CODEWITHSUNDEEP
python-3.xkivy
Lulupointu
Lulupointu

Reputation: 3584

Resizing rectangle when resizing main window while Rectangle's size is changed in python

What I try is part of a larger App but I posted here the minimum to understand my problem:

I want to change the size of a rectangle, and that this size depends on the root.height .

3 cases:

1) When I create a rectangle with "root.height/4" as a height, the size varies as I resize the root window. So far no problem

2) When I tried to assign "root.height/4" to an attribut and call this attribut when setting the size of my rectangle I get the following error: "TypeError: a float is required".

Python file:

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.graphics import Rectangle, Color


class BriqueApp(App):

    def build(self):
        return BriqueGUI()


class BriqueGUI(Widget):
    pass

BriqueApp().run()

Kv file:

#:kivy 1.9.1

<BriqueGUI>:
    h: root.height/4
    color: (1,0,0,1)

    canvas:
        Color: 
            rgba: root.color
        Rectangle:
            size: (200, self.h)
            pos: (0,0)

float error

3) When I tried to reassign a value depending on, for example "root.height/2", when an event is call (here on_touch_down) : The size of my Rectangle changes but when I resize my windows my rectangle doesn't resize with it. You can see the problem here loading the file, clicking in the main window, and changing its size.

Python file:

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.graphics import Rectangle, Color


class BriqueApp(App):

    def build(self):
        return BriqueGUI()


class BriqueGUI(Widget):

    def on_touch_down(self, touch):
        self.h = self.height/2

BriqueApp().run()

Kv file:

#:kivy 1.9.1

<BriqueGUI>:
    h: 20
    color: (1,0,0,1)

    canvas:
        Color: 
            rgba: root.color
        Rectangle:
            size: (200, self.h)
            pos: (0,0)

Upvotes: 1

Views: 2706

Answers (1)

Nykakin
Nykakin

Reputation: 8747

2) You have to create property in your Python code as well:

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.graphics import Rectangle, Color
from kivy.properties import NumericProperty
from kivy.lang import Builder

Builder.load_string(""" 
<BriqueGUI>:
    h: root.height/4
    color: (1,0,0,1)

    canvas:
        Color: 
            rgba: root.color
        Rectangle:
            size: (200, self.h)
            pos: (0,0)
""")

class BriqueApp(App):  
    def build(self):
        return BriqueGUI()


class BriqueGUI(Widget):
    h = NumericProperty(0.0)

BriqueApp().run()

3) You're only assigning once a value to your h property. What you need is bind method that allows you to associate a callback that will be called any time the property changes:

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.graphics import Rectangle, Color
from kivy.properties import NumericProperty
from kivy.lang import Builder

Builder.load_string(""" 
<BriqueGUI>:
    h: 20
    color: (1,0,0,1)

    canvas:
        Color: 
            rgba: root.color
        Rectangle:
            size: (200, self.h)
            pos: (0,0)
""")

class BriqueApp(App):

    def build(self):
        return BriqueGUI()


class BriqueGUI(Widget):

    def on_touch_down(self, touch):
        self.h = self.height/2
        self.bind(height=self.set_h)

    def set_h(self, instance, value):
        self.h = value/2

BriqueApp().run()

Upvotes: 6

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