doc/assy: add constraints (#850)

* doc/assy: add constraints

* doc/gen_colors.py: add script for generating color list

* doc/assy: initial locations

doc/gen_colors.py

@@ -0,0 +1,74 @@
+"""
+A script to generate RST (HTML only) for displaying all the colours supported
+by OCP. Used in the file assy.rst.
+"""
+
+from OCP import Quantity
+import cadquery as cq
+from typing import Dict
+from itertools import chain
+
+
+OCP_COLOR_LEADER, SEP = "Quantity_NOC", "_"
+
+TEMPLATE = """\
+      <div style="background-color:rgba({background_color});padding:10px;border-radius:5px;color:rgba({text_color});">{color_name}</div>\
+"""
+
+
+def color_to_rgba_str(c: cq.Color) -> str:
+    """ Convert a Color object to a string for the HTML/CSS template.
+    """
+    t = c.toTuple()
+    vals = [int(v * 255) for v in t[:3]]
+    return ",".join([str(v) for v in chain(vals, [t[3]])])
+
+
+def calc_text_color(c: cq.Color) -> str:
+    """ Calculate required overlay text color from background color.
+    """
+    val = sum(c.toTuple()[:3]) / 3
+    if val < 0.5:
+        rv = "255,255,255"
+    else:
+        rv = "0,0,0"
+
+    return rv
+
+
+def get_colors() -> Dict[str, cq.Color]:
+    """ Scan OCP for colors and output to a dict.
+    """
+    colors = {}
+    for name in dir(Quantity):
+        splitted = name.rsplit(SEP, 1)
+        if splitted[0] == OCP_COLOR_LEADER:
+            colors.update({splitted[1].lower(): cq.Color(splitted[1])})
+
+    return colors
+
+
+def rst():
+    """ Produce the text for a Sphinx directive.
+    """
+    lines = [
+        ".. raw:: html",
+        "",
+        '    <div class="color-grid" style="display:grid;grid-gap:10px;grid-template-columns:repeat(auto-fill, minmax(200px,1fr));">',
+    ]
+    colors = get_colors()
+    for name, c in colors.items():
+        lines += [
+            TEMPLATE.format(
+                background_color=color_to_rgba_str(c),
+                text_color=calc_text_color(c),
+                color_name=name,
+            )
+        ]
+
+    lines.append("    </div>")
+    return "\n".join(lines)
+
+
+if __name__ == "__main__":
+    print(rst())