Kivy 中的拖放行为

Question

I'm new in Python and Kivy.

My goal is to drag a button to a certain place (Label), each button and label have their own scores, and if I drag the button and my cursor is inside the label, it will show the tooltip to display the sum of the score of the button and the label, finally if I drop the button on the Label, the button will automatically be on the position the label was, and print the sum of the score. However, if I drop the button outside the label, the button will automatically be on the position the button was.

I want to implement some additional functions in DragBehavior:

• When I drag a button, make it be on the top of the other widgets.

I 've already seen this , but the functions are not enough to me.

Here is my .py file:

from kivy.app import App
from kivy.properties import StringProperty
from kivy.properties import BooleanProperty
from kivy.properties import ObjectProperty
from kivy.core.window import Window
from kivy.uix.button import Button
from kivy.uix.label import Label
from kivy.uix.behaviors import DragBehavior


class HoverBehavior(object):
    """Hover behavior.
    :Events:
        `on_enter`
            Fired when mouse enter the bbox of the widget.
        `on_leave`
            Fired when the mouse exit the widget
    """

    hovered = BooleanProperty(False)
    border_point = ObjectProperty(None)
    '''Contains the last relevant point received by the Hoverable. This can
    be used in `on_enter` or `on_leave` in order to know where was dispatched the event.
    '''

    def __init__(self, **kwargs):
        self.register_event_type('on_enter')
        self.register_event_type('on_leave')
        Window.bind(mouse_pos=self.on_mouse_pos)
        super(HoverBehavior, self).__init__(**kwargs)

    def on_mouse_pos(self, *args):
        if not self.get_root_window():
            return  # do proceed if I'm not displayed <=> If have no parent
        pos = args[1]
        # Next line to_widget allow to compensate for relative layout
        inside = self.collide_point(*self.to_widget(*pos))
        if self.hovered == inside:
            # We have already done what was needed
            return
        self.border_point = pos
        self.hovered = inside
        if inside:
            self.dispatch('on_enter')
        else:
            self.dispatch('on_leave')

    def on_enter(self):
        pass

    def on_leave(self):
        pass


class DraggableButton(DragBehavior, Button):
    def __init__(self, **kwargs):
        super(DraggableButton, self).__init__(**kwargs)


class DragToHereLabel(HoverBehavior, Label):
    name = StringProperty("")

    def __init__(self, **kwargs):
        super(DragToHereLabel, self).__init__(**kwargs)

    def on_enter(self):
        self.text = "Entered\nScore: 100"

    def on_leave(self):
        self.text = "Leaved\nScore: 100"


class TestApp(App):
    def build(self):
        pass


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

test.kv:

<DraggableButton>:
    drag_rectangle: self.x, self.y, self.width, self.height
    drag_timeout: 10000000
    drag_distance: 0
    halign: "center"


<DragToHereLabel>:
    text: "Drag to here\nScore: 100"
    halign: "center"
    canvas.before:
        Color:
            rgba: 0.2, 0.2, 0.2, 1
        Rectangle:
            pos: self.pos
            size: self.size


BoxLayout:
    orientation: "vertical"

    DraggableButton:
        text: "Drag me\nScore: 200"

    DragToHereLabel:

Thanks a lot for helping a Kivy beginner!

Answer 1

In the on_touch_down() of DraggableButton you can add;

        parent = self.parent
        parent.remove_widget(self)
        parent.add_widget(self)

This makes sure that the DraggableButton is on top of everything else.