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PHP的一個(gè)完美GIF等比縮放類,附帶去除縮放黑背景

更新時(shí)間：2014年04月01日 14:25:49 作者：

我這里沒有判斷文件類型,因?yàn)閜ng和jpeg縮放后都不會(huì)出現(xiàn)黑色背景,就單獨(dú)gif不行..查了下資料發(fā)現(xiàn)了一個(gè)完美的解決辦法,附帶有詳解

現(xiàn)在寫東西都喜歡封裝成類.....大家調(diào)用一下就行了..我就不說怎么調(diào)用了

<?php
class resize_image{
   private $o_img_width;//原圖像寬度
   private $o_img_height;//原圖像高度
   private $n_img_width;//新圖像寬度
   private $n_img_height;//新圖像高度
   private $o_img_file;//原圖像文件
   private $o_img_source;//原圖像資源
   private $n_img_file;//新圖像資源
   private $n_img_source;//新圖像資源
   private $o_to_n_per=0.5;//圖像縮放比

   //初始化內(nèi)部變量
   function __construct($oldfile,$newfile){
       list($width,$height)=getimagesize($oldfile);
       $this->o_img_file=$oldfile;
       $this->o_img_width=$width;
       $this->o_img_height=$height;
       $this->n_img_file=$newfile;
   }

   //等比例縮放并且解決GIF透明色為黑色背景的問題
   function get_resize_scaling_img(){
       $this->n_img_width=$this->o_img_width*$this->o_to_n_per;
       $this->n_img_height=$this->o_img_height*$this->o_to_n_per;
       //等比例縮放圖片(算法)
       if ( $this->n_img_width && ( $this->o_img_width <$this->o_img_height))
       {
             $this->n_img_width = ( $this->n_img_height/$this->o_img_height) * $this->o_img_width;
       }
       else
       {
            $this->n_img_height = ($this->n_img_width / $this->o_img_width) * $this->o_img_height;
       }
       $this->o_img_source=imagecreatefromgif($this->o_img_file);
       //創(chuàng)建一個(gè)等比例縮放大小的畫布
       $this->n_img_source=imagecreatetruecolor($this->o_img_width,$this->n_img_height);

       //美化:去除黑色不透明背景
       $trans_init=imagecolortransparent($this->o_img_source);
       //尋找透明色并且判斷是否在總顏色中
       if($trans_init>=0 && $trans_init < imagecolorstotal($this->o_img_source)){
           //如果在的話則搜索這個(gè)顏色的RGB色相
           $trans_index=imagecolorsforindex($this->o_img_source,$trans_init);
           //找到之后就創(chuàng)建這樣一個(gè)顏色
           $trans_new=imagecolorallocate($this->n_img_source,$trans_index["red"],$trans_index["green"],$trans_index["blue"]);
           //然后我們用這個(gè)顏色去填充新的圖像
           imagefill($this->n_img_source,0,0,$trans_new);
           //然后我們在把填充色設(shè)置為透明
           imagecolortransparent($this->n_img_source,$trans_new);
       }
       //拷貝原圖像到新畫板上
       imagecopyresized($this->n_img_source,$this->o_img_source,0,0,0,0,$this->n_img_width,$this->n_img_height,$this->o_img_width,$this->o_img_height);
       return $this->n_img_source;
   }
   //最終銷毀資源
   function __destruct(){
       imagedestroy($this->o_img_source);
       imagedestroy($this->n_img_source);

   }