1 files changed, 111 insertions, 0 deletions
diff --git a/misc/pylib/fontbuild/mitreGlyph.py b/misc/pylib/fontbuild/mitreGlyph.py
new file mode 100644
index 000000000..d0834ed84
--- /dev/null
+++ b/misc/pylib/fontbuild/mitreGlyph.py
@@ -0,0 +1,111 @@
+# Copyright 2015 Google Inc. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+"""Mitre Glyph: 
+
+mitreSize : Length of the segment created by the mitre. The default is 4.
+maxAngle :  Maximum angle in radians at which segments will be mitred. The default is .9 (about 50 degrees).
+            Works for both inside and outside angles
+
+"""
+
+import math
+from robofab.objects.objectsRF import RPoint, RSegment
+from fontbuild.convertCurves import replaceSegments
+
+def getTangents(contours):
+    tmap = []
+    for c in contours:
+        clen = len(c)
+        for i in range(clen):
+            s = c[i]
+            p = s.points[-1]
+            ns = c[(i + 1) % clen]
+            ps = c[(clen + i - 1) % clen]
+            np = ns.points[1] if ns.type == 'curve' else ns.points[-1]
+            pp = s.points[2] if s.type == 'curve' else ps.points[-1]
+            tmap.append((pp - p, np - p))
+    return tmap    
+
+def normalizeVector(p):
+    m = getMagnitude(p);
+    if m != 0:
+        return p*(1/m)
+    else:
+        return RPoint(0,0)
+
+def getMagnitude(p):
+    return math.sqrt(p.x*p.x + p.y*p.y)
+    
+def getDistance(v1,v2):
+    return getMagnitude(RPoint(v1.x - v2.x, v1.y - v2.y))
+
+def getAngle(v1,v2):
+    angle = math.atan2(v1.y,v1.x) - math.atan2(v2.y,v2.x)
+    return (angle + (2*math.pi)) % (2*math.pi)
+    
+def angleDiff(a,b):
+    return math.pi - abs((abs(a - b) % (math.pi*2)) - math.pi)
+
+def getAngle2(v1,v2):
+    return abs(angleDiff(math.atan2(v1.y, v1.x), math.atan2(v2.y, v2.x)))
+
+def getMitreOffset(n,v1,v2,mitreSize=4,maxAngle=.9):
+    
+    # dont mitre if segment is too short
+    if abs(getMagnitude(v1)) < mitreSize * 2 or abs(getMagnitude(v2)) < mitreSize * 2:
+        return
+    angle = getAngle2(v2,v1)
+    v1 = normalizeVector(v1)
+    v2 = normalizeVector(v2)
+    if v1.x == v2.x and v1.y == v2.y:
+        return
+    
+    
+    # only mitre corners sharper than maxAngle
+    if angle > maxAngle:
+        return
+    
+    radius = mitreSize / abs(getDistance(v1,v2))
+    offset1 = RPoint(round(v1.x * radius), round(v1.y * radius))
+    offset2 = RPoint(round(v2.x * radius), round(v2.y * radius))
+    return offset1, offset2
+
+def mitreGlyph(g,mitreSize,maxAngle):
+    if g == None:
+        return
+    
+    tangents = getTangents(g.contours)
+    sid = -1
+    for c in g.contours:
+        segments = []
+        needsMitring = False
+        for s in c:
+            sid += 1
+            v1, v2 = tangents[sid]
+            off = getMitreOffset(s,v1,v2,mitreSize,maxAngle)
+            s1 = s.copy()
+            if off != None:
+                offset1, offset2 = off
+                p2 = s.points[-1] + offset2
+                s2 = RSegment('line', [(p2.x, p2.y)])
+                s1.points[0] += offset1
+                segments.append(s1)
+                segments.append(s2)
+                needsMitring = True
+            else:
+                segments.append(s1)
+        if needsMitring:
+            replaceSegments(c, segments)