feat(plot): configure one or two marker pairs per axis

python/protocan/plot.py

@@ -102,6 +102,8 @@ class Bounds:
 class Markers:
     x_enabled: bool = True
     y_enabled: bool = False
+    x_pairs: int = 1
+    y_pairs: int = 1
     selected: Marker = Marker.A
     a: Optional[float] = None
     b: Optional[float] = None
@@ -112,11 +114,21 @@ class Markers:
     g: Optional[float] = None
     h: Optional[float] = None
 
+    def __post_init__(self) -> None:
+        if self.x_pairs not in (1, 2) or self.y_pairs not in (1, 2):
+            raise ValueError("Marker pair count must be 1 or 2")
+
     def value(self, marker: Marker) -> Optional[float]:
         return getattr(self, marker.name.lower())
 
     def enabled(self, marker: Marker) -> bool:
-        return self.y_enabled if marker.horizontal else self.x_enabled
+        if marker in (Marker.A, Marker.B):
+            return self.x_enabled
+        if marker in (Marker.C, Marker.D):
+            return self.x_enabled and self.x_pairs >= 2
+        if marker in (Marker.E, Marker.F):
+            return self.y_enabled
+        return self.y_enabled and self.y_pairs >= 2
 
     def move(self, marker: Marker, value: float) -> "Markers":
         return replace(self, **{marker.name.lower(): value})

python/tests/test_plot.py

@@ -5,6 +5,7 @@ import math
 import os
 from pathlib import Path
 import unittest
+from dataclasses import replace
 
 from protocan.plot import Bounds, Marker, Markers, PlotMath, Viewport
 
@@ -31,6 +32,9 @@ class PlotTests(unittest.TestCase):
     def test_markers_stay_in_data_coordinates_and_cross(self):
         bounds = Bounds(1000, 2000, -10, 10)
         markers = Markers().positioned(self.core, bounds)
+        self.assertTrue(markers.enabled(Marker.A))
+        self.assertFalse(markers.enabled(Marker.C))
+        self.assertTrue(replace(markers, x_pairs=2).enabled(Marker.C))
         zoomed = bounds.visible(self.core, Viewport(.25, .25, .5, .5))
         self.assertEqual(markers, markers.positioned(self.core, zoomed))
         moved = markers.drag(self.core, Marker.A, 50, 500, zoomed)