添加或删除对象时的动画

Question

当对象从布局 added/removed

时，如何使用可重复使用的方法为对象设置动画


from kivymd.app import MDApp
from kivy.lang import Builder
from kivy.factory import Factory 

kv='''
<Image_1@BoxLayout>:

    orientation:'vertical'
    #id:img_1   
    Image:
        source:"/storage/emulated/0/Download/download (37).jpeg"
    Button:
        text:"remove"
        on_press: self.parent.remove()             

BoxLayout:
    orientation:'vertical'
                            
    GridLayout:
        cols:1
        id:sc_grid
        
        Button:
            size_hint:None,None 
            text:"add"
            on_press:
                app.Add()      
                              
'''
class MyApp(MDApp):
    
    def build(self):
        return Builder.load_string(kv)
    
    def Add(self):
        
        Image=Factory.Image_1()
        Image.remove = lambda: self.root.ids.sc_grid.remove_widget(Image)
        self.root.ids.sc_grid.add_widget(Image)   
        
MyApp().run()

在上面的代码中，Add 方法将 Factory 对象 Image1 添加到布局中

Answer 1

您可以使用Animation（参见documentation）。在 Image_1 class 中添加一些方法可以使它更容易。这是使用 Animation:

的代码的修改版本

from kivy.animation import Animation
from kivy.uix.boxlayout import BoxLayout
from kivymd.app import MDApp
from kivy.lang import Builder

kv = '''
<Image_1>:

    orientation:'vertical'
    #id:img_1   
    Image:
        source:"/storage/emulated/0/Download/download (37).jpeg"
    Button:
        text:"remove"
        on_press: self.parent.remove()             

BoxLayout:
    orientation:'vertical'

    GridLayout:
        cols:1
        id:sc_grid

        Button:
            size_hint:None,None 
            text:"add"
            on_press:
                app.Add()      

'''

class Image_1(BoxLayout):
    def on_parent(self, *args):
        if self.parent:
            self.opacity = 0
            anim = Animation(opacity=1)
            anim.start(self)

    def remove(self):
        anim = Animation(opacity=0)
        anim.start(self)
        anim.on_complete = self.do_actual_remove

    def do_actual_remove(self, widget):
        self.parent.remove_widget(self)

class MyApp(MDApp):

    def build(self):
        return Builder.load_string(kv)

    def Add(self):
        Image = Image_1()
        self.root.ids.sc_grid.add_widget(Image)


MyApp().run()

添加或删除对象时的动画

Animation on adding or removal of an object

python

kivy