Allow layer switch directly from MultiPlotter

lib/plot.py

@@ -120,29 +120,6 @@ A4_PORTRAIT = Paper(210, 297, 20)
 A6_PORTRAIT = Paper(105, 148, 8)
 
 
-class MultiPlotter:
-    def __init__(self):
-        self.plotters = []
-
-    def move_to(self, point):
-        for plotter in self.plotters:
-            plotter.move_to(point)
-
-    def line_to(self, point):
-        for plotter in self.plotters:
-            plotter.line_to(point)
-
-    def add_layer(self, *args, **kwargs):
-        for plotter in self.plotters:
-            plotter.add_layer(*args, **kwargs)
-
-    def finalise(self):
-        for plotter in self.plotters:
-            plotter.finalise()
-
-    def register_plotter(self, plotter):
-        self.plotters.append(plotter)
-
 
 class Plotter:
 
@@ -286,3 +263,31 @@ class HPGLPlotter(Plotter):
         for i in range(len(self.layers)):
             with open(self._layer_file_name(i), 'at') as file:
                 file.write(';PU0,0;IN')
+
+
+class MultiPlotter(Plotter):
+    def __init__(self):
+        self.plotters = []
+
+    def move_to(self, point):
+        for plotter in self.plotters:
+            plotter.move_to(point)
+
+    def line_to(self, point):
+        for plotter in self.plotters:
+            plotter.line_to(point)
+
+    def add_layer(self, *args, **kwargs):
+        for plotter in self.plotters:
+            plotter.add_layer(*args, **kwargs)
+
+    def switch_layers(self, *args, **kwargs):
+        for plotter in self.plotters:
+            plotter.switch_layers(*args, **kwargs)
+
+    def finalise(self):
+        for plotter in self.plotters:
+            plotter.finalise()
+
+    def register_plotter(self, plotter):
+        self.plotters.append(plotter)