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Behaviors

New in version 1.8.0.

Behavior mixin classes

This module implements behaviors that can be mixed in with existing base widgets. The idea behind these classes is to encapsulate properties and events associated with certain types of widgets.

Isolating these properties and events in a mixin class allows you to define your own implementation for standard kivy widgets that can act as drop-in replacements. This means you can re-style and re-define widgets as desired without breaking compatibility: as long as they implement the behaviors correctly, they can simply replace the standard widgets.

Adding behaviors

Say you want to add Button capabilities to an Image, you could do:

class IconButton(ButtonBehavior, Image):
    pass

This would give you an Image with the events and properties inherited from ButtonBehavior. For example, the on_press and on_release events would be fired when appropriate:

class IconButton(ButtonBehavior, Image):
    def on_press(self):
        print("on_press")

Or in kv:

IconButton:
    on_press: print('on_press')

Naturally, you could also bind to any property changes the behavior class offers:

def state_changed(*args):
    print('state changed')

button = IconButton()
button.bind(state=state_changed)

Note

The behavior class must always be _before_ the widget class. If you don’t specify the inheritance in this order, the behavior will not work because the behavior methods are overwritten by the class method listed first.

Similarly, if you combine a behavior class with a class which requires the use of the methods also defined by the behavior class, the resulting class may not function properly. For example, when combining the ButtonBehavior with a Slider, both of which use the on_touch_up() method, the resulting class may not work properly.

Changed in version 1.9.1: The individual behavior classes, previously in one big behaviors.py file, has been split into a single file for each class under the behaviors module. All the behaviors are still imported in the behaviors module so they are accessible as before (e.g. both from kivy.uix.behaviors import ButtonBehavior and from kivy.uix.behaviors.button import ButtonBehavior work).

class kivy.uix.behaviors.ButtonBehavior(**kwargs)[source]

Bases: builtins.object

This mixin class provides Button behavior. Please see the button behaviors module documentation for more information.

Events:
on_press

Fired when the button is pressed.

on_release

Fired when the button is released (i.e. the touch/click that pressed the button goes away).

always_release

This determines whether or not the widget fires an on_release event if the touch_up is outside the widget.

New in version 1.9.0.

Changed in version 1.10.0: The default value is now False.

always_release is a BooleanProperty and defaults to False.

last_touch

Contains the last relevant touch received by the Button. This can be used in on_press or on_release in order to know which touch dispatched the event.

New in version 1.8.0.

last_touch is a ObjectProperty and defaults to None.

min_state_time

The minimum period of time which the widget must remain in the ‘down’ state.

New in version 1.9.1.

min_state_time is a float and defaults to 0.035. This value is taken from Config.

state

The state of the button, must be one of ‘normal’ or ‘down’. The state is ‘down’ only when the button is currently touched/clicked, otherwise its ‘normal’.

state is an OptionProperty and defaults to ‘normal’.

trigger_action(duration=0.1)[source]

Trigger whatever action(s) have been bound to the button by calling both the on_press and on_release callbacks.

This simulates a quick button press without using any touch events.

Duration is the length of the press in seconds. Pass 0 if you want the action to happen instantly.

New in version 1.8.0.

class kivy.uix.behaviors.ToggleButtonBehavior(**kwargs)[source]

Bases: kivy.uix.behaviors.button.ButtonBehavior

This mixin class provides togglebutton behavior. Please see the togglebutton behaviors module documentation for more information.

New in version 1.8.0.

allow_no_selection

This specifies whether the widgets in a group allow no selection i.e. everything to be deselected.

New in version 1.9.0.

allow_no_selection is a BooleanProperty and defaults to True

static get_widgets(groupname)[source]

Return a list of the widgets contained in a specific group. If the group doesn’t exist, an empty list will be returned.

