Lock scaling to stop molecule jumping when atoms are added

rdeditor/molViewWidget.py

@@ -304,13 +304,18 @@ def sanitizeDrawMol(self, kekulize=False, drawkekulize=False):
     finishedDrawing = QtCore.Signal(name="finishedDrawing")
 
     def getMolSvg(self):
-        self.drawer = rdMolDraw2D.MolDraw2DSVG(300, 300)
+        height = 300
+        width = 300
+        self.drawer = rdMolDraw2D.MolDraw2DSVG(width, height)
         # TODO, what if self._drawmol doesn't exist?
         if self._drawmol is not None:
             # Chiral tags on R/S
             # chiraltags = Chem.FindMolChiralCenters(self._drawmol)
             opts = self.drawer.drawOptions()
             opts.fixedBondLength = 15.0
+            maxv = Point2D(0.5 * width / opts.scalingFactor, 0.5 * height / opts.scalingFactor)
+            minv = Point2D(-maxv.x, -maxv.y)
+            self.drawer.SetScale(width, height, minv, maxv)
             if self._darkmode:
                 rdMolDraw2D.SetDarkMode(opts)
             if (not self.molecule_sanitizable) and self.unsanitizable_background_colour:

rdeditor/templatehandler.py

@@ -160,10 +160,6 @@ def apply_template_to_canvas(self, mol: Chem.Mol, point: Point2D, templatelabel:
         """Apply to canvas"""
         template = Chem.MolFromSmiles(self.templates[templatelabel]["canvas"], sanitize=False)
 
-        if mol.GetNumAtoms() == 0:
-            point.x = 0.0
-            point.y = 0.0
-
         combined = Chem.rdchem.RWMol(Chem.CombineMols(mol, template))
         # This should only trigger if we have an empty canvas
         if not combined.GetNumConformers():