命令类似于tkinter中的pygame的get_rel（）？

Question

我想知道当我将<Motion>事件绑定到函数时，如果在该函数中我可以使用pygame的{{1}版本定义x和y变量}，但在tkinter。

Answer 1

tkinter中的事件处理与pygame中的事件处理不同，因此代替直接mouse.get_rel()等效，似乎更适合创建每次鼠标移动时调用回调函数的内容（这是绑定到'<Motion>'事件的结果）。为了帮助执行此操作，定义了RelativeMotion类来隐藏和封装尽可能多的混乱细节。下面是它运行的截图。

import tkinter as tk

class RelativeMotion(object):
    """ Relative mouse motion controller. """
    def __init__(self, callback):
        self.__call__ = self._init_location  # first call
        self.callback = callback

    def __call__(self, *args, **kwargs):
        # Implicit invocations of special methods resolve to instance's type.
        self.__call__(*args, **kwargs)  # redirect call to instance itself

    def _init_location(self, event):
        self.x, self.y = event.x, event.y  # initialize current position
        self.__call__ = self._update_location  # change for any subsequent calls

    def _update_location(self, event):
        dx, dy = event.x-self.x, event.y-self.y
        self.x, self.y = event.x, event.y
        self.callback(dx, dy)

class Application(tk.Frame):  # usage demo
    def __init__(self, master=None):
        tk.Frame.__init__(self, master)
        self.grid()
        self.createWidgets()
        self.relative_motion = RelativeMotion(self.canvas_mouse_motion)
        self.canvas.bind('<Motion>', self.relative_motion)  # when over canvas

    def createWidgets(self):
        self.motion_str = tk.StringVar()
        self.canvas_mouse_motion(0, 0)  # initialize motion_str text
        label_width = len(self.motion_str.get())
        self.motion_lbl = tk.Label(self, bg='white', width=label_width,
                                   textvariable=self.motion_str)
        self.motion_lbl.grid(row=0, column=0)

        self.quit_btn = tk.Button(self, text='Quit', command=self.quit)
        self.quit_btn.grid(row=1, column=0)

        self.canvas = tk.Canvas(self, width='2i', height='2i', bg='white')
        self.canvas.grid(row=1, column=1)

    def canvas_mouse_motion(self, dx, dy):
        self.motion_str.set('{:3d}, {:3d}'.format(dx, dy))

app = Application()
app.master.title('Relative Motion Demo')
app.mainloop()

<强>运行