Note

Always release the result of this method! Holding a reference to any of these widgets can prevent them from being garbage collected. If in doubt, do:

l = ToggleButtonBehavior.get_widgets('mygroup')
# do your job
del l

Warning

It’s possible that some widgets that you have previously deleted are still in the list. The garbage collector might need to release other objects before flushing them.

group

Group of the button. If None, no group will be used (the button will be independent). If specified, group must be a hashable object, like a string. Only one button in a group can be in a ‘down’ state.

group is a ObjectProperty and defaults to None.

class kivy.uix.behaviors.DragBehavior(**kwargs)[source]

Bases: builtins.object

The DragBehavior mixin provides Drag behavior. When combined with a widget, dragging in the rectangle defined by drag_rectangle will drag the widget. Please see the drag behaviors module documentation for more information.

New in version 1.8.0.

drag_distance

Distance to move before dragging the DragBehavior, in pixels. As soon as the distance has been traveled, the DragBehavior will start to drag, and no touch event will be dispatched to the children. It is advisable that you base this value on the dpi of your target device’s screen.

drag_distance is a NumericProperty and defaults to the scroll_distance as defined in the user Config (20 pixels by default).

drag_rect_height

Height of the axis aligned bounding rectangle where dragging is allowed.

drag_rect_height is a NumericProperty and defaults to 100.

drag_rect_width

Width of the axis aligned bounding rectangle where dragging is allowed.

drag_rect_width is a NumericProperty and defaults to 100.

drag_rect_x

X position of the axis aligned bounding rectangle where dragging is allowed (in window coordinates).

drag_rect_x is a NumericProperty and defaults to 0.

drag_rect_y

Y position of the axis aligned bounding rectangle where dragging is allowed (in window coordinates).

drag_rect_Y is a NumericProperty and defaults to 0.

drag_rectangle

Position and size of the axis aligned bounding rectangle where dragging is allowed.

drag_rectangle is a ReferenceListProperty of (drag_rect_x, drag_rect_y, drag_rect_width, drag_rect_height) properties.

drag_timeout

Timeout allowed to trigger the drag_distance, in milliseconds. If the user has not moved drag_distance within the timeout, dragging will be disabled, and the touch event will be dispatched to the children.

drag_timeout is a NumericProperty and defaults to the scroll_timeout as defined in the user Config (55 milliseconds by default).

class kivy.uix.behaviors.FocusBehavior(**kwargs)[source]

Bases: builtins.object

Provides keyboard focus behavior. When combined with other FocusBehavior widgets it allows one to cycle focus among them by pressing tab. Please see the focus behavior module documentation for more information.

New in version 1.9.0.

focus

Whether the instance currently has focus.

Setting it to True will bind to and/or request the keyboard, and input will be forwarded to the instance. Setting it to False will unbind and/or release the keyboard. For a given keyboard, only one widget can have its focus, so focusing one will automatically unfocus the other instance holding its focus.

When using a software keyboard, please refer to the softinput_mode property to determine how the keyboard display is handled.

focus is a BooleanProperty and defaults to False.

focus_next

The FocusBehavior instance to acquire focus when tab is pressed and this instance has focus, if not None or StopIteration.

When tab is pressed, focus cycles through all the FocusBehavior widgets that are linked through focus_next and are focusable. If focus_next is None, it instead walks the children lists to find the next focusable widget. Finally, if focus_next is the StopIteration class, focus won’t move forward, but end here.

focus_next is an ObjectProperty and defaults to None.

focus_previous

The FocusBehavior instance to acquire focus when shift+tab is pressed on this instance, if not None or StopIteration.

When shift+tab is pressed, focus cycles through all the FocusBehavior widgets that are linked through focus_previous and are focusable. If focus_previous is None, it instead walks the children tree to find the previous focusable widget. Finally, if focus_previous is the StopIteration class, focus won’t move backward, but end here.

focus_previous is an ObjectProperty and defaults to None.

focused

An alias of focus.

focused is a BooleanProperty and defaults to False.

Warning

focused is an alias of focus and will be removed in 2.0.0.

get_focus_next()[source]

Returns the next focusable widget using either focus_next or the children similar to the order when tabbing forwards with the tab key.

get_focus_previous()[source]

Returns the previous focusable widget using either focus_previous or the children similar to the order when tab + shift key are triggered together.

hide_keyboard()[source]

Convenience function to hide the keyboard in managed mode.

ignored_touch = []

A list of touches that should not be used to defocus. After on_touch_up, every touch that is not in ignored_touch will defocus all the focused widgets if the config keyboard mode is not multi. Touches on focusable widgets that were used to focus are automatically added here.

