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   1  <?php 
   2  // $Id: imagerotate.inc,v 1.3.4.3 2009/03/18 08:35:59 drewish Exp $
   3  
   4  /** 
   5   * @file
   6   * provides the imagerotate function for php-gd extensions compiled with the 
   7   * upstream libgd instead of the libgd bundled with php.
   8   */
   9  
  10  
  11  // Define as included.
  12  define('IMAGEAPI_IMAGEROTATE_PHP', 1);
  13  
  14  function imagerotate(&$im, $angle, $bgcolor) {
  15    if ($angle === 0) { 
  16      return $im;
  17    }
  18    // imagerotate() in php's libgd rotates the image counterclockwise,
  19    // this implementation rotates clockwise. The angle needs to be
  20    // inverted to give the same behaviour between these implementations.
  21    $angle = 360 - $angle;
  22  
  23    $width  = imagesx($im);
  24    $height = imagesy($im);
  25    // background color.
  26    list($r, $g, $b, $a) = imageapi_hex2rgba($bgcolor);
  27  
  28    switch ($angle) {
  29      case 270:
  30      case 90:
  31        // flip dimensions.
  32        $rot_width = $height;
  33        $rot_height = $width;
  34        break;
  35      case 180:
  36        // maintain dims.
  37        $rot_width = $width;
  38        $rot_height = $height;
  39        break;
  40  
  41      default:
  42        // well it won't be easy but we'll actually rotate this
  43        // puppy ourselves.. gonna require a little trig.
  44        // @todo: convert to a polar equation and use 1/2 length of hypoteneus.
  45        $center_x = floor($width/2);
  46        $center_y = floor($height/2);
  47  
  48        // convert to radians and precompute ...
  49        $cosangle = cos(deg2rad($angle+180));
  50        $sinangle = sin(deg2rad($angle+180));
  51  
  52        // caluculate new width and height.
  53        $corners=array(array(0, 0), array($width, 0), array($width, $height), array(0, $height));
  54        $max_x = $min_x = $max_y = $min_y = 0;
  55        foreach ($corners as $key => $value) {
  56          $value[0] -= $center_x;        //Translate coords to center for rotation
  57          $value[1] -= $center_y;
  58          $x = $value[0] * $cosangle + $value[1] * $sinangle;
  59          $y = $value[1] * $cosangle - $value[0] * $sinangle;
  60          $max_x = max($x, $max_x);
  61          $min_x = min($x, $min_x);
  62          $max_y = max($y, $max_y);
  63          $min_y = min($y, $min_y);
  64        }
  65        $rot_width = (int)$max_x - $min_x;
  66        $rot_height = (int)$max_y - $min_y;
  67        $rot_center_x = floor($rot_width/2);
  68        $rot_center_y = floor($rot_height/2);
  69    }
  70  
  71    $rotate = imagecreatetruecolor($rot_width, $rot_height);
  72    $bg = imagecolorallocatealpha($rotate, $r, $g, $b, $a);
  73    imagefilledrectangle($rotate, 0, 0, $rot_width, $rot_height, $bg);
  74    imagealphablending($rotate, FALSE);
  75    imagesavealpha($rotate, TRUE);
  76  
  77    switch ($angle) {
  78      case 270:
  79        $rot_width--;
  80        for ($y = 0; $y < $height; ++$y)
  81          for ($x = 0; $x < $width; ++$x)
  82            imagesetpixel($rotate, $rot_width - $y, $x, imagecolorat($im, $x, $y));
  83        break;
  84      case 90:
  85        $rot_height--;
  86        for ($y = 0; $y < $height; ++$y)
  87          for ($x = 0; $x < $width; ++$x)
  88            imagesetpixel($rotate, $y, $rot_height - $x, imagecolorat($im, $x, $y));
  89        break;
  90      case 180:
  91        $rot_width--;
  92        $rot_height--;
  93        for ($y = 0; $y < $height; ++$y)
  94          for ($x = 0; $x < $width; ++$x)
  95            imagesetpixel($rotate, $rot_width - $x, $rot_height - $y, imagecolorat($im, $x, $y));
  96        break;
  97  
  98      default:
  99        for ($y = 0; $y < $rot_height; ++$y) {
 100          for ($x = 0; $x < $rot_width; ++$x) {
 101            $mod_y = $rot_center_y-$y;
 102            $mod_x = $rot_center_x-$x;
 103            $old_x = $mod_x * $cosangle + $mod_y * $sinangle + $center_x;
 104            $old_y = $mod_y * $cosangle - $mod_x * $sinangle + $center_y;
 105            if ($old_x >= 0 && $old_x < $width && $old_y >= 0 && $old_y < $height) {
 106              $color = imagecolorat($im, $old_x, $old_y);
 107              imagesetpixel($rotate, $x, $y,  $color);
 108            }
 109          }
 110        }
 111    }
 112    return $rotate;
 113  }
 114