"""
Components/Hero
===============
.. versionadded:: 1.0.0
.. rubric:: Use the :class:`~MDHeroFrom` widget to animate a widget from one
screen to the next.
- The hero refers to the widget that flies between screens.
- Create a hero animation using KivyMD’s :class:`~MDHeroFrom` widget.
- Fly the hero from one screen to another.
- Animate the transformation of a hero’s shape from circular to rectangular while flying it from one screen to another.
- The :class:`~MDHeroFrom` widget in KivyMD implements a style of animation commonly known as shared element transitions or shared element animations.
.. raw:: html
The widget that will move from screen A to screen B will be a hero. To move
a widget from one screen to another using hero animation, you need to do the
following:
- On screen **A**, place the :class:`~MDHeroFrom` container.
- Sets a tag (string) for the :class:`~MDHeroFrom` container.
- Place a hero in the :class:`~MDHeroFrom` container.
- On screen **B**, place the :class:`~MDHeroTo` container - our hero from screen **A** will fly into this container.
.. image:: https://github.com/HeaTTheatR/KivyMD-data/raw/master/gallery/kivymddoc/hero-base.png
:align: center
.. warning::
:class:`~MDHeroFrom` container cannot have more than one child widget.
Base example
------------
.. code-block:: python
from kivy.lang import Builder
from kivymd.app import MDApp
KV = '''
MDScreenManager:
MDScreen:
name: "screen A"
md_bg_color: "lightblue"
MDHeroFrom:
id: hero_from
tag: "hero"
size_hint: None, None
size: "120dp", "120dp"
pos_hint: {"top": .98}
x: 24
FitImage:
source: "bg.jpg"
size_hint: None, None
size: hero_from.size
MDButton:
pos_hint: {"center_x": .5}
y: "36dp"
on_release:
root.current_heroes = ["hero"]
root.current = "screen B"
MDButtonText:
text: "Move Hero To Screen B"
MDScreen:
name: "screen B"
hero_to: hero_to
md_bg_color: "cadetblue"
MDHeroTo:
id: hero_to
tag: "hero"
size_hint: None, None
size: "220dp", "220dp"
pos_hint: {"center_x": .5, "center_y": .5}
MDButton:
pos_hint: {"center_x": .5}
y: "36dp"
on_release:
root.current_heroes = ["hero"]
root.current = "screen A"
MDButtonText:
text: "Move Hero To Screen A"
'''
class Example(MDApp):
def build(self):
return Builder.load_string(KV)
Example().run()
.. image:: https://github.com/HeaTTheatR/KivyMD-data/raw/master/gallery/kivymddoc/hero-usage.gif
:align: center
Note that the child of the :class:`~MDHeroFrom` widget must have the size of the parent:
.. code-block:: kv
MDHeroFrom:
id: hero_from
tag: "hero"
FitImage:
size_hint: None, None
size: hero_from.size
To enable hero animation before setting the name of the current screen for the
screen manager, you must specify the name of the tag of the :class:`~MDHeroFrom`
container in which the hero is located:
.. code-block:: kv
MDButton:
on_release:
root.current_heroes = ["hero"]
root.current = "screen 2"
MDButtonText:
text: "Move Hero To Screen B"
If you need to switch to a screen that does not contain heroes, set the
`current_hero` attribute for the screen manager as "" (empty string):
.. code-block:: kv
MDButton:
on_release:
root.current_heroes = []
root.current = "another screen"
MDButtonText:
text: "Go To Another Screen"
Example
-------
.. code-block:: python
from kivy.lang import Builder
from kivymd.app import MDApp
KV = '''
MDScreenManager:
MDScreen:
name: "screen A"
md_bg_color: "lightblue"
MDHeroFrom:
id: hero_from
tag: "hero"
size_hint: None, None
size: "120dp", "120dp"
pos_hint: {"top": .98}
x: 24
FitImage:
source: "bg.jpg"
size_hint: None, None
size: hero_from.size
MDButton:
pos_hint: {"center_x": .5}
y: "36dp"
on_release:
root.current_heroes = ["hero"]
root.current = "screen B"
MDButtonText:
text: "Move Hero To Screen B"
MDScreen:
name: "screen B"
hero_to: hero_to
md_bg_color: "cadetblue"
MDHeroTo:
id: hero_to
tag: "hero"
size_hint: None, None
size: "220dp", "220dp"
pos_hint: {"center_x": .5, "center_y": .5}
MDButton:
pos_hint: {"center_x": .5}
y: "52dp"
on_release:
root.current_heroes = []
root.current = "screen C"
MDButtonText:
text: "Go To Screen C"
MDButton:
pos_hint: {"center_x": .5}
y: "8dp"
on_release:
root.current_heroes = ["hero"]
root.current = "screen A"
MDButtonText:
text: "Move Hero To Screen A"
MDScreen:
name: "screen C"
md_bg_color: "olive"
MDLabel:
text: "Screen C"
halign: "center"
MDButton:
pos_hint: {"center_x": .5}
y: "36dp"
on_release:
root.current = "screen B"
MDButtonText:
text: "Back To Screen B"
'''
class Example(MDApp):
def build(self):
return Builder.load_string(KV)
Example().run()
.. image:: https://github.com/HeaTTheatR/KivyMD-data/raw/master/gallery/kivymddoc/hero-switch-another-screen.gif
:align: center
Events
------
Two events are available for the hero:
- `on_transform_in` - when the hero flies from screen **A** to screen **B**.
