本来用phpthumb来缩略图片是十分方便的,但是最近在sae上写项目发现phpthumb在sae上保存文件时会出问题,想来实现一个简单的按最大宽高等比例缩放图片类也并不困难,于是便自己写了一个方便修改。    需GD库支持,可支持jpg、jpeg、png、gif格式的图片,代码短小适合新手学习用。   [php]<?php class slpic { //原图片文件,包含路径和文件名 var $orpic; //原图的临时图像 var $tempic; //缩略图 var $thpic; //原宽度 var $width; //原高度 var $height; //图片类型 var $type; //缩略后的宽度 var $thwidth; //缩略后的高度 var $thheight;

function __construct($file){
    $this->orpic = $file;
    $infos = getimagesize($file);
    $this->width = $infos[0];
    $this->height = $infos[1];
    $this->type = $infos[2];
}

//根据用户所指定最大宽高来计算缩略图尺寸
function cal_size($maxwidth, $maxheight){
    //缩略图最大宽度与最大高度比
    $thcrown = $maxwidth/$maxheight;    
    //原图宽高比
    $crown = $this->width/$this->height;    
    if($crown/$thcrown >= 1){
        $this->thwidth = $maxwidth;
        $this->thheight = $maxwidth/$crown;
    } else {
        $this->thheight = $maxheight;
        $this->thwidth = $maxheight*$crown;
    }
}

function init(){
    switch($this->type){
        case 1:		//GIF
            $this->tempic = imagecreatefromgif($this->orpic);
            break;
        case 2:		//JPG
            $this->tempic = imagecreatefromjpeg($this->orpic);
            break;
        case 3:		//PNG
            $this->tempic = imagecreatefrompng($this->orpic);
            break;
        default:
            echo '暂不支持该图片格式';
    }
}

function resize($maxwidth, $maxheight){
    //初始化图像
    $this->init();
    //计算出缩略图尺寸
    $this->cal_size($maxwidth, $maxheight);
	
    $this->thpic = imagecreatetruecolor($this->thwidth, $this->thheight);
    imagecopyresampled($this->thpic, $this->tempic, 0, 0, 0 ,0, $this->thwidth, $this->thheight, $this->width, $this->height);
}

function save($filename, $type){
    switch($type){
        case 'jpg':
        case 'jpeg':
            imagejpeg($this->thpic, $filename);
            break;
        case 'png':
            imagepng($$this->thpic, $filename);
            break;
        case 'gif':
            imagegif($$this->thpic, $filename);
            break;
        default:
            echo '暂不支持您所选择的格式';
    }
}

} ?>[/php]