Example usage:

class Unfocusable(Widget):

    def on_touch_down(self, touch):
        if self.collide_point(*touch.pos):
            FocusBehavior.ignored_touch.append(touch)

Notice that you need to access this as a class, not an instance variable.

input_type

The kind of input keyboard to request.

New in version 1.8.0.

input_type is an OptionsProperty and defaults to ‘text’. Can be one of ‘text’, ‘number’, ‘url’, ‘mail’, ‘datetime’, ‘tel’ or ‘address’.

is_focusable

Whether the instance can become focused. If focused, it’ll lose focus when set to False.

is_focusable is a BooleanProperty and defaults to True on a desktop (i.e. desktop is True in config), False otherwise.

keyboard

The keyboard to bind to (or bound to the widget) when focused.

When None, a keyboard is requested and released whenever the widget comes into and out of focus. If not None, it must be a keyboard, which gets bound and unbound from the widget whenever it’s in or out of focus. It is useful only when more than one keyboard is available, so it is recommended to be set to None when only one keyboard is available.

If more than one keyboard is available, whenever an instance gets focused a new keyboard will be requested if None. Unless the other instances lose focus (e.g. if tab was used), a new keyboard will appear. When this is undesired, the keyboard property can be used. For example, if there are two users with two keyboards, then each keyboard can be assigned to different groups of instances of FocusBehavior, ensuring that within each group, only one FocusBehavior will have focus, and will receive input from the correct keyboard. See keyboard_mode in config for more information on the keyboard modes.

Keyboard and focus behavior

When using the keyboard, there are some important default behaviors you should keep in mind.

  • When Config’s keyboard_mode is multi, each new touch is considered a touch by a different user and will set the focus (if clicked on a focusable) with a new keyboard. Already focused elements will not lose their focus (even if an unfocusable widget is touched).
  • If the keyboard property is set, that keyboard will be used when the instance gets focused. If widgets with different keyboards are linked through focus_next and focus_previous, then as they are tabbed through, different keyboards will become active. Therefore, typically it’s undesirable to link instances which are assigned different keyboards.
  • When a widget has focus, setting its keyboard to None will remove its keyboard, but the widget will then immediately try to get another keyboard. In order to remove its keyboard, rather set its focus to False.
  • When using a software keyboard, typical on mobile and touch devices, the keyboard display behavior is determined by the softinput_mode property. You can use this property to ensure the focused widget is not covered or obscured.

keyboard is an AliasProperty and defaults to None.

keyboard_mode

Determines how the keyboard visibility should be managed. ‘auto’ will result in the standard behaviour of showing/hiding on focus. ‘managed’ requires setting the keyboard visibility manually, or calling the helper functions show_keyboard() and hide_keyboard().

keyboard_mode is an OptionsProperty and defaults to ‘auto’. Can be one of ‘auto’ or ‘managed’.

keyboard_on_key_down(window, keycode, text, modifiers)[source]

The method bound to the keyboard when the instance has focus.

When the instance becomes focused, this method is bound to the keyboard and will be called for every input press. The parameters are the same as kivy.core.window.WindowBase.on_key_down().

When overwriting the method in the derived widget, super should be called to enable tab cycling. If the derived widget wishes to use tab for its own purposes, it can call super after it has processed the character (if it does not wish to consume the tab).

Similar to other keyboard functions, it should return True if the key was consumed.

keyboard_on_key_up(window, keycode)[source]

The method bound to the keyboard when the instance has focus.

When the instance becomes focused, this method is bound to the keyboard and will be called for every input release. The parameters are the same as kivy.core.window.WindowBase.on_key_up().

When overwriting the method in the derived widget, super should be called to enable de-focusing on escape. If the derived widget wishes to use escape for its own purposes, it can call super after it has processed the character (if it does not wish to consume the escape).