- `on_transform_out` - when the hero back from screen **B** to screen **A**.
The `on_transform_in`, `on_transform_out` events relate to the
:class:`~MDHeroFrom` container. For example, let's change the radius and
background color of the hero during the flight between the screens:
.. code-block:: python
from kivy import utils
from kivy.animation import Animation
from kivy.lang import Builder
from kivy.utils import get_color_from_hex
from kivymd.app import MDApp
from kivymd.uix.hero import MDHeroFrom
from kivymd.uix.relativelayout import MDRelativeLayout
KV = '''
MDScreenManager:
MDScreen:
name: "screen A"
md_bg_color: "lightblue"
MyHero:
id: hero_from
tag: "hero"
size_hint: None, None
size: "120dp", "120dp"
pos_hint: {"top": .98}
x: 24
MDRelativeLayout:
size_hint: None, None
size: hero_from.size
md_bg_color: "blue"
radius: [24, 12, 24, 12]
FitImage:
source: "https://github.com/kivymd/internal/raw/main/logo/kivymd_logo_blue.png"
MDButton:
pos_hint: {"center_x": .5}
y: "36dp"
on_release:
root.current_heroes = ["hero"]
root.current = "screen B"
MDButtonText:
text: "Move Hero To Screen B"
MDScreen:
name: "screen B"
hero_to: hero_to
md_bg_color: "cadetblue"
MDHeroTo:
id: hero_to
tag: "hero"
size_hint: None, None
size: "220dp", "220dp"
pos_hint: {"center_x": .5, "center_y": .5}
MDButton:
pos_hint: {"center_x": .5}
y: "36dp"
on_release:
root.current_heroes = ["hero"]
root.current = "screen A"
MDButtonText:
text: "Move Hero To Screen A"
'''
class Example(MDApp):
def build(self):
return Builder.load_string(KV)
class MyHero(MDHeroFrom):
def on_transform_in(
self, instance_hero_widget: MDRelativeLayout, duration: float
):
'''
Fired when the hero flies from screen **A** to screen **B**.
:param instance_hero_widget: dhild widget of the `MDHeroFrom` class.
:param duration of the transition animation between screens.
'''
Animation(
radius=[12, 24, 12, 24],
duration=duration,
md_bg_color=(0, 1, 1, 1),
).start(instance_hero_widget)
def on_transform_out(
self, instance_hero_widget: MDRelativeLayout, duration: float
):
'''Fired when the hero back from screen **B** to screen **A**.'''
Animation(
radius=[24, 12, 24, 12],
duration=duration,
md_bg_color=get_color_from_hex(utils.hex_colormap["blue"]),
).start(instance_hero_widget)
Example().run()
.. image:: https://github.com/HeaTTheatR/KivyMD-data/raw/master/gallery/kivymddoc/hero-events.gif
:align: center
Usage with ScrollView
---------------------
.. code-block:: python
from kivy.animation import Animation
from kivy.clock import Clock
from kivy.lang import Builder
from kivy.metrics import dp
from kivy.properties import StringProperty, ObjectProperty
from kivymd.app import MDApp
from kivymd.uix.hero import MDHeroFrom
KV = '''
size_hint_y: None
height: "200dp"
radius: "24dp"
MDSmartTile:
id: tile
size_hint: None, None
size: root.size
on_release: root.on_release()
MDSmartTileImage:
id: image
source: "bg.jpg"
radius: dp(24)
MDSmartTileOverlayContainer:
id: overlay
md_bg_color: 0, 0, 0, .5
adaptive_height: True
padding: "8dp"
spacing: "8dp"
radius: [0, 0, dp(24), dp(24)]
MDLabel:
text: root.tag
theme_text_color: "Custom"
text_color: "white"
adaptive_height: True
MDScreenManager:
md_bg_color: self.theme_cls.backgroundColor
MDScreen:
name: "screen A"
ScrollView:
MDGridLayout:
id: box
cols: 2
spacing: "12dp"
padding: "12dp"
adaptive_height: True
MDScreen:
name: "screen B"
heroes_to: [hero_to]
MDHeroTo:
id: hero_to
size_hint: 1, None
height: "220dp"
pos_hint: {"top": 1}
MDButton:
pos_hint: {"center_x": .5}
y: "36dp"
on_release:
root.current_heroes = [hero_to.tag]
root.current = "screen A"
MDButtonText:
text: "Move Hero To Screen A"
'''
class HeroItem(MDHeroFrom):
text = StringProperty()
manager = ObjectProperty()
def __init__(self, **kwargs):
super().__init__(**kwargs)
self.ids.image.ripple_duration_in_fast = 0.05
def on_transform_in(self, instance_hero_widget, duration):
for instance in [
