Column

Examples#

Column `spacing`#

import flet as ft


def main(page: ft.Page):
    def generate_items(count: int):
        """Generates a list of custom Containers with length `count`."""
        return [
            ft.Container(
                content=ft.Text(value=str(i)),
                alignment=ft.Alignment.CENTER,
                width=50,
                height=50,
                bgcolor=ft.Colors.AMBER,
                border_radius=ft.BorderRadius.all(5),
            )
            for i in range(1, count + 1)
        ]

    def handle_slider_change(e: ft.Event[ft.Slider]):
        """Updates the spacing between items based on slider value."""
        column.spacing = int(e.control.value)
        column.update()

    page.add(
        ft.Column(
            controls=[
                ft.Text("Spacing between items"),
                ft.Slider(
                    min=0,
                    max=100,
                    divisions=10,
                    value=0,
                    label="{value}",
                    width=500,
                    on_change=handle_slider_change,
                ),
            ]
        ),
        column := ft.Column(spacing=0, controls=generate_items(5)),
    )


ft.run(main)

Column wrapping#

import flet as ft

HEIGHT = 400


def main(page: ft.Page):
    def items(count: int):
        return [
            ft.Container(
                content=ft.Text(value=str(i)),
                alignment=ft.Alignment.CENTER,
                width=30,
                height=30,
                bgcolor=ft.Colors.AMBER,
                border_radius=ft.BorderRadius.all(5),
            )
            for i in range(1, count + 1)
        ]

    def handle_slider_change(e: ft.Event[ft.Slider]):
        col.height = float(e.control.value)
        col.update()

    page.add(
        ft.Column(
            controls=[
                ft.Text(
                    "Change the column height to see how child items wrap onto multiple columns:"
                ),
                ft.Slider(
                    min=0,
                    max=HEIGHT,
                    divisions=20,
                    value=HEIGHT,
                    label="{value}",
                    width=500,
                    on_change=handle_slider_change,
                ),
            ]
        ),
        ft.Container(
            bgcolor=ft.Colors.TRANSPARENT,
            content=(
                col := ft.Column(
                    wrap=True,
                    spacing=10,
                    run_spacing=10,
                    controls=items(10),
                    height=HEIGHT,
                )
            ),
        ),
    )


ft.run(main)

Column vertical alignments#

import flet as ft


class ColumnFromVerticalAlignment(ft.Column):
    def __init__(self, alignment: ft.MainAxisAlignment):
        super().__init__()
        self.controls = [
            ft.Text(str(alignment), size=10),
            ft.Container(
                content=ft.Column(self.generate_items(3), alignment=alignment),
                bgcolor=ft.Colors.AMBER_100,
                height=400,
            ),
        ]

    @staticmethod
    def generate_items(count: int):
        """Generates a list of custom Containers with length `count`."""
        return [
            ft.Container(
                content=ft.Text(value=str(i)),
                alignment=ft.Alignment.CENTER,
                width=50,
                height=50,
                bgcolor=ft.Colors.AMBER_500,
            )
            for i in range(1, count + 1)
        ]


def main(page: ft.Page):
    page.add(
        ft.Row(
            spacing=30,
            alignment=ft.MainAxisAlignment.START,
            scroll=ft.ScrollMode.AUTO,
            controls=[
                ColumnFromVerticalAlignment(ft.MainAxisAlignment.START),
                ColumnFromVerticalAlignment(ft.MainAxisAlignment.CENTER),
                ColumnFromVerticalAlignment(ft.MainAxisAlignment.END),
                ColumnFromVerticalAlignment(ft.MainAxisAlignment.SPACE_BETWEEN),
                ColumnFromVerticalAlignment(ft.MainAxisAlignment.SPACE_AROUND),
                ColumnFromVerticalAlignment(ft.MainAxisAlignment.SPACE_EVENLY),
            ],
        )
    )


ft.run(main)

Column horizontal alignments#

import flet as ft


class ColumnFromHorizontalAlignment(ft.Column):
    def __init__(self, alignment: ft.CrossAxisAlignment):
        super().__init__()
        self.controls = [
            ft.Text(str(alignment), size=16),
            ft.Container(
                bgcolor=ft.Colors.AMBER_100,
                width=100,
                content=ft.Column(
                    controls=self.generate_items(3),
                    alignment=ft.MainAxisAlignment.START,
                    horizontal_alignment=alignment,
                ),
            ),
        ]

    @staticmethod
    def generate_items(count: int):
        """Generates a list of custom Containers with length `count`."""
        return [
            ft.Container(
                content=ft.Text(value=str(i)),
                alignment=ft.Alignment.CENTER,
                width=50,
                height=50,
                bgcolor=ft.Colors.AMBER_500,
            )
            for i in range(1, count + 1)
        ]


def main(page: ft.Page):
    page.add(
        ft.Row(
            spacing=30,
            alignment=ft.MainAxisAlignment.START,
            controls=[
                ColumnFromHorizontalAlignment(ft.CrossAxisAlignment.START),
                ColumnFromHorizontalAlignment(ft.CrossAxisAlignment.CENTER),
                ColumnFromHorizontalAlignment(ft.CrossAxisAlignment.END),
            ],
        )
    )


ft.run(main)

