Python如何生成树形图案

# -*- coding: utf-8 -*-  import Tkinter import sys, random, math  class Point(object):   def __init__(self, x, y):     self.x = x     self.y = y    def __str__(self):     return "<Point>: (%f, %f)" % (self.x, self.y)  class Branch(object):   def __init__(self, bottom, top, branches, level = 0):     self.bottom = bottom     self.top = top     self.level = level     self.branches = branches     self.children = []    def __str__(self):     s = "Top: %s, Bottom: %s, Children Count: %d" % /       (self.top, self.bottom, len(self.children))     return s    def nextGen(self, n = -1, rnd = 1):     if n <= 0: n = self.branches     if rnd == 1:       n = random.randint(n / 2, n * 2)       if n <= 0: n = 1     dx = self.top.x - self.bottom.x     dy = self.top.y - self.bottom.y     r = 0.20 + random.random() * 0.2     if self.top.x == self.bottom.x:       # 如果是一条竖线       x = self.top.x       y = dy * r + self.bottom.y     elif self.top.y == self.bottom.y:       # 如果是一条横线       x = dx * r + self.bottom.x       y = self.top.y     else:       x = dx * r       y = x * dy / dx       x += self.bottom.x       y += self.bottom.y     oldTop = self.top     self.top = Point(x, y)     a = math.pi / (2 * n)     for i in range(n):       a2 = -a * (n - 1) / 2 + a * i - math.pi       a2 *= 0.9 + random.random() * 0.2       self.children.append(self.mkNewBranch(self.top, oldTop, a2))    def mkNewBranch(self, bottom, top, a):     dx1 = top.x - bottom.x     dy1 = top.y - bottom.y     r = 0.9 + random.random() * 0.2     c = math.sqrt(dx1 ** 2 + dy1 ** 2) * r     if dx1 == 0:       a2 = math.pi / 2     else:       a2 = math.atan(dy1 / dx1)       if (a2 < 0 and bottom.y > top.y) /         or (a2 > 0 and bottom.y < top.y) /         :         a2 += math.pi     b = a2 - a     dx2 = c * math.cos(b)     dy2 = c * math.sin(b)     newTop = Point(dx2 + bottom.x, dy2 + bottom.y)     return Branch(bottom, newTop, self.branches, self.level + 1)  class Tree(object):   def __init__(self, root, canvas, bottom, top, branches = 3, depth = 3):     self.root = root     self.canvas = canvas     self.bottom = bottom     self.top = top     self.branches = branches     self.depth = depth     self.new()    def gen(self, n = 1):     for i in range(n):       self.getLeaves()       for node in self.leaves:         node.nextGen()     self.show()    def new(self):     self.leavesCount = 0     self.branch = Branch(self.bottom, self.top, self.branches)     self.gen(self.depth)     print "leaves count: %d" % self.leavesCount    def chgDepth(self, d):     self.depth += d     if self.depth < 0: self.depth = 0     if self.depth > 10: self.depth = 10     self.new()    def chgBranch(self, d):     self.branches += d     if self.branches < 1: self.branches = 1     if self.branches > 10: self.branches = 10     self.new()    def getLeaves(self):     self.leaves = []     self.map(self.findLeaf)    def findLeaf(self, node):     if len(node.children) == 0:       self.leaves.append(node)    def show(self):     for i in self.canvas.find_all():       self.canvas.delete(i)     self.map(self.drawNode)     self.canvas.tag_raise("leaf")    def exit(self, evt):     sys.exit(0)    def map(self, func = lambda node: node):     # 遍历树     children = [self.branch]     while len(children) != 0:       newChildren = []       for node in children:         func(node)         newChildren.extend(node.children)       children = newChildren    def drawNode(self, node):     self.line2( #    self.canvas.create_line(         node.bottom.x,         node.bottom.y,         node.top.x,         node.top.y,         fill = "#100",         width = 1.5 ** (self.depth - node.level),         tags = "branch level_%d" % node.level,       )      if len(node.children) == 0:       # 画叶子       self.leavesCount += 1       self.canvas.create_oval(           node.top.x - 3,           node.top.y - 3,           node.top.x + 3,           node.top.y + 3,           fill = "#090",           tag = "leaf",         )      self.canvas.update()    def line2(self, x0, y0, x1, y1, width = 1, fill = "#000", minDist = 10, tags = ""):     dots = midDots(x0, y0, x1, y1, minDist)     dots2 = []     for i in range(len(dots) - 1):       dots2.extend([dots[i].x,         dots[i].y,         dots[i + 1].x,         dots[i + 1].y])     self.canvas.create_line(         dots2,         fill = fill,         width = width,         smooth = True,         tags = tags,       )  def midDots(x0, y0, x1, y1, d):   dots = []   dx, dy, r = x1 - x0, y1 - y0, 0   if dx != 0:     r = float(dy) / dx   c = math.sqrt(dx ** 2 + dy ** 2)   n = int(c / d) + 1   for i in range(n):     if dx != 0:       x = dx * i / n       y = x * r     else:       x = dx       y = dy * i / n     if i > 0:       x += d * (0.5 - random.random()) * 0.25       y += d * (0.5 - random.random()) * 0.25     x += x0     y += y0     dots.append(Point(x, y))   dots.append(Point(x1, y1))   return dots  if __name__ == "__main__":   root = Tkinter.Tk()   root.title("Tree")   gw, gh = 800, 600   canvas = Tkinter.Canvas(root,       width = gw,       height = gh,     )   canvas.pack()   tree = Tree(root, canvas, Point(gw / 2, gh - 20), Point(gw / 2, gh * 0.2), /     branches = 2, depth = 8)   root.bind("n", lambda evt: tree.new())   root.bind("=", lambda evt: tree.chgDepth(1))   root.bind("+", lambda evt: tree.chgDepth(1))   root.bind("-", lambda evt: tree.chgDepth(-1))   root.bind("b", lambda evt: tree.chgBranch(1))   root.bind("c", lambda evt: tree.chgBranch(-1))   root.bind("q", tree.exit)   root.mainloop()