add inkstitch.threads.ThreadPalette class

inkstitch/threads/__init__.py

@@ -1 +1,2 @@
 from color import ThreadColor
+from palette import ThreadPalette

inkstitch/threads/color.py

@@ -2,10 +2,11 @@ import simplestyle
 import re
 import colorsys
 
+
 class ThreadColor(object):
     hex_str_re = re.compile('#([0-9a-z]{3}|[0-9a-z]{6})', re.I)
 
-    def __init__(self, color, name=None, description=None):
+    def __init__(self, color, name=None, number=None, manufacturer=None):
         if color is None:
             self.rgb = (0, 0, 0)
         elif isinstance(color, (list, tuple)):
@@ -16,7 +17,8 @@ class ThreadColor(object):
             raise ValueError("Invalid color: " + repr(color))
 
         self.name = name
-        self.description = description
+        self.number = number
+        self.manufacturer = manufacturer
 
     def __eq__(self, other):
         if isinstance(other, ThreadColor):
@@ -77,4 +79,4 @@ class ThreadColor(object):
         # convert back to values in the range of 0-255
         color = tuple(value * 255 for value in color)
 
-        return ThreadColor(color, name=self.name, description=self.description)
+        return ThreadColor(color, name=self.name, number=self.number, manufacturer=self.manufacturer)

inkstitch/threads/palette.py

@@ -0,0 +1,72 @@
+from collections import Set
+from .color import ThreadColor
+from colormath.color_objects import sRGBColor, LabColor
+from colormath.color_conversions import convert_color
+from colormath.color_diff import delta_e_cie1994
+
+
+def compare_thread_colors(color1, color2):
+    # K_L=2 indicates textiles
+    return delta_e_cie1994(color1, color2, K_L=2)
+
+
+class ThreadPalette(Set):
+    """Holds a set of ThreadColors all from the same manufacturer."""
+
+    def __init__(self, palette_file):
+        self.threads = dict()
+        self.parse_palette_file(palette_file)
+
+    def parse_palette_file(self, palette_file):
+        """Read a GIMP palette file and load thread colors.
+
+        Example file:
+
+        GIMP Palette
+        Name: Ink/Stitch: Metro
+        Columns: 4
+        # RGB Value                                 Color Name Number
+        240     186     212                         Sugar Pink   1624
+        237     171     194                           Carnatio   1636
+
+        """
+
+        with open(palette_file) as palette:
+            line = palette.readline().strip()
+            if line.lower() != "gimp palette":
+                raise ValueError("Invalid gimp palette header")
+
+            self.name = palette.readline().strip()
+            if self.name.lower().startswith('name: ink/stitch: '):
+                self.name = self.name[18:]
+
+            columns_line = palette.readline()
+            headers_line = palette.readline()
+
+            for line in palette:
+                fields = line.split("\t", 3)
+                thread_color = [int(field) for field in fields[:3]]
+                thread_name, thread_number = fields[3].strip().rsplit(" ", 1)
+                thread_name = thread_name.strip()
+
+                thread = ThreadColor(thread_color, thread_name, thread_number, manufacturer=self.name)
+                self.threads[thread] = convert_color(sRGBColor(*thread_color, is_upscaled=True), LabColor)
+
+    def __contains__(self, thread):
+        return thread in self.threads
+
+    def __iter__(self):
+        return iter(self.threads)
+
+    def __len__(self):
+        return len(self.threads)
+
+    def nearest_color(self, color):
+        """Find the thread in this palette that looks the most like the specified color."""
+
+        if isinstance(color, ThreadColor):
+            color = color.rgb
+
+        color = convert_color(sRGBColor(*color, is_upscaled=True), LabColor)
+
+        return min(self, key=lambda thread: compare_thread_colors(self.threads[thread], color))