GestureDetector

Examples

Live example

Solitare game tutorial

Handling events

import flet as ft


def main(page: ft.Page):
    page.add(
        ft.GestureDetector(
            content=ft.Container(bgcolor=ft.Colors.GREEN, width=200, height=200),
            hover_interval=50,
            on_tap=lambda e: print(e),
            on_tap_down=lambda e: print(e),
            on_tap_up=lambda e: print(e),
            on_secondary_tap=lambda e: print(e),
            on_secondary_tap_down=lambda e: print(e),
            on_secondary_tap_up=lambda e: print(e),
            on_long_press_start=lambda e: print(e),
            on_long_press_end=lambda e: print(e),
            on_secondary_long_press_start=lambda e: print(e),
            on_secondary_long_press_end=lambda e: print(e),
            on_double_tap=lambda e: print(e),
            on_double_tap_down=lambda e: print(e),
            on_pan_start=lambda e: print(e),
            on_pan_update=lambda e: print(e),
            on_pan_end=lambda e: print(e),
            on_hover=lambda e: print(e),
            on_enter=lambda e: print(e),
            on_exit=lambda e: print(e),
        )
    )


ft.run(main)

Draggable containers

The following example demonstrates how a control can be freely dragged inside a Stack.

The sample also shows that GestureDetector can have a child control (blue container) as well as be nested inside another control (yellow container) giving the same results.

import flet as ft


def main(page: ft.Page):
    def handle_pan_update1(e: ft.DragUpdateEvent[ft.GestureDetector]):
        container = e.control.parent
        container.top = max(0.0, container.top + e.delta_y)
        container.left = max(0.0, container.left + e.delta_x)
        container.update()

    def handle_pan_update2(e: ft.DragUpdateEvent[ft.GestureDetector]):
        e.control.top = max(0.0, e.control.top + e.delta_y)
        e.control.left = max(0.0, e.control.left + e.delta_x)
        e.control.update()

    page.add(
        ft.Stack(
            width=1000,
            height=500,
            controls=[
                ft.Container(
                    bgcolor=ft.Colors.AMBER,
                    width=50,
                    height=50,
                    left=0,
                    top=0,
                    content=ft.GestureDetector(
                        mouse_cursor=ft.MouseCursor.MOVE,
                        drag_interval=50,
                        on_pan_update=handle_pan_update1,
                    ),
                ),
                ft.GestureDetector(
                    mouse_cursor=ft.MouseCursor.MOVE,
                    drag_interval=10,
                    on_vertical_drag_update=handle_pan_update2,
                    left=100,
                    top=100,
                    content=ft.Container(bgcolor=ft.Colors.BLUE, width=50, height=50),
                ),
            ],
        )
    )


ft.run(main)

Mouse Cursors

import flet as ft


def main(page: ft.Page):
    def on_pan_update(event: ft.DragUpdateEvent[ft.GestureDetector]):
        container.top = max(0.0, container.top + event.delta_y)
        container.left = max(0.0, container.left + event.delta_x)
        container.update()

    gesture_detector = ft.GestureDetector(
        mouse_cursor=ft.MouseCursor.BASIC,
        drag_interval=50,
        on_pan_update=on_pan_update,
    )
    container = ft.Container(
        content=gesture_detector,
        bgcolor=ft.Colors.AMBER,
        width=150,
        height=150,
        left=0,
        top=0,
    )

    def handle_button_click(e: ft.Event[ft.ElevatedButton]):
        gesture_detector.mouse_cursor = next(
            generate_mouse_cursors(list(ft.MouseCursor))
        )
        text.value = f"Mouse Cursor:  {gesture_detector.mouse_cursor}"
        page.update()

    def generate_mouse_cursors(m_list):
        while True:
            for i in m_list:
                yield i

    page.add(
        ft.Stack(controls=[container], width=1000, height=500),
        ft.ElevatedButton("Change mouse Cursor", on_click=handle_button_click),
        text := ft.Text(f"Mouse Cursor:  {gesture_detector.mouse_cursor}"),
    )


ft.run(main)

GestureDetector

Bases: ConstrainedControl, AdaptiveControl

A control that detects gestures.

Attempts to recognize gestures that correspond to its non-None callbacks.

If this control has a content, it defers to that child control for its sizing behavior, else it grows to fit the parent instead.

adaptive

adaptive: bool | None = None

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

allowed_devices

allowed_devices: list[PointerDeviceType] | None = None

TBD

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

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

content

content: Control | None = None

A child Control contained by the gesture detector.

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()
    ]
)

drag_interval

drag_interval: int = 0

Throttling in milliseconds for horizontal drag, vertical drag and pan update events.

When a user moves a pointer a lot of events are being generated to do precise tracking. drag_interval allows sending drag update events to a Flet program every X milliseconds, thus preserving the bandwidth (web and mobile apps).

Default is 0 - no throttling, all events are sent to a Flet program, very smooth tracking.

exclude_from_semantics

exclude_from_semantics: bool = False

TBD

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.

hover_interval

hover_interval: int = 0

Throttling in milliseconds for on_hover event.

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.

mouse_cursor

mouse_cursor: MouseCursor | None = None

The mouse cursor for mouse pointers that are hovering over the control.

multi_tap_touches

multi_tap_touches: int = 0

The minimum number of pointers to trigger on_multi_tap event.

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_double_tap

on_double_tap: (
    EventHandler[TapEvent[GestureDetector]] | None
) = None

The user has tapped the screen with a primary button at the same location twice in quick succession.

on_double_tap_down

on_double_tap_down: (
    EventHandler[TapEvent[GestureDetector]] | None
) = None

Called when a pointer that might cause a double tap has contacted the screen at a particular location.

