php生成图片缩略图：
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,类的源码见下文
调用此类的方法:
resizeimage = new resizeimage("图片源文件地址", "200", "100", "0","缩略图地址");
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//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
//使用如下类就可以生成图片缩略图,
class resizeimage
{
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//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
//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
{
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;
}
}
?>
