hoverable.py

from kivy.app import App
from kivy.uix.image import Image
from kivy.uix.behaviors import DragBehavior
from kivy.properties import BooleanProperty, ObjectProperty, StringProperty
from kivy.factory import Factory
from kivy.core.window import Window
from kivy.lang import Builder



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


Factory.register('HoverBehavior', HoverBehavior)


class DraggableImage(DragBehavior, HoverBehavior, Image):

    name = StringProperty("")

    def __init__(self, **args):
        super(DraggableImage, self).__init__(**args)
        self.source_file = ""
        self.is_on_hover = False

    def on_enter(self):
        self.source_file = self.source
        self.source = "green.png"
        self.is_on_hover = True
        print(self.name)

    def on_leave(self):
        self.source = self.source_file
        self.is_on_hover = False
        print(self.name)

    def on_touch_up(self, touch):
        if self.is_on_hover:
            print(self.name)




KV = """

<DraggableImage>:
    drag_rectangle: self.x, self.y, self.width, self.height
    drag_timeout: 10000000
    drag_distance: 0

BoxLayout:
    orientation: "horizontal"
    DraggableImage:
        name: "left_left"
        source: "red.png"
    DraggableImage:
        name: "left_right"
        source: "yellow.png"
    DraggableImage:
        name: "right_left"
        source: "red.png"
    DraggableImage:
        name: "right_right"
        source: "yellow.png"

"""


class TestApp(App):

    def build(self):
        root = Builder.load_string(KV)
        return root


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