下面的示例创建一个包含2点和1条线的画布。您将能够在周围移动点和线。
fromkivy.appimport App
fromkivy.graphicsimport Ellipse, Line
from kivy.uix.boxlayout import BoxLayout
class CustomLayout(BoxLayout):
def __init__(self, **kwargs):
super(CustomLayout, self).__init__(**kwargs)
self.canvas_edge= {}
self.canvas_nodes= {}
self.nodesize= [25, 25]
self.grabbed= {}
#declare a canvas
with self.canvas.after:
pass
self.define_nodes()
self.canvas.add(self.canvas_nodes[0])
self.canvas.add(self.canvas_nodes[1])
self.define_edge()
self.canvas.add(self.canvas_edge)
def define_nodes(self):
"""define all the node canvas elements as a list"""
self.canvas_nodes[0] = Ellipse(
size = self.nodesize,
pos = [100,100]
)
self.canvas_nodes[1] = Ellipse(
size = self.nodesize,
pos = [200,200]
)
def define_edge(self):
"""define an edge canvas elements"""
self.canvas_edge= Line(
points = [
self.canvas_nodes[0].pos[0] + self.nodesize[0] / 2,
self.canvas_nodes[0].pos[1] + self.nodesize[1] / 2,
self.canvas_nodes[1].pos[0] + self.nodesize[0] / 2,
self.canvas_nodes[1].pos[1] + self.nodesize[1] / 2
],
joint = 'round',
cap = 'round',
width = 3
)
def on_touch_down(self, touch):
for key, value in self.canvas_nodes.items():
if (value.pos[0] - self.nodesize[0]) <= touch.pos[0] <= (value.pos[0] + self.nodesize[0]):
if (value.pos[1] - self.nodesize[1]) <= touch.pos[1] <= (value.pos[1] + self.nodesize[1]):
touch.grab(self)
self.grabbed= self.canvas_nodes[key]
return True
def on_touch_move(self, touch):
iftouch.grab_currentis self:
self.grabbed.pos = [touch.pos[0] - self.nodesize[0] / 2, touch.pos[1] - self.nodesize[1] / 2]
self.canvas.clear()
self.canvas.add(self.canvas_nodes[0])
self.canvas.add(self.canvas_nodes[1])
self.define_edge()
self.canvas.add(self.canvas_edge)
else:
# it's a normal touch
pass
def on_touch_up(self, touch):
iftouch.grab_currentis self:
# I receive my grabbed touch, I must ungrab it!
touch.ungrab(self)
else:
# it's a normal touch
pass
class MainApp(App):
def build(self):
root = CustomLayout()
return root
if __name__ == '__main__':
MainApp().run()