This module defines a Prism-based event for propagating region-of-interest (ROI) channel selection changes across the application. Specifically, RegionOfInterestChannelsSelectedEvent is a PubSubEvent used to broadcast when a user or system component selects a set of channels (by name and ID) for a given ROI—identified by its suffix—along with the consumer responsible for the selection. It enables decoupled communication between ROI management UI components (e.g., channel selectors) and downstream consumers (e.g., visualization or processing modules) without tight coupling.
2. Public Interface
RegionOfInterestChannelsSelectedEvent Type:class (inherits from Prism.Events.PubSubEvent<RegionOfInterestChannelsSelectedEventArgs>) Behavior: A Prism event used to publish and subscribe to ROI channel selection changes. Subscribers receive an instance of RegionOfInterestChannelsSelectedEventArgs containing the selection details.
RegionOfInterestChannelsSelectedEventArgs Type:class Behavior: Encapsulates the payload of a channel selection event.
Constructor: RegionOfInterestChannelsSelectedEventArgs(string roiSuffix, string[] selectedChannelNames, long[] selectedChannelIds, object o)
Initializes the event args with the ROI suffix, selected channel names, selected channel IDs, and the consumer object. All properties are set once and immutable after construction.
Properties:
string RegionOfInterestSuffix { get; } — The suffix identifying the ROI (e.g., "Brain", "Tumor"), used to correlate the selection with a specific ROI context.
string[] ChannelNames { get; } — Ordered array of selected channel names (e.g., ["Red", "Green"]). May be empty.
long[] ChannelIds { get; } — Ordered array of corresponding selected channel IDs (e.g., [101L, 102L]). Must be same length as ChannelNames.
object Consumer { get; } — The object (typically a view model or service) that triggered or is responsible for the selection. Used to avoid re-processing events originating from the same consumer.
3. Invariants
ChannelNames.Length == ChannelIds.Length must hold for all valid instances (enforced by caller; no runtime validation is present in the class).
RegionOfInterestSuffix is non-null and non-empty (implied by usage context; not validated in the constructor).
ChannelNames and ChannelIds arrays are never null (constructor assigns them directly; caller must provide non-null arrays).
Consumer may be null, but typically represents a unique consumer instance to prevent echo loops.
The order of elements in ChannelNames and ChannelIds is semantically meaningful (i.e., index i in ChannelNames corresponds to index i in ChannelIds).
4. Dependencies
Dependencies on this module:
Prism.Events (via PubSubEvent<T>) — Required for event publication/subscription.
Prism.Regions — Imported but not used in this file (likely a remnant or for future extension).
Dependencies of this module:
Consumers of RegionOfInterestChannelsSelectedEvent (e.g., view models, services) must subscribe to it using Prism’s event aggregator.
Publishers must provide valid RegionOfInterestChannelsSelectedEventArgs instances.
Inferred consumers:
Any module handling ROI-specific channel logic (e.g., rendering, analysis pipelines) likely subscribes to this event.
5. Gotchas
No validation of array lengths or nulls in the constructor — Callers must ensure selectedChannelNames and selectedChannelIds are non-null and of equal length; otherwise, downstream consumers may encounter IndexOutOfRangeException or inconsistent state.
Consumer is an object — No type safety or interface contract is enforced. Subscribers must cast or check the type themselves (e.g., is IRegionOfInterestConsumer), risking runtime errors if misused.
Prism.Regions is imported but unused — Suggests possible historical or future use (e.g., region-scoped events), but currently adds no value and may confuse readers.
No documentation of expected ROI suffix format — The meaning of RegionOfInterestSuffix (e.g., casing, allowed characters) is application-specific and not defined here.
No mechanism to distinguish initial selection vs. subsequent updates — Subscribers must track state themselves to avoid redundant processing.
No cancellation or error handling support — The event is fire-and-forget; subscribers cannot signal failure or abort propagation.
