[PHP] Codeigniter 縮圖處理程式，等比例切圖

Codeigniter 內建的 圖片操作類 其中的 resize 處理函式 如果設定等比例的為 FALSE，那圖片就會變成強制指定 SIZE 的圖片，這時候就會扭曲變形

例圖

如果預設將 maintain_ratio 設定為 FALSE 的話，就會出現右圖的狀態

如果要設定等比例切圖變成左邊縮圖的狀態的話，至少要把圖片的最小邊變成指定的邊寬，然後縮圖在設定切圖

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
class MY_Image_lib extends CI_Image_lib{
 public function __construct($props = array())
 {
  if (count($props) > 0)
  {
   $this->initialize($props);
  }
  log_message('debug', "Image Lib Class Initialized");
 }
 public function get_info()
 {
  $result = array(
   'width'=>$this->width,
   'height'=>$this->height,
   'path'=> str_replace( str_replace('\\','/',FCPATH) , '', dirname($this->full_dst_path) ),
   'fullpath'=> $this->full_dst_path,
   'filename'=> $this->dest_image
  );
  $result['filepath'] = $result['path'] .'/' .$result['filename'];
  $result['url'] = base_url( $result['filepath'] );
  return $result;
 }
 public function resize()
 {
  $protocol = 'image_process_'.$this->image_library;
  if (preg_match('/gd2$/i', $protocol))
  {
   $protocol = ($this->maintain_ratio ) ? 'image_process_gd' : 'my_image_process_gd';
  }
  return $this->$protocol('resize');
 }
 function my_image_process_gd($action = 'resize')
 {
  $v2_override = FALSE;
  // If the target width/height match the source, AND if the new file name is not equal to the old file name
  // we'll simply make a copy of the original with the new name... assuming dynamic rendering is off.
  if ($this->dynamic_output === FALSE)
  {
   if ($this->orig_width == $this->width AND $this->orig_height == $this->height)
   {
    if ($this->source_image != $this->new_image)
    {
     if (@copy($this->full_src_path, $this->full_dst_path))
     {
      @chmod($this->full_dst_path, FILE_WRITE_MODE);
     }
    }
    return TRUE;
   }
  }
  $crop_w = $this->width;
  $crop_h = $this->height;
  $type_origin = $this->orig_height / $this->orig_width;
  if( $type_origin == 1 ){
   $type_origin = 'square';
  }else if( $type_origin < 1 ){
   $type_origin = 'w_rectangle';
  }else{
   $type_origin = 'h_rectangle';
  }
  $type_crop = $crop_h / $crop_w;
  if( $type_crop == 1 ){
   $type_crop = 'square';
  }else if( $type_crop < 1 ){
   $type_crop = 'w_rectangle';
  }else{
   $type_crop = 'h_rectangle';
  }
  $type_porp_w = round($crop_w / $this->orig_width,2);
  $type_porp_h = round($crop_h / $this->orig_height,2);

  $type_pw_w = ceil($this->orig_width * $type_porp_w);
  $type_pw_h = ceil($this->orig_height * $type_porp_w);

  $type_ph_w = ceil($this->orig_width * $type_porp_h);
  $type_ph_h = ceil($this->orig_height * $type_porp_h);
  
  if( $crop_h < $type_pw_h )
  {
   $this->width = $type_pw_w;
   $this->height= $type_pw_h;
  }else{
   $this->width = $type_ph_w;
   $this->height= $type_ph_h;
  }

  if ( ! ($src_img = $this->image_create_gd()))
  {
   return FALSE;
  }
  if ($this->image_library == 'gd2' AND function_exists('imagecreatetruecolor'))
  {
   $create = 'imagecreatetruecolor';
   $copy = 'imagecopyresampled';
  }
  else
  {
   $create = 'imagecreate';
   $copy = 'imagecopyresized';
  }
  
  $rst_img = $create($this->width, $this->height);
  if ($this->image_type == 3) // png we can actually preserve transparency
  {
   imagealphablending($rst_img, FALSE);
   imagesavealpha($rst_img, TRUE);
  }

  $copy($rst_img, $src_img, 0, 0, 0, 0, $this->width, $this->height, $this->orig_width, $this->orig_height);

  $dst_img = $create($crop_w, $crop_h);
  if ($this->image_type == 3) // png we can actually preserve transparency
  {
   imagealphablending($dst_img, FALSE);
   imagesavealpha($dst_img, TRUE);
  }

  if( $type_crop == 'square')
  {
   $crop_x = ( $type_origin == 'w_rectangle' ) ? ceil( ($this->width - $this->height) / 2 ) : 0 ;
   $crop_y = ( $type_origin == 'h_rectangle' ) ? ceil( ($this->height - $this->width) / 2 ) : 0 ;
  }else{
   $crop_x = ( $type_origin == 'w_rectangle' ) ? ceil( ($this->width - $crop_w) / 2 ) : 0 ;
   $crop_y = ( $type_origin == 'h_rectangle' ) ? ceil( ($this->height - $crop_h) / 2 ) : 0 ;
  }
  
  $copy($dst_img, $rst_img, 0, 0, $crop_x, $crop_y, $crop_w, $crop_h, $crop_w, $crop_h);
  $this->width = $crop_w;
  $this->height = $crop_h;
  
  //  Show the image
  if ($this->dynamic_output == TRUE)
  {
   $this->image_display_gd($dst_img);
  }
  else
  {
   // Or save it
   if ( ! $this->image_save_gd($dst_img))
   {
    return FALSE;
   }
  }

  //  Kill the file handles
  imagedestroy($rst_img);
  imagedestroy($dst_img);
  imagedestroy($src_img);
  // Set the file to 777
  @chmod($this->full_dst_path, FILE_WRITE_MODE);
  return TRUE;
 }
 // --------------------------------------------------------------------
}
// END Image_lib Class

/* End of file MY_Image_lib.php *//* Location: ./app/libraries/MY_Image_lib.php */

設定 MY_ 是在 config.php 裡面的 $config[‘subclass_prefix’]  = ‘MY_ ‘;

依照自己的設定的來跑，就可以出現等比例縮圖的裁切。

只針對 maintain_ratio = FALSE 來做處理。

另外設定了一個 get_info() 來做處理取得圖片內容