显示图片之前，先把图片压缩后再显示，怎么做？

[arfeng75]

比方说有张图片aa.jpg ，大小为500K，现在要在网页上显示出来，但是由于图片太大了，所以先对其进行压缩下，然后再显示，这个功能怎么做？

[arfeng75]

怎么弄?

[wonderlee]

网上找的一个很好用的类，共享一下。

<?
/***************************************/
/*功 能：利用PHP的GD库生成高质量的缩略图*/
/*运行环境:PHP5.01/GD2*/
/*类说明：可以选择是/否裁图。

如果裁图则生成的图的尺寸与您输入的一样。
原则：尽可能多保持原图完整

如果不裁图，则按照原图比例生成新图
原则：根据比例以输入的长或者宽为基准*/
/*参 数：$img:源图片地址
$wid:新图的宽度
$hei:新图的高度
$c:是否裁图，1为是，0为否*/

/***************************************/
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????建的图象
var $im;

function resizeimage($img, $wid, $hei,$c)
{
$this->srcimg = $img;
$this->resize_width = $wid;
$this->resize_height = $hei;
$this->cut = $c;
//图片的类型
$this->type = substr(strrchr($this->srcimg,"."),1);
//初始化图象
$this->initi_img();
//目标图象地址
$this -> dst_img();
//--
$this->width = imagesx($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()
{
$full_length = strlen($this->srcimg);
$type_length = strlen($this->type);
$name_length = $full_length-$type_length;
$name = substr($this->srcimg,0,$name_length-1);
$this->dstimg = $name."s.".$this->type;
}
}
?>

[szjq]

php有现成的调有和,你安装GD图形模块

[iasky]

mark