API reference

Component script

What a component's <script lang="cs"> may declare, and the Component class every component derives from. The attributes need no using.

Attributes

Declaration	Meaning
`[State] int count;`	Reactive state. The field becomes a property backed by a signal: assigning it updates what reads it. Make it `public` when game code sets it
`[Derived] string label => ...;`	A value computed from state. Cached; recomputed only when what it read changed; read-only
`[Prop] public string Title = "x";`	An input the parent sets: `<Card Title="Sword" />`. The initializer is the default
`[Prop(Required = true)] public Item Item;`	A prop the parent must give
`[Prop, Bindable] public float Value;`	A prop the child may assign. The parent writes `bind:Value={x}` and its `x` follows
`[Prop] public Action OnBuy;`	A callback prop: `OnBuy={() => Buy(item)}`
`[Effect] void Sync() { ... }`	Runs after the page updated, and again whenever state it read changes
`[Effect(EffectKind.Pre)] void Before() { ... }`	The same, before the page updates
`[Tick] float timeLeft => Round.TimeLeft;`	Read every frame. The page updates only when the value differs from last frame: for values game systems own

Avoid LINQ in [Derived] and [Tick]: it allocates on every run. Loops and interpolation do not.

Lifecycle

protected override void OnMount()   { /* the component's elements are in the page */ }
protected override void OnDestroy() { /* release what OnMount took */ }

Context

Context passes a value to every descendant without threading it through props.

using DevCore.UiEngine.Components;

public static readonly ContextKey<Theme> ThemeKey = new ContextKey<Theme>("theme");

SetContext(ThemeKey, theme);            // in an ancestor
var theme = GetContext(ThemeKey);       // in any descendant; default(T) when no ancestor set it

Texts

Member	Meaning
`T(string key)`	The text of `key` in the current locale. Reactive
`T(key, int \| long \| double count)`	The plural form for the number, with the number filled in
`T(key, params object[] args)`	The text with `{0}`, `{1}`… filled in, formatted for the locale
`Plural(key, long count)`	The plural form's text, not filled in. Allocates nothing

The Component class

DevCore.UiEngine.Components.Component. Generated component classes are sealed partial, so you can add members in another partial file.

Member	Meaning
`void Mount(Node target)`, `Mount(Node target, Node anchor)`	Builds the component's elements inside `target` (before `anchor`)
`void Destroy()`	Removes its elements, effects and children
`void ReplaceWith(Component replacement)`	Puts another component in its place
`Component Parent`, `IReadOnlyList<Component> Children`	The component tree
`Document Document`	The document it is mounted in
`Element RootElement`	Its first element
`bool IsMounted`, `bool IsDestroyed`	Its state
`bool Contains(Node node)`	Whether a node belongs to it
`Q`, `Q<T>`, `Query<T>`	Find elements and components inside it by name. See Queries by name
`static Component OwnerOf(Node node)`	The component a node belongs to
`static IReadOnlyList<Component> RootsOf(Document document)`	The components mounted directly in a document
`bool SetPropFromString(string name, string value)`	Sets a prop from text, as a page's HTML attributes do

Mounting from code

var view = GetComponent<UIView>();
var counter = view.Mount(new MyGame.UI.Counter());         // into the page's body
var toast = view.Mount(new MyGame.UI.Toast(), container);   // into an element

ComponentRegistry

Every compiled component registers itself by tag name and by full class name, so a page's HTML can use it as a tag.

Member	Meaning
`static void Register(string name, string fullName, Func<Component> factory)`	Registers a component
`static bool TryCreate(string name, out Component component)`	Creates one by tag name or full name
`static bool IsRegistered(string name)`	Whether a name is known
`static IEnumerable<string> Names`, `FullNames`	What is registered