Bezier-貝塞爾曲線

一。實現Bezier曲線的升階，降階和拖動。

#!/usr/bin/env python
# -*- coding: utf-8 -*-
'My Bezier'
import numpy as np
from scipy.special import comb, perm
from matplotlib import pyplot as plt

class MyBezier:
    def __init__(self, line):
        self.line = line
        self.index_02 = None #保存拖動的這個點的索引
        self.press = None # 狀態標識，1為按下，None為沒按下
        self.pick = None # 狀態標識，1為選中點並按下,None為沒選中
        self.motion = None #狀態標識，1為進入拖動,None為不拖動
        self.xs = list() # 保存點的x坐標
        self.ys = list() # 保存點的y坐標
        self.cidpress = line.figure.canvas.mpl_connect('button_press_event', self.on_press) # 鼠標按下事件
        self.cidrelease = line.figure.canvas.mpl_connect('button_release_event', self.on_release) # 鼠標放開事件
        self.cidmotion = line.figure.canvas.mpl_connect('motion_notify_event', self.on_motion) # 鼠標拖動事件
        self.cidpick = line.figure.canvas.mpl_connect('pick_event', self.on_picker) # 鼠標選中事件

    def on_press(self, event): # 鼠標按下調用
        if event.inaxes!=self.line.axes: return
        self.press = 1
        
    def on_motion(self, event): # 鼠標拖動調用
        if event.inaxes!=self.line.axes: return
        if self.press is None: return
        if self.pick is None: return
        if self.motion is None: # 整個if獲取鼠標選中的點是哪個點
            self.motion = 1
            x = self.xs
            xdata = event.xdata
            ydata = event.ydata
            index_01 = 0
            for i in x:
                if abs(i - xdata) < 0.02: # 0.02 為點的半徑
                    if abs(self.ys[index_01] - ydata) < 0.02:break
                index_01 = index_01 + 1
            self.index_02 = index_01
        if self.index_02 is None: return
        self.xs[self.index_02] = event.xdata # 鼠標的坐標覆蓋選中的點的坐標
        self.ys[self.index_02] = event.ydata
        self.draw_01()

    def on_release(self, event): # 鼠標按下調用
        if event.inaxes!=self.line.axes: return
        if self.pick == None: # 如果不是選中點，那就添加點
            self.xs.append(event.xdata)
            self.ys.append(event.ydata)
        if self.pick == 1 and self.motion != 1: # 如果是選中點，但不是拖動點，那就降階
            x = self.xs
            xdata = event.xdata
            ydata = event.ydata
            index_01 = 0
            for i in x:
                if abs(i - xdata) < 0.02:
                    if abs(self.ys[index_01] - ydata) < 0.02:break
                index_01 = index_01 + 1
            self.xs.pop(index_01)
            self.ys.pop(index_01)
        self.draw_01()
        self.pick = None # 所有狀態恢復，鼠標按下到稀放為一個周期
        self.motion = None
        self.press = None
        self.index_02 = None

    def on_picker(self, event): # 選中調用
        self.pick = 1

    def draw_01(self): # 繪圖
        self.line.clear() # 不清除的話會保留原有的圖
        self.line.axis([0,1,0,1]) # x和y范圍0到1
        self.bezier(self.xs,self.ys) # Bezier曲線
        self.line.scatter(self.xs, self.ys,color='b',s=200, marker="o",picker=5) # 畫點
        self.line.plot(self.xs, self.ys,color='r') # 畫線
        self.line.figure.canvas.draw() # 重構子圖

    def bezier(self,*args): # Bezier曲線公式轉換，獲取x和y
        t=np.linspace(0,1) # t 范圍0到1
        le = len(args[0]) - 1
        le_1 = 0
        b_x,b_y = 0,0
        for x in args[0]:
            b_x = b_x + x*(t**le_1)*((1-t)**le)*comb(len(args[0]) - 1,le_1) # comb 組合，perm 排列
            le = le - 1
            le_1 = le_1 + 1

        le = len(args[0]) - 1
        le_1 = 0
        for y in args[1]:
            b_y = b_y + y*(t**le_1)*((1-t)**le)*comb(len(args[0]) - 1,le_1)
            le = le - 1
            le_1 = le_1 + 1
        self.line.plot(b_x,b_y)

fig = plt.figure(2,figsize=(12,6)) #創建第2個繪圖對象,1200*600像素
ax = fig.add_subplot(111) #一行一列第一個子圖
ax.set_title('My Bezier')

myBezier = MyBezier(ax)
plt.xlabel('X')
plt.ylabel('Y')
plt.show()

二。運行結果

 

 

三。參考

http://blog.csdn.net/joogle/article/details/7975118

http://blog.csdn.net/wizardforcel/article/details/54782688