Inserting Python Buttons into KV Files

[edand19941]

I am generating buttons with a loop in a py file with the code below. The TileLayout class generates a StackLayout filled with buttons with an on_press callback function.

PY FILE-------------------------------

from kivy.uix.stacklayout import StackLayout
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from MathCrunchPkg import PackArray
from kivy.app import App
from kivy.config import Config

Config.set('graphics', 'resizable', True)

NUM_COLS = 15
NUM_ROWS = 10
TILE_ARRAY = []
TILE_ARRAY = PackArray.fill_arr(NUM_ROWS, NUM_COLS)

class TileMain(BoxLayout):
    def on_enter(self):
        print("ENTERED")

    def tile_select(self):
        print("SELECTED")

class TileLayout(StackLayout):      #@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        for j in range(0,NUM_ROWS):
            for i in range(0,NUM_COLS):
                    bt = Button()
                    bt.text=str(TILE_ARRAY[j][i][2])
                    bt.size_hint=(1/NUM_COLS,1.81/NUM_ROWS)
                    bt.background_color = 1,0,0,.6
                    bt.on_press = TileMain.tile_select(self)        #@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
                    bt.font_size = 42
                    self.add_widget(bt)

class MathCrushApp(App):
    pass


if __name__ == "__main__":
    MathCrushApp().run()

-------------------------------------------

The accompaning kv file follows.

KV FILE------------------------------------

TileMain:  # this is the root widget, use this to set the background
    orientation: "vertical"
    canvas.before:
        Color:
            rgba: 1,1,1,1
        Rectangle:
            source: "gameboard.png"
            size: self.size
            pos: self.pos

    TileLayout:     #@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@:

    FloatLayout:
        orientation: "horizontal"
        Label:
            text: "Attempts"
            size_hint: 0.1,120/640
            pos: "43dp",  "0dp"
            color: 0,0,0,1
            font_size: 40
            background_color: (1, 1, 1, 0)
            canvas.before:
                Color:
                    rgba: self.background_color
                Rectangle:
                    size: self.size
                    pos: self.pos

------------------------------------------------------------------------------

When executed in pycharm, I get this error messsage:

Error:
  File "C:\Users\eanderso\PycharmProjects\PythonProject2\.venv\lib\site-packages\kivy\uix\behaviors\button.py", line 151, in on_touch_down
     self.dispatch('on_press')
   File "kivy\\_event.pyx", line 731, in kivy._event.EventDispatcher.dispatch
 TypeError: 'NoneType' object is not callable 

The visual output (buttons, images, etc.) is as expected including active inserted buttons but the inserted buttons (from py file) do not call the callback function, but rather generate the error message. All my attempts to correct this have failed. Any suggestions or help would be appreciated.

[deanhystad]

Please post the entire error message, including the full traceback.

I think the problem is that you bind the button to a class instead of an instance to a class. TileMain cannot tile_select. You need to create an instance of TileMain and bind the instance.tile_select to your button.

[menator01]

Here is an example of creating kivy buttons
https://python-forum.io/thread-42326-pos...#pid179292

[buran]

bt.on_press = TileMain.tile_select(self) 

here you call tile_select() method of TileMain class and bind return value (which is None) to bt.on_pres. And None is not callable.