Screen Rotation and Re-layout

[RobertFlatt]

I am having a problem with screen rotate under Python for Android.

The example below does not re-layout on device rotation. The contents does rotate, but is not not resized for the new width and height. It does re-layout when I tap the screen after rotation.
It is compiled with "--orientation sensor". I am using p4a master branch dated 5/17/2018.

On device rotation, I'm looking for a way to trigger re-layout from Python. My code can implement the re-layout.

It appears that on_pause() and on_resume() are called when the app enters/returns from the background. Unlike Java on Android they are not called on rotation. Not my expectation, but I can see why it is that way.

It appears that on_rotate() is never called, either from the App class or layout class. What am I missing?

Once I have a trigger I assume I will have to get the new size using Java, because Python's Window.size does not appear to be updated till after re-layout.

Suggestions for handling screen rotation re-layout?

Thanks.

from kivy.lang import Builder
from kivy.uix.gridlayout import GridLayout
from kivy.properties import StringProperty
from kivy.app import App

Builder.load_string('''
<LifecycleScreen>:
    cols: 1
    Label:
        text: root.label0
    Label:
        text: root.label1
    Button:
        text: 'Reset'
        on_release: root.my_callback()
''')


class LifecycleScreen(GridLayout):
    label0 = StringProperty('Got Call:False,False,False.')
    label1 = StringProperty('Original Orientation')

    def on_rotate(self):
        label1 = StringProperty('Rotated')

    def my_callback(self):
        self.parent.pause = False
        self.parent.resume = False
        self.parent.rotate = False
        self.label1 = 'Orientation Reset'

class LifecycleApp(App):
    def __init__(self,**kwargs):
        super (LifecycleApp,self).__init__(**kwargs)
        self.screen = None
        self.pause = False
        self.resume = False
        self.rotate = False

    def build(self):
        self.screen = LifecycleScreen()
        return self.screen

    def label_text(self):
        self.screen.label0 = 'Got Call:{},{},{}.'.format(self.pause,
                                                         self.resume,
                                                         self.rotate)
        
    def on_pause(self):
        self.pause = True
        self.label_text()
        return True  
 
    def on_resume(self):
        self.resume = True
        self.label_text()

    def on_rotate(self):
        self.rotate = True
        self.label_text()


if __name__ == '__main__':
    LifecycleApp().run()

[RobertFlatt]

First, the workaround I used is below. This depends on a heartbeat, there has to be a better way?!

Second, I notice Settings().add_kivy_panel() has a 'rotation' key. On Windows and Android this rotates the window on all subsequent window create(). The App class also has a on_config_change() callback which should respond to changes in this key, this callback is a new addition and not released.

From an Android/Java viewpoint rotation is (re) creation. I suggest if , on device rotation, the Kivy Android bootstrap were to set the value of the 'rotation' key (and the callback were released). There would be an effective on_rotate() callback. An enhancement request for your consideration.

class LifecycleApp(App):
    def __init__(self,**kwargs):
        super (LifecycleApp,self).__init__(**kwargs)
        self.screen = None
        self.x, self.y = Window.size

    def build(self):
        self.screen = LifecycleScreen()
        Clock.schedule_interval(self.potential_on_rotate,1)
        return self.screen

    def potential_on_rotate(self,dt):
        x,y = Window.size
        if self.x == y and self.y == x:
            self.x = x
            self.y = y
            self.on_rotate()

    def on_rotate(self):
        self.screen.canvas.ask_update()

[inclement]

I think this is working better with SDL2.0.9, please feel free to reopen if not.