图片不变型裁剪

 $target_ratio){
    // image-to-height
    $cropped_width = $source_width;
    $cropped_height = $source_width * $target_ratio;
    $source_x = 0;
    $source_y = ($source_height - $cropped_height) / 2;
  }elseif ($source_ratio < $target_ratio){
    //image-to-widht
    $cropped_width = $source_height / $target_ratio;
    $cropped_height = $source_height;
    $source_x = ($source_width - $cropped_width) / 2;
    $source_y = 0;
  }else{
    //image-size-ok
    $cropped_width = $source_width;
    $cropped_height = $source_height;
    $source_x = 0;
    $source_y = 0;
  }
  switch ($source_mime){
    case 'image/gif':
      $source_image = imagecreatefromgif($source_path);
      break;
    case 'image/jpeg':
      $source_image = imagecreatefromjpeg($source_path);
      break;
    case 'image/png':
      $source_image = imagecreatefrompng($source_path);
      break;
    default:
      return ;
      break;
  }
  $target_image = imagecreatetruecolor($target_width, $target_height);
  $cropped_image = imagecreatetruecolor($cropped_width, $cropped_height);
  // copy
  imagecopy($cropped_image, $source_image, 0, 0, $source_x, $source_y, $cropped_width, $cropped_height);
  // zoom
  imagecopyresampled($target_image, $cropped_image, 0, 0, 0, 0, $target_width, $target_height, $cropped_width, $cropped_height);
  header('Content-Type: image/jpeg');
  imagejpeg($target_image);
  imagedestroy($source_image);
  imagedestroy($target_image);
  imagedestroy($cropped_image);
}
$filename = "8fcb7a0831b79c61.jpg";
imageCropper($filename,200,200);
?>

图片按比例裁剪