Spreadsheet: Add Python API for getUsedCells

Also adds access to getNonEmptyCells, and unit tests for both. Designed
to fix #7587.

src/Mod/Spreadsheet/App/SheetPy.xml

@@ -180,5 +180,26 @@ following dependency order.
         </UserDocu>
       </Documentation>
     </Methode>
+	  
+    <Methode Name="getUsedCells">
+      <Documentation>
+        <UserDocu>
+getUsedCells()
+
+Get a list of the names of all cells that are marked as used. These cells may
+or may not have a non-empty string content.
+        </UserDocu>
+      </Documentation>
+    </Methode>
+	  
+    <Methode Name="getNonEmptyCells">
+      <Documentation>
+        <UserDocu>
+getNonEmptyCells()
+
+Get a list of the names of all cells with data in them.
+        </UserDocu>
+      </Documentation>
+    </Methode>
   </PythonExport>
 </GenerateModel>

src/Mod/Spreadsheet/App/SheetPyImp.cpp

@@ -980,6 +980,27 @@ PyObject *SheetPy::recomputeCells(PyObject *args) {
     }PY_CATCH;
 }
 
+PyObject *SheetPy::getUsedCells(PyObject *args)
+{
+    auto usedCells = getSheetPtr()->getCells()->getUsedCells();
+    Py::List pyCellList;
+    for (const auto &cell : usedCells) { 
+        pyCellList.append(Py::String(cell.toString()));
+    }
+    return Py::new_reference_to(pyCellList);
+}
+
+PyObject *SheetPy::getNonEmptyCells(PyObject *args)
+{
+    auto usedCells = getSheetPtr()->getCells()->getNonEmptyCells();
+    Py::List pyCellList;
+    for (const auto &cell : usedCells) { 
+        pyCellList.append(Py::String(cell.toString())); 
+    }
+    return Py::new_reference_to(pyCellList);
+}
+
+
 // +++ custom attributes implementer ++++++++++++++++++++++++++++++++++++++++
 
 PyObject *SheetPy::getCustomAttributes(const char*) const

src/Mod/Spreadsheet/TestSpreadsheet.py

@@ -1345,6 +1345,40 @@ class SpreadsheetCases(unittest.TestCase):
         with self.assertRaises(AttributeError):
             self.assertEqual(ss1.B1, "fail")
 
+    def testGetUsedCells(self):
+        sheet = self.doc.addObject('Spreadsheet::Sheet','Spreadsheet')
+        test_cells = ['B13','C14','D15']
+        for i,cell in enumerate(test_cells):
+            sheet.set(cell,str(i))
+
+        used_cells = sheet.getUsedCells()
+        self.assertEqual(len(used_cells), len(test_cells))
+        for cell in test_cells:
+            self.assertTrue(cell in used_cells)
+
+        for cell in test_cells:
+            sheet.set(cell,"")
+            sheet.setAlignment(cell,"center")
+        non_empty_cells = sheet.getUsedCells()
+        self.assertEqual(len(non_empty_cells), len(test_cells)) # Alignment counts as "used"
+
+    def testGetNonEmptyCells(self):
+        sheet = self.doc.addObject('Spreadsheet::Sheet','Spreadsheet')
+        test_cells = ['B13','C14','D15']
+        for i,cell in enumerate(test_cells):
+            sheet.set(cell,str(i))
+
+        non_empty_cells = sheet.getNonEmptyCells()
+        self.assertEqual(len(non_empty_cells), len(test_cells))
+        for cell in test_cells:
+            self.assertTrue(cell in non_empty_cells)
+
+        for cell in test_cells:
+            sheet.set(cell,"")
+            sheet.setAlignment(cell,"center")
+        non_empty_cells = sheet.getNonEmptyCells()
+        self.assertEqual(len(non_empty_cells), 0) # Alignment does not count as "non-empty"
+
     def tearDown(self):
         #closing doc
         FreeCAD.closeDocument(self.doc.Name)