如何在 tkinter Canvas 中检测点击对象的标签？

Question

请问如何检测Pythontkinter.Canvas()中的标签。我已经用一些基本的 canvas 对象设置了一个示例程序，并且所有这些对象都已分配给某个标签。我想要的是在单击对象时获取该标记值，但不知道如何操作。

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)

我想获得这些值，例如 lines、ovals、square_5_4、square_7_1 等。有人知道如何做吗？ O:)

Answer 1

您可以遍历 canvas 上的所有项目 ID，获取它们的标签并将函数绑定到单击该对象（如果您需要所有对象（在 [=11 之前创建） =] 循环) 在 canvas 上执行此操作):

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 2

作为@Matiiss in a comment, you can use a Canvas object's tag_bind() 将回调函数绑定到特定事件（例如按钮 1 的点击）的方法。下面的代码——基于你的代码——说明了类似的事情是如何完成的。

它创建调用通用 pick() 单击事件处理函数并将原始事件对象传递给它的匿名 lambda 函数 plus 当前与对象关联的标签名称。

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()

Answer 3

您无需遍历所有项目即可获得 canvas 项目的标签。在 canvas 上单击的任何项目都分配有 "current" 标签。

您只需将 canvas.find_withtag 与 canvas.gettags 一起使用，或将 "current" 直接传递给 gettags，它将 return 您所有相关联的标签canvas 项。

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()

如何在 tkinter Canvas 中检测点击对象的标签？

How do I detect tags of clicked objects in tkinter Canvas?

python

tkinter

canvas

tkinter-canvas