您可以将canvas的角度绑定到NumericProperty，以从代码内部对其进行更改。您需要做的就是正确计算这些角度。在玩了一点之后，我创建了以下代码：
from kivy.app import App
from kivy.uix.widget import Widget
from kivy.lang import Builder
from kivy.animation import Animation
from kivy.properties import NumericProperty
import math
kv = '''
<Dial>:
canvas:
Rotate:
angle: root.angle
origin: self.center
Color:
rgb: 1, 0, 0
Ellipse:
size: min(self.size), min(self.size)
pos: 0.5*self.size[0] - 0.5*min(self.size), 0.5*self.size[1] - 0.5*min(self.size)
Color:
rgb: 0, 0, 0
Ellipse:
size: 50, 50
pos: 0.5*root.size[0]-25, 0.9*root.size[1]-25
'''
Builder.load_string(kv)
class Dial(Widget):
angle = NumericProperty(0)
def on_touch_down(self, touch):
y = (touch.y - self.center[1])
x = (touch.x - self.center[0])
calc = math.degrees(math.atan2(y, x))
self.prev_angle = calc if calc > 0 else 360+calc
self.tmp = self.angle
def on_touch_move(self, touch):
y = (touch.y - self.center[1])
x = (touch.x - self.center[0])
calc = math.degrees(math.atan2(y, x))
new_angle = calc if calc > 0 else 360+calc
self.angle = self.tmp + (new_angle-self.prev_angle)%360
def on_touch_up(self, touch):
Animation(angle=0).start(self)
class DialApp(App):
def build(self):
return Dial()
if __name__ == "__main__":
DialApp().run()
我正在计算初始（按鼠标后）和以后的角度之间的差异on_touch_move。由于angle是一个属性，因此我也可以使用它来修改它，kivy.animation以在释放鼠标按钮后使拨盘回旋。
on_touch_down 子圈子活动：
from kivy.app import App
from kivy.uix.widget import Widget
from kivy.uix.floatlayout import FloatLayout
from kivy.lang import Builder
from kivy.animation import Animation
from kivy.properties import NumericProperty
import math
kv = '''
<Dial>:
circle_id: circle_id
size: root.size
pos: 0, 0
canvas:
Rotate:
angle: self.angle
origin: self.center
Color:
rgb: 1, 0, 0
Ellipse:
size: min(self.size), min(self.size)
pos: 0.5*self.size[0] - 0.5*min(self.size), 0.5*self.size[1] - 0.5*min(self.size)
Circle:
id: circle_id
size_hint: 0, 0
size: 50, 50
pos: 0.5*root.size[0]-25, 0.9*root.size[1]-25
canvas:
Color:
rgb: 0, 1, 0
Ellipse:
size: 50, 50
pos: self.pos
'''
Builder.load_string(kv)
class Circle(Widget):
def on_touch_down(self, touch):
if self.collide_point(*touch.pos):
print "small circle clicked"
class Dial(Widget):
angle = NumericProperty(0)
def on_touch_down(self, touch):
if not self.circle_id.collide_point(*touch.pos):
print "big circle clicked"
y = (touch.y - self.center[1])
x = (touch.x - self.center[0])
calc = math.degrees(math.atan2(y, x))
self.prev_angle = calc if calc > 0 else 360+calc
self.tmp = self.angle
return super(Dial, self).on_touch_down(touch) # dispatch touch event futher
def on_touch_move(self, touch):
y = (touch.y - self.center[1])
x = (touch.x - self.center[0])
calc = math.degrees(math.atan2(y, x))
new_angle = calc if calc > 0 else 360+calc
self.angle = self.tmp + (new_angle-self.prev_angle)%360
def on_touch_up(self, touch):
Animation(angle=0).start(self)
class DialApp(App):
def build(self):
return Dial()
if __name__ == "__main__":
DialApp().run()
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