Checkbox

Examples#

Basic Example#

import flet as ft


def main(page: ft.Page):
    def handle_button_click(e: ft.Event[ft.Button]):
        message.value = f"Checkboxes values are:  {c1.value}, {c2.value}, {c3.value}, "
        f"{c4.value}, {c5.value}."
        page.update()

    page.add(
        c1 := ft.Checkbox(label="Unchecked by default checkbox", value=False),
        c2 := ft.Checkbox(
            label="Undefined by default tristate checkbox", tristate=True
        ),
        c3 := ft.Checkbox(label="Checked by default checkbox", value=True),
        c4 := ft.Checkbox(label="Disabled checkbox", disabled=True),
        c5 := ft.Checkbox(
            label="Checkbox with LEFT label_position",
            label_position=ft.LabelPosition.LEFT,
        ),
        ft.Button(content="Submit", on_click=handle_button_click),
        message := ft.Text(),
    )


if __name__ == "__main__":
    ft.run(main)

Handling events#

import flet as ft


def main(page: ft.Page):
    def handle_checkbox_change(e: ft.Event[ft.Checkbox]):
        page.add(ft.Text(f"Checkbox value changed to {e.control.value}"))
        page.update()

    page.add(
        ft.Checkbox(
            label="Checkbox with 'change' event",
            on_change=handle_checkbox_change,
        )
    )


ft.run(main)

Styled checkboxes#

import flet as ft


def main(page: ft.Page):
    page.add(
        ft.Checkbox(label="Checkbox with default style"),
        ft.Checkbox(
            label="Checkbox with constant fill color",
            fill_color=ft.Colors.RED,
            check_color=ft.Colors.YELLOW,
        ),
        ft.Checkbox(
            label="Checkbox with dynamic fill color",
            fill_color={
                ft.ControlState.HOVERED: ft.Colors.BLUE,
                ft.ControlState.SELECTED: ft.Colors.GREEN,
                ft.ControlState.DEFAULT: ft.Colors.RED,
            },
            # border_side={ft.ControlState.HOVERED: ft.BorderSide(width=1.0)},
        ),
    )


ft.run(main)

Checkbox #

Bases: LayoutControl, AdaptiveControl

Checkbox allows to select one or more items from a group, or switch between two mutually exclusive options (checked or unchecked, on or off).

active_color #

active_color: ColorValue | None = None

The color to use when this checkbox is checked.

adaptive #

adaptive: bool | None = None

Enables platform-specific rendering or inheritance of adaptiveness from parent controls.

align #

align: Alignment | None = None

Alignment of the control within its parent.

animate_align #

animate_align: AnimationValue | None = None

Enables implicit animation of the [align][flet.LayoutControl.] property.

More information here.

animate_margin #

animate_margin: AnimationValue | None = None

Enables implicit animation of the [margin][flet.LayoutControl.] property.

More information here.

animate_offset #

animate_offset: AnimationValue | None = None

Enables implicit animation of the [offset][flet.LayoutControl.] property.

More information here.

animate_opacity #

animate_opacity: AnimationValue | None = None

Enables implicit animation of the [opacity][flet.LayoutControl.] property.

More information here.

animate_position #

animate_position: AnimationValue | None = None

Enables implicit animation of the positioning properties ([left][flet.LayoutControl.], [right][flet.LayoutControl.], [top][flet.LayoutControl.] and [bottom][flet.LayoutControl.]).

More information here.

animate_rotation #

animate_rotation: AnimationValue | None = None

Enables implicit animation of the [rotate][flet.LayoutControl.] property.

More information here.

animate_scale #

animate_scale: AnimationValue | None = None

Enables implicit animation of the [scale][flet.LayoutControl.] property.

More information here.

animate_size #

animate_size: AnimationValue | None = None

TBD

aspect_ratio #

aspect_ratio: Number | None = None

The aspect ratio of the control. It is defined as the ratio of the width to the height.

autofocus #

autofocus: bool = False

True if the control will be selected as the initial focus. If there is more than one control on a page with autofocus set, then the first one added to the page will get focus.

badge #

badge: BadgeValue | None = None

A badge to show on top of this control.

border_side #

border_side: ControlStateValue[BorderSide] | None = None

The color and width of this checkbox's border in all or specific ControlStates.

Defaults to CheckboxTheme.border_side, or if that is None, falls back to BorderSide with a width of 2.0.

Note

Supported states: ControlState.SELECTED, ControlState.HOVERED, ControlState.DISABLED, ControlState.FOCUSED, ControlState.PRESSED, ControlState.ERROR, and ControlState.DEFAULT.

bottom #

bottom: Number | None = None

The distance that the child's bottom edge is inset from the bottom of the stack.

