Question

我正在学习tkinter＆amp;使用Python 2.7的对象和从给定点（x0，y0）到通过鼠标单击（x1，y1）选择的点绘制线条。

我试图在某些条件下保持线的长度相等（参见代码），然后指向鼠标选择的方向。

代码，

from Tkinter import *
import numpy as np

class App:

    def __init__(self, master):

        frame = Frame(master)
        frame.pack()

        self.can = Canvas(master, width=800, height=800)
        self.can.configure(cursor="crosshair")
        self.can.pack()
        self.start_point = [400, 400]
        self.end_point = [250, 400]
        self.line = self.can.create_line(self.start_point, self.end_point)
        self.can.bind("<Button-1>", self.line_end)
        self.can.bind("<Button-3>", self.del_line)

    def line_end(self, event):
        r = 150
        x0 = self.start_point[0]
        y0 = self.start_point[1]
        x1 = event.x
        y1 = event.y
        p = x1
        q = y1
        if x1 > x0 and y1 < y0:
            theta = np.arctan((y1-y0)/(x1-x0))
            p = int(x0 + r*np.cos(theta))
            q = int(y0 + r*np.sin(theta))
            print 'A'
        if x1 < x0 and y1 < y0:
            theta = np.arctan((y1-y0)/(x0-x1))
            p = int(x0 + r*np.cos(theta))
            q = int(y0 + r*np.sin(theta))
            print 'S'
        self.can.delete(self.line)
        self.line = self.can.create_line(x0, y0, p, q)
        print x0, y0, ' ........ ',x1, y1

    def del_line(self, event):
        self.can.delete(self.line)

root = Tk()
app = App(root)
root.mainloop()

如果确实存在满足条件的情况，则不会输入。我正确使用Pythons if 结构吗？

Answer 1

好的解决方案是两次，

1）在新的Python控制台中打开和运行解决了条件块的非条目问题。我不明白为什么，但它有效。

2）将坐标转换为float然后再转换为int＆amp;考虑到是stark说下面明显的不稳定行为停止了（愚蠢的弧度！），修改了下面的代码。

from Tkinter import *
import numpy as np

class App:

    def __init__(self, master):

        frame = Frame(master)
        frame.pack()

        self.can = Canvas(master, width=800, height=800)
        self.can.configure(cursor="crosshair")
        self.can.pack()
        self.start_point = [400, 400]
        self.end_point = [250, 400]
        self.line = self.can.create_line(self.start_point, self.end_point)
        self.can.bind("<Button-1>", self.line_end)
        self.can.bind("<Button-3>", self.del_line)

    def line_end(self, event):
        r = 150
        x0 = float(self.start_point[0])
        y0 = float(self.start_point[1])
        x1 = float(event.x)
        y1 = float(event.y)
        p = int(x1)
        q = int(y1)
        if x1 > x0 and y1 < y0:
            theta = np.arctan((y1-y0)/(x1-x0))
            p = int(x0 + r*np.cos(theta))
            q = int(y0 + r*np.sin(theta))
            print 'A', p, q, theta
        if x1 < x0 and y1 < y0:
            theta = np.arctan((y1-y0)/(x0-x1))
            p = int(x0 - r*np.cos(theta))
            q = int(y0 + r*np.sin(theta))
            print 'S', p, q, theta
        self.can.delete(self.line)
        self.line = self.can.create_line(x0, y0, p, q)
        print x0, y0, ' ........ ',x1, y1

    def del_line(self, event):
        self.can.delete(self.line)

root = Tk()
app = App(root)
root.mainloop()

如果条件Python被忽略？

1 个答案: