Getting the size of a layout

[Frédéric]

Hello all,

I'm always having troubles with sizes in Kivy.

Now I want to retrieve the size of a FloatLayout (to add dynamically objets in it).

The size I get is always the default one: (100,100)

For this program

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

kv = """
BoxLayout:
    orientation: "vertical"
    canvas:
        Color:
            rgb: 1, .7,  1
        Rectangle:
            pos: self.pos
            size: self.size
    Label:
        text:"Titre"
        color: 0, 0, 0
        size_hint: 1, 0.1
    FloatLayout:
        id: flt
        canvas:
            Color:
                rgb: 0.5, 1, 0.5
            Rectangle:
                pos: self.pos
                size: self.size
        Button:
            id: btn
            size_hint: None, None
            size: 95, 95
"""

class main(App):

    def build(self):
        return Builder.load_string(kv)

    def on_start(self, **kwargs):
        print (self.root.ids.flt.size)
        print (self.root.ids.btn.size)

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

--------

I can see the button, which size (95, 95), and the FloatLayout, in green.

The floatLayout is very big comparatively to the button, but the console output is

[100, 100]
[95, 95]

How can I retrieve the good information?

[ELLIOT GARBUS]

The default size for a widget is 100,100.  The sizes will be set a clock tick after on_start.  

I've modified your code to add print out the sizes after one clock tick.

I also added some print statements to the button.

You might be interested in the inspector tool.  You can use it to interactively  examine the widgets and their attributes.

Read:

https://kivy.org/doc/stable/api-kivy.modules.html#activate-a-module-via-the-commandline

https://kivy.org/doc/stable/api-kivy.modules.inspector.html#module-kivy.modules.inspector

from kivy.app import App

from kivy.lang import Builder

from kivy.clock import Clock

            on_release:

                print(f'{flt.size=} {btn.size=}')

"""

class Main(App):

    def build(self):

        return Builder.load_string(kv)

    def on_start(self, **kwargs):

        print(f'on_start: {self.root.ids.flt.size=}  {self.root.ids.btn.size=}')

        Clock.schedule_once(self.after_clock)

    def after_clock(self, _):

        print(f'after_clock: {self.root.ids.flt.size=}  {self.root.ids.btn.size=}')

if __name__ == "__main__":

    Main().run()

---

From: kivy-...@googlegroups.com <kivy-...@googlegroups.com> on behalf of Frédéric <freder...@gmail.com>
Sent: Thursday, June 27, 2024 8:57 AM
To: Kivy users support <kivy-...@googlegroups.com>
Subject: [kivy-users] Getting the size of a layout

 

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[Frédéric]

Thanks Elliot,

Your answer is perfect, once again!

As it makes more sense to me (I use on_start to refine the UI) , I then will now use on_start like this

    def on_start(self, **kwargs):
        self.on_will_firstlayout()
        Clock.schedule_once(self.on_did_firstlayout, 0)

[ELLIOT GARBUS]

I encourage you to try the inspector.  It is a very powerful tool. 

On the command line: python yourcode.py -m inspector

Then press cntrl-e 

Select inspect on the bar, and touch the widget.  Click on the bar to get the details.   It is a great debugging tool.

---

From: kivy-...@googlegroups.com <kivy-...@googlegroups.com> on behalf of Frédéric <freder...@gmail.com>

Sent: Friday, June 28, 2024 5:03 AM

To: Kivy users support <kivy-...@googlegroups.com>

Subject: Re: [kivy-users] Getting the size of a layout

 

To view this discussion on the web visit https://groups.google.com/d/msgid/kivy-users/8f1151dc-7333-4087-b3d2-f49515cdee5cn%40googlegroups.com.