Tkinter Canvas.create_oval不更新颜色

Question

我正在尝试使用功能change_red更改画布上绘制的Im线条的颜色。 单击运行该功能的按钮后，self.color的值将更改为红色，但是该行仍显示为黑色。

我试图在init方法中更改self.color，但它仍然仅以黑色绘制。

from PIL import Image, ImageTk
import tkinter as tk

class Window(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)
        self.color = "black"
        menubar = tk.Menu(self)
        self.config(menu=menubar)
        operation_menu = tk.Menu(menubar, tearoff=0)
        config_menu = tk.Menu(menubar, tearoff=0)
        menubar.add_cascade(label="Change Color", menu=operation_menu)
        menubar.add_cascade(label="Help", menu=config_menu)
        config_menu.add_command(label="Exit", command=lambda: exit())
        operation_menu.add_command(label="Red", command=lambda: self.change_red())
        self.im = ImageTk.PhotoImage(Image.open("Test.png"))
        self.geometry("500x500")
        self.title("Image Editor")
        self.resizable(False, False)
        self.im_cv = tk.Canvas(width=300, height=200)
        self.im_cv.pack(expand="yes", fill="both")
        self.im_cv.create_image(50, 10, image=self.im, anchor="nw")
        self.im_cv.bind("<B1-Motion>", self.paint)

    def change_red(self):
        self.color = "red"

    def paint(self, event):
        print(self.color)
        x1, y1 = (event.x - 1), (event.y - 1)
        x2, y2 = (event.x + 1), (event.y + 1)
        self.my_canvas = self.im_cv.create_oval(x1, y1,x2,y2, fill=self.color, width=5)

window = Window()
window.mainloop()

Answer 1

您需要认识到create_oval函数中的width属性实际上width of the border around the outside of the ellipse. Default is 1 pixel.的width of the border around the outside of the ellipse. Default is 1 pixel. width of the border around the outside of the ellipse. Default is 1 pixel. 因此，即使颜色已更改，您也无法在视觉上看到它。 为此，您需要更改椭圆/椭圆的厚度或将width=0设置width=0即无边框。 这是一个例子：

#I didn't have ImageTk so I have changed it accordingly
import tkinter as tk

class Window(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)
        self.color = "black"
        self.t = 2
        menubar = tk.Menu(self)
        self.config(menu=menubar)
        operation_menu = tk.Menu(menubar, tearoff=0)
        config_menu = tk.Menu(menubar, tearoff=0)
        menubar.add_cascade(label="Change Color", menu=operation_menu)
        menubar.add_cascade(label="Help", menu=config_menu)
        config_menu.add_command(label="Exit", command=lambda: exit())
        operation_menu.add_command(label="Red", command=lambda: self.change_red())
        self.im = tk.PhotoImage(file="ex.png")
        self.geometry("500x500")
        self.title("Image Editor")
        self.resizable(False, False)
        self.im_cv = tk.Canvas(self, width=300, height=200)
        self.im_cv.pack(expand="yes", fill="both")
        self.im_cv.create_image(50, 10, image=self.im, anchor="nw")
        self.im_cv.bind("<B1-Motion>", self.paint)

    def change_red(self):
        self.color = "red"

    def paint(self, event):
        # print(self.color)
        x1, y1 = (event.x - self.t), (event.y - self.t)
        x2, y2 = (event.x + self.t), (event.y + self.t)
        self.my_canvas = self.im_cv.create_oval(x1, y1, x2, y2, fill=self.color, width=0)

window = Window()
window.mainloop()