1 files changed, 82 insertions, 0 deletions
diff --git a/lib/threads/color.py b/lib/threads/color.py
new file mode 100644
index 00000000..af474127
--- /dev/null
+++ b/lib/threads/color.py
@@ -0,0 +1,82 @@
+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, number=None, manufacturer=None):
+        if color is None:
+            self.rgb = (0, 0, 0)
+        elif isinstance(color, (list, tuple)):
+            self.rgb = tuple(color)
+        elif self.hex_str_re.match(color):
+            self.rgb = simplestyle.parseColor(color)
+        else:
+            raise ValueError("Invalid color: " + repr(color))
+
+        self.name = name
+        self.number = number
+        self.manufacturer = manufacturer
+
+    def __eq__(self, other):
+        if isinstance(other, ThreadColor):
+            return self.rgb == other.rgb
+        else:
+            return self == ThreadColor(other)
+
+    def __hash__(self):
+        return hash(self.rgb)
+
+    def __ne__(self, other):
+        return not(self == other)
+
+    def __repr__(self):
+        return "ThreadColor" + repr(self.rgb)
+
+    def to_hex_str(self):
+        return "#%s" % self.hex_digits
+
+    @property
+    def hex_digits(self):
+        return "%02X%02X%02X" % self.rgb
+
+    @property
+    def rgb_normalized(self):
+        return tuple(channel / 255.0 for channel in self.rgb)
+
+    @property
+    def font_color(self):
+        """Pick a color that will allow text to show up on a swatch in the printout."""
+        hls = colorsys.rgb_to_hls(*self.rgb_normalized)
+
+        # We'll use white text unless the swatch color is too light.
+        if hls[1] > 0.7:
+            return (1, 1, 1)
+        else:
+            return (254, 254, 254)
+
+    @property
+    def visible_on_white(self):
+        """A ThreadColor similar to this one but visible on white.
+
+        If the thread color is white, we don't want to try to draw white in the
+        simulation view or print white in the print-out.  Choose a color that's
+        as close as possible to the actual thread color but is still at least
+        somewhat visible on a white background.
+        """
+
+        hls = list(colorsys.rgb_to_hls(*self.rgb_normalized))
+
+        # Capping lightness should make the color visible without changing it
+        # too much.
+        if hls[1] > 0.85:
+            hls[1] = 0.85
+
+        color = colorsys.hls_to_rgb(*hls)
+
+        # convert back to values in the range of 0-255
+        color = tuple(value * 255 for value in color)
+
+        return ThreadColor(color, name=self.name, number=self.number, manufacturer=self.manufacturer)