Initial

resources/app/client/pixi/extensions/observable-transform.js

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+/**
+ * A custom Transform class allowing to observe changes with a callback.
+ * @extends PIXI.Transform
+ *
+ * @param {Function} callback          The callback called to observe changes.
+ * @param {Object} scope               The scope of the callback.
+ */
+class ObservableTransform extends PIXI.Transform {
+  constructor(callback, scope) {
+    super();
+    if ( !(callback instanceof Function) ) {
+      throw new Error("The callback bound to an ObservableTransform class must be a valid function.")
+    }
+    if ( !(scope instanceof Object) ) {
+      throw new Error("The scope bound to an ObservableTransform class must be a valid object/class.")
+    }
+    this.scope = scope;
+    this.cb = callback;
+  }
+
+  /**
+   * The callback which is observing the changes.
+   * @type {Function}
+   */
+  cb;
+
+  /**
+   * The scope of the callback.
+   * @type {Object}
+   */
+  scope;
+
+  /* -------------------------------------------- */
+  /*  Methods                                     */
+  /* -------------------------------------------- */
+
+  /** @inheritDoc */
+  onChange() {
+    super.onChange();
+    this.cb.call(this.scope);
+  }
+
+  /* -------------------------------------------- */
+
+  /** @inheritDoc */
+  updateSkew() {
+    super.updateSkew();
+    this.cb.call(this.scope);
+  }
+}