基于GD2图形库的PHP生成图片缩略图类代码分享

要使用PHP生成图片缩略图,要保证你的PHP服务器安装了GD2图形库 使用一个类生成图片的缩略图

1.使用方法

    $resizeimage = new resizeimage("图片源文件地址", "200", "100", "0","缩略图地址");
    //就只用上面的一句话,就能生成缩略图,其中,源文件和缩略图地址可以相同,200,100分别代表宽和高

2. 缩略图类代码

    //使用如下类就可以生成图片缩略图,

    <?php
    class resizeimage
    {
      //图片类型
      var $type;
      //实际宽度
      var $width;
      //实际高度
      var $height;
      //改变后的宽度
      var $resize_width;
      //改变后的高度
      var $resize_height;
      //是否裁图
      var $cut;
      //源图象
      var $srcimg;
      //目标图象地址
      var $dstimg;
      //临时创建的图象
      var $im;

      function resizeimage($img, $wid, $hei,$c,$dstpath)
      {
        $this->srcimg = $img;
        $this->resize_width = $wid;
        $this->resize_height = $hei;
        $this->cut = $c;
        //图片的类型

    $this->type = strtolower(substr(strrchr($this->srcimg,"."),1));

        //初始化图象
        $this->initi_img();
        //目标图象地址
        $this -> dst_img($dstpath);
        //--
        $this->width = imagesx($this->im);
        $this->height = imagesy($this->im);
        //生成图象
        $this->newimg();
        ImageDestroy ($this->im);
      }
      function newimg()
      {
        //改变后的图象的比例
        $resize_ratio = ($this->resize_width)/($this->resize_height);
        //实际图象的比例
        $ratio = ($this->width)/($this->height);
        if(($this->cut)=="1")
        //裁图
        {
          if($ratio>=$resize_ratio)
          //高度优先
          {
            $newimg = imagecreatetruecolor($this->resize_width,$this->resize_height);
            imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width,$this->resize_height, (($this->height)*$resize_ratio), $this->height);
            ImageJpeg ($newimg,$this->dstimg);
          }
          if($ratio<$resize_ratio)
          //宽度优先
          {
            $newimg = imagecreatetruecolor($this->resize_width,$this->resize_height);
            imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, $this->resize_height, $this->width, (($this->width)/$resize_ratio));
            ImageJpeg ($newimg,$this->dstimg);
          }
        }
        else
        //不裁图
        {
          if($ratio>=$resize_ratio)
          {
            $newimg = imagecreatetruecolor($this->resize_width,($this->resize_width)/$ratio);
            imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, ($this->resize_width)/$ratio, $this->width, $this->height);
            ImageJpeg ($newimg,$this->dstimg);
          }
          if($ratio<$resize_ratio)
          {
            $newimg = imagecreatetruecolor(($this->resize_height)*$ratio,$this->resize_height);
            imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, ($this->resize_height)*$ratio, $this->resize_height, $this->width, $this->height);
            ImageJpeg ($newimg,$this->dstimg);
          }
        }
      }
      //初始化图象
      function initi_img()
      {
        if($this->type=="jpg")
        {
          $this->im = imagecreatefromjpeg($this->srcimg);
        }
        if($this->type=="gif")
        {
          $this->im = imagecreatefromgif($this->srcimg);
        }
        if($this->type=="png")
        {
          $this->im = imagecreatefrompng($this->srcimg);
        }
      }
      //图象目标地址
      function dst_img($dstpath)
      {
        $full_length = strlen($this->srcimg);

        $type_length = strlen($this->type);
        $name_length = $full_length-$type_length;


        $name     = substr($this->srcimg,0,$name_length-1);
        $this->dstimg = $dstpath;


    //echo $this->dstimg;
      }
    }
    ?>