如何在 tkinter canvas 中一起移动多个对象？

Question

Im trying to move some rectangles with text in them around a canvas with mouse dragNdrop. Im using find_overlapping to select rectangles to be moved. This means the text originally created as part of class object Rect is not moved. Is there a way to modify my code to move all objects in a class object or perhaps find the class object ID using find_overlapping?

Text on rectangles can be identical, as shown in example. Tagging all elements in the class object with a random tag to group them together was my first idea, but retrieving such tag info using find_ovelapping has not been succesful.

import tkinter as tk

root=tk.Tk()
PAB=tk.Canvas(width=400, height=400)

#checks if a certain canvas object has a certain tag
def hastag(tag, id):
    if any(tag in i for i in PAB.gettags(id)):return True
    else:return False


class Rect:
    def __init__(self, x1, y1, name):
        rec = PAB.create_rectangle(x1,y1,x1+40,y1+40, fill='#c0c0c0', tag=('movable', name))
        text = PAB.create_text(x1+20,y1+20, text=name)
#mouse click find object to move
def get_it(event):
    delta=5
    global cur_rec
    for i in PAB.find_overlapping(event.x-delta, event.y-delta, event.x+delta, event.y-delta):
        if hastag('movable', i):
            cur_rec = i
    
PAB.bind('<Button-1>', get_it)

#mouse movement moves object
def move_it(event):
    xPos, yPos = event.x, event.y
    xObject, yObject = PAB.coords(cur_rec)[0],PAB.coords(cur_rec)[1]
    PAB.move(cur_rec, xPos-xObject, yPos-yObject)
PAB.bind('<B1-Motion>', move_it)

#test rects
bob = Rect(20,20,'Bob')
rob = Rect(80,80,'Rob')
different_bob = Rect(160,160,'Bob')

PAB.pack()
root.mainloop()

Thanks. If any clarifications are neccesary Id be happy to help.

Answer 1

A better way would be to use the same tag for all the items that you want to move together so in your case both rectangle and text must have the same tag.

import tkinter as tk

root=tk.Tk()
PAB=tk.Canvas(width=400, height=400, bg="gray")

class Rect:
    def __init__(self, x1, y1, name):

        tag = f"movable{id(self)}"
        rec = PAB.create_rectangle(x1,y1,x1+40,y1+40, fill='#c0c0c0', tag=(tag, ))
        text = PAB.create_text(x1+20,y1+20, text=name, tag=(tag,))

def in_bbox(event, item):  # checks if the mouse click is inside the item
    bbox = PAB.bbox(item)

    return bbox[0] < event.x < bbox[2] and bbox[1] < event.y < bbox[3]
    
#mouse click find object to move
def get_it(event):
    delta=5
    global cur_rec
    cur_rec = PAB.find_closest(event.x, event.y)  # returns the closest object

    if not in_bbox(event, cur_rec):  # if its not in bbox then sets current_rec as None
        cur_rec = None

#mouse movement moves object
def move_it(event):
    if cur_rec:
        xPos, yPos = event.x, event.y
        xObject, yObject = PAB.coords(cur_rec)[0],PAB.coords(cur_rec)[1]
                
        PAB.move(PAB.gettags(cur_rec)[0], xPos-xObject, yPos-yObject) 

PAB.bind('<Button-1>', get_it)
PAB.bind('<B1-Motion>', move_it)
#test rects
bob = Rect(20,20,'Bob')
rob = Rect(80,80,'Rob')
different_bob = Rect(160,160,'Bob')

PAB.pack()
root.mainloop()

Answer 2

This will work but I'm not sure it's the best way to do it.

Basically it uses the fact that the text is added to the canvas after the rectangle so it can be identified using cur_rec+1 .

def move_it(event):
    xPos, yPos = event.x, event.y
    xObject, yObject = PAB.coords(cur_rec)[0],PAB.coords(cur_rec)[1]
    # move rectangle
    PAB.move(cur_rec, xPos-xObject, yPos-yObject)
    # move text associated with rectangle
    PAB.move(cur_rec+1, xPos-xObject, yPos-yObject)

Answer 3

Apply the same tag to both the text and the rectangle. Then, use the tag when calling move . Here's one way to do it:

class Rect:
    def __init__(self, x1, y1, name):
        identifier = f"id:{id(self)}"
        rec = PAB.create_rectangle(x1,y1,x1+40,y1+40, fill='#c0c0c0', tags=('movable', name, identifier))
        text = PAB.create_text(x1+20,y1+20, text=name, tags=('movable', identifier))

You can then return the identifier rather than then index of the selected item:

def get_it(event):
    delta=5
    global cur_rec
    for i in PAB.find_overlapping(event.x-delta, event.y-delta, event.x+delta, event.y-delta):
        if hastag('movable', i):
            identifier = [tag for tag in PAB.gettags(i) if tag.startswith("id:")][0]
            cur_rec = identifier