python - 我需要想办法在触摸屏上获取用户签名

Question

我正在制作一个 POS 系统，我想包含一个选项，以便在购买后进行签名。我已经尝试过使用 Canvas 的 Tkinter 方法，但速度很慢，而且非常四四方方，有什么建议吗？

这是我现在使用的代码:

from tkinter import *

canvas_width = 500
canvas_height = 150

def paint( event ):
   python_green = "#476042"
   x1, y1 = ( event.x - 1 ), ( event.y - 1 )
   x2, y2 = ( event.x + 1 ), ( event.y + 1 )
   w.create_oval( x1, y1, x2, y2, fill = python_green )

master = Tk()
master.title( "Painting using Ovals" )
w = Canvas(master, 
           width=canvas_width, 
           height=canvas_height)
w.pack(expand = YES, fill = BOTH)
w.bind( "<B1-Motion>", paint )

message = Label( master, text = "Press and Drag the mouse to draw" )
message.pack( side = BOTTOM )

mainloop()

顺便说一句，这段代码不是我的，我是从this得到的网站

Answer 1

一个干净的例子:

import tkinter as tk

class Signature(tk.Canvas):
    def __init__(self, *args, **kwargs):
        self.thickness = kwargs.pop('thickness', 4)
        tk.Canvas.__init__(self, *args, **kwargs)
        self._xold = None
        self._yold = None

        self.bind('<B1-Motion>', self._on_motion)

    def _on_motion(self, event):
        x1, y1 = ( event.x - self.thickness ), ( event.y - self.thickness )
        x2, y2 = ( event.x + self.thickness ), ( event.y + self.thickness )
        event.widget.create_oval( x1, y1, x2, y2, fill='black' )
        if self._xold is not None and self._yold is not None:
            self.create_oval( x1, y1, x2, y2, fill='black' )
            self.create_line(self._xold,self._yold,event.x,event.y,smooth=True,width=self.thickness*2+1)
    # here's where you draw it. smooth. neat.
        self._xold = event.x
        self._yold = event.y

if __name__ == '__main__':
    canvas_width = '500'
    canvas_height = '500'

    root = tk.Tk()
    sig = Signature(root, width=canvas_width,height=canvas_height,bg='white', thickness=1)
    sig.pack()

    root.mainloop()

请注意，这会在事件的位置绘制一个椭圆，并用一条线将其与最后一个事件连接起来，这有助于平滑线。