'''Screen Manager ============== .. image:: images/screenmanager.gif :align: right .. versionadded:: 1.4.0 The screen manager is a widget dedicated to managing multiple screens for your application. The default :class:`ScreenManager` displays only one :class:`Screen` at a time and uses a :class:`TransitionBase` to switch from one Screen to another. Multiple transitions are supported based on changing the screen coordinates / scale or even performing fancy animation using custom shaders. Basic Usage ----------- Let's construct a Screen Manager with 4 named screens. When you are creating a screen, **you absolutely need to give a name to it**:: from kivy.uix.screenmanager import ScreenManager, Screen # Create the manager sm = ScreenManager() # Add few screens for i in range(4): screen = Screen(name='Title %d' % i) sm.add_widget(screen) # By default, the first screen added into the ScreenManager will be # displayed. You can then change to another screen. # Let's display the screen named 'Title 2' # A transition will automatically be used. sm.current = 'Title 2' The default :attr:`ScreenManager.transition` is a :class:`SlideTransition` with options :attr:`~SlideTransition.direction` and :attr:`~TransitionBase.duration`. Please note that by default, a :class:`Screen` displays nothing: it's just a :class:`~kivy.uix.relativelayout.RelativeLayout`. You need to use that class as a root widget for your own screen, the best way being to subclass. .. warning:: As :class:`Screen` is a :class:`~kivy.uix.relativelayout.RelativeLayout`, it is important to understand the :ref:`kivy-uix-relativelayout-common-pitfalls`. Here is an example with a 'Menu Screen' and a 'Settings Screen':: from kivy.app import App from kivy.lang import Builder from kivy.uix.screenmanager import ScreenManager, Screen # Create both screens. Please note the root.manager.current: this is how # you can control the ScreenManager from kv. Each screen has by default a # property manager that gives you the instance of the ScreenManager used. Builder.load_string(""" : BoxLayout: Button: text: 'Goto settings' on_press: root.manager.current = 'settings' Button: text: 'Quit' : BoxLayout: Button: text: 'My settings button' Button: text: 'Back to menu' on_press: root.manager.current = 'menu' """) # Declare both screens class MenuScreen(Screen): pass class SettingsScreen(Screen): pass class TestApp(App): def build(self): # Create the screen manager sm = ScreenManager() sm.add_widget(MenuScreen(name='menu')) sm.add_widget(SettingsScreen(name='settings')) return sm if __name__ == '__main__': TestApp().run() Changing Direction ------------------ A common use case for :class:`ScreenManager` involves using a :class:`SlideTransition` which slides right to the next screen and slides left to the previous screen. Building on the previous example, this can be accomplished like so:: Builder.load_string(""" : BoxLayout: Button: text: 'Goto settings' on_press: root.manager.transition.direction = 'left' root.manager.current = 'settings' Button: text: 'Quit' : BoxLayout: Button: text: 'My settings button' Button: text: 'Back to menu' on_press: root.manager.transition.direction = 'right' root.manager.current = 'menu' """) Advanced Usage -------------- From 1.8.0, you can now switch dynamically to a new screen, change the transition options and remove the previous one by using :meth:`~ScreenManager.switch_to`:: sm = ScreenManager() screens = [Screen(name='Title {}'.format(i)) for i in range(4)] sm.switch_to(screens[0]) # later sm.switch_to(screens[1], direction='right') Note that this method adds the screen to the :class:`ScreenManager` instance and should not be used if your screens have already been added to this instance. To switch to a screen which is already added, you should use the :attr:`~ScreenManager.current` property. Changing transitions -------------------- You have multiple transitions available by default, such as: - :class:`NoTransition` - switches screens instantly with no animation - :class:`SlideTransition` - slide the screen in/out, from any direction - :class:`CardTransition` - new screen slides on the previous or the old one slides off the new one depending on the mode - :class:`SwapTransition` - implementation of the iOS swap transition - :class:`FadeTransition` - shader to fade the screen in/out - :class:`WipeTransition` - shader to wipe the screens from right to left - :class:`FallOutTransition` - shader where the old screen 'falls' and becomes transparent, revealing the new one behind it. - :class:`RiseInTransition` - shader where the new screen rises from the screen centre while fading from transparent to opaque. You can easily switch transitions by changing the :attr:`ScreenManager.transition` property:: sm = ScreenManager(transition=FadeTransition()) .. note:: Currently, none of Shader based Transitions use anti-aliasing. This is because they use the FBO which doesn't have any logic to handle supersampling. This is a known issue and we are working on a transparent implementation that will give the same results as if it had been rendered on screen. To be more concrete, if you see sharp edged text during the animation, it's normal. ''' __all__ = ('Screen', 'ScreenManager', 'ScreenManagerException', 'TransitionBase', 'ShaderTransition', 'SlideTransition', 'SwapTransition', 'FadeTransition', 'WipeTransition', 'FallOutTransition', 'RiseInTransition', 'NoTransition', 'CardTransition') from kivy.compat import iteritems from kivy.logger import Logger from kivy.event import EventDispatcher from kivy.clock import Clock from kivy.uix.floatlayout import FloatLayout from kivy.properties import (StringProperty, ObjectProperty, AliasProperty, NumericProperty, ListProperty, OptionProperty, BooleanProperty, ColorProperty) from kivy.animation import Animation, AnimationTransition from kivy.uix.relativelayout import RelativeLayout from kivy.lang import Builder from kivy.graphics import (RenderContext, Rectangle, Fbo, ClearColor, ClearBuffers, BindTexture, PushMatrix, PopMatrix, Translate, Callback, Scale) class ScreenManagerException(Exception): '''Exception for the :class:`ScreenManager`. ''' pass class Screen(RelativeLayout): '''Screen is an element intended to be used with a :class:`ScreenManager`. Check module documentation for more information. :Events: `on_pre_enter`: () Event fired when the screen is about to be used: the entering animation is started. `on_enter`: () Event fired when the screen is displayed: the entering animation is complete. `on_pre_leave`: () Event fired when the screen is about to be removed: the leaving animation is started. `on_leave`: () Event fired when the screen is removed: the leaving animation is finished. .. versionchanged:: 1.6.0 Events `on_pre_enter`, `on_enter`, `on_pre_leave` and `on_leave` were added. ''' name = StringProperty('') ''' Name of the screen which must be unique within a :class:`ScreenManager`. This is the name used for :attr:`ScreenManager.current`. :attr:`name` is a :class:`~kivy.properties.StringProperty` and defaults to ''. ''' manager = ObjectProperty(None, allownone=True) ''':class:`ScreenManager` object, set when the screen is added to a manager. :attr:`manager` is an :class:`~kivy.properties.ObjectProperty` and defaults to None, read-only. ''' transition_progress = NumericProperty(0.) '''Value that represents the completion of the current transition, if any is occurring. If a transition is in progress, whatever the mode, the value will change from 0 to 1. If you want to know if it's an entering or leaving animation, check the :attr:`transition_state`. :attr:`transition_progress` is a :class:`~kivy.properties.NumericProperty` and defaults to 0. ''' transition_state = OptionProperty('out', options=('in', 'out')) '''Value that represents the state of the transition: - 'in' if the transition is going to show your screen - 'out' if the transition is going to hide your screen After the transition is complete, the state will retain its last value (in or out). :attr:`transition_state` is an :class:`~kivy.properties.OptionProperty` and defaults to 'out'. ''' __events__ = ('on_pre_enter', 'on_enter', 'on_pre_leave', 'on_leave') def on_pre_enter(self, *args): pass def on_enter(self, *args): pass def on_pre_leave(self, *args): pass def on_leave(self, *args): pass def __repr__(self): return '' % self.name class TransitionBase(EventDispatcher): '''TransitionBase is used to animate 2 screens within the :class:`ScreenManager`. This class acts as a base for other implementations like the :class:`SlideTransition` and :class:`SwapTransition`. :Events: `on_progress`: Transition object, progression float Fired during the animation of the transition. `on_complete`: Transition object Fired when the transition is finished. ''' screen_out = ObjectProperty() '''Property that contains the screen to hide. Automatically set by the :class:`ScreenManager`. :class:`screen_out` is an :class:`~kivy.properties.ObjectProperty` and defaults to None. ''' screen_in = ObjectProperty() '''Property that contains the screen to show. Automatically set by the :class:`ScreenManager`. :class:`screen_in` is an :class:`~kivy.properties.ObjectProperty` and defaults to None. ''' duration = NumericProperty(.4) '''Duration in seconds of the transition. :class:`duration` is a :class:`~kivy.properties.NumericProperty` and defaults to .4 (= 400ms). .. versionchanged:: 1.8.0 Default duration has been changed from 700ms to 400ms. ''' manager = ObjectProperty() ''':class:`ScreenManager` object, set when the screen is added to a manager. :attr:`manager` is an :class:`~kivy.properties.ObjectProperty` and defaults to None, read-only. ''' is_active = BooleanProperty(False) '''Indicate whether the transition is currently active or not. :attr:`is_active` is a :class:`~kivy.properties.BooleanProperty` and defaults to False, read-only. ''' # privates _anim = ObjectProperty(allownone=True) __events__ = ('on_progress', 'on_complete') def start(self, manager): '''(internal) Starts the transition. This is automatically called by the :class:`ScreenManager`. ''' if self.is_active: raise ScreenManagerException('start() is called twice!') self.manager = manager self._anim = Animation(d=self.duration, s=0) self._anim.bind(on_progress=self._on_progress, on_complete=self._on_complete) self.add_screen(self.screen_in) self.screen_in.transition_progress = 0. self.screen_in.transition_state = 'in' self.screen_out.transition_progress = 0. self.screen_out.transition_state = 'out' self.screen_in.dispatch('on_pre_enter') self.screen_out.dispatch('on_pre_leave') self.is_active = True self._anim.start(self) self.dispatch('on_progress', 0) def stop(self): '''(internal) Stops the transition. This is automatically called by the :class:`ScreenManager`. ''' if self._anim: self._anim.cancel(self) self.dispatch('on_complete') self._anim = None self.is_active = False def add_screen(self, screen): '''(internal) Used to add a screen to the :class:`ScreenManager`. ''' self.manager.real_add_widget(screen) def remove_screen(self, screen): '''(internal) Used to remove a screen from the :class:`ScreenManager`. ''' self.manager.real_remove_widget(screen) def on_complete(self): self.remove_screen(self.screen_out) def on_progress(self, progression): pass def _on_progress(self, *l): progress = l[-1] self.screen_in.transition_progress = progress self.screen_out.transition_progress = 1. - progress self.dispatch('on_progress', progress) def _on_complete(self, *l): self.is_active = False self.dispatch('on_complete') self.screen_in.dispatch('on_enter') self.screen_out.dispatch('on_leave') self._anim = None class ShaderTransition(TransitionBase): '''Transition class that uses a Shader for animating the transition between 2 screens. By default, this class doesn't assign any fragment/vertex shader. If you want to create your own fragment shader for the transition, you need to declare the header yourself and include the "t", "tex_in" and "tex_out" uniform:: # Create your own transition. This shader implements a "fading" # transition. fs = """$HEADER uniform float t; uniform sampler2D tex_in; uniform sampler2D tex_out; void main(void) { vec4 cin = texture2D(tex_in, tex_coord0); vec4 cout = texture2D(tex_out, tex_coord0); gl_FragColor = mix(cout, cin, t); } """ # And create your transition tr = ShaderTransition(fs=fs) sm = ScreenManager(transition=tr) ''' fs = StringProperty(None) '''Fragment shader to use. :attr:`fs` is a :class:`~kivy.properties.StringProperty` and defaults to None.''' vs = StringProperty(None) '''Vertex shader to use. :attr:`vs` is a :class:`~kivy.properties.StringProperty` and defaults to None.''' clearcolor = ColorProperty([0, 0, 0, 1]) '''Sets the color of Fbo ClearColor. .. versionadded:: 1.9.0 :attr:`clearcolor` is a :class:`~kivy.properties.ColorProperty` and defaults to [0, 0, 0, 