Kivy Popup rendering issue

问题

I'm working on a bus driver app. Once in a while, there are messages published on a MQTT topic which the app is subscribed to (by a server). When such message comes, a popup must appear. I customized the default Kivy popup: changed the background, added as the content a FloatLayout with a Lable and a Button.

The problem is that once in several cases (5-6) the texture elements of the popup jumps away, like the background, or the Label text, or the button's image.

Here is the Kivy definition of my Popup class:

<BktsPopup@Popup>:
title: 'Alert message'
title_align: 'center'
title_size: 25
size_hint: (0.6, 0.6)
# size: (400, 300)
auto_dismiss: False
separator_height: 0
message: popup_msg
border: (14, 14, 14, 14)

FloatLayout:
    BktsLabel:
        id: popup_msg
        font_size: 20
        size_hint_y: 0.7
        pos_hint: {'center_x': 0.5, 'y': 0.5}
        # size_hint_y: 60
    BktsButton:
        id: ok_btn
        background_normal: 'res/btn_released_gray.png'
        background_down: 'res/btn_pressed_gray.png'        
        size_hint_x: 0.4
        size_hint_y: 0.3
        pos_hint: {'center_x': 0.5, 'y': 0.1}
        text: 'OK'
        font_size: 25
        on_press: root.dismiss()

Here is the python class:

class BktsPopup(Popup):
    popup_back_color = ListProperty([])
    message = ObjectProperty()

    def __init__(self, text, title, level):
        Popup.__init__(self)
        self.title = title
        self.message.text = text
        if level is LEVEL_NORMAL:
            self.background = 'res/popup_back_green.png'
        elif level is LEVEL_URGENT:
            self.background = 'res/popup_back_red.png'

Here's how the popup is being opened:

def on_dispatcher_message(self, level, text):
    popup = BktsPopup(text, 'Dispatcher', level)
    popup.bind(on_dismiss=self.send_message_ack)
    popup.open()
    self.store_event(text)

Here's the normal appearance of the popup:

Here's a texture-anomaly case:

Sometimes, the whole background jumps and appears in the left-bottom corner. Any ideas why?

来源：https://stackoverflow.com/questions/38183393/kivy-popup-rendering-issue

标签

python

popup

kivy

render