signaturefield.module

<?php
/**
 * @file
 * Signature Field module.
 */

/**
 * get list of modules and inlclude elements as required.
 */
foreach (module_list() as $module) {
  if (file_exists($file = dirname(__FILE__) . "/includes/{$module}.inc")) {
    require_once $file;
  }
}


/**
 * Converts SignatureField json string to a png image
 */
function signaturefield_json_to_image($element, $json) {
  $src_image = imagecreatetruecolor($element['#width'] * 12, $element['#height'] * 12);
  $color = _signaturefield_hex2rgb($element['#color']);
  $bg = imagecolorallocatealpha($src_image, 0, 0, 0, 127);
  $pen = imagecolorallocate($src_image, $color[0], $color[1], $color[2]);
  imagefill($src_image, 0, 0, $bg);

  $json = is_string($json) ? json_decode($json) : $json;

  foreach ($json as $coord) {
    signaturefield_drawline($src_image, $coord->lx * 12, $coord->ly * 12, $coord->mx * 12, $coord->my * 12, $pen, 2 * (12 / 2));
  }

  // Preserve transparency settings.
  imagealphablending($src_image, TRUE);
  imagesavealpha($src_image, TRUE);

  $dest_image = imagecreatetruecolor($element['#width'], $element['#height']);

  $bg = imagecolorallocatealpha($dest_image, 0, 0, 0, 127);
  imagefill($dest_image, 0, 0, $bg);

  // Preserve transparency settings.
  imagealphablending($dest_image, TRUE);
  imagesavealpha($dest_image, TRUE);

  imagecopyresampled($dest_image, $src_image, 0, 0, 0, 0, $element['#width'], $element['#width'], $element['#width'] * 12, $element['#width'] * 12);

  imagedestroy($src_image);
  $dir = drupal_realpath(file_default_scheme() . '://signaturefield/');

  if (file_prepare_directory($dir, FILE_CREATE_DIRECTORY)) {
    $filepath = "{$dir}/" . time() . rand(1000, 9999) . '.png';
    imagepng($dest_image, $filepath);
    imagedestroy($dest_image);

    return serialize(
      array(
        'json' => json_encode($json),
        'filepath' => str_replace($dir, file_default_scheme() . '://signaturefield/', $filepath),
      )
    );
  }

  return FALSE;
}

/**
 * Draws a thick line
 * Changing the thickness of a line using imagesetthickness doesn't produce as nice of result
 *
 * @param object $src_image
 * @param int $startX
 * @param int $startY
 * @param int $endX
 * @param int $endY
 * @param object $colour
 * @param int $thickness
 *
 * @return void
 */
function signaturefield_drawline($src_image, $startX, $startY, $endX, $endY, $color, $thickness) {
  $angle = (atan2(($startY - $endY), ($endX - $startX)));

  $dist_x = $thickness * (sin($angle));
  $dist_y = $thickness * (cos($angle));

  $x1 = ceil(($startX + $dist_x));
  $y1 = ceil(($startY + $dist_y));
  $x2 = ceil(($endX + $dist_x));
  $y2 = ceil(($endY + $dist_y));
  $x3 = ceil(($endX - $dist_x));
  $y3 = ceil(($endY - $dist_y));
  $x4 = ceil(($startX - $dist_x));
  $y4 = ceil(($startY - $dist_y));

  $array = array($x1, $y1, $x2, $y2, $x3, $y3, $x4, $y4);
  imagefilledpolygon($src_image, $array, (count($array) / 2), $color);
}

/**
 *  Convert a hex color representation to it's rgb integer components.
 *
 *  @param $hex
 *    Hex representation of the color.
 *    Can be in the formats: '#ABC','ABC','#AABBCC','AABBCC'
 *  @return
 *    Array with three components RGB.
 */
function _signaturefield_hex2rgb($hex) {
  $r = $g = $b = '';

  $hex = ltrim($hex, '#');
  if (preg_match('/^[0-9a-f]{3}$/i', $hex)) {
    // 'FA3' is the same as 'FFAA33' so r=FF, g=AA, b=33
    $r = str_repeat($hex{0}, 2);
    $g = str_repeat($hex{1}, 2);
    $b = str_repeat($hex{2}, 2);
  }
  elseif (preg_match('/^[0-9a-f]{6}$/i', $hex)) {
    // #FFAA33 or r=FF, g=AA, b=33
    $r = drupal_substr($hex, 0, 2);
    $g = drupal_substr($hex, 2, 2);
    $b = drupal_substr($hex, 4, 2);
  }

  $r = hexdec($r);
  $g = hexdec($g);
  $b = hexdec($b);
  return array($r, $g, $b);
}