Infinite scrolling#

This example demonstrates adding of list items on-the-fly, as user scroll to the bottom, creating the illusion of infinite list:

import threading

import flet as ft


class State:
    i = 0


s = State()
sem = threading.Semaphore()


def main(page: ft.Page):
    def on_scroll(e: ft.OnScrollEvent):
        if e.pixels >= e.max_scroll_extent - 100:
            if sem.acquire(blocking=False):
                try:
                    for i in range(0, 10):
                        cl.controls.append(
                            ft.Text(f"Text line {s.i}", scroll_key=str(s.i))
                        )
                        s.i += 1
                    cl.update()
                finally:
                    sem.release()

    cl = ft.Column(
        spacing=10,
        height=200,
        width=200,
        scroll=ft.ScrollMode.ALWAYS,
        scroll_interval=0,
        on_scroll=on_scroll,
    )
    for i in range(0, 50):
        cl.controls.append(ft.Text(f"Text line {s.i}", scroll_key=str(s.i)))
        s.i += 1

    page.add(ft.Container(cl, border=ft.Border.all(1)))


ft.run(main)

Scrolling programmatically#

This example shows how to use scroll_to() to programmatically scroll a column:

import flet as ft


def main(page: ft.Page):
    column = ft.Column(
        spacing=10,
        height=200,
        width=float("inf"),
        scroll=ft.ScrollMode.ALWAYS,
        controls=[ft.Text(f"Text line {i}", scroll_key=str(i)) for i in range(0, 100)],
    )

    def scroll_to_offset(e):
        column.scroll_to(offset=500, duration=1000)

    def scroll_to_start(e):
        column.scroll_to(offset=0, duration=1000)

    def scroll_to_end(e):
        column.scroll_to(offset=-1, duration=2000, curve=ft.AnimationCurve.EASE_IN_OUT)

    def scroll_to_key(e):
        column.scroll_to(scroll_key="20", duration=1000)

    def scroll_to_delta(e):
        column.scroll_to(delta=100, duration=200)

    def scroll_to_minus_delta(e):
        column.scroll_to(delta=-100, duration=200)

    page.add(
        ft.Container(content=column, border=ft.Border.all(1)),
        ft.ElevatedButton("Scroll to offset 500", on_click=scroll_to_offset),
        ft.Row(
            controls=[
                ft.ElevatedButton("Scroll -100", on_click=scroll_to_minus_delta),
                ft.ElevatedButton("Scroll +100", on_click=scroll_to_delta),
            ]
        ),
        ft.ElevatedButton("Scroll to key '20'", on_click=scroll_to_key),
        ft.Row(
            controls=[
                ft.ElevatedButton("Scroll to start", on_click=scroll_to_start),
                ft.ElevatedButton("Scroll to end", on_click=scroll_to_end),
            ]
        ),
    )


ft.run(main)

Column #

Bases: ConstrainedControl, ScrollableControl, AdaptiveControl

Container allows to decorate a control with background color and border and position it with padding, margin and alignment.

adaptive #

adaptive: bool | None = None

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

alignment #

alignment: MainAxisAlignment = START

How the child Controls should be placed vertically.

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

auto_scroll #

auto_scroll: bool = False

True if scrollbar should automatically move its position to the end when children updated. Must be False for scroll_to() method to work.

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

controls #

controls: list[Control] = field(default_factory=list)

A list of controls to display.

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()
    ]
)

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.

horizontal_alignment #

horizontal_alignment: CrossAxisAlignment = START

Defines how the controls should be placed horizontally.

key #

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

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.

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_scroll #

on_scroll: EventHandler[OnScrollEvent] | None = None

Called when scroll position is changed by a user. class.

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).

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)
)

rtl #

rtl: bool = False

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

run_alignment #

run_alignment: MainAxisAlignment = START

How the runs should be placed in the cross-axis when wrap is True.

run_spacing #

run_spacing: Number = 10

The spacing between runs when wrap is True.

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)
)

scroll #

scroll: ScrollMode | None = None

Enables a vertical scrolling for the Column to prevent its content overflow.

Defaults to ScrollMode.None.

scroll_interval #

scroll_interval: Number = 10

Throttling in milliseconds for on_scroll event.

spacing #

spacing: Number = 10

Spacing between the controls.

It is applied only when alignment is MainAxisAlignment.START, MainAxisAlignment.END or MainAxisAlignment.CENTER.

tight #

tight: bool = False

Determines how vertical space is allocated.

If False (default), children expand to fill the available vertical space. If True, only the minimum vertical space required by the children is used.