See keyboard_on_key_down()

show_keyboard()[source]

Convenience function to show the keyboard in managed mode.

unfocus_on_touch

Whether a instance should lose focus when clicked outside the instance.

When a user clicks on a widget that is focus aware and shares the same keyboard as this widget (which in the case of only one keyboard, are all focus aware widgets), then as the other widgets gains focus, this widget loses focus. In addition to that, if this property is True, clicking on any widget other than this widget, will remove focus form this widget.

unfocus_on_touch is a BooleanProperty and defaults to False if the keyboard_mode in Config is ‘multi’ or ‘systemandmulti’, otherwise it defaults to True.

class kivy.uix.behaviors.CompoundSelectionBehavior(**kwargs)[source]

Bases: builtins.object

The Selection behavior mixin implements the logic behind keyboard and touch selection of selectable widgets managed by the derived widget. Please see the compound selection behaviors module documentation for more information.

New in version 1.9.0.

clear_selection()[source]

Deselects all the currently selected nodes.

deselect_node(node)[source]

Deselects a possibly selected node.

It is called by the controller when it deselects a node and can also be called from the outside to deselect a node directly. The derived widget should overwrite this method and change the node to its unselected state when this is called

Parameters:
node

The node to be deselected.

Warning

This method must be called by the derived widget using super if it is overwritten.

get_index_of_node(node, selectable_nodes)[source]

(internal) Returns the index of the node within the selectable_nodes returned by get_selectable_nodes().

get_selectable_nodes()[source]

(internal) Returns a list of the nodes that can be selected. It can be overwritten by the derived widget to return the correct list.

This list is used to determine which nodes to select with group selection. E.g. the last element in the list will be selected when home is pressed, pagedown will move (or add to, if shift is held) the selection from the current position by negative page_count nodes starting from the position of the currently selected node in this list and so on. Still, nodes can be selected even if they are not in this list.

Note

It is safe to dynamically change this list including removing, adding, or re-arranging its elements. Nodes can be selected even if they are not on this list. And selected nodes removed from the list will remain selected until deselect_node() is called.

Warning

Layouts display their children in the reverse order. That is, the contents of children is displayed form right to left, bottom to top. Therefore, internally, the indices of the elements returned by this function are reversed to make it work by default for most layouts so that the final result is consistent e.g. home, although it will select the last element in this list visually, will select the first element when counting from top to bottom and left to right. If this behavior is not desired, a reversed list should be returned instead.

Defaults to returning children.

goto_node(key, last_node, last_node_idx)[source]

(internal) Used by the controller to get the node at the position indicated by key. The key can be keyboard inputs, e.g. pageup, or scroll inputs from the mouse scroll wheel, e.g. scrollup. ‘last_node’ is the last node selected and is used to find the resulting node. For example, if the key is up, the returned node is one node up from the last node.

It can be overwritten by the derived widget.

Parameters:
key

str, the string used to find the desired node. It can be any of the keyboard keys, as well as the mouse scrollup, scrolldown, scrollright, and scrollleft strings. If letters are typed in quick succession, the letters will be combined before it’s passed in as key and can be used to find nodes that have an associated string that starts with those letters.

last_node

The last node that was selected.

last_node_idx

The cached index of the last node selected in the get_selectable_nodes() list. If the list hasn’t changed it saves having to look up the index of last_node in that list.

Returns:

tuple, the node targeted by key and its index in the get_selectable_nodes() list. Returning (last_node, last_node_idx) indicates a node wasn’t found.

keyboard_select

Determines whether the keyboard can be used for selection. If False, keyboard inputs will be ignored.

keyboard_select is a BooleanProperty and defaults to True.

multiselect

Determines whether multiple nodes can be selected. If enabled, keyboard shift and ctrl selection, optionally combined with touch, for example, will be able to select multiple widgets in the normally expected manner. This dominates touch_multiselect when False.

multiselect is a BooleanProperty and defaults to False.

nodes_order_reversed

(Internal) Indicates whether the order of the nodes as displayed top- down is reversed compared to their order in get_selectable_nodes() (e.g. how the children property is reversed compared to how it’s displayed).