1]. .. versionchanged:: 2.0.0 Changed from :class:`~kivy.properties.ListProperty` to :class:`~kivy.properties.ColorProperty`. ''' def make_screen_fbo(self, screen): fbo = Fbo(size=screen.size, with_stencilbuffer=True) with fbo: ClearColor(*self.clearcolor) ClearBuffers() fbo.add(screen.canvas) with fbo.before: PushMatrix() Translate(-screen.x, -screen.y, 0) with fbo.after: PopMatrix() return fbo def on_progress(self, progress): self.render_ctx['t'] = progress def on_complete(self): self.render_ctx['t'] = 1. super(ShaderTransition, self).on_complete() def _remove_out_canvas(self, *args): if (self.screen_out and self.screen_out.canvas in self.manager.canvas.children and self.screen_out not in self.manager.children): self.manager.canvas.remove(self.screen_out.canvas) def add_screen(self, screen): self.screen_in.pos = self.screen_out.pos self.screen_in.size = self.screen_out.size self.manager.real_remove_widget(self.screen_out) self.manager.canvas.add(self.screen_out.canvas) def remove_screen_out(instr): Clock.schedule_once(self._remove_out_canvas, -1) self.render_ctx.remove(instr) self.fbo_in = self.make_screen_fbo(self.screen_in) self.fbo_out = self.make_screen_fbo(self.screen_out) self.manager.canvas.add(self.fbo_in) self.manager.canvas.add(self.fbo_out) self.render_ctx = RenderContext(fs=self.fs, vs=self.vs, use_parent_modelview=True, use_parent_projection=True) with self.render_ctx: BindTexture(texture=self.fbo_out.texture, index=1) BindTexture(texture=self.fbo_in.texture, index=2) x, y = self.screen_in.pos w, h = self.fbo_in.texture.size Rectangle(size=(w, h), pos=(x, y), tex_coords=self.fbo_in.texture.tex_coords) Callback(remove_screen_out) self.render_ctx['tex_out'] = 1 self.render_ctx['tex_in'] = 2 self.manager.canvas.add(self.render_ctx) def remove_screen(self, screen): self.manager.canvas.remove(self.fbo_in) self.manager.canvas.remove(self.fbo_out) self.manager.canvas.remove(self.render_ctx) self._remove_out_canvas() self.manager.real_add_widget(self.screen_in) def stop(self): self._remove_out_canvas() super(ShaderTransition, self).stop() class NoTransition(TransitionBase): '''No transition, instantly switches to the next screen with no delay or animation. .. versionadded:: 1.8.0 ''' duration = NumericProperty(0.0) def on_complete(self): self.screen_in.pos = self.manager.pos self.screen_out.pos = self.manager.pos super(NoTransition, self).on_complete() class SlideTransition(TransitionBase): '''Slide Transition, can be used to show a new screen from any direction: left, right, up or down. ''' direction = OptionProperty('left', options=('left', 'right', 'up', 'down')) '''Direction of the transition. :attr:`direction` is an :class:`~kivy.properties.OptionProperty` and defaults to 'left'. Can be one of 'left', 'right', 'up' or 'down'. ''' def on_progress(self, progression): a = self.screen_in b = self.screen_out manager = self.manager x, y = manager.pos width, height = manager.size direction = self.direction al = AnimationTransition.out_quad progression = al(progression) if direction == 'left': a.y = b.y = y a.x = x + width * (1 - progression) b.x = x - width * progression elif direction == 'right': a.y = b.y = y b.x = x + width * progression a.x = x - width * (1 - progression) elif direction == 'down': a.x = b.x = x a.y = y + height * (1 - progression) b.y = y - height * progression elif direction == 'up': a.x = b.x = x b.y = y + height * progression a.y = y - height * (1 - progression) def on_complete(self): self.screen_in.pos = self.manager.pos self.screen_out.pos = self.manager.pos super(SlideTransition, self).on_complete() class CardTransition(SlideTransition): '''Card transition that looks similar to Android 4.x application drawer interface animation. It supports 4 directions like SlideTransition: left, right, up and down, and two modes, pop and push. If push mode is activated, the previous screen does not move, and the new one slides in from the given direction. If the pop mode is activated, the previous screen slides out, when the new screen is already on the position of the ScreenManager. .. versionadded:: 1.10 ''' mode = OptionProperty('push', options=['pop', 'push']) '''Indicates if the transition should push or pop the screen on/off the ScreenManager. - 'push' means the screen slides