形状识别器实现

Question

我有一个简单的绘图kivy，我想添加形状识别器，类似于xournal。你知道吗

Quoting docs: "The shape recognizer is also a special operating mode of the pen and highlighter tools. When it is enabled, Xournal attempts to recognize geometric shapes as they are drawn, and if successful will replace the drawn strokes accordingly. The shapes that can be recognized are: line segments, circles, rectangles, arrows, triangles and quadrilaterals. Polygonal shapes can be drawn in a single stroke or in a sequence of consecutive strokes."

代码：

from kivy.base import EventLoop
from kivy.config import Config
from kivy.graphics import Color, Line
from kivy.uix.behaviors import ToggleButtonBehavior
from kivy.uix.togglebutton import ToggleButton
from kivy.uix.widget import Widget
from kivy.utils import get_color_from_hex
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.label import Label
from kivy.uix.popup import Popup
from kivy.clock import Clock
class Update_Location(Widget):
    pass

class CanvasWidget(Widget):
    line_width = 2

    def on_touch_down(self, touch):
        if Widget.on_touch_down(self, touch):
           return

        with self.canvas:
            touch.ud['current_line'] = Line(
                points=(touch.x, touch.y),
                width=self.line_width)

    def on_touch_move(self, touch):
        if 'current_line' in touch.ud:
            touch.ud['current_line'].points += (touch.x, touch.y)

    def set_color(self, new_color):
        self.last_color = new_color
        self.canvas.add(Color(*new_color))

    def set_line_width(self, line_width='Normal'):
        self.line_width = {
            'Thin': 1, 'Normal': 2, 'Thick': 4
        }[line_width]

    def clear_canvas(self):
        saved = self.children[:]
        self.clear_widgets()
        self.canvas.clear()
        for widget in saved:
            self.add_widget(widget)
        self.set_color(self.last_color)
    def start_server(self):
        host = '127.0.0.1'
        port = 5000
        notification_text="Server started on host: "+host+" and port: "+str(port)
        server_start=Popup(title='Notification',content=Label(text=notification_text),size_hint=(.75,.75),auto_dismiss=True)
        server_start.open()
        Clock.schedule_interval(server_start.dismiss, 3)


class PaintApp(App):
    def build(self):
        EventLoop.ensure_window()
        if EventLoop.window.__class__.__name__.endswith('Pygame'):
            try:
                from pygame import mouse

                a, b = pygame_compile_cursor()
                mouse.set_cursor((24, 24), (9, 9), a, b)
            except:
                pass
        #boxlayout
        self.layout = BoxLayout(orientation='vertical')

        self.canvas_widget = CanvasWidget()
        self.canvas_widget.set_color(
            get_color_from_hex('#2980b9'))
        self.layout.add_widget(self.canvas_widget)
        #self.layout.add_widget(Label(text="Started Server : False , Connected to Server : False",color=(1,1,1),size_hint=(1, .1)))
        return self.layout

        #return self.canvas_widget


class RadioButton(ToggleButton):
    def _do_press(self):
        if self.state == 'normal':
            ToggleButtonBehavior._do_press(self)


def pygame_compile_cursor(black='@', white='-'):
    aa, bb = [], []
    a = b = 0
    i = 8
    for s in CURSOR:
        for c in s:
            a <<= 1
            b <<= 1
            i -= 1
            if c == black:
                a |= 1
                b |= 1
            elif c == white:
                b |= 1

            if not i:
                aa.append(a)
                bb.append(b)
                a = b = 0
                i = 8

    return tuple(aa), tuple(bb)

if __name__ == '__main__':
    Config.set('graphics', 'width', '960')
    Config.set('graphics', 'height', '540')  # 16:9
    # Config.set('graphics', 'resizable', '0')
    # Config.set('input', 'mouse', 'mouse,disable_multitouch')

    from kivy.core.window import Window
    Window.clearcolor = get_color_from_hex('#ffffff')

    PaintApp().run()

现在，我在touch.ud['current_line']中存储了一组点。在on_touch_up上，我应该传递这些点/坐标集，用相应大小的形状替换它们。有没有这样的代码在可用，我没有找到在xounlal源代码清楚。你知道吗