如何解决Python KIvy 旋转矩形在调整大小时移动
我有一个旋转的矩形，当我调整它的大小时，它会稍微改变它的位置。 但我不希望它移动...
发生这种位置变化，当我重置中心时，如果我不改变中心，它不会移动，但对我来说中心是正确的很重要。
我创建了 2 个视频。 这是目前：https://youtu.be/TqY3Ji0rnLw 这就是我想要的（我删除了中心重置，但正如我之前说过的，我想要一个中心重置）：https://youtu.be/Jfq777nzu6o
我该如何解决这个问题？
这是我的代码：
from kivy.app import App
from kivy.uix.widget import Widget
from kivy.graphics import Color,Rectangle,Pushmatrix,Rotate,PopMatrix
from kivy.clock import Clock
from kivy.core.window import Window
class Canvas:
def __init__(self,root,pos,size,rotation=0,color=(1,1)):
with root.canvas:
Pushmatrix()
self._color_instruction = Color(rgba=color)
self._rotation_instruction = Rotate(angle=rotation,origin=(150,150))
self._rectangle_instruction = Rectangle(pos=pos,size=size)
PopMatrix()
@property
def center(self):
pos = self.pos
size = self.size
center_x = pos[0] + size[0] / 2
center_y = pos[1] + size[1] / 2
return (center_x,center_y)
@property
def pos(self):
return self._rectangle_instruction.pos
@pos.setter
def pos(self,value):
self._rectangle_instruction.pos = value
self._rotation_instruction.origin = self.center
@property
def size(self):
return self._rectangle_instruction.size
@size.setter
def size(self,value):
self._rectangle_instruction.size = value
self._rotation_instruction.origin = self.center
@property
def rotation(self):
return self._rotation_instruction.angle
@rotation.setter
def rotation(self,value):
self._rotation_instruction.angle = value
@property
def color(self):
return self._color_instruction.rgba
@color.setter
def color(self,value):
self._color_instruction.rgba = value
class Root(Widget):
def __init__(self,**kwargs):
super(Root,self).__init__(**kwargs)
self.rectangle = Canvas(self,(100,100),rotation=45)
self.keys_pressed = set()
self._keyboard = Window.request_keyboard(self._on_keyboard_closed,self)
self._keyboard.bind(on_key_down = self._on_key_down)
self._keyboard.bind(on_key_up = self._on_key_up)
Clock.schedule_interval(self.step,0)
def step(self,dt):
x = self.rectangle.pos[0]
y = self.rectangle.pos[1]
width = self.rectangle.size[0]
height = self.rectangle.size[1]
rotation = self.rectangle.rotation
step_size = 300 * dt
if "up" in self.keys_pressed:
y += step_size
if "left" in self.keys_pressed:
x -= step_size
if "right" in self.keys_pressed:
x += step_size
if "down" in self.keys_pressed:
y -= step_size
if "y" in self.keys_pressed:
rotation += step_size
if "x" in self.keys_pressed:
rotation -= step_size
if "w" in self.keys_pressed:
height = min(height + step_size,300)
if "a" in self.keys_pressed:
width = max(width - step_size,10)
if "d" in self.keys_pressed:
width = min(width + step_size,300)
if "s" in self.keys_pressed:
height = max(height - step_size,10)
self.rectangle.pos = (x,y)
self.rectangle.size = (width,height)
self.rectangle.rotation = rotation
def _on_keyboard_closed(self):
self._keyboard.unbind(_on_key_down = self._on_key_down)
self._keyboard.ubind(_on_key_up = self._on_key_up)
self._keyboard = None
def _on_key_down(self,keyboard,keycode,text,modifiers):
self.keys_pressed.add(text if text != None else keycode[1])
def _on_key_up(self,keycode):
if keycode[1] in self.keys_pressed:
self.keys_pressed.remove(keycode[1])
class TestApp(App):
def __init__(self,**kwargs):
super(TestApp,self).__init__(**kwargs)
def build(self):
return Root()
def main():
app = TestApp()
app.run()
if __name__ == "__main__":
main()
我该如何改变它在第二个视频中的位置？
解决方法
这是您的代码的修改版本，它使用 kv 和现有的 canvas 对象来绘制 Rectangle：
from kivy.app import App
from kivy.lang import Builder
from kivy.properties import ListProperty,NumericProperty
from kivy.uix.widget import Widget
from kivy.clock import Clock
from kivy.core.window import Window
class MyCanvas(Widget):
color = ListProperty([1,1])
rotation = NumericProperty(0)
Builder.load_string('''
<MyCanvas>:
size_hint: None,None
canvas:
Color:
rgba: self.color
PushMatrix:
Translate:
xy: self.x,self.y
Rotate:
axis: 0,1
origin: 0,0
angle: self.rotation
Scale:
origin: 0,0
xyz: self.width,self.height,1
Rectangle: # unit rectangle centered on origin
pos: -0.5,-0.5
size: 1,1
PopMatrix:
''')
class Root(Widget):
def __init__(self,**kwargs):
super(Root,self).__init__(**kwargs)
# self.rectangle = Canvas(self,(100,100),rotation=45)
self.rectangle = MyCanvas(pos=(100,size=(100,rotation=45)
self.add_widget(self.rectangle)
self.keys_pressed = set()
self._keyboard = Window.request_keyboard(self._on_keyboard_closed,self)
self._keyboard.bind(on_key_down = self._on_key_down)
self._keyboard.bind(on_key_up = self._on_key_up)
Clock.schedule_interval(self.step,0)
def step(self,dt):
x = self.rectangle.pos[0]
y = self.rectangle.pos[1]
width = self.rectangle.size[0]
height = self.rectangle.size[1]
rotation = self.rectangle.rotation
step_size = 300 * dt
if "up" in self.keys_pressed:
y += step_size
if "left" in self.keys_pressed:
x -= step_size
if "right" in self.keys_pressed:
x += step_size
if "down" in self.keys_pressed:
y -= step_size
if "y" in self.keys_pressed:
rotation += step_size
if "x" in self.keys_pressed:
rotation -= step_size
if "w" in self.keys_pressed:
height = min(height + step_size,300)
if "a" in self.keys_pressed:
width = max(width - step_size,10)
if "d" in self.keys_pressed:
width = min(width + step_size,300)
if "s" in self.keys_pressed:
height = max(height - step_size,10)
self.rectangle.pos = (x,y)
self.rectangle.size = (width,height)
self.rectangle.rotation = rotation
def _on_keyboard_closed(self):
self._keyboard.unbind(_on_key_down = self._on_key_down)
self._keyboard.ubind(_on_key_up = self._on_key_up)
self._keyboard = None
def _on_key_down(self,keyboard,keycode,text,modifiers):
self.keys_pressed.add(text if text != None else keycode[1])
def _on_key_up(self,keycode):
if keycode[1] in self.keys_pressed:
self.keys_pressed.remove(keycode[1])
class TestApp(App):
def __init__(self,**kwargs):
super(TestApp,self).__init__(**kwargs)
def build(self):
return Root()
def main():
app = TestApp()
app.run()
if __name__ == "__main__":
main()
Rectangle 的大小与您的视频显示的不完全一样，但很接近。
您可以通过将 kv 更改为：
<MyCanvas>:
size_hint: None,None
canvas.before:
PushMatrix:
Rotate:
axis: 0,1
origin: self.pos
angle: self.rotation
canvas:
Color:
rgba: self.color
Rectangle:
pos: self.pos
size: self.size
canvas.after:
PopMatrix:
但这会影响旋转行为，因此旋转是围绕 Rectangle 而不是 center 的一个角进行的。
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