TermUI.Event.Propagation (TermUI v0.2.0)

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Event propagation utilities for the component tree.

Handles bubbling and capturing phases of event propagation. Events bubble up from target to root until handled.

Propagation Phases

  1. Capture - Event travels from root to target (optional)
  2. Target - Event delivered to target component
  3. Bubble - Event travels from target to root (default)

Usage

# Propagate event up through parent chain
Propagation.bubble(event, component_id)

# Build parent chain for propagation
parents = Propagation.get_parent_chain(component_id)

Summary

Types

phase()
propagation_result()

Functions

bubble(event, start_id, opts \\ [])

Bubbles an event up through the parent chain.

capture(event, target_id)

Captures an event down through the parent chain to target.

get_children(component_id)

Gets children of a component.

get_parent_chain(component_id)

Gets the parent chain for a component.

set_parent(component_id, parent_id)

Sets the parent for a component.

stopped?(result)

Checks if an event should stop propagating.

with_phase(event, phase)

Adds metadata about propagation phase to event.

Types

phase()

@type phase() :: :capture | :target | :bubble

propagation_result()

@type propagation_result() :: :handled | :unhandled | :stopped

Functions

bubble(event, start_id, opts \\ [])

@spec bubble(term(), term(), keyword()) :: propagation_result()

Bubbles an event up through the parent chain.

Starts from the given component and propagates up to parents until a component handles the event or the root is reached.

Parameters

  • event - The event to propagate
  • start_id - Component to start bubbling from
  • opts - Options:
    • :skip_start - Skip the starting component (default: false)

Returns

  • :handled - A component handled the event
  • :unhandled - No component handled the event

capture(event, target_id)

@spec capture(term(), term()) :: propagation_result()

Captures an event down through the parent chain to target.

Starts from the root and propagates down to the target component. Each component can intercept before reaching target.

Parameters

  • event - The event to propagate
  • target_id - Target component

Returns

  • :handled - A component handled the event
  • :unhandled - No component handled the event

get_children(component_id)

@spec get_children(term()) :: [term()]

Gets children of a component.

Returns

List of child component ids.

get_parent_chain(component_id)

@spec get_parent_chain(term()) :: [term()]

Gets the parent chain for a component.

Returns list of parent component ids from immediate parent to root.

Example

# If component tree is: root -> container -> button
get_parent_chain(:button)
# => [:container, :root]

set_parent(component_id, parent_id)

@spec set_parent(term(), term() | nil) :: :ok

Sets the parent for a component.

Used to build the component tree for propagation.

Parameters

  • component_id - Child component
  • parent_id - Parent component (or nil for root)

stopped?(result)

@spec stopped?(term()) :: boolean()

Checks if an event should stop propagating.

Events can be marked to stop propagation by returning :stop from handle_event.

with_phase(event, phase)

@spec with_phase(term(), phase()) :: map()

Adds metadata about propagation phase to event.

Parameters

  • event - The event
  • phase - Current propagation phase

Returns

Event with :propagation_phase metadata.