neyric/wireit

YUI.add('arrow-wire', function (Y, NAME) {

'use strict';

/**
 * @module arrow-wire
 */

/**
 * Extend CanvasWire to draw an arrow wire
 * @class ArrowWire
 * @extends WireBase
 * @constructor
 * @param {Object} config the configuration for the ArrowWire attributes
 */
Y.ArrowWire = function (config) {
   Y.ArrowWire.superclass.constructor.apply(this, arguments);
};

Y.ArrowWire.NAME = 'arrowwire';

Y.extend(Y.ArrowWire, Y.WireBase, {

   _drawArrow: function(src, tgt) {


      var d = 7, // arrow width/2
          distance = Math.sqrt(Math.pow(src[0]-tgt[0],2) + Math.pow(src[1]-tgt[1],2)),
          dlug = 20, //arrow length
          t = (distance === 0) ? 0 : 1 - (dlug/distance),

          //point on the wire with constant distance (dlug) from terminal2
          z = [
            Math.abs( src[0] + t * (tgt[0] - src[0]) ),
            Math.abs( src[1] + t * (tgt[1] - src[1]) )
          ],

      // start drawing arrows

      // line which connects the terminals: y=ax+b
          W = src[0] - tgt[0],
          Wa = src[1] - tgt[1],
          Wb = src[0] * tgt[1] - src[1] * tgt[0],
          a, b, aProst, bProst,
          A,B,C,
          delta,
          x1,x2,y1,y2,
          o;

      if (W !== 0) {
         a = Wa / W;
         b = Wb / W;
      }
      else {
         a = 0;
      }
      
      // line perpendicular to the main line: y = aProst*x + b
      if (a === 0) {
         aProst = 0;
      }
      else {
         aProst = -1 / a;
      }
      bProst = z[1] - aProst * z[0]; //point z lays on this line
        
      // we have to calculate coordinates of 2 points, which lay on perpendicular line and have the same distance (d) from point z
      A = 1 + Math.pow(aProst, 2);
      B = 2 * aProst * bProst - 2 * z[0] - 2 * z[1] * aProst;
      C = -2 * z[1] * bProst + Math.pow(z[0], 2) + Math.pow(z[1], 2) - Math.pow(d, 2) + Math.pow(bProst, 2);

      delta = Math.pow(B, 2) - 4 * A * C;
      if (delta < 0) { return; }
        
      x1 = (-B + Math.sqrt(delta)) / (2 * A);
      x2 = (-B - Math.sqrt(delta)) / (2 * A);
      y1 = aProst * x1 + bProst;
      y2 = aProst * x2 + bProst;
        
      if (src[1] === tgt[1]) {
         o = (src[0] > tgt[0]) ? 1 : -1;
         x1 = tgt[0] + o * dlug;
         x2 = x1;
         y1 -= d;
         y2 += d;
      }

      // triangle border
      this.moveTo(tgt[0] + 6, tgt[1] + 6);
      this.lineTo(x1 + 6, y1 + 6);
      this.moveTo(tgt[0] + 6, tgt[1] + 6);
      this.lineTo(x2 + 6, y2 + 6);

   },

   /**
    * @method _draw
    * @private
    */
   _draw: function () {

      this.clear();

      var src = this.get('src').getXY(),
          tgt = this.get('tgt').getXY();


      this.moveTo((src[0] + 6), (src[1] + 6));
      this.lineTo((tgt[0] + 6), (tgt[1] + 6));

      this._drawArrow(src, tgt);

      this.end();
   }
});

Y.ArrowWire.ATTRS = Y.merge(Y.WireBase.ATTRS, {});


}, '@VERSION@', {"requires": ["wire-base"]});