<?php
function graphstat_generate_imagemap_coords($values, $standard_deviation = NULL) {
  $coords = array();
	if ($standard_deviation) {
    foreach ($values as $key => $value) {
      $max[] = $value + $standard_deviation[$key];
    }
  }
  else {
    $max = $values;
  }
  $y_scale = _graphstat_y_scale(max($max));
			
  $x_offset_bar = 70;
  $y_offset_bar = 90;
	$t1 = '0';
  foreach ($values as $key => $value) {
    $height = 199 - ($value / $y_scale * 200);
		$coords[$t1] = $x_offset_bar .','. $height .' '. $y_offset_bar .',199';
    $x_offset_bar = $x_offset_bar + 30;
    $y_offset_bar = $y_offset_bar + 30;
		$t1 = $t1 + 2;
  }
	
	return $coords;
}

/**
 * Determine maximum y-axis value
 */
function _graphstat_y_scale($max) {
  $y_scale = 1;
  $odd = 1;
  while ($y_scale <= ($max + (0.1 * $max))) {
    if ($odd % 2) {
      $y_scale = $y_scale * 5;
    }
    else {
      $y_scale = $y_scale * 2;
    }
    $odd++;
  }
  return $y_scale;
}