refactor: move selection rendering to dedicated UILayer

src/client/graphics/layers/UILayer.ts

@@ -0,0 +1,207 @@
+import { Colord } from "colord";
+import { Theme } from "../../../core/configuration/Config";
+import { UnitType } from "../../../core/game/Game";
+import { Layer } from "./Layer";
+import { EventBus } from "../../../core/EventBus";
+import { ClientID } from "../../../core/Schemas";
+import { GameView, UnitView } from "../../../core/game/GameView";
+import { UnitSelectionEvent } from "../../InputHandler";
+import { TransformHandler } from "../TransformHandler";
+
+/**
+ * Layer responsible for drawing UI elements that overlay the game
+ * such as selection boxes, health bars, etc.
+ */
+export class UILayer implements Layer {
+  private canvas: HTMLCanvasElement;
+  private context: CanvasRenderingContext2D;
+
+  private theme: Theme = null;
+  private selectionAnimTime = 0;
+
+  // Keep track of currently selected unit
+  private selectedUnit: UnitView | null = null;
+
+  // Keep track of previous selection box position for cleanup
+  private lastSelectionBoxCenter: {
+    x: number;
+    y: number;
+    size: number;
+  } | null = null;
+
+  // Visual settings for selection
+  private readonly SELECTION_BOX_SIZE = 6; // Size of the selection box (should be larger than the warship)
+
+  constructor(
+    private game: GameView,
+    private eventBus: EventBus,
+    private clientID: ClientID,
+    private transformHandler: TransformHandler,
+  ) {
+    this.theme = game.config().theme();
+  }
+
+  shouldTransform(): boolean {
+    return true;
+  }
+
+  tick() {
+    // Update the selection animation time
+    this.selectionAnimTime = (this.selectionAnimTime + 1) % 60;
+
+    // If there's a selected warship, redraw to update the selection box animation
+    if (this.selectedUnit && this.selectedUnit.type() === UnitType.Warship) {
+      this.drawSelectionBox(this.selectedUnit);
+    }
+  }
+
+  init() {
+    this.eventBus.on(UnitSelectionEvent, (e) => this.onUnitSelection(e));
+    this.redraw();
+  }
+
+  renderLayer(context: CanvasRenderingContext2D) {
+    context.drawImage(
+      this.canvas,
+      -this.game.width() / 2,
+      -this.game.height() / 2,
+      this.game.width(),
+      this.game.height(),
+    );
+  }
+
+  redraw() {
+    this.canvas = document.createElement("canvas");
+    this.context = this.canvas.getContext("2d");
+
+    this.canvas.width = this.game.width();
+    this.canvas.height = this.game.height();
+  }
+
+  /**
+   * Handle the unit selection event
+   */
+  private onUnitSelection(event: UnitSelectionEvent) {
+    if (event.isSelected) {
+      this.selectedUnit = event.unit;
+      if (event.unit && event.unit.type() === UnitType.Warship) {
+        this.drawSelectionBox(event.unit);
+      }
+    } else {
+      if (this.selectedUnit === event.unit) {
+        // Clear the selection box
+        if (this.lastSelectionBoxCenter) {
+          const { x, y, size } = this.lastSelectionBoxCenter;
+          this.clearSelectionBox(x, y, size);
+          this.lastSelectionBoxCenter = null;
+        }
+        this.selectedUnit = null;
+      }
+    }
+  }
+
+  /**
+   * Clear the selection box at a specific position
+   */
+  private clearSelectionBox(x: number, y: number, size: number) {
+    for (let px = x - size; px <= x + size; px++) {
+      for (let py = y - size; py <= y + size; py++) {
+        if (
+          px === x - size ||
+          px === x + size ||
+          py === y - size ||
+          py === y + size
+        ) {
+          this.clearCell(px, py);
+        }
+      }
+    }
+  }
+
+  /**
+   * Draw a selection box around the given unit
+   */
+  public drawSelectionBox(unit: UnitView) {
+    if (!unit || !unit.isActive()) {
+      return;
+    }
+
+    // Use the configured selection box size
+    const selectionSize = this.SELECTION_BOX_SIZE;
+
+    // Calculate pulsating effect based on animation time (25% variation in opacity)
+    const baseOpacity = 200;
+    const pulseAmount = 55;
+    const opacity =
+      baseOpacity + Math.sin(this.selectionAnimTime * 0.1) * pulseAmount;
+
+    // Get the unit's owner color for the box
+    const ownerColor = this.theme.territoryColor(unit.owner().info());
+
+    // Create a brighter version of the owner color for the selection
+    const selectionColor = ownerColor.lighten(0.2);
+
+    // Get current center position
+    const center = unit.tile();
+    const centerX = this.game.x(center);
+    const centerY = this.game.y(center);
+
+    // Clear previous selection box if it exists and is different from current position
+    if (
+      this.lastSelectionBoxCenter &&
+      (this.lastSelectionBoxCenter.x !== centerX ||
+        this.lastSelectionBoxCenter.y !== centerY)
+    ) {
+      const lastSize = this.lastSelectionBoxCenter.size;
+      const lastX = this.lastSelectionBoxCenter.x;
+      const lastY = this.lastSelectionBoxCenter.y;
+
+      // Clear the previous selection box
+      this.clearSelectionBox(lastX, lastY, lastSize);
+    }
+
+    // Draw the selection box
+    for (let x = centerX - selectionSize; x <= centerX + selectionSize; x++) {
+      for (let y = centerY - selectionSize; y <= centerY + selectionSize; y++) {
+        // Only draw if it's on the border (not inside or outside the box)
+        if (
+          x === centerX - selectionSize ||
+          x === centerX + selectionSize ||
+          y === centerY - selectionSize ||
+          y === centerY + selectionSize
+        ) {
+          // Create a dashed effect by only drawing some pixels
+          const dashPattern = (x + y) % 2 === 0;
+          if (dashPattern) {
+            this.paintCell(x, y, selectionColor, opacity);
+          }
+        }
+      }
+    }
+
+    // Store current selection box position for next cleanup
+    this.lastSelectionBoxCenter = {
+      x: centerX,
+      y: centerY,
+      size: selectionSize,
+    };
+  }
+
+  /**
+   * Draw health bar for a unit (placeholder for future implementation)
+   */
+  public drawHealthBar(unit: UnitView) {
+    // This is a placeholder for future health bar implementation
+    // It would draw a health bar above units that have health
+  }
+
+  paintCell(x: number, y: number, color: Colord, alpha: number) {
+    this.clearCell(x, y);
+    this.context.fillStyle = color.alpha(alpha / 255).toRgbString();
+    this.context.fillRect(x, y, 1, 1);
+  }
+
+  clearCell(x: number, y: number) {
+    this.context.clearRect(x, y, 1, 1);
+  }
+}