Class WatchersSystem
The Watchers provides an optional high-level helper for getting callback-like functionality in an Entity Component System (ECS) environment.
Inheritance
Namespace: Unity.Tiny.Watchers
Syntax
public class WatchersSystem : ComponentSystemRemarks
While callbacks are not a very ECS-friendly concept (Components store only data, and systems contain only code that operates on data), callback-like functionality can be useful for certain things.
For example, you can use watchers for UI event handlers such as OnClick, or to get notifications about the state of a tween animation such as OnEnded or OnLoopPoint.
The base DefaultWatchersSystem is auto-scheduled and watchers may be added immediately. For advanced use cases it is possible to schedule additional WatchersSystem by creating a new subclass and scheduling it where desired.
WatchersSystems are standalone systems that group multiple watched values. A WatchersSystems must be scheduled as a system in order to trigger delegates/callbacks.
Callbacks have the same restrictions as code running in ComponentSystem. They are called from the watching system, just like code called from any other ComponentSystem. They are executed when the watching system runs, and not immediately when a value changes.
Methods
OnUpdate()
Declaration
protected override void OnUpdate()RemoveAllWatchers()
Removes all watchers in this system
Declaration
public void RemoveAllWatchers()RemoveWatcher(Int32)
Removes a watcher with a specific id.
Declaration
public bool RemoveWatcher(int id)Parameters
| Type | Name | Description |
|---|---|---|
| System.Int32 | id |
Returns
| Type | Description |
|---|---|
| System.Boolean | Returns true if the watcher was found and removed. |
Remarks
Ids are returned by the various Watch* functions. Watchers can also be removed by returning false from the delegate callback.
WatchChanged(Entity, TypeManager.FieldInfo, WatchersSystem.WatchValueDelegateBool)
Watches an entity for changes to a bool component.
Declaration
public int WatchChanged(Entity e, TypeManager.FieldInfo fieldInfo, WatchersSystem.WatchValueDelegateBool callback)Parameters
| Type | Name | Description |
|---|---|---|
| Entity | e | |
| TypeManager.FieldInfo | fieldInfo | |
| WatchersSystem.WatchValueDelegateBool | callback |
Returns
| Type | Description |
|---|---|
| System.Int32 |
WatchChanged(Entity, TypeManager.FieldInfo, WatchersSystem.WatchValueDelegateFloat)
Watches an entity for changes to a float component.
Declaration
public int WatchChanged(Entity e, TypeManager.FieldInfo fieldInfo, WatchersSystem.WatchValueDelegateFloat callback)Parameters
| Type | Name | Description |
|---|---|---|
| Entity | e | Target entity to watch. |
| TypeManager.FieldInfo | fieldInfo | The field to watch; generally implicitly cast from the supplied string, for example "Translation.position.x", "TweenComponent.ended", or "SequencePlayer.playing". |
| WatchersSystem.WatchValueDelegateFloat | callback | Delegate method to call when the value changes. |
Returns
| Type | Description |
|---|---|
| System.Int32 | An id that can be passed to RemoveWatcher(Int32) |
Remarks
Note that all watching callbacks are called when the watching system runs, not when the value is changed.
WatchChanged(Entity, TypeManager.FieldInfo, WatchersSystem.WatchValueDelegateInt)
Watches an entity for changes to a int component.
Declaration
public int WatchChanged(Entity e, TypeManager.FieldInfo fieldInfo, WatchersSystem.WatchValueDelegateInt callback)Parameters
| Type | Name | Description |
|---|---|---|
| Entity | e | |
| TypeManager.FieldInfo | fieldInfo | |
| WatchersSystem.WatchValueDelegateInt | callback |
Returns
| Type | Description |
|---|---|
| System.Int32 |