page_count

Determines by how much the selected node is moved up or down, relative to the position of the last selected node, when pageup (or pagedown) is pressed.

page_count is a NumericProperty and defaults to 10.

right_count

Determines by how much the selected node is moved up or down, relative to the position of the last selected node, when the right (or left) arrow on the keyboard is pressed.

right_count is a NumericProperty and defaults to 1.

scroll_count

Determines by how much the selected node is moved up or down, relative to the position of the last selected node, when the mouse scroll wheel is scrolled.

right_count is a NumericProperty and defaults to 0.

select_node(node)[source]

Selects a node.

It is called by the controller when it selects a node and can be called from the outside to select a node directly. The derived widget should overwrite this method and change the node state to selected when called.

Parameters:
node

The node to be selected.

Returns:

bool, True if the node was selected, False otherwise.

Warning

This method must be called by the derived widget using super if it is overwritten.

select_with_key_down(keyboard, scancode, codepoint, modifiers, **kwargs)[source]

Processes a key press. This is called when a key press is to be used for selection. Depending on the keyboard keys pressed and the configuration, it could select or deselect nodes or node ranges from the selectable nodes list, get_selectable_nodes().

The parameters are such that it could be bound directly to the on_key_down event of a keyboard. Therefore, it is safe to be called repeatedly when the key is held down as is done by the keyboard.

Returns:bool, True if the keypress was used, False otherwise.
select_with_key_up(keyboard, scancode, **kwargs)[source]

(internal) Processes a key release. This must be called by the derived widget when a key that select_with_key_down() returned True is released.

The parameters are such that it could be bound directly to the on_key_up event of a keyboard.

Returns:bool, True if the key release was used, False otherwise.
select_with_touch(node, touch=None)[source]

(internal) Processes a touch on the node. This should be called by the derived widget when a node is touched and is to be used for selection. Depending on the keyboard keys pressed and the configuration, it could select or deslect this and other nodes in the selectable nodes list, get_selectable_nodes().

Parameters:
node

The node that received the touch. Can be None for a scroll type touch.

touch

Optionally, the touch. Defaults to None.

Returns:

bool, True if the touch was used, False otherwise.

selected_nodes

The list of selected nodes.

Note

Multiple nodes can be selected right after one another e.g. using the keyboard. When listening to selected_nodes, one should be aware of this.

selected_nodes is a ListProperty and defaults to the empty list, []. It is read-only and should not be modified.

text_entry_timeout

When typing characters in rapid sucession (i.e. the time difference since the last character is less than text_entry_timeout), the keys get concatenated and the combined text is passed as the key argument of goto_node().

New in version 1.10.0.

touch_deselect_last

Determines whether the last selected node can be deselected when multiselect or touch_multiselect is False.

New in version 1.10.0.

touch_deselect_last is a BooleanProperty and defaults to True on mobile, False on desktop platforms.

touch_multiselect

A special touch mode which determines whether touch events, as processed by select_with_touch(), will add the currently touched node to the selection, or if it will clear the selection before adding the node. This allows the selection of multiple nodes by simply touching them.

This is different from multiselect because when it is True, simply touching an unselected node will select it, even if ctrl is not pressed. If it is False, however, ctrl must be pressed in order to add to the selection when multiselect is True.

Note

multiselect, when False, will disable touch_multiselect.

touch_multiselect is a BooleanProperty and defaults to False.

up_count

Determines by how much the selected node is moved up or down, relative to the position of the last selected node, when the up (or down) arrow on the keyboard is pressed.

up_count is a NumericProperty and defaults to 1.

class kivy.uix.behaviors.CodeNavigationBehavior[source]

Bases: kivy.event.EventDispatcher

Code navigation behavior. Modifies the navigation behavior in TextInput to work like an IDE instead of a word processor. Please see the code navigation behaviors module documentation for more information.

New in version 1.9.1.

class kivy.uix.behaviors.EmacsBehavior(**kwargs)[source]

Bases: builtins.object

A mixin that enables Emacs-style keyboard shortcuts for the TextInput widget. Please see the Emacs behaviors module documentation for more information.

