I recently started learning kivy and don't fully understand how the interaction between .kv file and python file works. For example,
class TimelineScr(ScrollView):
scroll_wheel_distance = 60
If I want to change this variable inside
<TimelineScr>:
Label:
canvas.before:
Color:
rgb: define.LIGHT_BLUE
Rectangle:
pos: self.pos
size: root.width, self.texture_size[1]
Color:
rgb: (0.78, 0.92, 0.91)
Rectangle:
size: root.width-40, self.texture_size[1]-40
pos: 20, 20
size_hint_y: None
height: self.texture_size[1]
padding_y: 40
#shorter: True
line_height: 2
color: define.TEXT_GREEN
font_size: 20
font_name: 'src/fonts/static/Inter-Regular.ttf'
text: str(main.timeline)
text_size: (root.width - 80, None)
can I do it and how?
Sorry for my English
I am not really a pro with kivy but here is with what i often start:
i have a main.py like this:
import # what u need
Builder.load_file('the.kv')
class fscreen(Widget):
def __init__(self, **kwargs):
super().__init__(**kwargs)
class secscreen(Widget):
def __init__(self,**kwargs):
super().__init__(**kwargs)
pass
class thscreen(Widget):
def __init__(self,**kwargs):
super().__init__(**kwargs)
pass
class theapp(App):
def build(self):
self.screenm = ScreenManager()
self.fscreen = fscreen()
screen = Screen(name = "first screen")
screen.add_widget(self.fscreen)
self.screenm.add_widget(screen)
self.secscreen = secscreen()
screen = Screen(name = "secondscreen")
screen.add_widget(self.secscreen)
self.screenm.add_widget(screen)
self.thscreen = thscreen()
screen = Screen(name = "thirdscreen")
screen.add_widget(self.thscreen)
self.screenm.add_widget(screen)
return self.screenm
if __name__ == "__main__":
theapp = theapp()
theapp.run()
and a the.kv like this:
<fscreen>
canvas.before:
Color:
rgba: 1, 1, 1, 1
Rectangle:
size: root.width, root.height
pos: 0, 0
ScrollView:
id: scroll_view
size: root.width*0.4, root.height*0.4
pos: root.height*0.3, root.height*0.3
Label:
id: output
color: 0, 0, 0, 1
text: ''
size_hint_x: 1.0
size_hint_y: None
text_size: self.width, None
height: self.texture_size[1]
now if i want to change the label thats in the the.kv file there is two ways of changing it:
Button in our kv file in our <fscreen> and a function in our main.py like this:in the.kv file:
Button:
text: ' change label by id'
size: root.width*0.4, root.height*0.05
pos: root.width*0.3, root.height*0.1
on_press: root.change_label()
in main.py:
def change_label(self):
self.ids.output.text = 'label has been changed by id'
same if we want to change ScrollView by id:
the ScrollView id takes a lot of attributes same as the label for example lets say we have another Button and another function as shown before we can change anything by id like this:
def change_by_id(self):
self.ids.scroll_view.size[0] = self.width*0.5
self.ids.scroll_view.size[1] = self.height*0.5
self.ids.scroll_view.pos[0] = self.width*0.25
self.ids.scroll_view.pos[1] = self.height*0.25
self.ids.scroll_view.#valid attribute = ...
self.ids.output.text = 'something'
self.ids.output.font_size = #....
self.ids.output.color = #.... # and so on
for this lets change something in the the.kv file:
ScrollView:
id: scroll_view
size: root.width*0.4, root.height*0.4
pos: root.height*0.3, root.height*0.3
Label:
id: output
color: 0, 0, 0, 1
text: root.string ###### this is what we changed
size_hint_x: 1.0
size_hint_y: None
text_size: self.width, None
height: self.texture_size[1]
Button:
text: ' change label by prop'
size: root.width*0.4, root.height*0.05
pos: root.width*0.3, root.height*0.1
on_press: root.change_by_prop()
now the main.py has to have a string property like this:
class fscreen(Widget):
string = StringProperty()
def __init__(self, **kwargs):
super().__init__(**kwargs
self.string = ''
def change_by_prop(self):
self.string = 'text has been changed by property'
and ofc there are many properties NumericProperty(), StringProperty() and so on ...
this is how I change things in kv file from python main.