instance_hero_widget,
instance_hero_widget._overlay_container,
instance_hero_widget._image,
]:
Animation(radius=[0, 0, 0, 0], duration=duration).start(instance)
def on_transform_out(self, instance_hero_widget, duration):
for instance, radius in {
instance_hero_widget: [dp(24), dp(24), dp(24), dp(24)],
instance_hero_widget._overlay_container: [0, 0, dp(24), dp(24)],
instance_hero_widget._image: [dp(24), dp(24), dp(24), dp(24)],
}.items():
Animation(
radius=radius,
duration=duration,
).start(instance)
def on_release(self):
def switch_screen(*args):
self.manager.current_heroes = [self.tag]
self.manager.ids.hero_to.tag = self.tag
self.manager.current = "screen B"
Clock.schedule_once(switch_screen, 0.2)
class Example(MDApp):
def build(self):
return Builder.load_string(KV)
def on_start(self):
for i in range(12):
hero_item = HeroItem(
text=f"Item {i + 1}", tag=f"Tag {i}", manager=self.root
)
if not i % 2:
hero_item.md_bg_color = "lightgrey"
self.root.ids.box.add_widget(hero_item)
Example().run()
.. image:: https://github.com/HeaTTheatR/KivyMD-data/raw/master/gallery/kivymddoc/hero-usage-with-scrollview.gif
:align: center
Using multiple heroes at the same time
--------------------------------------
.. code-block:: python
from kivy.lang import Builder
from kivymd.app import MDApp
KV = '''
MDScreenManager:
MDScreen:
name: "screen A"
md_bg_color: "lightblue"
MDHeroFrom:
id: hero_kivymd
tag: "kivymd"
size_hint: None, None
size: "200dp", "200dp"
pos_hint: {"top": .98}
x: 24
FitImage:
source: "avatar.png"
size_hint: None, None
size: hero_kivymd.size
radius: self.height / 2
MDHeroFrom:
id: hero_kivy
tag: "kivy"
size_hint: None, None
size: "200dp", "200dp"
pos_hint: {"top": .98}
x: 324
FitImage:
source: "bg.jpg"
size_hint: None, None
size: hero_kivy.size
radius: self.height / 2
MDButton:
pos_hint: {"center_x": .5}
y: "36dp"
on_release:
root.current_heroes = ["kivymd", "kivy"]
root.current = "screen B"
MDButtonText:
text: "Move Hero To Screen B"
MDScreen:
name: "screen B"
heroes_to: hero_to_kivymd, hero_to_kivy
md_bg_color: "cadetblue"
MDHeroTo:
id: hero_to_kivy
tag: "kivy"
size_hint: None, None
pos_hint: {"center_x": .5, "center_y": .5}
MDHeroTo:
id: hero_to_kivymd
tag: "kivymd"
size_hint: None, None
pos_hint: {"right": 1, "top": 1}
MDButton:
pos_hint: {"center_x": .5}
y: "36dp"
on_release:
root.current_heroes = ["kivy", "kivymd"]
root.current = "screen A"
MDButtonText:
text: "Move Hero To Screen A"
'''
class Test(MDApp):
def build(self):
return Builder.load_string(KV)
Example().run()
.. image:: https://github.com/HeaTTheatR/KivyMD-data/raw/master/gallery/kivymddoc/hero-multiple-heroes.gif
:align: center
"""
from kivy.properties import StringProperty
from kivymd.uix.boxlayout import MDBoxLayout
class MDHeroFrom(MDBoxLayout):
"""
The container from which the hero begins his flight.
For more information, see in the
:class:`~kivymd.uix.boxlayout.MDBoxLayout` class documentation.
:Events:
`on_transform_in`
when the hero flies from screen **A** to screen **B**.
`on_transform_out`
Fired when the hero back from screen **B** to screen **A**.
"""
tag = StringProperty(allownone=True)
"""
Tag ID for heroes.
:attr:`tag` is an :class:`~kivy.properties.StringProperty`
and defaults to `''`.
"""
def __init__(self, **kwargs):
super().__init__(**kwargs)
self.register_event_type("on_transform_in")
self.register_event_type("on_transform_out")
def on_transform_in(self, *args):
"""Fired when the hero flies from screen **A** to screen **B**."""
def on_transform_out(self, *args):
"""Fired when the hero back from screen **B** to screen **A**."""
class MDHeroTo(MDBoxLayout):
"""
The container in which the hero comes.
For more information, see in the
:class:`~kivymd.uix.boxlayout.MDBoxLayout` class documentation.
"""
tag = StringProperty(allownone=True)
"""
Tag ID for heroes.
:attr:`tag` is an :class:`~kivy.properties.StringProperty`
and defaults to `''`.
"""