Trait LayoutOps 

pub trait LayoutOps {
    // Required methods
    fn measure_child(&mut self, child: RNode, p: Proposal) -> Size;
    fn place_child(&mut self, child: RNode, rect: Rect);
    fn flex_of(&self, child: RNode) -> Flex;
    fn children_of(&self, node: RNode) -> Vec<RNode>;
    fn measure_leaf(&mut self, p: Proposal) -> Size;
    fn baseline_of(&mut self, child: RNode, size: Size) -> Option<f64>;
    fn set_scroll_content(&mut self, content: Size);

    // Provided methods
    fn place_child_native(&mut self, child: RNode, rect: Rect) { ... }
    fn scroll_bar_inset(&mut self, _vertical: bool) -> f64 { ... }
    fn report_overflow(&mut self, _needed: f64, _available: f64) { ... }
}

The engine surface visible to Layout implementations.

Required Methods

fn measure_child(&mut self, child: RNode, p: Proposal) -> Size

fn place_child(&mut self, child: RNode, rect: Rect)

fn flex_of(&self, child: RNode) -> Flex

fn children_of(&self, node: RNode) -> Vec<RNode>

fn measure_leaf(&mut self, p: Proposal) -> Size

Native intrinsic measurement of the current node (leaves).

fn baseline_of(&mut self, child: RNode, size: Size) -> Option<f64>

A child’s first text baseline at size, from the top of its box (docs/baseline.md): the toolkit answers for a native leaf, the child’s own Layout::baseline for a container. None ⇒ no baseline to align to.

fn set_scroll_content(&mut self, content: Size)

Report scroll content size for the current node (§7.6).

Provided Methods

fn place_child_native(&mut self, child: RNode, rect: Rect)

Place a child whose on-screen frame is native-owned (nav pages in splitter panes / nav-controller views): never direction-mirrored, because the toolkit positions it.

fn scroll_bar_inset(&mut self, _vertical: bool) -> f64

The room the current scroll node’s scroll bar takes from its content area while the content overflows (Toolkit::scroll_bar_inset); 0 where bars overlay the content.

fn report_overflow(&mut self, _needed: f64, _available: f64)

Report that the current node’s children outgrew the bounds its place() was given (needed vs available main-axis points). A diagnostic hook, not a layout input: the engine logs it once per node in debug builds and ignores it in release, and placement proceeds unchanged either way. Scroll containers never report, since content larger than the viewport is their normal state.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl<B: Toolkit> LayoutOps for EngineCx<'_, B>