Note

Effective only if this control is a descendant of one of the following: [Stack][flet.] control, [Page.overlay][flet.] list.

check_color #

check_color: ColorValue | None = None

The color to use for the check icon when this checkbox is checked.

col #

col: ResponsiveNumber = 12

If a parent of this control is a [ResponsiveRow][flet.], this property is used to determine how many virtual columns of a screen this control will span.

Can be a number or a dictionary configured to have a different value for specific breakpoints, for example col={"sm": 6}.

This control spans the 12 virtual columns by default.

Dimensions

Breakpoint	Dimension
xs	<576px
sm	≥576px
md	≥768px
lg	≥992px
xl	≥1200px
xxl	≥1400px

data #

data: Any = skip_field()

Arbitrary data of any type.

disabled #

disabled: bool = False

Every control has disabled property which is False by default - control and all its children are enabled.

Note

The value of this property will be propagated down to all children controls recursively.

Example

For example, if you have a form with multiple entry controls you can disable them all together by disabling container:

ft.Column(
    disabled = True,
    controls=[
        ft.TextField(),
        ft.TextField()
    ]
)

error #

error: bool = False

Whether this checkbox wants to show an error state.

If True this checkbox will have a different default container color and check color.

expand #

expand: bool | int | None = None

Specifies whether/how this control should expand to fill available space in its parent layout.

More information here.

Note

Has effect only if the direct parent of this control is one of the following controls, or their subclasses: [Column][flet.], [Row][flet.], [View][flet.], [Page][flet.].

expand_loose #

expand_loose: bool = False

Allows the control to expand along the main axis if space is available, but does not require it to fill all available space.

More information here.

Note

If expand_loose is True, it will have effect only if:

expand is not None and
the direct parent of this control is one of the following controls, or their subclasses: [Column][flet.], [Row][flet.], [View][flet.], [Page][flet.].

fill_color #

fill_color: ControlStateValue[ColorValue] | None = None

The color that fills this checkbox in all or specific ControlStates.

Note

Supported states: ControlState.SELECTED, ControlState.HOVERED, ControlState.DISABLED, ControlState.FOCUSED, and ControlState.DEFAULT.

focus_color #

focus_color: ColorValue | None = None

The color for the checkbox's Material when it has the input focus. If overlay_color returns a non-None color in the ControlState.FOCUSED state, it will be used instead.

Defaults to CheckboxTheme.overlay_color in the ControlState.FOCUSED state, or if that is None, falls back to Theme.focus_color.

height #

height: Number | None = None

Imposed Control height in virtual pixels.

hover_color #

hover_color: ColorValue | None = None

The color to use when this checkbox is hovered.

key #

key: KeyValue | None = None

label #

label: StrOrControl | None = None

The clickable label to display on the right of a checkbox.

label_position #

label_position: LabelPosition = RIGHT

Defines on which side of the checkbox the label should be shown.

label_style #

label_style: TextStyle | None = None

The label's text style.

left #

left: Number | None = None

The distance that the child's left edge is inset from the left of the stack.

Note

Effective only if this control is a descendant of one of the following: [Stack][flet.] control, [Page.overlay][flet.] list.

margin #

margin: MarginValue | None = None

Sets the margin of the control.

mouse_cursor #

mouse_cursor: MouseCursor | None = None

The cursor to be displayed when a mouse pointer enters or is hovering over this checkbox.

Defaults to CheckboxTheme.mouse_cursor, or if that is None, falls back to MouseCursor.CLICK.

offset #

offset: OffsetValue | None = None

Applies a translation transformation before painting the control.

The translation is expressed as an Offset scaled to the control's size. So, Offset(x=0.25, y=0), for example, will result in a horizontal translation of one quarter the width of this control.

Example

The following example displays container at 0, 0 top left corner of a stack as transform applies -1 * 100, -1 * 100 (offset * control's size) horizontal and vertical translations to the control:

import flet as ft

def main(page: ft.Page):
    page.add(
        ft.Stack(
            width=1000,
            height=1000,
            controls=[
                ft.Container(
                    bgcolor="red",
                    width=100,
                    height=100,
                    left=100,
                    top=100,
                    offset=ft.Offset(-1, -1),
                )
            ],
        )
    )

ft.run(main)

on_animation_end #

on_animation_end: (
    ControlEventHandler[LayoutControl] | None
) = None

Called when animation completes.

Can be used to chain multiple animations.

