Tkinter 画布为空

Question

我从http://zetcode.com/tkinter/drawing/ 的第一个示例中获取了这段代码，我对其进行了改装，以便它可以在同一个文件中打印地图。没有固有的错误，它会通过循环，甚至正确地命中所有 if 语句。但最后画布/框架里面什么都没有。谁能告诉我为什么？

from tkinter import Tk, Canvas, Frame, BOTH, NW


    class Example(Frame):

        def __init__(self, parent):
            Frame.__init__(self, parent)   

            self.parent = parent        
            self.initUI()

        def initUI(self):

            self.parent.title("Board")        
            self.pack(fill=BOTH, expand=1)

            canvas = Canvas(self)

            #The first four parameters are the x,y coordinates of the two bounding points.
            #The top-left and the bottom-right. 
            color = ""
            for x in range(10):
                for y in range(10):
                    if type(landMass[x][y]) is Land:
                        color = "grey" 
                    if type(landMass[x][y]) is Food:
                        color = "green"
                    if type(landMass[x][y]) is Water:
                        color = "blue"
                    if type(landMass[x][y]) is Shelter:
                        color = "black"
                    rec = canvas.create_rectangle(3 + 50 * y, 3 + 50 * x, 53 + 50 * y, 53 + 50 * x , fill=color)
                    text = canvas.create_text(3 + 50 * y, 3 + 50 * x, anchor=NW, fill="white", text=landMass[x][y].elevation)

    def main():

        root = Tk()
        ex = Example(root)
        root.geometry("500x500+500+500")
        root.mainloop()  


    if __name__ == '__main__':
        main() 

Answer 1

检查链接，您在函数末尾省略了对canvas.pack(fill=BOTH, expand=1) 的调用。

在此之后：

for x in range(10):
    for y in range(10):
        if type(landMass[x][y]) is Land:
            color = "grey" 
        if type(landMass[x][y]) is Food:
            color = "green"
        if type(landMass[x][y]) is Water:
            color = "blue"
        if type(landMass[x][y]) is Shelter:
            color = "black"
        rec = canvas.create_rectangle(3 + 50 * y, 3 + 50 * x, 53 + 50 * y, 53 + 50 * x , fill=color)
        text = canvas.create_text(3 + 50 * y, 3 + 50 * x, anchor=NW, fill="white", text=landMass[x][y].elevation)

你应该有：

canvas.pack(fill=BOTH, expand=1)