ui.kv

<MyLayout>:
    orientation: 'vertical'
    padding: 0
    spacing: 0
    size: root.width, root.height

    GridLayout:
        rows: 3
        
        RelativeLayout:
            size_hint: 1, 1
            pos_hint: 1, 1

            AndroidCamera:
                index: 0
                id: a_cam
                resolution: self.camera_resolution
                allow_stretch: True
                play: True
                canvas.before:
                    PushMatrix
                    Rotate:
                        angle: -90
                        origin: self.center
                    Scale:
                        x: self.cam_ratio
                        y: self.cam_ratio
                        origin: self.center
                canvas.after:
                    PopMatrix
            
            Label:
                size_hint: 1, 0.1
                id: fps_text
                text_size: self.size
                halign: 'left'
                valign: 'bottom'
                font_size: self.height * 0.1
                text: ''
                padding_x: 20
                padding_y: 0
       
        Button:
            size_hint: 1, 0.2
            id: text_out
            font_size: self.height * 0.1
            text: ''
            on_release:
                self.interact()