等比例生成缩略图的php程序

等比例生成缩略图的php教程程序
这个程序很实现，但只是用来进来等比例生成缩略图哦，你要把文件上传到服务器，然后再由此函数来操作，有需要的朋友参考一下。

function reSizeImg($imgSrc, $resize_width, $resize_height, $isCut=false) {
//图片的类型
$type = substr ( strrchr ( $imgSrc, "." ), 1 );
//初始化图象
if ($type == "jpg") {
$im = imagecreatefromjpeg ( $imgSrc );
}
if ($type == "gif") {
$im = imagecreatefromgif ( $imgSrc );
}
if ($type == "png") {
$im = imagecreatefrompng ( $imgSrc );
}
//目标图象地址
$full_length = strlen ( $imgSrc );
$type_length = strlen ( $type );
$name_length = $full_length - $type_length;
$name = substr ( $imgSrc, 0, $name_length - 1 );
$dstimg = $name . "_s." . $type;

$width = imagesx ( $im );
$height = imagesy ( $im );

//生成图象
//改变后的图象的比例
$resize_ratio = ($resize_width) / ($resize_height);
//实际图象的比例
$ratio = ($width) / ($height);
if (($isCut) == 1) //裁图
{
if ($ratio >= $resize_ratio) //高度优先
{
$newimg = imagecreatetruecolor ( $resize_width, $resize_height );
imagecopyresampled ( $newimg, $im, 0, 0, 0, 0, $resize_width, $resize_height, (($height) * $resize_ratio), $height );
ImageJpeg ( $newimg, $dstimg );
}
if ($ratio {
$newimg = imagecreatetruecolor ( $resize_width, $resize_height );
imagecopyresampled ( $newimg, $im, 0, 0, 0, 0, $resize_width, $resize_height, $width, (($width) / $resize_ratio) );
ImageJpeg ( $newimg, $dstimg );
}
} else //不裁图
{
if ($ratio >= $resize_ratio) {
$newimg = imagecreatetruecolor ( $resize_width, ($resize_width) / $ratio );
imagecopyresampled ( $newimg, $im, 0, 0, 0, 0, $resize_width, ($resize_width) / $ratio, $width, $height );
ImageJpeg ( $newimg, $dstimg );
}
if ($ratio $newimg = imagecreatetruecolor ( ($resize_height) * $ratio, $resize_height );
imagecopyresampled ( $newimg, $im, 0, 0, 0, 0, ($resize_height) * $ratio, $resize_height, $width, $height );
ImageJpeg ( $newimg, $dstimg );
}
}
ImageDestroy ( $im );
}

调用方法简单，直接reSizeImg就可以了，参考很简单。