feat: solve the problem of circular dependency.

Author: drawcall

src/core/Particle.js

@@ -4,6 +4,7 @@
 import Rgb from "../utils/Rgb";
 import Puid from "../utils/Puid";
 import Util from "../utils/Util";
+import PropUtil from "../utils/PropUtil";
 import ease from "../math/ease";
 import Vector2D from "../math/Vector2D";
 import MathUtil from "../math/MathUtil";
@@ -62,7 +63,7 @@ export default class Particle {
 
     this.rgb = new Rgb();
     this.reset();
-    conf && Util.setProp(this, conf);
+    conf && PropUtil.setProp(this, conf);
   }
 
   getDirection() {

src/initialize/InitializeUtil.js

@@ -1,4 +1,4 @@
-import Util from "../utils/Util";
+import PropUtil from "../utils/PropUtil";
 import Initialize from "./Initialize";
 import MathUtil from "../math/MathUtil";
 
@@ -20,8 +20,8 @@ export default {
 
   // init
   init(emitter, particle, initialize) {
-    Util.setProp(particle, initialize);
-    Util.setVectorVal(particle, initialize);
+    PropUtil.setProp(particle, initialize);
+    PropUtil.setVectorVal(particle, initialize);
   },
 
   bindEmitter(emitter, particle) {

src/utils/PropUtil.js

@@ -0,0 +1,63 @@
+export default {
+  hasProp(target, key) {
+    if (!target) return false;
+    return target[key] !== undefined;
+    // return obj.hasOwnProperty(key);
+  },
+
+  /**
+   * set the prototype in a given prototypeObject
+   *
+   * @memberof Proton#Proton.Util
+   * @method setProp
+   *
+   * @todo add description for param `target`
+   * @todo translate desription from chinese to english
+   *
+   * @param {Object} target
+   * @param {Object} prototypeObject An object of single prototypes
+   *
+   * @return {Object} target
+   */
+  setProp(target, props) {
+    for (let prop in props) {
+      if (target.hasOwnProperty(prop)) {
+        target[prop] = Span.getSpanValue(props[prop]);
+      }
+    }
+
+    return target;
+  },
+
+  /**
+   * @memberof Proton#Proton.Util
+   * @method setVectorVal
+   *
+   * @todo add description for param `target`
+   * @todo add description for param `conf`
+   * @todo add description for function
+   *
+   * @param {Object} target
+   * @param {Object} conf
+   */
+  setVectorVal(particle, conf = null) {
+    if (!conf) return;
+
+    if (this.hasProp(conf, "x")) particle.p.x = conf["x"];
+    if (this.hasProp(conf, "y")) particle.p.y = conf["y"];
+
+    if (this.hasProp(conf, "vx")) particle.v.x = conf["vx"];
+    if (this.hasProp(conf, "vy")) particle.v.y = conf["vy"];
+
+    if (this.hasProp(conf, "ax")) particle.a.x = conf["ax"];
+    if (this.hasProp(conf, "ay")) particle.a.y = conf["ay"];
+
+    if (this.hasProp(conf, "p")) particle.p.copy(conf["p"]);
+    if (this.hasProp(conf, "v")) particle.v.copy(conf["v"]);
+    if (this.hasProp(conf, "a")) particle.a.copy(conf["a"]);
+
+    if (this.hasProp(conf, "position")) particle.p.copy(conf["position"]);
+    if (this.hasProp(conf, "velocity")) particle.v.copy(conf["velocity"]);
+    if (this.hasProp(conf, "accelerate")) particle.a.copy(conf["accelerate"]);
+  }
+};

src/utils/Util.js

@@ -1,4 +1,3 @@
-import Span from "../math/Span";
 import ImgUtil from "./ImgUtil";
 
 export default {
@@ -86,68 +85,6 @@ export default {
     }
   },
 
-  /**
-   * @memberof Proton#Proton.Util
-   * @method setVectorVal
-   *
-   * @todo add description for param `target`
-   * @todo add description for param `conf`
-   * @todo add description for function
-   *
-   * @param {Object} target
-   * @param {Object} conf
-   */
-  setVectorVal(particle, conf = null) {
-    if (!conf) return;
-
-    if (this.hasProp(conf, "x")) particle.p.x = conf["x"];
-    if (this.hasProp(conf, "y")) particle.p.y = conf["y"];
-
-    if (this.hasProp(conf, "vx")) particle.v.x = conf["vx"];
-    if (this.hasProp(conf, "vy")) particle.v.y = conf["vy"];
-
-    if (this.hasProp(conf, "ax")) particle.a.x = conf["ax"];
-    if (this.hasProp(conf, "ay")) particle.a.y = conf["ay"];
-
-    if (this.hasProp(conf, "p")) particle.p.copy(conf["p"]);
-    if (this.hasProp(conf, "v")) particle.v.copy(conf["v"]);
-    if (this.hasProp(conf, "a")) particle.a.copy(conf["a"]);
-
-    if (this.hasProp(conf, "position")) particle.p.copy(conf["position"]);
-    if (this.hasProp(conf, "velocity")) particle.v.copy(conf["velocity"]);
-    if (this.hasProp(conf, "accelerate")) particle.a.copy(conf["accelerate"]);
-  },
-
-  hasProp(target, key) {
-    if (!target) return false;
-    return target[key] !== undefined;
-    // return obj.hasOwnProperty(key);
-  },
-
-  /**
-   * set the prototype in a given prototypeObject
-   *
-   * @memberof Proton#Proton.Util
-   * @method setProp
-   *
-   * @todo add description for param `target`
-   * @todo translate desription from chinese to english
-   *
-   * @param {Object} target
-   * @param {Object} prototypeObject An object of single prototypes
-   *
-   * @return {Object} target
-   */
-  setProp(target, props) {
-    for (let prop in props) {
-      if (target.hasOwnProperty(prop)) {
-        target[prop] = Span.getSpanValue(props[prop]);
-      }
-    }
-
-    return target;
-  },
-
   /**
    * This will get the image data. It could be necessary to create a Proton.Zone.
    *