in in the given direction - 'pop' means the screen slides out in the given direction :attr:`mode` is an :class:`~kivy.properties.OptionProperty` and defaults to 'push'. ''' def start(self, manager): '''(internal) Starts the transition. This is automatically called by the :class:`ScreenManager`. ''' super(CardTransition, self).start(manager) mode = self.mode a = self.screen_in b = self.screen_out # ensure that the correct widget is "on top" if mode == 'push': manager.canvas.remove(a.canvas) manager.canvas.add(a.canvas) elif mode == 'pop': manager.canvas.remove(b.canvas) manager.canvas.add(b.canvas) def on_progress(self, progression): a = self.screen_in b = self.screen_out manager = self.manager x, y = manager.pos width, height = manager.size direction = self.direction mode = self.mode al = AnimationTransition.out_quad progression = al(progression) if mode == 'push': b.pos = x, y if direction == 'left': a.pos = x + width * (1 - progression), y elif direction == 'right': a.pos = x - width * (1 - progression), y elif direction == 'down': a.pos = x, y + height * (1 - progression) elif direction == 'up': a.pos = x, y - height * (1 - progression) elif mode == 'pop': a.pos = x, y if direction == 'left': b.pos = x - width * progression, y elif direction == 'right': b.pos = x + width * progression, y elif direction == 'down': b.pos = x, y - height * progression elif direction == 'up': b.pos = x, y + height * progression class SwapTransition(TransitionBase): '''Swap transition that looks like iOS transition when a new window appears on the screen. ''' def __init__(self, **kwargs): super(SwapTransition, self).__init__(**kwargs) self.scales = {} def start(self, manager): for screen in self.screen_in, self.screen_out: with screen.canvas.before: PushMatrix(group='swaptransition_scale') scale = Scale(group='swaptransition_scale') with screen.canvas.after: PopMatrix(group='swaptransition_scale') screen.bind(center=self.update_scale) self.scales[screen] = scale super(SwapTransition, self).start(manager) def update_scale(self, screen, center): self.scales[screen].origin = center def add_screen(self, screen): self.manager.real_add_widget(screen, 1) def on_complete(self): self.screen_in.pos = self.manager.pos self.screen_out.pos = self.manager.pos for screen in self.screen_in, self.screen_out: for canvas in screen.canvas.before, screen.canvas.after: canvas.remove_group('swaptransition_scale') super(SwapTransition, self).on_complete() def on_progress(self, progression): a = self.screen_in b = self.screen_out manager = self.manager self.scales[b].xyz = [1. - progression * 0.7 for xyz in 'xyz'] self.scales[a].xyz = [0.5 + progression * 0.5 for xyz in 'xyz'] a.center_y = b.center_y = manager.center_y al = AnimationTransition.in_out_sine if progression < 0.5: p2 = al(progression * 2) width = manager.width * 0.7 widthb = manager.width * 0.2 a.x = manager.center_x + p2 * width / 2. b.center_x = manager.center_x - p2 * widthb / 2. else: if self.screen_in is self.manager.children[-1]: self.manager.real_remove_widget(self.screen_in) self.manager.real_add_widget(self.screen_in) p2 = al((progression - 0.5) * 2) width = manager.width * 0.85 widthb = manager.width * 0.2 a.x = manager.x + width * (1 - p2) b.center_x = manager.center_x - (1 - p2) * widthb / 2. class WipeTransition(ShaderTransition): '''Wipe transition, based on a fragment Shader. ''' WIPE_TRANSITION_FS = '''$HEADER$ uniform float t; uniform sampler2D tex_in; uniform sampler2D tex_out; void main(void) { vec4 cin = texture2D(tex_in, tex_coord0); vec4 cout = texture2D(tex_out, tex_coord0); gl_FragColor = mix(cout, cin, clamp((-1.5 + 1.5*tex_coord0.x + 2.5*t), 0.0, 1.0)); } ''' fs = StringProperty(WIPE_TRANSITION_FS) class FadeTransition(ShaderTransition): '''Fade transition, based on a fragment Shader. ''' FADE_TRANSITION_FS = '''$HEADER$ uniform float t; uniform sampler2D tex_in; uniform sampler2D tex_out; void main(void) { vec4 cin = vec4(texture2D(tex_in, tex_coord0.st)); vec4 cout = vec4(texture2D(tex_out, tex_coord0.st)); vec4 frag_col = vec4(t * cin) + vec4((1.0 - t) * cout); gl_FragColor = frag_col; } ''' fs = StringProperty(FADE_TRANSITION_FS) class FallOutTransition(ShaderTransition): '''Transition where the new screen 'falls' from the screen centre, becoming