class OrderShortestPath(OrderHandler):
""" This uses Dijkstra's algorithm to find the shortest path.
"""
name = QApplication.translate("job", "Shortest Path")
time_limit = 0.2 # This is in the UI thread
def order(self, job, path):
""" Sort subpaths by minimizing the distances between all start
and end points.
"""
subpaths = split_painter_path(path)
log.debug("Subpath count: {}".format(len(subpaths)))
# Cache all start and end points
time_limit = time() + self.time_limit
zero = QVector2D(0, 0)
for sp in subpaths:
# Average start and end into one "vertex"
start = sp.elementAt(0)
end = sp.elementAt(sp.elementCount() - 1)
sp.start_point = QVector2D(start.x, start.y)
sp.end_point = QVector2D(end.x, end.y)
distance = QVector2D.distanceToPoint
original = subpaths[:]
result = []
p = zero
while subpaths:
best = sys.maxsize
shortest = None
for sp in subpaths:
d = distance(p, sp.start_point)
if d < best:
best = d
shortest = sp
p = shortest.end_point
result.append(shortest)
subpaths.remove(shortest)
# time.time() is slow so limit the calls
if time() > time_limit:
result.extend(subpaths) # At least part of it is optimized
log.debug("Shortest path search aborted (time limit reached)")
break
d = self.subpath_move_distance(zero, original)
d = d - self.subpath_move_distance(zero, result)
log.debug("Shortest path search: Saved {} in of movement ".format(
to_unit(d, 'in')))
return join_painter_paths(result)
def subpath_move_distance(self, p, subpaths, limit=sys.maxsize):
# Collect start and end points
d = 0
# Local ref saves a lookup per iter
distance = QVector2D.distanceToPoint
for sp in subpaths:
d += distance(p, sp.start_point)
if d > limit:
break # Over the limit already abort
p = sp.end_point
return d
class OrderReversed(OrderHandler):
name = QApplication.translate("job", "Reversed")
def order(self, job, path):
return path.toReversed()
class OrderMaxY(OrderHandler):
name = QApplication.translate("job", 'Max Y')
def order(self, job, path):
return self.order_by_func(job, path, lambda p: p.boundingRect().top())
class OrderNormal(OrderHandler):
name = QApplication.translate("job", "Normal")
def order(self, job, path):
return path
def tr(*args, **kwargs):
""" Alias to translate """
from enaml.qt.QtWidgets import QApplication
return QApplication.translate(*args, **kwargs)