from tkinter import *#1.獲取到小圓當前的圓心坐標(x1, y1)#2.獲取到小圓移動的圓心坐標(x2, y2)#3.把小圓從坐標(x1, y1)移動到坐標(x2, y2)__author__ = {'name' : 'Hongten',       'mail' : 'hongtenzone@foxmail.com',       'blog' : 'http://blog.csdn.net/',       'QQ': '648719819',       'created' : '2013-09-20'}class Eay(Frame):  def createWidgets(self):    ## The playing field    self.draw = Canvas(self, width=500, height=500)    #鼠標位置    self.mouse_x = 450    self.mouse_y = 250    #圓心坐標(x,y)    self.oval_zero_x = 250    self.oval_zero_y = 250    #外面大圓半徑    self.oval_r = 100    #里面小圓半徑    self.oval_R = 30    self.oval_r1 = self.oval_r - self.oval_R + 0.5    self.oval_r2 = self.oval_r - self.oval_R - 0.5    #小圓    self.letter_ball_x1 = 250    self.letter_ball_y1 = 250    # The ball 外面大圓    self.ball = self.draw.create_oval((self.oval_zero_x - self.oval_r),                     (self.oval_zero_y - self.oval_r),                     (self.oval_zero_x + self.oval_r),                     (self.oval_zero_y + self.oval_r),                     fill="white")    self.ball = self.draw.create_oval((self.oval_zero_x - self.oval_r1),                     (self.oval_zero_y - self.oval_r1),                     (self.oval_zero_x + self.oval_r1),                     (self.oval_zero_y + self.oval_r1),                     fill="blue")    self.ball = self.draw.create_oval((self.oval_zero_x - self.oval_r2),                     (self.oval_zero_y - self.oval_r2),                     (self.oval_zero_x + self.oval_r2),                     (self.oval_zero_y + self.oval_r2),                     fill="white")    #里面小圓    self.ball_over = self.draw.create_oval((self.oval_zero_x - self.oval_R),                        (self.oval_zero_y - self.oval_R),                        (self.oval_zero_x + self.oval_R),                        (self.oval_zero_y + self.oval_R),                        fill="red")    self.draw.pack(side=LEFT)  def mouseMove(self, event):    self.mouse_x = event.x    self.mouse_y = event.y    if SHOW_LOG:      print('#' * 50)      print('鼠標的坐標為：({}, {})'.format(self.mouse_x, self.mouse_y))      print('小圓當前坐標為：({}, {})'.format(self.letter_ball_x1, self.letter_ball_y1))    '''獲取到小圓移動的圓心坐標(x2, y2)'''    ax_x = abs(self.mouse_x - self.oval_zero_x)    ax_y = abs(self.mouse_y - self.oval_zero_y)    if SHOW_LOG:      print('坐標A(oval_zero_x, oval_zero_y)到坐標X(mouse_x, mouse_y)的距離為AX')      print('AX中ax_x = {}, ax_y = {}'.format(ax_x, ax_y))    ax_len = ((ax_x ** 2) + (ax_y ** 2))**0.5    if SHOW_LOG:      print('AX的長度為：{}'.format(ax_len))    #如果鼠標坐標在(ax_len > |r-R|)    if ax_len > abs(self.oval_r - self.oval_R):      ac_len = abs(self.oval_r - self.oval_R)      if SHOW_LOG:        print('AC的產度為:{}'.format(ac_len))      if int(self.mouse_x - self.oval_zero_x) != 0:        if int(self.mouse_y - self.oval_zero_y) != 0:          #求直線斜率 y = kx + b          k = (self.mouse_y - self.oval_zero_y)/(self.mouse_x - self.oval_zero_x)          if SHOW_LOG:            print('鼠標到大圓圓心的直線的斜率為：{}'.format(k))          b = self.mouse_y - (k * self.mouse_x)          ###################################################          #小圓移動后的坐標          #這里有三個條件：          #  1.小圓的圓心坐標(x1, y1)在直線AC上(y = kx + b)          #  2.(r-R)^2 = x1^2 + y1^2  由1,2可以得到 => (r-R)^2 = x1^2 + 2*x1*k*b + b^2  => x1有兩個值，通過3判斷x1的符號，從而求出y1          #  3.if self.mousex_x > 0:          #     x1 > 0          #這是一個二元二次方程，方程的解有兩組，不過通過鼠標的位置self.mouse_x(self.mouse_y)可以判斷圓心坐標x1(y1)          letter_ball_x2 = ((ac_len * (abs(self.mouse_x - self.oval_zero_x)))/ax_len) + self.letter_ball_x1          letter_ball_y2 = (letter_ball_x2 * k) + b          if SHOW_LOG:            print('小圓當前坐標為：({}, {})'.format(self.letter_ball_x1, self.letter_ball_y1))            print('小圓移動后坐標為：({}, {})'.format(letter_ball_x2, letter_ball_y2))          #把小圓從坐標(x1, y1)移動到坐標(x2, y2)          self.moved_x2 = letter_ball_x2 - self.letter_ball_x1          self.moved_y2 = letter_ball_y2 - self.letter_ball_y1          if SHOW_LOG:            print('需要移動的距離是：({}, {})'.format(int(self.moved_x2), int(self.moved_y2)))          self.draw.move(self.ball_over, int(self.moved_x2), int(self.moved_y2))          self.letter_ball_x1 = letter_ball_x2          self.letter_ball_y1 = letter_ball_y2        else:          print('鼠標在X軸上')       else:        print('鼠標在Y軸上')    else:      if SHOW_LOG:        print('小圓的移動后的坐標就是鼠標坐標')      #小圓移動后的坐標      letter_ball_x2 = self.mouse_x      letter_ball_y2 = self.mouse_y      if SHOW_LOG:        print('小圓移動后坐標為：({}, {})'.format(letter_ball_x2, letter_ball_y2))      #把小圓從坐標(x1, y1)移動到坐標(x2, y2)      self.moved_x2 = letter_ball_x2 - self.letter_ball_x1      self.moved_y2 = letter_ball_y2 - self.letter_ball_y1      if SHOW_LOG:        print('需要移動的距離是：({}, {})'.format(int(self.moved_x2), int(self.moved_y2)))      self.draw.move(self.ball_over, int(self.moved_x2), int(self.moved_y2))      self.letter_ball_x1 = letter_ball_x2      self.letter_ball_y1 = letter_ball_y2  def move_ball(self, *args):    #當鼠標在窗口中按下左鍵拖動的時候執行    #Widget.bind(self.draw, "<B1-Motion>", self.mouseMove)    #當鼠標在大圓內移動的時候執行    self.draw.tag_bind(self.ball, "<Any-Enter>", self.mouseMove)  def __init__(self, master=None):    global letter_ball_x2    letter_ball_x2 = 0    global letter_ball_y2    letter_ball_y2 = 0    global SHOW_LOG    SHOW_LOG = True    Frame.__init__(self, master)    Pack.config(self)    self.createWidgets()    self.after(10, self.move_ball)game = Eay()game.mainloop()