ScrollDirection 继承自： Enum

User scroll direction reported by Flutter user-scroll notifications.

Used by direction when event_type is USER.

示例

import flet as ft


def main(page: ft.Page):
    page.horizontal_alignment = ft.CrossAxisAlignment.CENTER

    counts = {direction: 0 for direction in ft.ScrollDirection}
    count_labels = {
        direction: ft.Text(f"{direction.name}: 0") for direction in ft.ScrollDirection
    }

    def on_scroll(e: ft.OnScrollEvent):
        if e.event_type == ft.ScrollType.USER and e.direction is not None:
            counts[e.direction] += 1
            count_labels[
                e.direction
            ].value = f"{e.direction.name}: {counts[e.direction]}"
            last.value = f"Last USER direction: {e.direction.name}"
            for label in count_labels.values():
                label.update()
            last.update()

    page.appbar = ft.AppBar(title="ScrollDirection Showcase")
    page.add(
        ft.SafeArea(
            content=ft.Column(
                controls=[
                    ft.Text("Scroll the list and watch USER direction notifications."),
                    last := ft.Text("Last USER direction: none"),
                    ft.Row(
                        wrap=True,
                        spacing=10,
                        controls=[count_labels[d] for d in ft.ScrollDirection],
                        alignment=ft.MainAxisAlignment.CENTER,
                    ),
                    ft.Container(
                        width=360,
                        height=240,
                        border=ft.Border.all(1, ft.Colors.OUTLINE),
                        border_radius=8,
                        padding=8,
                        content=ft.Column(
                            scroll=ft.ScrollMode.ALWAYS,
                            on_scroll=on_scroll,
                            controls=[
                                ft.Text(f"Scrollable item {i + 1}") for i in range(60)
                            ],
                        ),
                    ),
                ],
            ),
        )
    )


if __name__ == "__main__":
    ft.run(main)

枚举值

名称	类型	默认值	说明
IDLE	—	'idle'	No active user-driven scroll direction.
FORWARD	—	'forward'	Scrolling in the forward axis direction.
REVERSE	—	'reverse'	Scrolling in the reverse axis direction.