动态添加项目到Tkinter Canvas

Question

我正在尝试学习Tkinter,目标是能够创建一个"实时"范围来绘制数据.作为测试,每次按下"绘制"按钮时,我都会尝试在画布上绘制多边形.三角形位置是随机的.我有两个问题:

1. 一旦程序启动,画布上就会出现一个三角形,为什么以及如何解决这个问题呢？

2. 当我按下按钮时,它不会绘制任何三角形,至少没有我能看到的.

码

---

from Tkinter import *

from random import randint

class App:

    def __init__(self,master):

        #frame = Frame(master)
        #frame.pack(side = LEFT)

        self.plotspc = Canvas(master,height = 100, width = 200, bg = "white")
        self.plotspc.grid(row=0,column = 2, rowspan = 5)

        self.button = Button(master, text = "Quit", fg = "red", \
                             command = master.quit)
        self.button.grid(row=0,column=0)

        self.drawbutton = Button(master, text = "Draw", command = \
                               self.pt([50,50]))
        self.drawbutton.grid(row = 0, column = 1)        

    def pt(self, coords):
        coords[0] = coords[0] + randint(-20,20)
        coords[1] = coords[1] + randint(-20,20)
        x = (0,5,10)
        y = (0,10,0)
        xp = [coords[0] + xv for xv in x]
        yp = [coords[1] + yv for yv in y]
        ptf = zip(xp,yp)
        self.plotspc.create_polygon(*ptf)        

    if __name__ == "__main__":
        root = Tk()
        app = App(root)
        root.mainloop()

Answer 1

command=self.pt([50,50])(您在Button构建Draw按钮的调用中使用)会立即执行您要执行的调用,并将result(None)绑定到command.相反,使用相同的:

, command=lambda: self.pt([50, 50]) )

每次按下该按钮时延迟执行调用.