convex_hull for faster rotate_and_scale_to_fit

axi/drawing.py

@@ -2,7 +2,8 @@ from __future__ import division
 
 from math import sin, cos, radians
 
-from .paths import simplify_paths, sort_paths, join_paths, crop_paths
+from .paths import (
+    simplify_paths, sort_paths, join_paths, crop_paths, convex_hull)
 
 try:
     import cairo
@@ -61,10 +62,18 @@ class Drawing(object):
         with open(filename, 'w') as fp:
             fp.write(self.dumps_svg())
 
+    @property
+    def points(self):
+        return [(x, y) for path in self.paths for x, y in path]
+
+    @property
+    def convex_hull(self):
+        return convex_hull(self.points)
+
     @property
     def bounds(self):
         if not self._bounds:
-            points = [(x, y) for path in self.paths for x, y in path]
+            points = self.points
             if points:
                 x1 = min(x for x, y in points)
                 x2 = max(x for x, y in points)
@@ -168,16 +177,18 @@ class Drawing(object):
         scale = min(width / self.width, height / self.height)
         return self.scale(scale, scale).center(width, height)
 
-    def rotate_and_scale_to_fit(self, width, height, padding=0, step=5):
-        drawings = []
+    def rotate_and_scale_to_fit(self, width, height, padding=0, step=1):
+        values = []
         width -= padding * 2
         height -= padding * 2
+        hull = Drawing([self.convex_hull])
         for angle in range(0, 180, step):
-            drawing = self.rotate(angle)
-            scale = min(width / drawing.width, height / drawing.height)
-            drawings.append((scale, angle, drawing))
-        scale, angle, drawing = max(drawings)
-        return drawing.scale(scale, scale).center(width, height)
+            d = hull.rotate(angle)
+            scale = min(width / d.width, height / d.height)
+            print angle, d.width, d.height
+            values.append((scale, angle))
+        scale, angle = max(values)
+        return self.rotate(angle).scale(scale, scale).center(width, height)
 
     def remove_paths_outside(self, width, height):
         e = 1e-8
@@ -192,10 +203,12 @@ class Drawing(object):
                 paths.append(path)
         return Drawing(paths)
 
-    def render(self, scale=109, margin=1, line_width=0.5/25.4, show_bounds=True):
+    def render(self, scale=109, margin=1, line_width=0.5/25.4,
+            use_axi_bounds=True, show_axi_bounds=True):
         if cairo is None:
             raise Exception('Drawing.render() requires cairo')
-        # x1, y1, x2, y2 = self.bounds
+        x1, y1, x2, y2 = self.bounds
+        if use_axi_bounds:
             x1, y1, x2, y2 = (0, 0, 12, 8.5)
         w = x2 - x1
         h = y2 - y1
@@ -211,7 +224,7 @@ class Drawing(object):
         dc.translate(-x1, -y1)
         dc.set_source_rgb(1, 1, 1)
         dc.paint()
-        if show_bounds:
+        if show_axi_bounds:
             dc.set_source_rgb(0.5, 0.5, 0.5)
             dc.set_line_width(1 / scale)
             dc.rectangle(0, 0, 12, 8.5)

axi/paths.py

@@ -1,5 +1,5 @@
 from math import hypot
-from shapely.geometry import LineString
+from shapely import geometry
 
 from .spatial import Index
 
@@ -17,7 +17,7 @@ def load_paths(filename):
 def simplify_path(points, tolerance):
     if len(points) < 2:
         return points
-    line = LineString(points)
+    line = geometry.LineString(points)
     line = line.simplify(tolerance, preserve_topology=False)
     return list(line.coords)
 
@@ -109,3 +109,13 @@ def crop_paths(paths, x1, y1, x2, y2):
     for path in paths:
         result.extend(crop_path(path, x1, y1, x2, y2))
     return result
+
+def convex_hull(points):
+    hull = geometry.MultiPoint(points).convex_hull
+    if isinstance(hull, geometry.Polygon):
+        return list(hull.exterior.coords)
+    if isinstance(hull, geometry.LineString):
+        return list(hull.coords)
+    if isinstance(hull, geometry.Point):
+        return list(hull.coords)
+    raise Exception('unhandled convex hull geometry')

examples/ribbon.py

@@ -84,15 +84,16 @@ def main():
     ds = []
     for filename, angle in zip(filenames, angles):
         ds.append(axi.Drawing(axi.load_paths(filename)).scale_to_fit(8.5, 12).scale(1, -1))
-    d = grid_drawings(ds, 2, 1)
+    # d = grid_drawings(ds, 2, 1)
+    d = ds[0]
     print len(d.paths)
     print 'joining paths'
     d = d.join_paths(0.01)
     print len(d.paths)
     print 'transforming paths'
     # d = d.scale(1, -1)
-    d = d.rotate_and_scale_to_fit(8.5, 12 - text.height - 0.75, step=5)
-    d = d.origin()
+    d = d.rotate_and_scale_to_fit(8.5, 12 - text.height - 0.75)
+    # d = d.origin()
     print 'sorting paths'
     d = d.sort_paths()
     print 'joining paths'