Triggered immediately after the down event of the second tap.

on_enter

on_enter: (
    EventHandler[HoverEvent[GestureDetector]] | None
) = None

Called when a mouse pointer has entered this control.

on_exit

on_exit: (
    EventHandler[HoverEvent[GestureDetector]] | None
) = None

Called when a mouse pointer has exited this control.

on_horizontal_drag_end

on_horizontal_drag_end: (
    EventHandler[DragEndEvent[GestureDetector]] | None
) = None

Called when a pointer moving horizontally is no longer in contact and was moving at a specific velocity.

on_horizontal_drag_start

on_horizontal_drag_start: (
    EventHandler[DragStartEvent[GestureDetector]] | None
) = None

Called when a pointer has contacted the screen with a primary button and has begun to move horizontally.

on_horizontal_drag_update

on_horizontal_drag_update: (
    EventHandler[DragUpdateEvent[GestureDetector]] | None
) = None

Called when a pointer that is in contact with the screen and moving horizontally has moved in the horizontal direction.

on_hover

on_hover: (
    EventHandler[HoverEvent[GestureDetector]] | None
) = None

Called when a mouse pointer has entered this control.

on_long_press_end

on_long_press_end: (
    EventHandler[LongPressEndEvent[GestureDetector]] | None
) = None

Called when a pointer that has triggered a long-press with a primary button has stopped contacting the screen.

on_long_press_start

on_long_press_start: (
    EventHandler[LongPressStartEvent[GestureDetector]]
    | None
) = None

Called when a long press gesture with a primary button has been recognized.

Triggered when a pointer has remained in contact with the screen at the same location for a long period of time.

on_multi_long_press

on_multi_long_press: (
    EventHandler[LongPressEndEvent[GestureDetector]] | None
) = None

Called when a long press gesture with multiple pointers has been recognized.

on_multi_tap

on_multi_tap: (
    EventHandler[TapEvent[GestureDetector]] | None
) = None

Called when multiple pointers contacted the screen.

on_pan_end

on_pan_end: (
    EventHandler[DragEndEvent[GestureDetector]] | None
) = None

Called when a pointer is no longer in contact and was moving at a specific velocity.

on_pan_start

on_pan_start: (
    EventHandler[DragStartEvent[GestureDetector]] | None
) = None

Called when a pointer has contacted the screen and has begun to move.

on_pan_update

on_pan_update: (
    EventHandler[DragUpdateEvent[GestureDetector]] | None
) = None

Called when a pointer that is in contact with the screen and moving has moved again.

on_scale_end

on_scale_end: (
    EventHandler[ScaleEndEvent[GestureDetector]] | None
) = None

TBD

on_scale_start

on_scale_start: (
    EventHandler[ScaleStartEvent[GestureDetector]] | None
) = None

Called when the pointers in contact with the screen have established a focal point and initial scale of 1.0.

on_scale_update

on_scale_update: (
    EventHandler[ScaleUpdateEvent[GestureDetector]] | None
) = None

TBD

on_scroll

on_scroll: (
    EventHandler[ScrollEvent[GestureDetector]] | None
) = None

TBD

on_secondary_long_press_end

on_secondary_long_press_end: (
    EventHandler[LongPressEndEvent[GestureDetector]] | None
) = None

Called when a pointer that has triggered a long-press with a secondary button has stopped contacting the screen.

on_secondary_long_press_start

on_secondary_long_press_start: (
    EventHandler[LongPressStartEvent[GestureDetector]]
    | None
) = None

Called when a long press gesture with a secondary button has been recognized.

Triggered when a pointer has remained in contact with the screen at the same location for a long period of time.

on_secondary_tap

on_secondary_tap: (
    EventHandler[TapEvent[GestureDetector]] | None
) = None

A tap with a secondary button has occurred.

on_secondary_tap_down

on_secondary_tap_down: (
    EventHandler[TapEvent[GestureDetector]] | None
) = None

Called when a pointer that might cause a tap with a secondary button has contacted the screen at a particular location.

on_secondary_tap_up

on_secondary_tap_up: (
    EventHandler[TapEvent[GestureDetector]] | None
) = None

Called when a pointer that will trigger a tap with a secondary button has stopped contacting the screen at a particular location.

on_tap

on_tap: EventHandler[TapEvent[GestureDetector]] | None = (
    None
)

Called when a tap with a primary button has occurred.

on_tap_down

on_tap_down: (
    EventHandler[TapEvent[GestureDetector]] | None
) = None

Called when a pointer that might cause a tap with a primary button has contacted the screen at a particular location.

on_tap_up

on_tap_up: (
    EventHandler[TapEvent[GestureDetector]] | None
) = None

Called when a pointer that will trigger a tap with a primary button has stopped contacting the screen at a particular location.

on_vertical_drag_end

on_vertical_drag_end: (
    EventHandler[DragEndEvent[GestureDetector]] | None
) = None

Called when a pointer moving vertically is no longer in contact and was moving at a specific velocity.

on_vertical_drag_start

on_vertical_drag_start: (
    EventHandler[DragStartEvent[GestureDetector]] | None
) = None

Called when a pointer has contacted the screen and has begun to move vertically.

on_vertical_drag_update

on_vertical_drag_update: (
    EventHandler[DragUpdateEvent[GestureDetector]] | None
) = None

A pointer moving vertically has moved in the vertical direction.

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).

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)
)

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.

trackpad_scroll_causes_scale

trackpad_scroll_causes_scale: bool = False

TBD

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.

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()