最近做个项目，正好需要缩略图的代码,特给大家分享下

<?php

/**
* 功能:生成缩略图
* 作者:phpox
* 日期:Thu May 17 09:57:05 CST 2007
*/

class CreatMiniature
{
//公共变量
var $srcFile=""; //原图
var $echoType; //输出图片类型，link--不保存为文件；file--保存为文件
var $im=""; //临时变量
var $srcW=""; //原图宽
var $srcH=""; //原图高

//设置变量及初始化
function SetVar($srcFile,$echoType)
{
if (!file_exists($srcFile)){
echo '源图片文件不存在!';
exit();
}
$this->srcFile=$srcFile;
$this->echoType=$echoType;

$info = "";
$data = GetImageSize($this->srcFile,$info);
switch ($data[2])
{
case 1:
if(!function_exists("imagecreatefromgif")){
echo "你的GD库不能使用GIF格式的图片，请使用Jpeg或PNG格式！<a href='javascript:go(-1);'>返回</a>";
exit();
}
$this->im = ImageCreateFromGIF($this->srcFile);
break;
case 2:
if(!function_exists("imagecreatefromjpeg")){
echo "你的GD库不能使用jpeg格式的图片，请使用其它格式的图片！<a href='javascript:go(-1);'>返回</a>";
exit();
}
$this->im = ImageCreateFromJpeg($this->srcFile);
break;
case 3:
$this->im = ImageCreateFromPNG($this->srcFile);
break;
}
$this->srcW=ImageSX($this->im);
$this->srcH=ImageSY($this->im);
}

//生成扭曲型缩图
function Distortion($toFile,$toW,$toH)
{
$cImg=$this->CreatImage($this->im,$toW,$toH,0,0,0,0,$this->srcW,$this->srcH);
return $this->EchoImage($cImg,$toFile);
ImageDestroy($cImg);
}

//生成按比例缩放的缩图
function Prorate($toFile,$toW,$toH)
{
$toWH=$toW/$toH;
$srcWH=$this->srcW/$this->srcH;
if($toWH<=$srcWH)
{
$ftoW=$toW;
$ftoH=$ftoW*($this->srcH/$this->srcW);
}
else
{
$ftoH=$toH;
$ftoW=$ftoH*($this->srcW/$this->srcH);
}
if($this->srcW>$toW||$this->srcH>$toH)
{
$cImg=$this->CreatImage($this->im,$ftoW,$ftoH,0,0,0,0,$this->srcW,$this->srcH);
return $this->EchoImage($cImg,$toFile);
ImageDestroy($cImg);
}
else
{
$cImg=$this->CreatImage($this->im,$this->srcW,$this->srcH,0,0,0,0,$this->srcW,$this->srcH);
return $this->EchoImage($cImg,$toFile);
ImageDestroy($cImg);
}
}

//生成最小裁剪后的缩图
function Cut($toFile,$toW,$toH)
{
$toWH=$toW/$toH;
$srcWH=$this->srcW/$this->srcH;
if($toWH<=$srcWH)
{
$ctoH=$toH;
$ctoW=$ctoH*($this->srcW/$this->srcH);
}
else
{
$ctoW=$toW;
$ctoH=$ctoW*($this->srcH/$this->srcW);
}
$allImg=$this->CreatImage($this->im,$ctoW,$ctoH,0,0,0,0,$this->srcW,$this->srcH);
$cImg=$this->CreatImage($allImg,$toW,$toH,0,0,($ctoW-$toW)/2,($ctoH-$toH)/2,$toW,$toH);
return $this->EchoImage($cImg,$toFile);
ImageDestroy($cImg);
ImageDestroy($allImg);
}

//生成背景填充的缩图
function BackFill($toFile,$toW,$toH,$bk1=255,$bk2=255,$bk3=255)
{
$toWH=$toW/$toH;
$srcWH=$this->srcW/$this->srcH;
if($toWH<=$srcWH)
{
$ftoW=$toW;
$ftoH=$ftoW*($this->srcH/$this->srcW);
}
else
{
$ftoH=$toH;
$ftoW=$ftoH*($this->srcW/$this->srcH);
}
if(function_exists("imagecreatetruecolor"))
{
@$cImg=ImageCreateTrueColor($toW,$toH);
if(!$cImg)
{
$cImg=ImageCreate($toW,$toH);
}
}
else
{
$cImg=ImageCreate($toW,$toH);
}
$backcolor = imagecolorallocate($cImg, $bk1, $bk2, $bk3); //填充的背景颜色
ImageFilledRectangle($cImg,0,0,$toW,$toH,$backcolor);
if($this->srcW>$toW||$this->srcH>$toH)
{
$proImg=$this->CreatImage($this->im,$ftoW,$ftoH,0,0,0,0,$this->srcW,$this->srcH);
if($ftoW<$toW)
{
ImageCopy($cImg,$proImg,($toW-$ftoW)/2,0,0,0,$ftoW,$ftoH);
}
else if($ftoH<$toH)
{
ImageCopy($cImg,$proImg,0,($toH-$ftoH)/2,0,0,$ftoW,$ftoH);
}
else
{
ImageCopy($cImg,$proImg,0,0,0,0,$ftoW,$ftoH);
}
}
else
{
ImageCopyMerge($cImg,$this->im,($toW-$ftoW)/2,($toH-$ftoH)/2,0,0,$ftoW,$ftoH,100);
}
return $this->EchoImage($cImg,$toFile);
ImageDestroy($cImg);
}


function CreatImage($img,$creatW,$creatH,$dstX,$dstY,$srcX,$srcY,$srcImgW,$srcImgH)
{
if(function_exists("imagecreatetruecolor"))
{
@$creatImg = ImageCreateTrueColor($creatW,$creatH);
if($creatImg)
ImageCopyResampled($creatImg,$img,$dstX,$dstY,$srcX,$srcY,$creatW,$creatH,$srcImgW,$srcImgH);
else
{
$creatImg=ImageCreate($creatW,$creatH);
ImageCopyResized($creatImg,$img,$dstX,$dstY,$srcX,$srcY,$creatW,$creatH,$srcImgW,$srcImgH);
}
}
else
{
$creatImg=ImageCreate($creatW,$creatH);
ImageCopyResized($creatImg,$img,$dstX,$dstY,$srcX,$srcY,$creatW,$creatH,$srcImgW,$srcImgH);
}
return $creatImg;
}

//输出图片，link---只输出，不保存文件。file--保存为文件
function EchoImage($img,$to_File)
{
switch($this->echoType)
{
case "link":
if(function_exists('imagejpeg')) return ImageJpeg($img);
else return ImagePNG($img);
break;
case "file":
if(function_exists('imagejpeg')) return ImageJpeg($img,$to_File);
else return ImagePNG($img,$to_File);
break;
}
}
}
?>