[Kivy]2本指操作の判定（ピンチ・スワイプ）

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy import platform
from kivy.clock import Clock
from kivy.graphics import Point

class TouchAction(BoxLayout):

    image_size = 50
    image_pos_x = 50
    image_pos_y = 50

    move_pre_pos = {} # 移動前のタッチ位置保持用
    touch_pair = [] # タッチペア

    shape = None

    def __init__(self, **kwargs) -> None:
        super(TouchAction, self).__init__(**kwargs)

        Clock.schedule_interval(self.update, 1.0 / 30)

    def update(self, dt):
        self.draw_shapes()

    def draw_shapes(self):
        self.clear_shapes()

        with self.canvas:
            self.shape = Point(points=[self.image_pos_x, self.image_pos_y], pointsize=self.image_size, source= 'test.png')

    def clear_shapes(self):
        if self.shape is not None:
            self.canvas.remove(self.shape)
            self.shape = None

    def on_image_touch_down(self, touch):
        #タッチ位置の保持
        self.move_pre_pos[touch.uid] = (touch.x,touch.y)

    def on_image_touch_move(self, touch):
        w,h = self.size #画面サイズ
        if len(self.move_pre_pos.keys()) >= 2:

            px1,py1 = self.move_pre_pos[touch.uid] #処理中のタッチ
            for uid in self.move_pre_pos.keys():
                # 3本指以上のタッチは無視
                if uid != touch.uid:
                    px2,py2 = self.move_pre_pos[uid] #同時されているタッチ
                    # uidのペアを保持
                    self.touch_pair = [touch.uid,uid]

            # 移動前の2点間の距離
            bdx = abs(px1 - px2)
            bdy = abs(py1 - py2)
            # 移動前の2点間の中点
            bax = (px1 + px2) / 2
            bay = (py1 + py2) / 2
            # 移動後の2点間の距離
            adx = abs(touch.x - px2)
            ady = abs(touch.y - py2)
            # 移動前の2点間の中点
            aax = (touch.x + px2) / 2
            aay = (touch.y + py2) / 2

            if (bdx <= adx) and (bdy <= ady):
                #ピンチアウト
                self.image_size = self.image_size + int(max(adx-bdx,ady-bdy)) # xとyの移動前後で差分が大きい方

                # 範囲外判定
                if self.image_size > 500 :
                    self.image_size = 500

            if (bdx >= adx) and (bdy >= ady):
                #ピンチイン
                self.image_size = self.image_size - int(max(bdx-adx,bdy-ady)) # xとyの移動前後で差分が大きい方
                
                # 範囲外判定
                if self.image_size < 10 :
                    self.image_size = 10

            # 2本指スワイプ
            mx = round(aax - bax) #移動距離
            my = round(aay - bay ) #移動距離
            self.image_pos_x = self.image_pos_x + mx
            self.image_pos_y = self.image_pos_y + my

            # 範囲外の制御
            if self.image_pos_x < 0:
                self.image_pos_x = 0
            if self.image_pos_y < 0:
                self.image_pos_y = 0
            if (self.image_pos_x + self.image_size) > w:
                self.image_pos_x = (w - self.image_size)
            if (self.image_pos_y + self.image_size) > h:
                self.image_pos_y = (h - self.image_size)

        elif touch.uid in self.touch_pair:
            # 2指操作の片割れの場合は処理抜け
            return

        else:
            # 通常（1本指）のタッチイベントがあればこっちに
            pass
            
        self.move_pre_pos[touch.uid] = (touch.x,touch.y)

    def on_image_touch_up(self, touch):
        # 解放
        if touch.uid in self.move_pre_pos.keys():
            del self.move_pre_pos[touch.uid]

class TestTouchActionApp(App):

    def build(self):

        return TouchAction()

if __name__ == '__main__':
    TestTouchActionApp().run()