New in version 1.9.1.

delete_word_left()[source]

Delete text left of the cursor to the beginning of word

delete_word_right()[source]

Delete text right of the cursor to the end of the word

key_bindings

String name which determines the type of key bindings to use with the TextInput. This allows Emacs key bindings to be enabled/disabled programmatically for widgets that inherit from EmacsBehavior. If the value is not 'emacs', Emacs bindings will be disabled. Use 'default' for switching to the default key bindings of TextInput.

key_bindings is a StringProperty and defaults to 'emacs'.

New in version 1.10.0.

class kivy.uix.behaviors.CoverBehavior(**kwargs)[source]

Bases: builtins.object

The CoverBehavior mixin provides rendering a texture covering full widget size keeping aspect ratio of the original texture.

New in version 1.10.0.

cover_pos

Position of the aspect ratio aware texture. Gets calculated in CoverBehavior.calculate_cover.

cover_pos is a ListProperty and defaults to [0, 0].

cover_size

Size of the aspect ratio aware texture. Gets calculated in CoverBehavior.calculate_cover.

cover_size is a ListProperty and defaults to [0, 0].

reference_size

Reference size used for aspect ratio approximation calculation.

reference_size is a ListProperty and defaults to [].

class kivy.uix.behaviors.TouchRippleBehavior(**kwargs)[source]

Bases: builtins.object

Touch ripple behavior.

Supposed to be used as mixin on widget classes.

Ripple behavior does not trigger automatically, concrete implementation needs to call ripple_show() respective ripple_fade() manually.

Here we create a Label which renders the touch ripple animation on interaction:

class RippleLabel(TouchRippleBehavior, Label):

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

    def on_touch_down(self, touch):
        collide_point = self.collide_point(touch.x, touch.y)
        if collide_point:
            touch.grab(self)
            self.ripple_show(touch)
            return True
        return False

    def on_touch_up(self, touch):
        if touch.grab_current is self:
            touch.ungrab(self)
            self.ripple_fade()
            return True
        return False
ripple_duration_in

Animation duration taken to show the overlay.

ripple_duration_in is a NumericProperty and defaults to 0.5.

ripple_duration_out

Animation duration taken to fade the overlay.

ripple_duration_out is a NumericProperty and defaults to 0.2.

ripple_fade()[source]

Finish ripple animation on current widget.

ripple_fade_from_alpha

Alpha channel for ripple color the animation starts with.

ripple_fade_from_alpha is a NumericProperty and defaults to 0.5.

ripple_fade_to_alpha

Alpha channel for ripple color the animation targets to.

ripple_fade_to_alpha is a NumericProperty and defaults to 0.8.

ripple_func_in

Animation callback for showing the overlay.

ripple_func_in is a StringProperty and defaults to in_cubic.

ripple_func_out

Animation callback for hiding the overlay.

ripple_func_out is a StringProperty and defaults to out_quad.

ripple_rad_default

Default radius the animation starts from.

ripple_rad_default is a NumericProperty and defaults to 10.

ripple_scale

Max scale of the animation overlay calculated from max(width/height) of the decorated widget.

ripple_scale is a NumericProperty and defaults to 2.0.

ripple_show(touch)[source]

Begin ripple animation on current widget.

Expects touch event as argument.

class kivy.uix.behaviors.TouchRippleButtonBehavior(**kwargs)[source]

Bases: kivy.uix.behaviors.touchripple.TouchRippleBehavior

This mixin class provides a similar behavior to ButtonBehavior but provides touch ripple animation instead of button pressed/released as visual effect.

Events:
on_press

Fired when the button is pressed.

on_release

Fired when the button is released (i.e. the touch/click that pressed the button goes away).

always_release

This determines whether or not the widget fires an on_release event if the touch_up is outside the widget.

always_release is a BooleanProperty and defaults to False.

last_touch

Contains the last relevant touch received by the Button. This can be used in on_press or on_release in order to know which touch dispatched the event.

last_touch is a ObjectProperty and defaults to None.