes after it has been made non-circular (by commenting out the relevant parts of the code so that changes are reflected only one way rather than both ways).
I noticed the code worked fine when writing to a cell that didn't have an event listener set to it.
How can I write to one of the cells with event listeners set to them without causing LibreOffice to crash?
You may want to download the following file. Please run Main and then try editing the cell C3 of the Planning sheet. The arbitrary string "C" should be written in the cell C4 of the Services sheet.
Here is a simplified version of the code :
REM ***** BASIC *****
const SERVICESSHEET_NUMBER = 2
const SERVICESSHEET_SERVICES_COLUMN = 2
Type cellStruct
columnNumber As Integer
rowNumber As Integer
End Type
Sub UpdateServicesSheet(editedCell As cellStruct, newValue As String)
Dim oSheets
Dim servicesSheet
oSheets = ThisComponent.getSheets()
servicesSheet = oSheets.getByIndex(SERVICESSHEET_NUMBER)
servicesSheet.getCellByPosition(SERVICESSHEET_SERVICES_COLUMN, 3).setString(newValue)
End Sub
Private oListener, cellRange as Object
Sub AddListener
Dim sheet, cell as Object
sheet = ThisComponent.Sheets.getByIndex(0) 'get leftmost sheet
servicesSheet = ThisComponent.Sheets.getByIndex(2)
cellRange = sheet.getCellrangeByName("C3")
oListener = createUnoListener("Modify_","com.sun.star.util.XModifyListener") 'create a listener
cellRange.addModifyListener(oListener) 'register the listener
cellRange = servicesSheet.getCellrangeByName("C4")
oListener = createUnoListener("Modify_","com.sun.star.util.XModifyListener") 'create a listener
cellRange.addModifyListener(oListener) 'register the listener
End Sub
global CircularReferenceAllowed As boolean
Sub Modify_modified(oEv)
Dim editedCell As cellStruct
Dim newValue As String
editedCell.columnNumber = 2
editedCell.rowNumber = 2
If CircularReferenceAllowed Then
CircularReferenceAllowed = false
UpdateServicesSheet(editedCell, "C")
End If
End Sub
Sub Modify_disposing(oEv)
End Sub
Sub RmvListener
cellRange.removeModifyListener(oListener)
End Sub
Sub Main
CircularReferenceAllowed = true
AddListener
End Sub
Crossposted to :
OpenOffice forums
LibreOffice discourse platform

Answer 1

It seems like the event trigger is within another event's function is causing the crash. In any case, the solution is to remove the listener, then add it back after modifying the other cell.
You do need to global the Listener and the Cell objects to make this work.
This code is simplified to work on C3 and C15 on the first sheet. It would also output some information on C14, which isn't really necessary for your purpose, but I use it to see what's happening. You need to adopt the according to what you need.
global goListener as Object
global goListener2 as Object
global goCellR as Object
global goCellR2 as Object
global goSheet as Object
global giRun as integer
global giUpd as Integer
Sub Modify_modified(oEv)
Dim sCurStr$
Dim sNewStr As String
'xRay oEv
giRun = giRun + 1
sCurStr = oEv.source.string
oCell = goSheet.getCellByPosition(2, 14)
If (oCell.getString() <> sCurStr) Then
' only update if it's different.
giUpd = giUpd + 1
goCellR2.removeModifyListener(goListener2)
oCell.setString(sCurStr)
goCellR2.addModifyListener(goListener2)
End If
sNewStr =sCurStr & " M1 Run=" & giRun & " Upd=" & giUpd
goSheet.getCellByPosition(2, 13).setString(sNewStr)
End Sub
Sub Modify2_modified(oEv)
Dim sCurStr$
Dim sNewStr As String
Dim oCell as Object
'xRay oEv
giRun = giRun + 1
sCurStr = oEv.source.string
oCell = goSheet.getCellByPosition(2, 2)
If (oCell.getString() <> sCurStr) Then
' only update if it's different.
giUpd = giUpd + 1
goCellR.removeModifyListener(goListener)
oCell.setString(sCurStr)
goCellR.addModifyListener(goListener)
End If
sNewStr =sCurStr & " M2 Run=" & giRun & " Upd=" & giUpd
goSheet.getCellByPosition(2, 13).setString(sNewStr)
End Sub
Sub Modify_disposing(oEv)
MsgBox "In Modify_disposing"
End Sub
Sub Modify2_disposing(oEv)
MsgBox "In Modify2_disposing"
End Sub
Sub RmvListener
MsgBox "In RmvListener"
goCellR.removeModifyListener(goListener)
goCellR2.removeModifyListener(goListener2)
End Sub
Sub AddListener
goSheet = ThisComponent.Sheets.getByIndex(0) 'get leftmost goSheet
'servicesSheet = ThisComponent.Sheets.getByIndex(2)
goCellR = goSheet.getCellrangeByName("C3")
goListener = createUnoListener("Modify_","com.sun.star.util.XModifyListener") 'create a listener
goCellR.addModifyListener(goListener) 'register the listener
goCellR2 = goSheet.getCellrangeByName("C15")
goListener2 = createUnoListener("Modify2_","com.sun.star.util.XModifyListener") 'create a listener
goCellR2.addModifyListener(goListener2) 'register the listener
End Sub
Sub Main
giRun = 0
giUpd = 0
AddListener
End Sub