smaller and more transparent until it disappears, and revealing the new screen behind it. Mimics the popular/standard Android transition. .. versionadded:: 1.8.0 ''' duration = NumericProperty(0.15) '''Duration in seconds of the transition, replacing the default of :class:`TransitionBase`. :class:`duration` is a :class:`~kivy.properties.NumericProperty` and defaults to .15 (= 150ms). ''' FALLOUT_TRANSITION_FS = '''$HEADER$ uniform float t; uniform sampler2D tex_in; uniform sampler2D tex_out; void main(void) { /* quantities for position and opacity calculation */ float tr = 0.5*sin(t); /* 'real' time */ vec2 diff = (tex_coord0.st - 0.5) * (1.0/(1.0-tr)); vec2 dist = diff + 0.5; float max_dist = 1.0 - tr; /* in and out colors */ vec4 cin = vec4(texture2D(tex_in, tex_coord0.st)); vec4 cout = vec4(texture2D(tex_out, dist)); /* opacities for in and out textures */ float oin = clamp(1.0-cos(t), 0.0, 1.0); float oout = clamp(cos(t), 0.0, 1.0); bvec2 outside_bounds = bvec2(abs(tex_coord0.s - 0.5) > 0.5*max_dist, abs(tex_coord0.t - 0.5) > 0.5*max_dist); vec4 frag_col; if (any(outside_bounds) ){ frag_col = vec4(cin.x, cin.y, cin.z, 1.0); } else { frag_col = vec4(oout*cout.x + oin*cin.x, oout*cout.y + oin*cin.y, oout*cout.z + oin*cin.z, 1.0); } gl_FragColor = frag_col; } ''' fs = StringProperty(FALLOUT_TRANSITION_FS) class RiseInTransition(ShaderTransition): '''Transition where the new screen rises from the screen centre, becoming larger and changing from transparent to opaque until it fills the screen. Mimics the popular/standard Android transition. .. versionadded:: 1.8.0 ''' duration = NumericProperty(0.2) '''Duration in seconds of the transition, replacing the default of :class:`TransitionBase`. :class:`duration` is a :class:`~kivy.properties.NumericProperty` and defaults to .2 (= 200ms). ''' RISEIN_TRANSITION_FS = '''$HEADER$ uniform float t; uniform sampler2D tex_in; uniform sampler2D tex_out; void main(void) { /* quantities for position and opacity calculation */ float tr = 0.5 - 0.5*sqrt(sin(t)); /* 'real' time */ vec2 diff = (tex_coord0.st - 0.5) * (1.0/(1.0-tr)); vec2 dist = diff + 0.5; float max_dist = 1.0 - tr; /* in and out colors */ vec4 cin = vec4(texture2D(tex_in, dist)); vec4 cout = vec4(texture2D(tex_out, tex_coord0.st)); /* opacities for in and out textures */ float oin = clamp(sin(2.0*t), 0.0, 1.0); float oout = clamp(1.0 - sin(2.0*t), 0.0, 1.0); bvec2 outside_bounds = bvec2(abs(tex_coord0.s - 0.5) > 0.5*max_dist, abs(tex_coord0.t - 0.5) > 0.5*max_dist); vec4 frag_col; if (any(outside_bounds) ){ frag_col = vec4(cout.x, cout.y, cout.z, 1.0); } else { frag_col = vec4(oout*cout.x + oin*cin.x, oout*cout.y + oin*cin.y, oout*cout.z + oin*cin.z, 1.0); } gl_FragColor = frag_col; } ''' fs = StringProperty(RISEIN_TRANSITION_FS) class ScreenManager(FloatLayout): '''Screen manager. This is the main class that will control your :class:`Screen` stack and memory. By default, the manager will show only one screen at a time. ''' current = StringProperty(None, allownone=True) ''' Name of the screen currently shown, or the screen to show. :: from kivy.uix.screenmanager import ScreenManager, Screen sm = ScreenManager() sm.add_widget(Screen(name='first')) sm.add_widget(Screen(name='second')) # By default, the first added screen will be shown. If you want to # show another one, just set the 'current' property. sm.current = 'second' :attr:`current` is a :class:`~kivy.properties.StringProperty` and defaults to None. ''' transition = ObjectProperty(baseclass=TransitionBase) '''Transition object to use for animating the transition from the current screen to the next one being shown. For example, if you want to use a :class:`WipeTransition` between slides:: from kivy.uix.screenmanager import ScreenManager, Screen, WipeTransition sm = ScreenManager(transition=WipeTransition()) sm.add_widget(Screen(name='first')) sm.add_widget(Screen(name='second')) # by default, the first added screen will be shown. If you want to # show another one, just set the 'current' property. sm.current = 'second' :attr:`transition` is an :class:`~kivy.properties.ObjectProperty` and defaults to a :class:`SlideTransition`. .. versionchanged:: 1.8.0 Default transition has been changed from :class:`SwapTransition` to :class:`SlideTransition`. ''' screens = ListProperty() '''List of all the :class:`Screen` widgets added. You should not change this list manually. Use the :meth:`add_widget ` method instead. :attr:`screens` is a :class:`~kivy.properties.ListProperty` and defaults to [], read-only. ''' current_screen = ObjectProperty(None, allownone=True) '''Contains the currently displayed screen. You must not change this property manually, use :attr:`current` instead. :attr:`current_screen` is an :class:`~kivy.properties.ObjectProperty` and defaults to None, read-only. ''' def _get_screen_names(self): return [s.name for s in self.screens] screen_names = AliasProperty(_get_screen_names, bind=('screens',)) '''List of the names of all the :class:`Screen` widgets added. The list is read only. :attr:`screens_names` is an :class:`~kivy.properties.AliasProperty` and is read-only. It is updated if the screen list changes or the name of a screen changes. ''' def __init__(self, **kwargs): if 'transition' not in kwargs: self.transition = SlideTransition() super(ScreenManager, self).__init__(**kwargs) self.fbind('pos', self._update_pos) def _screen_name_changed(self, screen, name): self.property('screen_names').dispatch(self) if screen == self.current_screen: self.current = name def add_widget(self, widget, *args, **kwargs): ''' .. versionchanged:: 2.1.0 Renamed argument `screen` to `widget`. ''' if not isinstance(widget, Screen): raise ScreenManagerException( 'ScreenManager accepts only Screen widget.') if widget.manager: if widget.manager is self: raise ScreenManagerException( 'Screen already managed by this ScreenManager (are you ' 'calling `switch_to` when you should be setting ' '`current`?)') raise ScreenManagerException( 'Screen already managed by another ScreenManager.') widget.manager = self widget.bind(name=self._screen_name_changed) self.screens.append(widget) if self.current is None: self.current = widget.name def remove_widget(self, widget, *args, **kwargs): if not isinstance(widget, Screen): raise ScreenManagerException( 'ScreenManager uses remove_widget only for removing Screens.') if widget not in self.screens: return if self.current_screen == widget: other = next(self) if widget.name == other: self.current = None widget.parent.real_remove_widget(widget) else: self.current = other widget.manager = None widget.unbind(name=self._screen_name_changed) self.screens.remove(widget) def clear_widgets(self, children=None, *args, **kwargs): ''' .. versionchanged:: 2.1.0 Renamed argument `screens` to `children`. ''' if children is None: # iterate over a copy of screens, as self.remove_widget # modifies self.screens in place children = self.screens[:] remove_widget = self.remove_widget for widget in children: remove_widget(widget) def real_add_widget(self, screen, *args): # ensure screen is removed from its previous parent parent = screen.parent if parent: parent.real_remove_widget(screen) super(ScreenManager, self).add_widget(screen) def real_remove_widget(self, screen, *args): super(ScreenManager, self).remove_widget(screen) def on_current(self, instance, value): if value is None: self.transition.stop() self.current_screen = None return screen = self.get_screen(value) if screen == self.current_screen: return self.transition.stop() previous_screen = self.current_screen self.current_screen = screen if previous_screen: self.transition.screen_in = screen self.transition.screen_out = previous_screen self.transition.start(self) else: self.real_add_widget(screen) screen.pos = self.pos self.do_layout() screen.dispatch('on_pre_enter') screen.dispatch('on_enter') def get_screen(self, name): '''Return the screen widget associated with the name or raise a :class:`ScreenManagerException` if not found. ''' matches = [s for s in self.screens if s.name == name] num_matches = len(matches) if num_matches == 0: raise ScreenManagerException('No Screen with name "%s".' % name) if num_matches > 1: Logger.warn('Multiple screens named "%s": %s' % (name, matches)) return matches[0] def has_screen(self, name): '''Return True if a screen with the `name` has been found. .. versionadded:: 1.6.0 ''' return bool([s for s in self.screens if s.name == name]) def __next__(self): '''Py2K backwards compatibility without six or other lib. ''' screens = self.screens if not screens: return try: index = screens.index(self.current_screen) index = (index + 1) % len(screens) return screens[index].name except ValueError: return def next(self): '''Return the name of the next screen from the screen list.''' return self.