GanttArrow.php

<?php
/**
 * Copyright (C) 2022 Graham Breach
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
/**
 * For more information, please contact <graham@goat1000.com>
 */

namespace Goat1000\SVGGraph;

/**
 * A class for drawing arrows
 */
class GanttArrow extends Arrow {

  protected $type = 0;
  protected $vsplit = false;
  protected $space = 10;

  public function __construct(Point $a, Point $b, $wa, $ha, $wb, $hb, $type, $sp)
  {
    switch($type) {

    case 'SS':
      $this->vsplit = ($a->x < $b->x);
      break;

    case 'FF':
      $a->x += $wa;
      $b->x += $wb;
      $this->vsplit = ($a->x > $b->x);
      break;

    case 'SF':
      $b->x += $wb;
      $this->vsplit = ($a->x < $b->x);
      break;

    case 'FS':
    default:
      $a->x += $wa;
      $this->vsplit = ($a->x > $b->x);
    }
    $a->y += $ha;

    // only start horizontal if the first element has some width
    if($wa < 1)
      $this->vsplit = true;

    parent::__construct($a, $b);
    $this->type = $type;
    $this->space = max(5, $sp);
  }

  /**
   * Returns the PathData for an arrow line
   */
  protected function getArrowPath()
  {
    $p = new PathData('M', $this->a);
    $dx = $this->b->x - $this->a->x;
    $dy = $this->b->y - $this->a->y;

    if($dx && $this->vsplit) {
      $v1 = new Number($dy - $this->space);
      $v2 = new Number($this->space);
      $p->add('v', $v1);
      $p->add('h', new Number($dx));
      $p->add('v', $v2);

    } else {
      // if horizontal very small, ignore it
      if(abs($dx) > 0.1)
        $p->add('h', new Number($dx));
      $p->add('v', new Number($this->b->y - $this->a->y));
    }
    return $p;
  }
}