我需要设法在触摸屏上获取用户签名

Question

我正在制作一个 POS 系统，我想包括一个购买后签名的选项。我已经尝试过使用画布的 Tkinter 方法，但是速度很慢，而且非常四四方方，有什么建议吗？这是我现在正在使用的代码：from tkinter import *canvas_width = 500canvas_height = 150def 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，这个代码不是我的，我是从这个网站上得到的

Answer 1

这是一个简单的 tkinter 绘图应用程序。

from tkinter import *

b1 = "up"

xold, yold = None, None

display_width = '500'

display_height = '500'

canvas_width = '500'

canvas_height = '500'

def main():

    root = Tk()

    root.geometry((display_width+"x"+display_height))

    drawing_area = Canvas(root,width=canvas_width,height=canvas_height,bg="white")

    drawing_area.bind("<Motion>", motion)

    drawing_area.bind("<ButtonPress-1>", b1down)

    drawing_area.bind("<ButtonRelease-1>", b1up)

    drawing_area.pack(side=RIGHT)

    root.mainloop()

def b1down(event):

    global b1

    x1, y1 = ( event.x - 4 ), ( event.y - 4 )

    x2, y2 = ( event.x + 4 ), ( event.y + 4 )

    event.widget.create_oval( x1, y1, x2, y2, fill = "black" )

    b1 = "down"           # you only want to draw when the button is down

                          # because "Motion" events happen -all the time-

def b1up(event):

    global b1, xold, yold

    b1 = "up"

    xold = None           # reset the line when you let go of the button

    yold = None

def motion(event):

    if b1 == "down":

        global xold, yold

        x1, y1 = ( event.x - 4 ), ( event.y - 4 )

        x2, y2 = ( event.x + 4 ), ( event.y + 4 )

        event.widget.create_oval( x1, y1, x2, y2, fill = "black" )

        if xold is not None and yold is not None:

            python_green = "#476042"

            x1, y1 = ( event.x - 4 ), ( event.y - 4 )

            x2, y2 = ( event.x + 4 ), ( event.y + 4 )

            event.widget.create_oval( x1, y1, x2, y2, fill = "black" )

            event.widget.create_line(xold,yold,event.x,event.y,smooth=TRUE,width=9)

    # here's where you draw it. smooth. neat.

        xold = event.x

        yold = event.y

if __name__ == "__main__":

    main()

Answer 2

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形，并绘制一条线将其与最后一个事件连接起来，这有助于平滑线。