Kivy矩形重绘，self.pos和self.size是（0,0）

Question

我正在使用循环创建27个标签实例。这些标签需要使用Label.text方法编号 - 我已经实现了。

我还需要能够使用python函数（基于其他输入）为这些标签（画布矩形）重新着色。 这是不起作用

基本上该位，GridLayout的的INIT方法创建custButton（）标签的29个实例。此循环还重新编号（label.text）按钮，但重新着色一个标签不起作用。

我已经分离出self.pos和self.size都在xBackground_Color函数返回（0,0） - 这就是为什么旧的清除后，新矩形不画（清作品）。

为什么self.pos和self.size不能从python方面工作？

我试过soooooooo很多东西！如果可以的话请帮忙。

这里的kvMain.kv：

#:kivy 1.0.9 

FloatLayout: 
    canvas: 
     Color: 
      rgba: (64/255, 64/255, 64/255, 1) #Whole screen background 
     Rectangle: 
      pos: self.pos 
      size: self.size 
    BoxLayout: 
     orientation: 'vertical' 
     padding: 10 
     FloatLayout: #Dummy widget 
     myGrid: 


<myGrid>: 
    cols: 9 
    spacing: 3 
    padding: 3 
    canvas.before: 
     Color: 
      rgba: (216/255, 216/255, 216/255, 1) 
     Rectangle: 
      pos: self.pos 
      size: self.size 

<custButtom>: 
    canvas.before: 
     Color: 
      rgba: (191/255, 191/255, 191/255, 1) 
     Rectangle: 
      pos: self.pos 
      size: self.size 
    font_size: 14 
    color: (90/255, 90/255, 90/255, 1) 
    text: 'Er' #Don't ever want to see this text. Will set each label in loop 
    size: self.texture_size 

这里的main.py：

from kivy.app import App 
from kivy.lang import Builder 

from kivy.uix.gridlayout import GridLayout 
from kivy.uix.boxlayout import BoxLayout 
from kivy.uix.floatlayout import FloatLayout 
from kivy.uix.label import Label 

from kivy.graphics.vertex_instructions import Rectangle, Line 
from kivy.graphics.context_instructions import Color 

IN_Labels = {} 

class custButtom(Label): 
    def __init__(self, **kwargs): 
     super(custButtom, self).__init__(**kwargs) 

    def xtext(self, newText): 
     self.text = newText 
     self.size = self.texture_size 

    def xbackground_color(self, newR, newG, newB, newA): 
     print('IN_Labels[14] pos ('+ str(IN_Labels[14].pos[0]) + ',' + str(IN_Labels[14].pos[1]) + ') size ('+ str(IN_Labels[14].size[0]) + ',' + str(IN_Labels[14].size[1]) + ')') 
     print('self pos ('+ str(self.pos[0]) + ',' + str(self.pos[1]) + ') size ('+ str(self.size[0]) + ',' + str(self.size[1]) + ')') 
     self.canvas.before.clear() 

     with self.canvas.before: 
      Color(newR, newG, newB, newA) 
      #Problem is that self.size and self.pos are both (0,0) 
      Rectangle(size=self.size, pos=self.pos) 


class myGrid(GridLayout): 
    def __init__(self, **kwargs): 
     super(myGrid, self).__init__(**kwargs) 

     for i in range(0, 27, 1): 
      IN_Labels[i] = custButtom() 
      self.add_widget(IN_Labels[i]) 
      #CAN change text, needs more work to get it right 
      IN_Labels[i].xtext(str(i)) 

     # I need to be able to change backgroundcolor programatically 
     IN_Labels[14].xbackground_color(1,0,0,1) 

class MainApp(App): 
    def build(self): 
     return kvMain 

kvMain = Builder.load_file("kvMain.kv") 

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

Answer 1

找到了！我认为问题在于标签在被要求提供self.size和self.pos时并没有真正的大小和位置。

绑定函数来调整大小和重新定位它可以解决问题。

感谢亚历山大·泰勒的出色YouTube视频和他的博客，我找到了答案：https://blog.kivy.org/2014/10/updating-canvas-instructions-declared-in-python/

kvMain.kv变为：

#:kivy 1.0.9 

FloatLayout: 
    canvas: 
     Color: 
      rgba: (64/255, 64/255, 64/255, 1) #Whole screen background 
     Rectangle: 
      pos: self.pos 
      size: self.size 
    BoxLayout: 
     orientation: 'vertical' 
     padding: 10 
     FloatLayout: #Dummy widget 
     myGrid: 


<myGrid>: 
    cols: 9 
    spacing: 3 
    padding: 3 
    canvas.before: 
     Color: 
      rgba: (216/255, 216/255, 216/255, 1) 
     Rectangle: 
      pos: self.pos 
      size: self.size 

<custButtom>: 
    #CANVAS INSTRUCTION MOVED TO PYTHON INIT 
    font_size: 14 
    color: (90/255, 90/255, 90/255, 1) 
    text: 'Er' #Don't ever want to see this text. Will set each label in loop 
    size: self.texture_size 

main.py变为：

from kivy.app import App 
from kivy.lang import Builder 

from kivy.uix.gridlayout import GridLayout 
from kivy.uix.boxlayout import BoxLayout 
from kivy.uix.floatlayout import FloatLayout 
from kivy.uix.label import Label 

from kivy.graphics.vertex_instructions import Rectangle, Line 
from kivy.graphics.context_instructions import Color 

IN_Labels = {} 

class custButtom(Label): 
    def __init__(self, **kwargs): 
     super(custButtom, self).__init__(**kwargs) 

     with self.canvas.before: 
      Color(191/255, 191/255, 191/255, 1) 
      self.rect = Rectangle(pos=self.pos, size=self.size) 

     #Ensure that everytime the Rectangle is updated, it's repositioned correctly 
     self.bind(pos=self.update_rect, size=self.update_rect) 

    def update_rect(self, *args): 
     self.rect.pos = self.pos 
     self.rect.size = self.size 

    def xtext(self, newText): 
     self.text = newText 
     self.size = self.texture_size 

    def xbackground_color(self, newR, newG, newB, newA): 
     print('IN_Labels[14] pos ('+ str(IN_Labels[14].pos[0]) + ',' + str(IN_Labels[14].pos[1]) + ') size ('+ str(IN_Labels[14].size[0]) + ',' + str(IN_Labels[14].size[1]) + ')') 
     print('self pos ('+ str(self.pos[0]) + ',' + str(self.pos[1]) + ') size ('+ str(self.size[0]) + ',' + str(self.size[1]) + ')') 
     self.canvas.before.clear() 

     with self.canvas.before: 
      Color(newR, newG, newB, newA) 
      self.rect = Rectangle(size=self.size, pos=self.pos) 


class myGrid(GridLayout): 
    def __init__(self, **kwargs): 
     super(myGrid, self).__init__(**kwargs) 

     for i in range(0, 27, 1): 
      IN_Labels[i] = custButtom() 
      self.add_widget(IN_Labels[i]) 
      #CAN change text, needs more work to get it right 
      IN_Labels[i].xtext(str(i)) 

     # I need to be able to change backgroundcolor programatically 
     IN_Labels[14].xbackground_color(1,0,0,1) 

class MainApp(App): 
    def build(self): 
     return kvMain 

kvMain = Builder.load_file("kvMain.kv") 

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