__next__() def previous(self): '''Return the name of the previous screen from the screen list. ''' screens = self.screens if not screens: return try: index = screens.index(self.current_screen) index = (index - 1) % len(screens) return screens[index].name except ValueError: return def switch_to(self, screen, **options): '''Add a new or existing screen to the ScreenManager and switch to it. The previous screen will be "switched away" from. `options` are the :attr:`transition` options that will be changed before the animation happens. If no previous screens are available, the screen will be used as the main one:: sm = ScreenManager() sm.switch_to(screen1) # later sm.switch_to(screen2, direction='left') # later sm.switch_to(screen3, direction='right', duration=1.) If any animation is in progress, it will be stopped and replaced by this one: you should avoid this because the animation will just look weird. Use either :meth:`switch_to` or :attr:`current` but not both. The `screen` name will be changed if there is any conflict with the current screen. .. versionadded: 1.8.0 ''' assert screen is not None if not isinstance(screen, Screen): raise ScreenManagerException( 'ScreenManager accepts only Screen widget.') # stop any transition that might be happening already self.transition.stop() # ensure the screen name will be unique if screen not in self.screens: if self.has_screen(screen.name): screen.name = self._generate_screen_name() # change the transition if given explicitly old_transition = self.transition specified_transition = options.pop("transition", None) if specified_transition: self.transition = specified_transition # change the transition options for key, value in iteritems(options): setattr(self.transition, key, value) # add and leave if we are set as the current screen if screen.manager is not self: self.add_widget(screen) if self.current_screen is screen: return old_current = self.current_screen def remove_old_screen(transition): if old_current in self.children: self.remove_widget(old_current) self.transition = old_transition transition.unbind(on_complete=remove_old_screen) self.transition.bind(on_complete=remove_old_screen) self.current = screen.name def _generate_screen_name(self): i = 0 while True: name = '_screen{}'.format(i) if not self.has_screen(name): return name i += 1 def _update_pos(self, instance, value): for child in self.children: if self.transition.is_active and \ (child == self.transition.screen_in or child == self.transition.screen_out): continue child.pos = value def on_motion(self, etype, me): if self.transition.is_active: return False return super().on_motion(etype, me) def on_touch_down(self, touch): if self.transition.is_active: return False return super(ScreenManager, self).on_touch_down(touch) def on_touch_move(self, touch): if self.transition.is_active: return False return super(ScreenManager, self).on_touch_move(touch) def on_touch_up(self, touch): if self.transition.is_active: return False return super(ScreenManager, self).on_touch_up(touch) if __name__ == '__main__': from kivy.app import App from kivy.uix.button import Button Builder.load_string(''' : canvas: Color: rgb: .2, .2, .2 Rectangle: size: self.size GridLayout: cols: 2 Button: text: 'Hello world' Button: text: 'Hello world' Button: text: 'Hello world' Button: text: 'Hello world' ''') class TestApp(App): def change_view(self, *l): # d = ('left', 'up', 'down', 'right') # di = d.index(self.sm.transition.direction) # self.sm.transition.direction = d[(di + 1) % len(d)] self.sm.current = next(self.sm) def remove_screen(self, *l): self.sm.remove_widget(self.sm.get_screen('test1')) def build(self): root = FloatLayout() self.sm = sm = ScreenManager(transition=SwapTransition()) sm.add_widget(Screen(name='test1')) sm.add_widget(Screen(name='test2')) btn = Button(size_hint=(None, None)) btn.bind(on_release=self.change_view) btn2 = Button(size_hint=(None, None), x=100) btn2.bind(on_release=self.remove_screen) root.add_widget(sm) root.add_widget(btn) root.add_widget(btn2) return root TestApp().run()