Struct LayoutChanged 

pub struct LayoutChanged {
    pub new_box: Rect,
    pub new_content_box: Rect,
    pub new_window_origin: Point,
}

Event fired when a view’s layout changes

This is fired when the view’s size or position in the layout changes. It does not fire for visual-only changes from transforms (translation, scale, rotation).

Important: Layout vs Visual Coordinates

WARNING: The window coordinates provided by this event (new_window_origin, box_window(), content_box_window()) represent the position in the box layout tree, NOT the final visual position after transforms are applied. If transforms like translation, scale, or rotation are applied to this view or its ancestors, the actual rendered position will differ from these coordinates.

Use VisualChanged instead if you need the actual rendered position in the window after all transforms have been applied.

When to use LayoutChanged vs VisualChanged

• Use LayoutChanged: When you need layout box sizes or relative positioning within the layout tree
• Use VisualChanged: When you need to know where the view actually appears on screen, or to position elements relative to the view’s visual appearance

Coordinate Spaces in Floem

Note: All event handling and painting in Floem happen in the view’s local coordinate space. Floem automatically handles transformations to and from local coordinates. You typically don’t need window coordinates unless you’re positioning elements relative to other views’ visual positions or interacting with platform APIs that expect window coordinates.

Use box_local() and content_box_local() to get coordinates in the view’s local space.

Fields

new_box: Rect

The new layout box relative to the parent layout

new_content_box: Rect

The new content box relative to the parent layout

new_window_origin: Point

The position of the layout box’s origin in window coordinates (box layout position, NOT visual position)

WARNING: This does point is not the final vistual position of the view because it intentionally does not include transforms. Use VisualChanged for actual rendered position.

Implementations

impl LayoutChanged

pub fn listener() -> LayoutChangedListener

Get the event listener for this custom event

pub fn extract(event: &Event) -> Option<&LayoutChanged>

Attempt to extract this event type from a generic [Event].

Equivalent to: Self::listener_key().extract(event)

impl LayoutChanged

pub fn box_local(&self) -> Rect

Get the layout box in the view’s local coordinate space (relative to its own origin which is Point::ZERO)

pub fn content_box_local(&self) -> Rect

Get the content box in the view’s local coordinate space (relative to the box origin)

pub fn box_window(&self) -> Rect

Get the layout box in window coordinates (box layout position, NOT visual position)

WARNING: This does not include transforms. The actual rendered position may differ if transforms are applied. Use VisualChanged for the actual visual position.

pub fn content_box_window(&self) -> Rect

Get the content box in window coordinates (box layout position, NOT visual position)

WARNING: This does not include transforms. The actual rendered position may differ if transforms are applied. Use VisualChanged for the actual visual position.

Trait Implementations

impl Clone for LayoutChanged

fn clone(&self) -> LayoutChanged

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for LayoutChanged

impl CustomEvent for LayoutChanged

fn listener_key() -> EventListenerKey

Get the unique key for this event type

fn listener_key_dyn(&self) -> EventListenerKey

Get the listener key for this trait object

fn allow_disabled(&self) -> bool

fn as_any(&self) -> &dyn Any

Downcast helper

fn clone_box(&self) -> Box<dyn CustomEvent>

Clone this event into a Box without requiring Clone on the trait

fn transform(&mut self, transform: Affine)

fn debug_fmt(&self, f: &mut Formatter<'_>) -> Result

Format for Debug output. Default uses the type name.

impl Debug for LayoutChanged

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for LayoutChanged

fn eq(&self, other: &LayoutChanged) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for LayoutChanged