[Python] Python kivy how to set maximum/minimum size of a widget

If we can set window.minimum/maximum_width/height then is it possible to set a widget.minimum/maximum_width/height?

For example:

The idea is the box will auto fit the words inside (I can do that base on here), but when we resize the screen and the text_size is wider than 70% of the app's screen the words will down the line like the picture and start writing from the left (I can't make it write from the left, cause I'm using halign="right"). (Like messenger)

Although I can do the auto fit, the problem is the box width is always 100% (default text's halign="center") that is why I'm looking for a way to set maximum width stretch is 70%, the box is align right and text's halign="left". (Like messenger)

I just wonder if we have any widget.minimum/maximum_width/height or something like that?

About the text's box, I'm currently using Button: to set up its background instead of using canvas

And if you are about to tell me to generate a BoxLayout that takes width 70% and aligns right, I just want to say that I also want this to be 2 people talking to each other (like messenger).

update2: About the line below my code:

Another bug at >>+dp(10)<<: texture_size=lambda *x: self.setter('size')(self,(self.texture_size[0]>>+dp(10)<<,self.texture_size1+dp(10)))
​

I found out the reason from here

I fixed that bug by replace the line:

width=lambda *x: self.setter('text_size')(self, (self.width, None))


with:

width=lambda *x: self.setter('text_size')(self, (self.app.root.width, None))


And the result is it still fits the screen but is not a wrapped text anymore.

update1: my code

.py file

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.uix.gridlayout import GridLayout
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.anchorlayout import AnchorLayout
from kivy.uix.button import Button
from kivy.uix.label import Label
from kivy.core.image import Image
from kivy.properties import StringProperty, NumericProperty
from kivy.core.window import Window
from kivy.graphics.context_instructions import Color
from kivy.graphics.vertex_instructions import Line,Rectangle,Ellipse
from kivy.graphics.texture import Texture
from kivy.metrics import dp
from kivy.uix.textinput import TextInput, FL_IS_LINEBREAK
from kivy.uix.screenmanager import Screen
from kivy.properties import ObjectProperty
import copy

class MainWidget(Widget):
request = StringProperty("Welcome")
window_size = (305,400)
refresh_key = False

def __init__(self,**kwargs):
super().__init__(**kwargs)
self.Window_minimum()
Window.bind(on_key_down=self._on_keyboard_down)

def on_size(self,*args):
print(self.width,self.height)
#self.ids.class_Chat_history_update

def Window_minimum(self):
Window.minimum_width,Window.minimum_height=self.window_size

def on_text_validate_button(self):
if self.ids.text_input_box.focus == True:
self.ids.text_input_box.focus = False
self.ids.class_Chat_history_update.Chat_history_generate(self.ids.text_input_box.text)

def _on_keyboard_down(self, instance, keyboard, keycode, text, modifiers):
# ENTER KEY CONDITION
print(instance, keyboard, keycode, text, modifiers)
if len(modifiers) == 2 and modifiers[1] == 'shift' and keyboard == 13:
self.ids.text_input_box.text=self.ids.text_input_box.text+"\n"

if len(modifiers) == 2 and modifiers[0] == 'ctrl' and keyboard == 13:
self.ids.text_input_box.text=self.ids.text_input_box.text+"\n"

if len(modifiers) == 1 and keyboard == 13 and self.ids.text_input_box.focus == True:
self.ids.text_input_box.focus = False
self.ids.class_Chat_history_update.Chat_history_generate(self.ids.text_input_box.text)

class Chat_history_update(BoxLayout):
def __init__(self,**kwargs):
super().__init__(**kwargs)
self.app = App.get_running_app()
l = Label(text="Welcome",size_hint=(1, None),height=("50dp"))
self.add_widget(l)
def Chat_history_generate(self,input_text):
label = WrappedLabel(text=self.app.root.ids.text_input_box.text, #<<<<<<<<<<<<<< Wrapped Label getting
halign="right",pos_hint={"right":.98},
size_hint=(1 ,None), #<<<<<<<<<<<<<<<<<<< The WrappedLabel won't work if None,None
color=(1,1,1),disabled=True,background_disabled_normal='',
background_color=(204/255,153/255,255/255,0.9))
#label.height = label.texture_size[1]+dp(15)
#label.width = label.texture_size[0]+dp(15)
self.add_widget(label)

class WrappedLabel(Button): #<<<<<<<<<<<<<<<<<<<<<<<<< Main wrapped label function based on another solution
def __init__(self, **kwargs):
super().__init__(**kwargs)
self.bind(
width=lambda *x: self.setter('text_size')(self, (self.width, None)),
texture_size=lambda *x: self.setter('height')(None,self.texture_size[1]+dp(10)))
# Another bug at >>+dp(10)<<: texture_size=lambda *x: self.setter('size')(self,(self.texture_size[0]>>+dp(10)<<,self.texture_size[1]+dp(10)))
#self.texture_update()
print(self.texture_size)
# self.height = self.texture_size[1]+dp(15)
# self.width = self.texture_size[0]+dp(15)
class Assistant(App):
pass

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


.kv file

MainWidget:

<MainWidget>:
BoxLayout:
canvas.before:
Color:
rgba: (105/255,105/255,105/255,1)
Rectangle:
size: self.size
pos: self.pos
size: root.size
orientation: "vertical"
GridLayout:
cols: 3
size_hint: 1,None
height: "50dp"
spacing: "10dp"
padding: "10dp"
Label:
text:"Assistant"
Button:
text:"Edit Path"
Button:
text:"Setting"
BoxLayout:
size: self.size
orientation: "vertical"
spacing: "10dp"
padding: "10dp"
ScrollView: #<<<<<<<<<<<<<<<<<<<<<<<<<<< history chat box
id: chat_history_box
Chat_history_update:
id: class_Chat_history_update
orientation: "vertical"
size_hint: 1, None
height: self.minimum_height
spacing: "15dp"
BoxLayout:
size_hint: 1,None
height: "40dp"
spacing: "5dp"
ScrollView:
id: scrlv
size_hint: .9, None
height: "40dp"
scroll_type: ['content','bars']
bar_width: '10dp'
TextInput:
id: text_input_box
hint_text: "Insert here"
#text_size: self.width*.7, None
size_hint: 1, None
height: max(self.minimum_height, scrlv.height)
#multiline: False
cursor: 0, 0

on_text_validate:
root.on_text_validate(self)
Button:
id: emit_button
text: "GO"
size_hint: .1, None
height: "40dp"
focus: True
background_color: (1,0,0,1) if self.focus else (0,0,1,1)
on_press:
root.on_text_validate_button()

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