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.

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.

wrap #

wrap: bool = False

Whether the controls should wrap into additional columns (runs) when they don't fit in a single vertical column.

before_event #

before_event(e: ControlEvent)

before_update #

before_update()

clean #

clean() -> None

did_mount #

did_mount()

init #

init()

is_isolated #

is_isolated()

scroll_to #

scroll_to(
    offset: Number | None = None,
    delta: Number | None = None,
    scroll_key: str
    | int
    | float
    | bool
    | ScrollKey
    | None = None,
    duration: DurationValue | None = None,
    curve: AnimationCurve | None = None,
)

Moves scroll position to either absolute offset, relative delta or jump to the control with specified key.

offset is an absolute value between minimum and maximum extents of a scrollable control, for example:

products.scroll_to(offset=100, duration=1000)

offset could be a negative to scroll from the end of a scrollable. For example, to scroll to the very end:

products.scroll_to(offset=-1, duration=1000)

delta allows moving scroll relatively to the current position. Use positive delta to scroll forward and negative delta to scroll backward. For example, to move scroll on 50 pixels forward:

products.scroll_to(delta=50)

key allows moving scroll position to a control with specified key. Most of Flet controls have key property which is translated to Flutter as "global key". key must be unique for the entire page/view. For example:

import flet as ft

def main(page: ft.Page):
    cl = ft.Column(
        spacing=10,
        height=200,
        width=200,
        scroll=ft.ScrollMode.ALWAYS,
    )
    for i in range(0, 50):
        cl.controls.append(ft.Text(f"Text line {i}", key=str(i)))

    def scroll_to_key(e):
        cl.scroll_to(key="20", duration=1000)

    page.add(
        ft.Container(cl, border=ft.border.all(1)),
        ft.ElevatedButton("Scroll to key '20'", on_click=scroll_to_key),
    )

ft.run(main)

Note

scroll_to() method won't work with ListView and GridView controls building their items dynamically.

duration is scrolling animation duration in milliseconds. Defaults to 0 - no animation.

curve configures animation curve. Property value is AnimationCurve enum. Defaults to AnimationCurve.EASE.

scroll_to_async #

scroll_to_async(
    offset: float | None = None,
    delta: float | None = None,
    scroll_key: str
    | int
    | float
    | bool
    | ScrollKey
    | None = None,
    duration: DurationValue | None = None,
    curve: AnimationCurve | None = None,
)

Moves scroll position to either absolute offset, relative delta or jump to the control with specified key.

offset is an absolute value between minimum and maximum extents of a scrollable control, for example:

products.scroll_to(offset=100, duration=1000)

offset could be a negative to scroll from the end of a scrollable. For example, to scroll to the very end:

products.scroll_to(offset=-1, duration=1000)

delta allows moving scroll relatively to the current position. Use positive delta to scroll forward and negative delta to scroll backward. For example, to move scroll on 50 pixels forward:

products.scroll_to(delta=50)

key allows moving scroll position to a control with specified key. Most of Flet controls have key property which is translated to Flutter as "global key". key must be unique for the entire page/view. For example:

import flet as ft

def main(page: ft.Page):
    cl = ft.Column(
        spacing=10,
        height=200,
        width=200,
        scroll=ft.ScrollMode.ALWAYS,
    )
    for i in range(0, 50):
        cl.controls.append(ft.Text(f"Text line {i}", key=str(i)))

    def scroll_to_key(e):
        cl.scroll_to(key="20", duration=1000)

    page.add(
        ft.Container(cl, border=ft.border.all(1)),
        ft.ElevatedButton("Scroll to key '20'", on_click=scroll_to_key),
    )

ft.run(main)

Note

scroll_to() method won't work with ListView and GridView controls building their items dynamically.

duration is scrolling animation duration in milliseconds. Defaults to 0 - no animation.

curve configures animation curve. Property value is AnimationCurve enum. Defaults to AnimationCurve.EASE.

update #

update() -> None

will_unmount #

will_unmount()

Column

Examples#

Column spacing#

Column wrapping#

Column vertical alignments#

Column horizontal alignments#

Infinite scrolling#

Scrolling programmatically#

Column #

adaptive #

alignment #

animate_offset #

animate_opacity #

animate_position #

animate_rotation #

animate_scale #

animate_size #

aspect_ratio #

auto_scroll #

badge #

bottom #

col #

controls #

data #

disabled #

expand #

expand_loose #

height #

horizontal_alignment #

key #

left #

offset #

on_animation_end #

on_scroll #

opacity #

page #

parent #

right #

rotate #

rtl #

run_alignment #

run_spacing #

scale #

scroll #

scroll_interval #

spacing #

tight #

tooltip #

top #

visible #

width #

wrap #

before_event #

before_update #

clean #

did_mount #

init #

is_isolated #

scroll_to #

scroll_to_async #

update #

will_unmount #

Column `spacing`#