Typing indicator (typing chat bubble) (#8215)

Content.Client/Chat/TypingIndicator/TypingIndicatorVisualizerSystem.cs

@@ -0,0 +1,50 @@
+using Content.Shared.Chat.TypingIndicator;
+using Robust.Client.GameObjects;
+using Robust.Client.Graphics;
+using Robust.Shared.Prototypes;
+
+namespace Content.Client.Chat.TypingIndicator;
+
+public sealed class TypingIndicatorVisualizerSystem : VisualizerSystem<TypingIndicatorComponent>
+{
+    [Dependency] private readonly IPrototypeManager _prototypeManager = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+        SubscribeLocalEvent<TypingIndicatorComponent, ComponentInit>(OnInit);
+    }
+
+    private void OnInit(EntityUid uid, TypingIndicatorComponent component, ComponentInit args)
+    {
+        if (!TryComp(uid, out SpriteComponent? sprite))
+            return;
+
+        if (!_prototypeManager.TryIndex<TypingIndicatorPrototype>(component.Prototype, out var proto))
+        {
+            Logger.Error($"Unknown typing indicator id: {component.Prototype}");
+            return;
+        }
+
+        var layer = sprite.LayerMapReserveBlank(TypingIndicatorLayers.Base);
+        sprite.LayerSetRSI(layer, proto.SpritePath);
+        sprite.LayerSetState(layer, proto.TypingState);
+        sprite.LayerSetShader(layer, proto.Shader);
+        sprite.LayerSetOffset(layer, proto.Offset);
+        sprite.LayerSetVisible(layer, false);
+    }
+
+    protected override void OnAppearanceChange(EntityUid uid, TypingIndicatorComponent component, ref AppearanceChangeEvent args)
+    {
+        base.OnAppearanceChange(uid, component, ref args);
+
+        if (!TryComp(uid, out SpriteComponent? sprite))
+            return;
+
+        args.Component.TryGetData(TypingIndicatorVisuals.IsTyping, out bool isTyping);
+        if (sprite.LayerMapTryGet(TypingIndicatorLayers.Base, out var layer))
+        {
+            sprite.LayerSetVisible(layer, isTyping);
+        }
+    }
+}