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GestureDetector

A control that detects gestures.

Attempts to recognize gestures that correspond to its non-null callbacks.

If this control has a content, it defers to that child control for its sizing behavior. If it does not have a content, it grows to fit the parent instead.

Examples​

Live example

Solitare game tutorial

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 on_pan_update1(e: ft.DragUpdateEvent):
        c.top = max(0, c.top + e.delta_y)
        c.left = max(0, c.left + e.delta_x)
        c.update()

    def on_pan_update2(e: ft.DragUpdateEvent):
        e.control.top = max(0, e.control.top + e.delta_y)
        e.control.left = max(0, e.control.left + e.delta_x)
        e.control.update()

    gd = ft.GestureDetector(
        mouse_cursor=ft.MouseCursor.MOVE,
        drag_interval=50,
        on_pan_update=on_pan_update1,
    )

    c = ft.Container(gd, bgcolor=ft.Colors.AMBER, width=50, height=50, left=0, top=0)

    gd1 = ft.GestureDetector(
        mouse_cursor=ft.MouseCursor.MOVE,
        drag_interval=10,
        on_vertical_drag_update=on_pan_update2,
        left=100,
        top=100,
        content=ft.Container(bgcolor=ft.Colors.BLUE, width=50, height=50),
    )

    page.add( ft.Stack([c, gd1], width=1000, height=500))

ft.app(main)

Properties​

content​

A child Control contained by the gesture detector.

mouse_cursor​

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

Value is of type MouseCursor.

drag_interval​

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.

hover_interval​

Throttling in milliseconds for on_hover event.

Events​

multi_tap_touches​

The minimum number of pointers to trigger on_multi_tap event.

on_double_tap​

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

on_double_tap_down​

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.

Event handler argument is of type MapTapEvent.

on_enter​

Triggered when a mouse pointer has entered this control.

Event handler argument is of type HoverEvent.

on_exit​

Triggered when a mouse pointer has exited this control.

Event handler argument is of type HoverEvent.

on_horizontal_drag_end​

A pointer that was previously in contact with the screen with a primary button and moving horizontally is no longer in contact with the screen and was moving at a specific velocity when it stopped contacting the screen.

Event handler argument is of type DragEndEvent.

on_horizontal_drag_start​

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

Event handler argument is of type DragStartEvent.

on_horizontal_drag_update​

A pointer that is in contact with the screen with a primary button and moving horizontally has moved in the horizontal direction.

Event handler argument is of type DragUpdateEvent.

on_hover​

Triggered when a mouse pointer has entered this control.

Event handler argument is of type HoverEvent.

on_long_press_end​

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

Event handler argument is of type LongPressEndEvent.

on_long_press_start​

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.

Event handler argument is of type LongPressStartEvent.

on_pan_end​

A pointer that was previously in contact with the screen with a primary button and moving is no longer in contact with the screen and was moving at a specific velocity when it stopped contacting the screen.

Event handler argument is of type DragEndEvent.

on_pan_start​

A pointer has contacted the screen with a primary button and has begun to move.

Event handler argument is of type DragStartEvent.

on_pan_update​

A pointer that is in contact with the screen with a primary button and moving has moved again.

Event handler argument is of type DragUpdateEvent.

on_scale_end​

Event handler argument is of type ScaleEndEvent.

on_scale_start​

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

Event handler argument is of type ScaleStartEvent.

on_scale_update​

Event handler argument is of type ScaleUpdateEvent.

on_secondary_long_press_end​

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

Event handler argument is of type LongPressEndEvent.

on_secondary_long_press_start​

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.

Event handler argument is of type LongPressStartEvent.

on_secondary_tap​

A tap with a secondary button has occurred.

on_secondary_tap_down​

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

Event handler argument is of type MapTapEvent.

on_secondary_tap_up​

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

Event handler argument is of type MapTapEvent.

on_tap​

A tap with a primary button has occurred.

on_tap_down​

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

Event handler argument is of type MapTapEvent.

on_tap_up​

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

Event handler argument is of type MapTapEvent.

on_vertical_drag_end​

A pointer that was previously in contact with the screen with a primary button and moving vertically is no longer in contact with the screen and was moving at a specific velocity when it stopped contacting the screen.

Event handler argument is of type DragEndEvent.

on_vertical_drag_start​

A pointer has contacted the screen with a primary button and has begun to move vertically.

Event handler argument is of type DragStartEvent.

on_vertical_drag_update​

A pointer that is in contact with the screen with a primary button and moving vertically has moved in the vertical direction.

Event handler argument is of type DragUpdateEvent.

on_multi_long_press​

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

on_multi_tap​

Triggered when multiple pointers contacted the screen.

Event handler argument is of type MultiTapEvent.

on_scroll​

Event handler argument is of type ScrollEvent.