Tkinter中用鼠标实时绘图

Question

我很喜欢在 Tkinter 中绘图，但只有松开鼠标按钮才能看到形状。 拖动鼠标时如何查看形状？ 我使用下面的代码已经完成了一半，但是如果你运行它，你会看到它不会更新以删除由运动 function 制作的每个绘图。

from tkinter import *

window = Tk()

canvas = Canvas(bg='black')
canvas.pack()

def locate_xy(event):
    global current_x, current_y
    current_x, current_y = event.x, event.y

def draw_circle(event):
    global current_x, current_y
    canvas.create_oval((current_x, current_y, event.x, event.y), outline='white')
    current_x, current_y = event.x, event.y

def update_circle(event):
    global current_x, current_y
    canvas.create_oval((current_x, current_y, event.x, event.y), outline='white')

canvas.bind('<ButtonPress-1>', locate_xy)
canvas.bind('<ButtonRelease-1>', draw_circle)
canvas.bind('<B1-Motion>', update_circle)

window.mainloop()

Answer 1

您已经在事件<B1-Motion>按下左键的情况下跟踪鼠标移动，因此只需在此处添加绘图：

from tkinter import *

window = Tk()

canvas = Canvas(bg='black')
canvas.pack()

def draw_line(event):
    x, y = event.x, event.y
    canvas.create_oval((x-2, y-2, x+2, y+2), outline='white')

canvas.bind('<B1-Motion>', draw_line)

window.mainloop()

Answer 2

您只需要在locate_xy()内创建椭圆并在update_circle()内更新其坐标。 <ButtonRelease-1>的绑定不是必须的：

def locate_xy(event):
    global current_x, current_y, current_item
    current_x, current_y = event.x, event.y
    # create the oval item and save its ID
    current_item = canvas.create_oval((current_x, current_y, event.x, event.y), outline='white')

def update_circle(event):
    # update coords of the oval item
    canvas.coords(current_item, (current_x, current_y, event.x, event.y))

canvas.bind('<ButtonPress-1>', locate_xy)
canvas.bind('<B1-Motion>', update_circle)