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Data Input Watchers

Often you are interested in knowing when the value of a data input changes. For example, let's say you have the following code that lets the user select a file from the MyPluginFiles directory in the data folder:

[DataInput]
[AutoCompleteList(nameof(AutoCompletePluginFiles), forceSelection: true)]
public string SelectedFile;

protected async UniTask<AutoCompleteList> AutoCompletePluginFiles() {
return AutoCompleteList.Single(Context.PersistentDataManager.GetFileEntries("MyPluginFiles").Select(it => new AutoCompleteEntry {
label = it.fileName,
value = it.path
}));
}

You want to know when the user selects a new file. The naive way is to check the value of SelectedFile every frame, but this is inefficient and cumbersome. Instead, you can register a watcher in OnCreate():

protected override void OnCreate() {
base.OnCreate();
Watch<string>(nameof(SelectedFile), OnSelectedFileChanged);
}

protected void OnSelectedFileChanged(string from, string to) {
if (to == null) {
// The user has cleared the selected file
}
// More logic to handle the file change
}

You can also watch another entity's data input by using the overloaded Watch<T>(Entity otherEntity, string dataInputKey, Action<T, T> onChange, bool deep = true) method.

提示

Watchers are automatically unregistered when the entity is destroyed.

Watching Asset States

Sometimes, you want to watch more than just the value change. For example, consider the following simple asset that prints a message whenever the user selects a new Character:

[DataInput]
public CharacterAsset Character;

protected override void OnCreate() {
base.OnCreate();
Watch<CharacterAsset>(nameof(Character), OnCharacterChanged);
}

protected void OnCharacterChanged(CharacterAsset from, CharacterAsset to) {
if (to != null) Debug.Log("New character file selected! " + to.Source);
}

However, the watcher is only triggered when the value of Character data input in the current asset changes; that means if the scene has two characters, the watcher is triggered when the user changes from one character to another. However, let's say there is only one character asset in the scene, and the user goes into the character asset and change the Source data input, then this watcher will not be triggered.

In this case, you can use WatchAsset:

protected override void OnCreate() {
base.OnCreate();
WatchAsset(nameof(Character), OnCharacterChanged);
}

protected void OnCharacterChanged() {
if (Character.IsNonNullAndActive()) Debug.Log("New character file selected! " + Character.Source);
}

The watcher is now triggered both when the value of Character changes and when the Source data input of the Character asset changes.

信息

Why does this work? The WatchAsset method will additionally trigger the watcher when an asset's active state changes. In Warudo, all assets that have a Source data input toggles the active state based on the Source data input. For example, CharacterAsset uses Source to load a .vrm model or .warudo character mod, PropAsset uses Source to load a .warudo prop mod, and so on. The active state is only true if the Source is successfully loaded.

Say we have a currently active asset with a Source selected. When the user selects a new Source, the active state is set to false (triggering the watcher), and then if the new Source is successfully loaded, set to true again (triggering the watcher again). In the above code, only the second trigger will print the message, since when the first trigger is called, the character asset is not yet active.

Watching Multiple Data Inputs

If you need to watch multiple data inputs and only care about executing a callback function when any of them changes, you can use the WatchAll method:

protected override void OnCreate() {
base.OnCreate();
WatchAll(new [] { nameof(A), nameof(B), nameof(C) }, OnAnyDataInputChanged);
}

protected void OnAnyDataInputChanged() {
// Called when A, B, or C changes
}

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上次更新于 2024.07.11