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Controls reference

Flet UI is built of controls. Controls are organized into hierarchy, or a tree, where each control has a parent (except Page) and container controls like Column, Dropdown can contain child controls, for example:

Page
 ├─ TextField
 ├─ Dropdown
 │   ├─ Option
 │   └─ Option
 └─ Row
     ├─ ElevatedButton
     └─ ElevatedButton

Control gallery live demo

Controls by categories​

Common control properties​

Flet controls have the following properties:

adaptive​

adaptive property can be specified for a control in the following cases:

bottom​

Effective inside Stack only. The distance that the child's bottom edge is inset from the bottom of the stack.

data​

Arbitrary data that can be attached to a control.

disabled​

Every control has disabled property which is False by default - control and all its children are enabled. disabled property is mostly used with data entry controls like TextField, Dropdown, Checkbox, buttons. However, disabled could be set to a parent control and its value will be propagated down to all children recursively.

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

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

expand​

When a child Control is placed into a Column or a Row you can "expand" it to fill the available space. expand property could be a boolean value (True - expand control to fill all available space) or an integer - an "expand factor" specifying how to divide a free space with other expanded child controls.

For more information and examples about expand property see "Expanding children" sections in Column or Row.

expand_loose​

Effective only if expand is True.

If expand_loose is True, the child control of a Column or a Row will be given the flexibility to expand to fill the available space in the main axis (e.g., horizontally for a Row or vertically for a Column), but will not be required to fill the available space.

The default value is False.

Here is the example of Containers placed in Rows with expand_loose = True:

import flet as ft


class Message(ft.Container):
    def __init__(self, author, body):
        super().__init__()
        self.content = ft.Column(
            controls=[
                ft.Text(author, weight=ft.FontWeight.BOLD),
                ft.Text(body),
            ],
        )
        self.border = ft.border.all(1, ft.colors.BLACK)
        self.border_radius = ft.border_radius.all(10)
        self.bgcolor = ft.colors.GREEN_200
        self.padding = 10
        self.expand = True
        self.expand_loose = True


def main(page: ft.Page):
    chat = ft.ListView(
        padding=10,
        spacing=10,
        controls=[
            ft.Row(
                alignment=ft.MainAxisAlignment.START,
                controls=[
                    Message(
                        author="John",
                        body="Hi, how are you?",
                    ),
                ],
            ),
            ft.Row(
                alignment=ft.MainAxisAlignment.END,
                controls=[
                    Message(
                        author="Jake",
                        body="Hi I am good thanks, how about you?",
                    ),
                ],
            ),
            ft.Row(
                alignment=ft.MainAxisAlignment.START,
                controls=[
                    Message(
                        author="John",
                        body="Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.",
                    ),
                ],
            ),
            ft.Row(
                alignment=ft.MainAxisAlignment.END,
                controls=[
                    Message(
                        author="Jake",
                        body="Thank you!",
                    ),
                ],
            ),
        ],
    )

    page.window.width = 393
    page.window.height = 600
    page.window.always_on_top = False

    page.add(chat)


ft.app(target=main)

height​

Imposed Control height in virtual pixels.

left​

Effective inside Stack only. The distance that the child's left edge is inset from the left of the stack.

parent​

Points to 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.

Effective inside Stack only. The distance that the child's right edge is inset from the right of the stack.

top​

Effective inside Stack only. The distance that the child's top edge is inset from the top of the stack.

visible​

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​

Imposed Control width in virtual pixels.

Transformations​

offset​

Applies a translation transformation before painting the control.

The translation is expressed as a transform.Offset scaled to the control's size. For example, an Offset with a x of 0.25 will result in a horizontal translation of one quarter the width of the control.

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

import flet as ft

def main(page: ft.Page):

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

ft.app(target=main)

opacity​

Defines the transparency of the control.

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

rotate​

Transforms control using a rotation around the 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.
  • transform.Rotate - allows to specify rotation angle as well as alignment - the location of rotation center.

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)
)

scale​

Scale control along the 2D plane. Default scale factor is 1.0 - control is not scaled. 0.5 - the control is twice smaller, 2.0 - the control is twice larger.

Different scale multipliers can be specified for x and y axis, but setting Control.scale property to an instance of transform.Scale class:

from dataclasses import field

class Scale:
    scale: float = field(default=None)
    scale_x: float = field(default=None)
    scale_y: float = field(default=None)
    alignment: Alignment = field(default=None)

Either scale or scale_x and scale_y could be specified, but not all of them, for example:

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