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Drupal example source code file (imagerotate.inc)

This example Drupal source code file (imagerotate.inc) is included in the DevDaily.com "Drupal Source Code Warehouse" project. The intent of this project is to help you "Learn Drupal by Example".

PHP - Drupal tags/keywords

array, case, for, gif, image, jpg, math, png, rot_height, rot_width, rotate, value

The imagerotate.inc Drupal example source code

<?php

/**
 * @file
 * provides the imagerotate function for php-gd extensions compiled with the
 * upstream libgd instead of the libgd bundled with php.
 */


// Define as included.
define('IMAGEAPI_IMAGEROTATE_PHP', 1);

function imagerotate(&$im, $angle, $bgcolor) {
  if ($angle === 0) {
    return $im;
  }
  // imagerotate() in php's libgd rotates the image counterclockwise,
  // this implementation rotates clockwise. The angle needs to be
  // inverted to give the same behaviour between these implementations.
  $angle = 360 - $angle;

  $width  = imagesx($im);
  $height = imagesy($im);
  // background color.
  list($r, $g, $b, $a) = imageapi_hex2rgba($bgcolor);

  switch ($angle) {
    case 270:
    case 90:
      // flip dimensions.
      $rot_width = $height;
      $rot_height = $width;
      break;
    case 180:
      // maintain dims.
      $rot_width = $width;
      $rot_height = $height;
      break;

    default:
      // well it won't be easy but we'll actually rotate this
      // puppy ourselves.. gonna require a little trig.
      // @todo: convert to a polar equation and use 1/2 length of hypoteneus.
      $center_x = floor($width/2);
      $center_y = floor($height/2);

      // convert to radians and precompute ...
      $cosangle = cos(deg2rad($angle+180));
      $sinangle = sin(deg2rad($angle+180));

      // caluculate new width and height.
      $corners=array(array(0, 0), array($width, 0), array($width, $height), array(0, $height));
      $max_x = $min_x = $max_y = $min_y = 0;
      foreach ($corners as $key => $value) {
        $value[0] -= $center_x;        //Translate coords to center for rotation
        $value[1] -= $center_y;
        $x = $value[0] * $cosangle + $value[1] * $sinangle;
        $y = $value[1] * $cosangle - $value[0] * $sinangle;
        $max_x = max($x, $max_x);
        $min_x = min($x, $min_x);
        $max_y = max($y, $max_y);
        $min_y = min($y, $min_y);
      }
      $rot_width = (int)$max_x - $min_x;
      $rot_height = (int)$max_y - $min_y;
      $rot_center_x = floor($rot_width/2);
      $rot_center_y = floor($rot_height/2);
  }

  $rotate = imagecreatetruecolor($rot_width, $rot_height);
  $bg = imagecolorallocatealpha($rotate, $r, $g, $b, $a);
  imagefilledrectangle($rotate, 0, 0, $rot_width, $rot_height, $bg);
  imagealphablending($rotate, false);
  imagesavealpha($rotate, true);

  switch ($angle) {
    case 90:
      $rot_width--;
      for ($y = 0; $y < $height; ++$y)
        for ($x = 0; $x < $width; ++$x)
          imagesetpixel($rotate, $rot_width - $y, $x, imagecolorat($im, $x, $y));
      break;
    case 270:
      $rot_height--;
      for ($y = 0; $y < $height; ++$y)
        for ($x = 0; $x < $width; ++$x)
          imagesetpixel($rotate, $y, $rot_height - $x, imagecolorat($im, $x, $y));
      break;
    case 180:
      $rot_width--;
      $rot_height--;
      for ($y = 0; $y < $height; ++$y)
        for ($x = 0; $x < $width; ++$x)
          imagesetpixel($rotate, $rot_width - $x, $rot_height - $y, imagecolorat($im, $x, $y));
      break;

    default:
      for ($y = 0; $y < $rot_height; ++$y) {
        for ($x = 0; $x < $rot_width; ++$x) {
          $mod_y = $rot_center_y-$y;
          $mod_x = $rot_center_x-$x;
          $old_x = $mod_x * $cosangle + $mod_y * $sinangle + $center_x;
          $old_y = $mod_y * $cosangle - $mod_x * $sinangle + $center_y;
          if ($old_x >= 0 && $old_x < $width && $old_y >= 0 && $old_y < $height) {
            $color = imagecolorat($im, $old_x, $old_y);
            imagesetpixel($rotate, $x, $y,  $color);
          }
        }
      }
  }
  return $rotate;
}

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