The data property of the event handler argument contains the name of the animation.

More information here.

on_blur #

on_blur: ControlEventHandler[Checkbox] | None = None

Called when this checkbox has lost focus.

on_change #

on_change: ControlEventHandler[Checkbox] | None = None

Called when the state of this checkbox is changed.

on_focus #

on_focus: ControlEventHandler[Checkbox] | None = None

Called when this checkbox has received focus.

opacity #

opacity: Number = 1.0

Defines the transparency of the control.

Value ranges from 0.0 (completely transparent) to 1.0 (completely opaque without any transparency).

overlay_color #

overlay_color: ControlStateValue[ColorValue] | None = None

The color of this checkbox's overlay in various ControlState states.

Note

Supported states: ControlState.PRESSED, ControlState.SELECTED, ControlState.HOVERED, ControlState.FOCUSED, and ControlState.DEFAULT.

page #

page: Page | BasePage | None

The page to which this control belongs to.

parent #

parent: BaseControl | None

The direct ancestor(parent) of this control.

It defaults to None and will only have a value when this control is mounted (added to the page tree).

The Page control (which is the root of the tree) is an exception - it always has parent=None.

right #

right: Number | None = None

The distance that the child's right edge is inset from the right of the stack.

Note

Effective only if this control is a descendant of one of the following: [Stack][flet.] control, [Page.overlay][flet.] list.

rotate #

rotate: RotateValue | None = None

Transforms this control using a rotation around its center.

The value of rotate property could be one of the following types:

number - a rotation in clockwise radians. Full circle 360° is math.pi * 2 radians, 90° is pi / 2, 45° is pi / 4, etc.
Rotate - allows to specify rotation angle as well as alignment - the location of rotation center.

Example

For example:

ft.Image(
    src="https://picsum.photos/100/100",
    width=100,
    height=100,
    border_radius=5,
    rotate=Rotate(angle=0.25 * pi, alignment=ft.Alignment.CENTER_LEFT)
)

rtl #

rtl: bool = False

Whether the text direction of the control should be right-to-left (RTL).

scale #

scale: ScaleValue | None = None

Scales this control along the 2D plane. Default scale factor is 1.0, meaning no-scale.

Setting this property to 0.5, for example, makes this control twice smaller, while 2.0 makes it twice larger.

Different scale multipliers can be specified for x and y axis, by setting Control.scale property to an instance of Scale class. Either scale or scale_x and scale_y could be specified, but not all of them.

Example

ft.Image(
    src="https://picsum.photos/100/100",
    width=100,
    height=100,
    border_radius=5,
    scale=ft.Scale(scale_x=2, scale_y=0.5)
)

semantics_label #

semantics_label: str | None = None

The semantic label for the checkbox that is not shown in the UI, but will be announced by screen readers in accessibility modes (e.g TalkBack/VoiceOver).

shape #

shape: OutlinedBorder | None = None

The shape of the checkbox.

Defaults to CheckboxTheme.shape, or if that is None, falls back to RoundedRectangleBorder(radius=2).

splash_radius #

splash_radius: Number | None = None

The radius of the circular Material ink response (ripple) in logical pixels.

Defaults to CheckboxTheme.splash_radius, or if that is None, falls back to 20.0.

tooltip #

tooltip: TooltipValue | None = None

The tooltip ot show when this control is hovered over.

top #

top: Number | None = None

The distance that the child's top edge is inset from the top of the stack.

Note

Effective only if this control is a descendant of one of the following: [Stack][flet.] control, [Page.overlay][flet.] list.

tristate #

tristate: bool = False

If True the checkbox's value can be True, False, or None.

value #

value: bool | None = False

The value of this checkbox.

If True, this checkbox is checked.
If False, this checkbox is unchecked.
If None and tristate is True, this checkbox is indeterminate (displayed as a dash).

visible #

visible: bool = True

Every control has visible property which is True by default - control is rendered on the page. Setting visible to False completely prevents control (and all its children if any) from rendering on a page canvas. Hidden controls cannot be focused or selected with a keyboard or mouse and they do not emit any events.

visual_density #

visual_density: VisualDensity | None = None

Defines how compact the checkbox's layout will be.

width #

width: Number | None = None

Imposed Control width in virtual pixels.

before_event #

before_event(e: ControlEvent)

before_update #

before_update()

build #

build()

Called once during control initialization to define its child controls. self.page is available in this method.

clean #

clean() -> None

did_mount #

did_mount()

init #

init()

is_isolated #

is_isolated()

update #

update() -> None

will_unmount #

will_unmount()