PHP实现图片不变型裁剪及图片按比例裁剪的方法

<?php
/**
 * imagecropper
 * @param string $source_path
 * @param string $target_width
 * @param string $target_height
 */
function imagecropper($source_path, $target_width, $target_height){
  $source_info  = getimagesize($source_path);
  $source_width = $source_info[0];
  $source_height = $source_info[1];
  $source_mime  = $source_info['mime'];
  $source_ratio = $source_height / $source_width;
  $target_ratio = $target_height / $target_width;
  if ($source_ratio > $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);
?>

<?php
/**
 * imagezoom
 * @param string $file
 * @param double $zoom
 */
function imagezoom($filename,$zoom=0.6){
  //baseinfo
  $sourceimageinfo = getimagesize($filename);
  $sourcewidth = $sourceimageinfo[0];
  $sourceheight = $sourceimageinfo[1];
  $sourcemine = $sourceimageinfo['mime'];
  $sourceratio = $sourcewidth/$sourceheight;
  $sourcex = 0;
  $sourcey = 0;
  //zoom
  $targetratio = $zoom;
  //target-widht-height
  $targetwidth = $sourcewidth*$targetratio;
  $targetheight = $sourceheight*$targetratio;
  //init-params
  $sourceimage = null;
  switch($sourcemine){
    case 'image/gif':
      $sourceimage = imagecreatefromgif($filename);
      break;
    case 'image/jpeg':
      $sourceimage = imagecreatefromjpeg($filename);
      break;
    case 'image/png':
      $sourceimage = imagecreatefrompng($filename);
      break;
    default:
      return ;
      break;
  }
  //temp-target-image
  $tempsourceimage = imagecreatetruecolor($sourcewidth, $sourceheight);
  $targetimage = imagecreatetruecolor($targetwidth,$targetheight);
  //copy
  imagecopy($tempsourceimage, $sourceimage, 0, 0, $sourcex, $sourcey, $sourcewidth, $sourceheight);
  //zoom
  imagecopyresampled($targetimage, $tempsourceimage, 0, 0, 0, 0, $targetwidth, $targetheight, $sourcewidth, $sourceheight);
  //header
  header('content-type: image/jpeg');
  //image-loading
  imagejpeg($targetimage);
  //destroy
  imagedestroy($tempsourceimage);
  imagedestroy($sourceimage);
  imagedestroy($targetimage);
}
$filename = "8fcb7a0831b79c61.jpg";
imagezoom($filename);
?>