fix(pec): do not use reserved machine function from thread catalog

src/pystitch/EmbThread.py

@@ -54,7 +54,7 @@ def find_nearest_color_index(find_color, values):
     closest_index = None
     current_closest_value = float("inf")
     for current_index, t in enumerate(values):
-        if t is None:
+        if t is None or getattr(t, "reserved", False):
             continue
         dist = color_distance_red_mean(
             red, green, blue, t.get_red(), t.get_green(), t.get_blue()

src/pystitch/EmbThreadPec.py

@@ -65,17 +65,19 @@ def get_thread_set():
         EmbThreadPec(9, 91, 166, "Electric Blue", "59"),
         EmbThreadPec(240, 249, 112, "Lemon Yellow", "60"),
         EmbThreadPec(227, 243, 91, "Fresh Green", "61"),
-        EmbThreadPec(255, 153, 0, "Orange", "62"),
-        EmbThreadPec(255, 240, 141, "Cream Yellow", "63"),
-        EmbThreadPec(255, 200, 200, "Applique", "64"),
+        # Machine functions, not real thread colors
+        EmbThreadPec(255, 200, 100, "Applique Material", "62", reserved=True),
+        EmbThreadPec(255, 200, 200, "Applique Position", "63", reserved=True),
+        EmbThreadPec(255, 200, 200, "Applique", "64", reserved=True),
     ]
 
 
 class EmbThreadPec(EmbThread):
-    def __init__(self, red, green, blue, description, catalog_number):
+    def __init__(self, red, green, blue, description, catalog_number, reserved=False):
         EmbThread.__init__(self)
         self.set_color(red, green, blue)
         self.description = description
         self.catalog_number = catalog_number
         self.brand = "Brother"
         self.chart = "Brother"
+        self.reserved = reserved

test/test_palette.py

@@ -43,7 +43,10 @@ def test_unique_palette_max(self):
         """If the entries equal the list they should all map."""
         pattern = EmbPattern()
         threadset = get_thread_set()
-        for i in range(0, len(threadset)-2):
+        matchable_count = sum(
+            1 for t in threadset if t is not None and not getattr(t, "reserved", False)
+        )
+        for i in range(0, matchable_count):
             thread = EmbThread()
             thread.set_color(i, i, i)
             pattern += thread
@@ -90,6 +93,31 @@ def test_nonrepeat_palette_same(self):
         self.assertEqual(palette[0], palette[3], "Red and Red")
         self.assertEqual(palette[1], palette[2], "Blue and Blue")
 
+    def test_reserved_indices_excluded_from_matching(self):
+        threadset = get_thread_set()
+        for i in (62, 63, 64):
+            self.assertTrue(threadset[i].reserved)
+
+        # Two colliding "Deep Gold" threads used to fall through to the
+        # reserved index 62 slot (inkstitch#1105).
+        pattern = EmbPattern()
+        gold1 = EmbThread()
+        gold1.set_color(0xE8, 0xA9, 0x00)
+        gold2 = EmbThread()
+        gold2.set_color(0xE8, 0xA9, 0x00)
+        pattern.threadlist = [gold1, gold2]
+        palette = build_unique_palette(get_thread_set(), pattern.threadlist)
+        self.assertNotIn(62, palette)
+        self.assertNotIn(63, palette)
+        self.assertNotIn(64, palette)
+
+        # An RGB value that lands on reserved must resolve to a real color
+        # instead.
+        exact = EmbThread()
+        exact.set_color(255, 200, 200)
+        index = exact.find_nearest_color_index(get_thread_set())
+        self.assertNotIn(index, (62, 63, 64))
+
     def test_palette(self):
         """Similar colors map to the same index"""
         pattern = EmbPattern()