Refactored line drawing for Bezier edges (#3122)

Code in the `_line()` of the sibling Bezier edge types was either extremely similar or identical.
The Bezier drawing code has been consolidated in a single method in the parent class.

lib/network/modules/components/edges/BezierEdgeDynamic.js

@@ -103,20 +103,7 @@ class BezierEdgeDynamic extends BezierEdgeBase {
    * @private
    */
   _line(ctx, values, viaNode) {
-    // draw a straight line
-    ctx.beginPath();
-    ctx.moveTo(this.fromPoint.x, this.fromPoint.y);
-    // fallback to normal straight edges
-    if (viaNode.x === undefined) {
-      ctx.lineTo(this.toPoint.x, this.toPoint.y);
-    }
-    else {
-      ctx.quadraticCurveTo(viaNode.x, viaNode.y, this.toPoint.x, this.toPoint.y);
-    }
-    // draw shadow if enabled
-    this.enableShadow(ctx, values);
-    ctx.stroke();
-    this.disableShadow(ctx, values);
+    this._bezierCurve(ctx, values, viaNode);
   }
 
   getViaNode() {

lib/network/modules/components/edges/BezierEdgeStatic.js

@@ -11,21 +11,7 @@ class BezierEdgeStatic extends BezierEdgeBase {
    * @private
    */
   _line(ctx, values, viaNode) {
-    // draw a straight line
-    ctx.beginPath();
-    ctx.moveTo(this.fromPoint.x, this.fromPoint.y);
-
-    // fallback to normal straight edges
-    if (viaNode.x === undefined) {
-      ctx.lineTo(this.toPoint.x, this.toPoint.y);
-    }
-    else {
-      ctx.quadraticCurveTo(viaNode.x, viaNode.y, this.toPoint.x, this.toPoint.y);
-    }
-    // draw shadow if enabled
-    this.enableShadow(ctx, values);
-    ctx.stroke();
-    this.disableShadow(ctx, values);
+    this._bezierCurve(ctx, values, viaNode);
   }
 
   getViaNode() {

lib/network/modules/components/edges/CubicBezierEdge.js

@@ -14,22 +14,7 @@ class CubicBezierEdge extends CubicBezierEdgeBase {
     // get the coordinates of the support points.
     let via1 = viaNodes[0];
     let via2 = viaNodes[1];
-
-    // start drawing the line.
-    ctx.beginPath();
-    ctx.moveTo(this.fromPoint.x, this.fromPoint.y);
-
-    // fallback to normal straight edges
-    if (viaNodes === undefined || via1.x === undefined) {
-      ctx.lineTo(this.toPoint.x, this.toPoint.y);
-    }
-    else {
-      ctx.bezierCurveTo(via1.x, via1.y, via2.x, via2.y, this.toPoint.x, this.toPoint.y);
-    }
-    // draw shadow if enabled
-    this.enableShadow(ctx, values);
-    ctx.stroke();
-    this.disableShadow(ctx, values);
+    this._bezierCurve(ctx, values, via1, via2);
   }
 
   _getViaCoordinates() {
@@ -90,4 +75,4 @@ class CubicBezierEdge extends CubicBezierEdgeBase {
 }
 
 
-export default CubicBezierEdge;
+export default CubicBezierEdge;

lib/network/modules/components/edges/util/BezierEdgeBase.js

@@ -101,6 +101,47 @@ class BezierEdgeBase extends EdgeBase {
 
     return minDistance;
   }
+
+
+  /**
+   * Draw a bezier curve between two nodes
+   *
+   * The method accepts zero, one or two control points.
+   * Passing zero control points just draws a straight line
+   *
+   * @param {CanvasRenderingContext2D} ctx
+   * @param {Object}           values   | options for shadow drawing
+   * @param {Object|undefined} viaNode1 | first control point for curve drawing
+   * @param {Object|undefined} viaNode2 | second control point for curve drawing
+   *
+   * @protected
+   */
+  _bezierCurve(ctx, values, viaNode1, viaNode2) {
+    var hasNode1 = (viaNode1 !== undefined && viaNode1.x !== undefined);
+    var hasNode2 = (viaNode2 !== undefined && viaNode2.x !== undefined);
+
+    ctx.beginPath();
+    ctx.moveTo(this.fromPoint.x, this.fromPoint.y);
+
+    if (hasNode1 && hasNode2) {
+      ctx.bezierCurveTo(viaNode1.x, viaNode1.y, viaNode2.x, viaNode2.y, this.toPoint.x, this.toPoint.y);
+    } else if (hasNode1) {
+      ctx.quadraticCurveTo(viaNode1.x, viaNode1.y, this.toPoint.x, this.toPoint.y);
+    } else {
+      // fallback to normal straight edge
+      ctx.lineTo(this.toPoint.x, this.toPoint.y);
+    }
+
+    // draw shadow if enabled
+    this.enableShadow(ctx, values);
+    ctx.stroke();
+    this.disableShadow(ctx, values);
+  }
+
+
+  getViaNode() {
+    return this._getViaCoordinates();
+  }
 }
 
-export default BezierEdgeBase;
+export default BezierEdgeBase;