如何在tkinter上绘制递归树

Question

我尝试在python tkinter上根据用户输入的深度绘制递归树，下面是我到目前为止的代码:

from tkinter import * # Import tkinter
import math
#angleFactor = math.pi/5
#sizeFactor = 0.58
class Main:
    def __init__(self):
        window = Tk() # Create a window
        window.title("Recursive Tree") # Set a title
        self.width = 200
        self.height = 200
        self.canvas = Canvas(window, 
        width = self.width, height = self.height,bg="white")
        self.canvas.pack()
        # Add a label, an entry, and a button to frame1
        frame1 = Frame(window) # Create and add a frame to window
        frame1.pack()
        Label(frame1, 
        text = "Enter the depth: ").pack(side = LEFT)
        self.depth = StringVar()
        entry = Entry(frame1, textvariable = self.depth, 
                  justify = RIGHT).pack(side = LEFT)
        Button(frame1, text = "Display Recursive Tree", 
        command = self.display).pack(side = LEFT)
        self.angleFactor = math.pi/5
        self.sizeFactor = 0.58          
        window.mainloop() # Create an event loop
    def drawLine(self, x1,x2,y1,y2):
        self.canvas.create_line(x1,y1,x2,y2, tags = "line")    
    def display(self):
        self.canvas.delete("line")
        return self.paintBranch(int(self.depth.get()),self.width/2, self.height /2   , self.height/3, math.pi/2)
    def paintBranch(self,depth, x1, y1, length, angle):
        if depth >= 0:
            x2 = x1 +int( math.cos(angle) * length)
            y2 = y1 + int(math.sin(angle) * length)

            # Draw the line
            self.drawLine(x1,y1,x2,y2)

            # Draw the left branch
            self.paintBranch(depth - 1, x2, y2, length * self.sizeFactor, angle + self.angleFactor  )
            # Draw the right branch
            self.paintBranch(depth - 1, x2, y2, length * self.sizeFactor, angle - self.angleFactor )        

Main()

当用户进入depth=0的代码是工作的，但在depth >=1递归时，代码无法绘制树，我需要帮助我的代码，感谢前

Answer 1

您的主要问题是您弄乱了drawLine方法的参数。您将其定义为

drawLine(self, x1,x2,y1,y2)

但是你叫它

self.drawLine(x1,y1,x2,y2)

所以你传递给它的y1参数用于x2参数，x2参数用于y1参数。

你还需要改变你的初始y1值，并在从y1计算y2时改变符号，因为Tkinter中的Y坐标随着你往下屏幕而增加。

这是你的代码的修复版本。

from tkinter import * # Import tkinter
import math
class Main:
    def __init__(self):
        window = Tk() # Create a window
        window.title("Recursive Tree") # Set a title
        self.width = 400
        self.height = 400
        self.canvas = Canvas(window, 
        width = self.width, height = self.height,bg="white")
        self.canvas.pack()
        # Add a label, an entry, and a button to frame1
        frame1 = Frame(window) # Create and add a frame to window
        frame1.pack()
        Label(frame1, 
            text = "Enter the depth: ").pack(side = LEFT)
        self.depth = StringVar()
        Entry(frame1, textvariable = self.depth, 
            justify = RIGHT).pack(side = LEFT)
        Button(frame1, text = "Display Recursive Tree", 
            command = self.display).pack(side = LEFT)
        self.angleFactor = math.pi/5
        self.sizeFactor = 0.58
        window.mainloop() # Create an event loop
    def drawLine(self, x1,y1, x2,y2):
        self.canvas.create_line(x1,y1, x2,y2, tags = "line")    
    def display(self):
        self.canvas.delete("line")
        depth = int(self.depth.get())
        return self.paintBranch(depth, self.width/2, self.height, self.height/3, math.pi/2)
    def paintBranch(self, depth, x1, y1, length, angle):
        if depth >= 0:
            depth -= 1
            x2 = x1 + int(math.cos(angle) * length)
            y2 = y1 - int(math.sin(angle) * length)
            # Draw the line
            self.drawLine(x1,y1, x2,y2)
            # Draw the left branch
            self.paintBranch(depth, x2, y2, length * self.sizeFactor, angle + self.angleFactor  )
            # Draw the right branch
            self.paintBranch(depth, x2, y2, length * self.sizeFactor, angle - self.angleFactor )        

Main()