Slider

Slider

Bases: ConstrainedControl, AdaptiveControl

A slider provides a visual indication of adjustable content, as well as the current setting in the total range of content.

Use a slider when you want people to set defined values (such as volume or brightness), or when people would benefit from instant feedback on the effect of setting changes.

RAISES	DESCRIPTION
AssertionError	If min is greater than or equal to max.
AssertionError	If min is greater than or equal to value.
AssertionError	If max is less than or equal to value.

active_color

active_color: ColorValue | None = None

The color to use for the portion of the slider track that is active.

The "active" side of the slider is the side between the thumb and the minimum value.

adaptive

adaptive: bool | None = None

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

animate_offset

animate_offset: AnimationValue | None = None

Enables implicit animation of the offset property.

More information here.

animate_opacity

animate_opacity: AnimationValue | None = None

Enables implicit animation of the opacity property.

More information here.

animate_position

animate_position: AnimationValue | None = None

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

More information here.

animate_rotation

animate_rotation: AnimationValue | None = None

Enables implicit animation of the rotate property.

More information here.

animate_scale

animate_scale: AnimationValue | None = None

Enables implicit animation of the scale property.

More information here.

animate_size

animate_size: AnimationValue | None = None

TBD

aspect_ratio

aspect_ratio: Number | None = None

TBD

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.

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 control, Page.overlay list.

col

col: ResponsiveNumber = 12

If a parent of this control is a ResponsiveRow, 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()
    ]
)

divisions

divisions: int | None = None

The number of discrete divisions.

Typically used with label to show the current discrete value.

If None, this slider is continuous.

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, Row, View, Page.

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, Row, View, Page.

height

height: Number | None = None

Imposed Control height in virtual pixels.

inactive_color

inactive_color: ColorValue | None = None

The color for the inactive portion of the slider track.

The "inactive" side of the slider is the side between the thumb and the maximum value.

interaction

interaction: SliderInteraction | None = None

The allowed way for the user to interact with this slider.

If None, SliderTheme.interaction is used. If that's is also None, defaults to SliderInteraction.TAP_AND_SLIDE.

key

key: (
    str | int | float | bool | ValueKey | ScrollKey | None
) = None

label

label: str | None = None

A label to show above the slider when the slider is active. The value of label may contain {value} which will be dynamicly replaced with a current slider value. For example, "Volume: {value}".

It is used to display the value of a discrete slider, and it is displayed as part of the value indicator shape.

If not set, then the value indicator will not be displayed.

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 control, Page.overlay list.

max

max: Number = 1.0

The maximum value the user can select.

Note

• Must be greater than or equal to min.
• If the min is equal to the max, then this slider is disabled.

min

min: Number = 0.0

The minimum value the user can select.

Note

• Must be less than or equal to max.
• If the max is equal to the min, then this slider is disabled.

mouse_cursor

mouse_cursor: MouseCursor | None = None

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

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[ConstrainedControl] | 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[Slider] | None = None

Called when this slider has lost focus.

on_change

on_change: ControlEventHandler[Slider] | None = None

Called when the state of this slider is changed.

on_change_end

on_change_end: ControlEventHandler[Slider] | None = None

Called when the user is done selecting a new value for this slider.

on_change_start

on_change_start: ControlEventHandler[Slider] | None = None

Called when the user starts selecting a new value for this slider.

on_focus

on_focus: ControlEventHandler[Slider] | None = None

Called when this slider 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 highlight color that's typically used to indicate that the range slider thumb is in ControlState.HOVERED or ControlState.DRAGGED states.

padding

padding: PaddingValue | None = None

Determines the padding around this slider.

page

page: Page | PageView | None

The page (of type Page or PageView) 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 control, Page.overlay 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)
)

round

round: int = 0

The number of decimals displayed on the label containing value.

Defaults to 0, which displays value rounded to the nearest integer.

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)
)

secondary_active_color

secondary_active_color: ColorValue | None = None

The color to use for the portion of the slider track between the thumb and the secondary_track_value.

secondary_track_value

secondary_track_value: Number | None = None

The secondary track value for this slider.

If not null, a secondary track using secondary_active_color is drawn between the thumb and this value, over the inactive track. If less than value, then the secondary track is not shown.

It can be ideal for media scenarios such as showing the buffering progress while the value shows the play progress.

thumb_color

thumb_color: ColorValue | None = None

The color of the thumb.

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 control, Page.overlay list.

value

value: Number | None = None

The currently selected value for this slider.

The slider's thumb is drawn at a position that corresponds to this value.

Defaults to value of min.

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.

width

width: Number | None = None

Imposed Control width in virtual pixels.

year_2023

year_2023: bool | None = None

If this is set to False, this slider will use the latest Material Design 3 appearance, which was introduced in December 2023.

When True, the Slider will use the 2023 Material Design 3 appearance.

If not set, then the SliderTheme.year_2023 will be used, which is False by default.

If Theme.use_material3 is False, then this property is ignored.

before_event

before_event(e: ControlEvent)

before_update

before_update()

clean

clean() -> None

did_mount

did_mount()

init

init()

is_isolated

is_isolated()

update

update() -> None

will_unmount

will_unmount()

Examples

Live example

Basic Example

import flet as ft


def main(page: ft.Page):
    page.add(
        ft.Text("Default slider:"),
        ft.Slider(),
        ft.Text("Default disabled slider:"),
        ft.Slider(disabled=True),
    )


ft.run(main)

Setting a custom label

Handling events

import flet as ft


def main(page: ft.Page):
    def slider_changed(e: ft.Event[ft.Slider]):
        message.value = f"Slider changed to {e.control.value}"
        message.update()

    page.add(
        ft.Text("Slider with 'on_change' event:"),
        ft.Slider(
            min=0,
            max=100,
            divisions=10,
            label="{value}%",
            on_change=slider_changed,
        ),
        message := ft.Text(),
    )


ft.run(main)

Random values

import asyncio
import random

import flet as ft


async def main(page: ft.Page):
    def handle_slider_change(e: ft.Event[ft.Slider]):
        message.value = f"Slider.value changed to {e.control.value}"
        message.update()

    page.add(
        ft.Text("Slider with 'on_change' event:"),
        slider := ft.Slider(label="{value}", on_change=handle_slider_change),
        message := ft.Text(),
    )

    while True:
        await asyncio.sleep(1)
        slider.value = random.random()
        event = ft.Event("_", slider, data=slider.value)
        handle_slider_change(event)
        slider.update()


ft.run(main)