PHP按最大宽高等比例缩放图片类

   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]