Trait ScrollDataSource 

pub trait ScrollDataSource {
    // Required method
    fn get_offset(&self, node_id: NodeId) -> f32;
}

A source of scroll offsets for scroll containers.

The layout engine calls get_offset for each LayoutOp::Scroll node to learn how far the user has scrolled. Platform backends implement this trait (or pass a closure, which also implements it).

Example

use fission_layout::ScrollDataSource;
use fission_ir::NodeId;

// A closure works as a ScrollDataSource:
let source = |_node: NodeId| -> f32 { 0.0 };
assert_eq!(source.get_offset(NodeId::explicit("scroll")), 0.0);

Required Methods

fn get_offset(&self, node_id: NodeId) -> f32

Returns the current scroll offset for the given scroll container node.

Dyn Compatibility

This trait is dyn compatible.

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

Implementors

impl<F> ScrollDataSource for F

where F: Fn(NodeId) -> f32,