OnScrollEvent

Payload for flet.ScrollableControl.on_scroll handlers.

Inherits: Event

Properties

• at_edge - Whether pixels is exactly at either scroll edge.
• direction - User scroll direction reported by Flutter.
• event_type - Logical type of the scroll notification.
• extent_after - Quantity of content conceptually "after" the viewport.
• extent_before - Quantity of content conceptually "before" the viewport.
• extent_total - Total conceptual content extent available to the scrollable.
• max_scroll_extent - Maximum in-range value for pixels.
• min_scroll_extent - Minimum in-range value for pixels.
• out_of_range - Whether pixels is outside scroll extents.
• overscroll - Logical pixels that were prevented from being applied to pixels.
• pixels - Current scroll offset in logical pixels.
• scroll_delta - Delta in logical pixels since the previous update.
• velocity - Scroll velocity when overscroll occurred, in logical pixels per second.
• viewport_dimension - Visible viewport extent along the scroll axis, in logical pixels.

Properties

buildat_edgeproperty

at_edge: bool

Whether pixels is exactly at either scroll edge.

Returns:

• bool - True when pixels equals min_scroll_extent or max_scroll_extent; otherwise False.

builddirectionclass-attributeinstance-attribute

direction: Optional[ScrollDirection] = None

User scroll direction reported by Flutter.

Populated for flet.ScrollType.USER notifications.

buildevent_typeinstance-attribute

event_type: ScrollType

Logical type of the scroll notification.

Determines which optional fields are populated:

• flet.ScrollType.UPDATE: scroll_delta
• flet.ScrollType.USER: direction
• flet.ScrollType.OVERSCROLL: overscroll and velocity

buildextent_afterproperty

extent_after: float

Quantity of content conceptually "after" the viewport.

This corresponds to the content following the visible region in the current scroll direction.

buildextent_beforeproperty

extent_before: float

Quantity of content conceptually "before" the viewport.

This corresponds to the content preceding the visible region in the current scroll direction.

buildextent_totalproperty

extent_total: float

Total conceptual content extent available to the scrollable.

Equivalent to: max_scroll_extent - min_scroll_extent

• viewport_dimension.

buildmax_scroll_extentinstance-attribute

max_scroll_extent: float

Maximum in-range value for pixels.

pixels may still be out_of_range during overscroll. For unbounded scrollables this value can be positive infinity.

buildmin_scroll_extentinstance-attribute

min_scroll_extent: float

Minimum in-range value for pixels.

pixels may still be out_of_range during overscroll. For unbounded scrollables this value can be negative infinity.

buildout_of_rangeproperty

out_of_range: bool

Whether pixels is outside scroll extents.

Returns:

• bool - True if pixels < min_scroll_extent or pixels > max_scroll_extent; otherwise False.

buildoverscrollclass-attributeinstance-attribute

overscroll: Optional[float] = None

Logical pixels that were prevented from being applied to pixels.

Negative values indicate overscroll on the start side; positive values indicate overscroll on the end side. Populated for flet.ScrollType.OVERSCROLL.

buildpixelsinstance-attribute

pixels: float

Current scroll offset in logical pixels.

buildscroll_deltaclass-attributeinstance-attribute

scroll_delta: Optional[float] = None

Delta in logical pixels since the previous update.

Populated for flet.ScrollType.UPDATE notifications.

buildvelocityclass-attributeinstance-attribute

velocity: Optional[float] = None

Scroll velocity when overscroll occurred, in logical pixels per second.

Populated for flet.ScrollType.OVERSCROLL.

buildviewport_dimensioninstance-attribute

viewport_dimension: float

Visible viewport extent along the scroll axis, in logical pixels.