如何使tkinter 按下 时事件起作用？

Question

我想像在油漆中一样填充矩形。当按下鼠标按钮时，我希望我输入的每个矩形都被填充，否则我不希望发生任何事件。

这是我的代码：

from tkinter import Canvas
import tkinter

_width = 50
_height = 50
_size = 8

root = tkinter.Tk()
root.title("draw me a lovely matrix")
canv = Canvas(root, width=_width * _size, height=_height * _size)


class Wrapper:
    btn1d = False


def set_btn1d(value):
    print(value)
    Wrapper.btn1d = value


def toggle_color(rect):
    print('called')
    if Wrapper.btn1d:
        color = canv.itemcget(rect, 'fill')
        canv.itemconfig(rect, fill=("#aaa" if color == '#fff' else '#fff'))


rects = []
canv.bind('<ButtonPress-1>', lambda e, value=True: set_btn1d(value))
canv.bind('<ButtonRelease-1>', lambda e, value=False: set_btn1d(value))
for i in range(_size):
    for j in range(_size):
        rect = canv.create_rectangle(_width * j, _height * i, _width * (j + 1), _height * (i + 1), fill="#fff", width=0)
        rects.append(rect)
        canv.tag_bind(rect, '<Enter>', lambda e, rect=rect: toggle_color(rect))

canv.pack()
root.mainloop()

问题是，当我按下鼠标按钮时，只有被按下鼠标的单元格才能检测到鼠标指针的进入（以及最后将释放鼠标的单元格）

有关我的代码的任何有益的一般建议当然会受到赞赏。

Answer 1

根本不需要使用<Enter>。试试：

from tkinter import Canvas
import tkinter

_width = 50
_height = 50
_size = 8

root = tkinter.Tk()
root.title("draw me a lovely matrix")
canv = Canvas(root, width=_width * _size, height=_height * _size)
rects = []

# B1-Motion activates every time the mouse is moved with button 1 held down
# See https://effbot.org/tkinterbook/tkinter-events-and-bindings.htm
# We fill every item that the mouse comes in contact with while button 1 is held
# The tag tied to the item the event was called on, "current", points to the
#   item under the pointer when the button was pressed, i.e. the first box.
# Only the x and y properties change, so we configure the item closest to those.
def motion(event):
  canv.itemconfig(canv.find_closest(event.x, event.y), fill="#aaa")
canv.bind("<B1-Motion>", motion)

for i in range(_size):
  for j in range(_size):
    rects.append(canv.create_rectangle(_width * j, _height * i, _width * (j + 1), _height * (i + 1), fill="#fff", width=0))
    # don't need to bind anything to <Enter>

canv.pack()
root.mainloop()

[不幸的是，没有可能使用<Enter>解决方案。如果<Enter>按照您希望的方式工作，则以下无效代码在理论上将是正确的。

import tkinter

_width = 50
_height = 50
_size = 8

root = tkinter.Tk()
root.title("draw me a lovely matrix")
canv = tkinter.Canvas(root, width=_width * _size, height=_height * _size)
rects = []

# This javascript-like approach doesn't work in tkinter because
# <Enter> and <Leave> events aren't called while any mouse buttons
# are held.
def fill(tag):
  canv.itemconfig(tag, fill="#aaa")
def enter(event):
  fill("current")
def mousedown(event):
  fill("current")
  canv.tag_bind("all", "<Enter>", enter, add="+")
def mouseup(event):
  canv.tag_unbind("all", "<Enter>")
canv.bind("<Button-1>", mousedown)
canv.bind("<ButtonRelease-1>", mouseup)

for i in range(_size):
  for j in range(_size):
    rects.append(canv.create_rectangle(_width * j, _height * i, _width * (j + 1), _height * (i + 1), fill="#fff", width=0))

canv.pack()
root.mainloop()

在python 3.8.2，tkinter 8.6中测试