Adding a GameMap class that helps tracking when the properties of the tiles the user is changes (when the user moves)

front/src/Phaser/Game/GameMap.ts

@@ -0,0 +1,97 @@
+import {ITiledMap} from "../Map/ITiledMap";
+
+export type PropertyChangeCallback = (oldValue: string | number | boolean | undefined, newValue: string | number | boolean | undefined) => void;
+
+/**
+ * A wrapper around a ITiledMap interface to provide additional capabilities.
+ * It is used to handle layer properties.
+ */
+export class GameMap {
+    private key: number|undefined;
+    private lastProperties = new Map<string, string|boolean|number>();
+    private callbacks = new Map<string, Array<PropertyChangeCallback>>();
+
+    public constructor(private map: ITiledMap) {
+    }
+
+    /**
+     * Sets the position of the current player (in pixels)
+     * This will trigger events if properties are changing.
+     */
+    public setPosition(x: number, y: number) {
+        const xMap = Math.floor(x / this.map.tilewidth);
+        const yMap = Math.floor(y / this.map.tileheight);
+        const key = xMap + yMap * this.map.width;
+        if (key === this.key) {
+            return;
+        }
+        this.key = key;
+
+        const newProps = this.getProperties(key);
+        const oldProps = this.lastProperties;
+
+        // Let's compare the 2 maps:
+        // First new properties vs oldProperties
+        for (const [newPropName, newPropValue] of newProps.entries()) {
+            const oldPropValue = oldProps.get(newPropName);
+            if (oldPropValue !== newPropValue) {
+                this.trigger(newPropName, oldPropValue, newPropValue);
+            }
+        }
+
+        for (const [oldPropName, oldPropValue] of oldProps.entries()) {
+            if (!newProps.has(oldPropName)) {
+                // We found a property that disappeared
+                this.trigger(oldPropName, oldPropValue, undefined);
+            }
+        }
+
+        this.lastProperties = newProps;
+    }
+
+    private getProperties(key: number): Map<string, string|boolean|number> {
+        const properties = new Map<string, string|boolean|number>();
+
+        for (const layer of this.map.layers) {
+            if (layer.type !== 'tilelayer') {
+                continue;
+            }
+            const tiles = layer.data as number[];
+            if (tiles[key] == 0) {
+                continue;
+            }
+            // There is a tile in this layer, let's embed the properties
+            if (layer.properties !== undefined) {
+                for (const layerProperty of layer.properties) {
+                    if (layerProperty.value === undefined) {
+                        continue;
+                    }
+                    properties.set(layerProperty.name, layerProperty.value);
+                }
+            }
+        }
+
+        return properties;
+    }
+
+    private trigger(propName: string, oldValue: string | number | boolean | undefined, newValue: string | number | boolean | undefined) {
+        let callbacksArray = this.callbacks.get(propName);
+        if (callbacksArray !== undefined) {
+            for (const callback of callbacksArray) {
+                callback(oldValue, newValue);
+            }
+        }
+    }
+
+    /**
+     * Registers a callback called when the user moves to a tile where the property propName is different from the last tile the user was on.
+     */
+    public onPropertyChange(propName: string, callback: PropertyChangeCallback) {
+        let callbacksArray = this.callbacks.get(propName);
+        if (callbacksArray === undefined) {
+            callbacksArray = new Array<PropertyChangeCallback>();
+            this.callbacks.set(propName, callbacksArray);
+        }
+        callbacksArray.push(callback);
+    }
+}