如何检测tkinter Canvas中单击对象的标签

Question

我想问一下如何检测Pythontkinter.Canvas()中的标记。我已经用一些基本的画布对象设置了一个示例程序，所有这些对象都被分配给了一些标签。如果我点击对象但不知道如何操作，我想要的是获得该标记值。

例如，当我有以下代码时：

import tkinter
canvas = tkinter.Canvas(width=800, height=400)
canvas.pack()
canvas.create_line(20, 100, 150, 350, tags="lines")
canvas.create_line(50, 20, 300, 20, tags="lines")
canvas.create_oval(200, 250, 300, 350, fill="yellow", tags="ovals")
canvas.create_oval(400, 250, 500, 350, fill="blue", tags="ovals")
for j in range(4):
for i in range(10):
canvas.create_rectangle(i * 70 + 10, j * 60 + 10, i * 70 + 60, j * 60 + 50, fill="lightblue", tags=f"square_{j}_{i}")
def click(coords):
print(coords.x, coords.y)
canvas.bind("<Button-1>", click)

我想得到这些值，如lines、ovals、square_5_4、square_7_1等。有人知道怎么做吗？O： (

Answer 1

您不需要遍历所有项目来获得画布项目的标签。画布上单击的任何项目都被分配了"current"标记。

您只需要将canvas.find_withtag与canvas.gettags一起使用，或者将"current"直接传递给gettags，它就会返回与画布项目关联的所有标记。

import tkinter

canvas = tkinter.Canvas(width=800, height=400)
canvas.pack()
canvas.create_line(20, 100, 150, 350, tags="lines")
canvas.create_oval(400, 250, 500, 350, fill="blue", tags="ovals")
for j in range(4):
for i in range(10):
canvas.create_rectangle(i * 70 + 10, j * 60 + 10, i * 70 + 60, j * 60 + 50, fill="lightblue", tags=f"square_{j}_{i}")
def click(event):
#currently_clicked = canvas.find_withtag("current")
#if currently_clicked:
print(canvas.gettags("current")) # the first index will contain your desired output

canvas.bind("<Button-1>", click)
canvas.mainloop()

Answer 2

您可以循环浏览画布上的所有项目ID，获取它们的标签，并绑定一个函数来点击该对象(如果您需要画布上所有的对象(在for循环之前创建(来执行此操作(：

import tkinter as tk

root = tk.Tk()
canvas = tk.Canvas(root, width=800, height=400)
canvas.pack()
canvas.create_line(20, 100, 150, 350, tags="lines")
canvas.create_line(50, 20, 300, 20, tags="lines")
canvas.create_oval(200, 250, 300, 350, fill="yellow", tags="ovals")
canvas.create_oval(400, 250, 500, 350, fill="blue", tags="ovals")
for j in range(4):
for i in range(10):
canvas.create_rectangle(i * 70 + 10, j * 60 + 10, i * 70 + 60, j * 60 + 50, fill="lightblue", tags=f"square_{j}_{i}")

# loop over all items on the canvas, get their first tag (for simplicity) and bind that tag
# to clicking on the object and make that call the function that will print the tag name
# use a default value so that the correct tag is printed
for item_id in canvas.find_all():
tag = canvas.gettags(item_id)[0]
canvas.tag_bind(tag, '<Button-1>', lambda _, t=tag: print(t))
root.mainloop()

Answer 3

正如@Matiss在评论中建议的那样，您可以使用Canvas对象的tag_bind()方法将回调函数绑定到特定事件，例如单击按钮1。下面的代码——基于您的代码——说明了类似的事情是如何完成的。

它创建匿名的lambda函数，这些函数调用通用的pick()点击事件处理函数，并将原始事件对象加上当前与对象关联的标记名传递给它。

import tkinter
def pick(event, tag):
print(f'tag: {tag!r}, coords: {event.x}, {event.y}')
canvas = tkinter.Canvas(width=800, height=400)
canvas.pack()
canvas.create_line(20, 100, 150, 350, tags='lines')
canvas.create_line(50, 20, 300, 20, tags='lines')
canvas.tag_bind('lines', '<Button-1>', lambda event: pick(event, 'lines'))
canvas.create_oval(200, 250, 300, 350, fill='yellow', tags='ovals')
canvas.create_oval(400, 250, 500, 350, fill='blue', tags='ovals')
canvas.tag_bind('ovals', '<Button-1>', lambda event: pick(event, 'ovals'))
for j in range(4):
for i in range(10):
tag = f'square_{j}_{i}'
canvas.create_rectangle(i*70 + 10, j*60 + 10, i*70 + 60, j*60 + 50,
fill='lightblue', tags=tag)
canvas.tag_bind(tag, '<Button-1>', lambda event, tag=tag: pick(event, tag))
tkinter.mainloop()