fpspreadsheet: Fix crash of visual controls when workbook.RemoveAllWorksheets is called. Visual controls can handle the case of active worksheet = nil.

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@5937 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/fpspreadsheet/source/common/fpspreadsheet.pas

@@ -688,7 +688,7 @@ type
   {@@ Event procedure containing a specific worksheet }
   TsWorksheetEvent = procedure (Sender: TObject; ASheet: TsWorksheet) of object;
 
-  {@@ Event procedure called when a worksheet is removed }
+  {@@ Event procedure called when a worksheet is removed. ASheetIndex = -1 --> all sheets }
   TsRemoveWorksheetEvent = procedure (Sender: TObject; ASheetIndex: Integer) of object;
 
 
@@ -8051,7 +8051,9 @@ end;
 -------------------------------------------------------------------------------}
 destructor TsWorkbook.Destroy;
 begin
+  DisableNotifications;
   RemoveAllWorksheets;
+  EnableNotifications;
   FWorksheets.Free;
 
   FCellFormatList.Free;
@@ -8791,7 +8793,11 @@ end;
 -------------------------------------------------------------------------------}
 procedure TsWorkbook.RemoveAllWorksheets;
 begin
+  FActiveWorksheet := nil;
   FWorksheets.ForEachCall(RemoveWorksheetsCallback, nil);
+  FWorksheets.Clear;
+  if (FLockCount = 0) and Assigned(FOnRemoveWorksheet) then
+    FOnRemoveWorksheet(self, -1);
 end;
 
 {@@ ----------------------------------------------------------------------------

components/fpspreadsheet/source/visual/fpspreadsheetctrls.pas

@@ -1610,7 +1610,11 @@ begin
     else
       sheet := Workbook.GetWorksheetbyIndex(ASheetIndex);
   end else
-    sheet := FWorksheet;
+  if ASheetIndex > -1 then
+    sheet := FWorksheet
+  else
+    sheet := nil;  // all sheets were removed
+
 //  FWorksheet := sheet;  // is needed by listeners!
   NotifyListeners([lniWorksheetRemove]);
   SelectWorksheet(sheet);
@@ -1882,6 +1886,9 @@ end;
 
 procedure TsCellEdit.DoEnter;
 begin
+  if Worksheet = nil then
+    exit;
+
   if not CanEditCell(Worksheet.ActiveCellRow, Worksheet.ActiveCellCol) then
   begin
     MessageDlg('This cell is protected from editing. Unlock worksheet protection '+

components/fpspreadsheet/source/visual/fpspreadsheetgrid.pas

@@ -2242,6 +2242,8 @@ var
   TL: TPoint;
 begin
   inherited;
+  if Worksheet = nil then
+    exit;
 
   FTopLeft := CalcTopLeft(false);
 
@@ -4351,6 +4353,9 @@ var
   clipArea: TRect;
 
 begin
+  if Worksheet = nil then
+    exit;
+
   sr := GetWorksheetRow(ARow);
   scLastused := Worksheet.GetLastColIndex;
   gc := AFirstCol;
@@ -4966,6 +4971,9 @@ var
   cell: PCell;
   r, c: Cardinal;
 begin
+  if Worksheet = nil then
+    exit;
+
   if FAllowDragAndDrop and
      (not Assigned(DragManager) or not DragManager.IsDragging) and
      (ssLeft in Shift) and
@@ -5016,6 +5024,9 @@ procedure TsCustomWorksheetGrid.MouseMove(Shift: TShiftState; X, Y: Integer);
 var
   prevMouseCell: TPoint;
 begin
+  if Worksheet = nil then
+    exit;
+
   prevMouseCell := GCache.MouseCell;
 
   inherited;
@@ -5264,7 +5275,7 @@ var
   cp: TsCellprotections;
 begin
   Result := inherited;
-  if Result and Worksheet.IsProtected then
+  if Result and Assigned(Worksheet) and Worksheet.IsProtected then
   begin
     cell := Worksheet.FindCell(GetWorksheetRow(ARow), GetWorksheetCol(ACol));
     cp := Worksheet.ReadCellProtection(cell);