《PHP编程最快明白》第七讲：php图片验证码与缩略图

实例22 图片验证的核心代码
代码如下:
<?php
//header("content-type:image/png");
$num ='1234';
$imagewidth=60;
$imageheight=18;
$numimage = imagecreate($imagewidth,$imageheight);
imagecolorallocate($numimage,240,240,240);
for($i=0;$i<strlen($num);$i++){
$x = mt_rand(1,8)+$imagewidth*$i/4;
$y = mt_rand(1,$imageheight/4);
$color=imagecolorallocate($numimage,mt_rand(0,150),mt_rand(0,150),mt_rand(0,150));
imagestring($numimage,5,$x,$y,$num[$i],$color);
}
for($i=0;$i<200;$i++){
$randcolor=imagecolorallocate($numimage,rand(200,255),rand(200,255),rand(200,255));
imagesetpixel($numimage,rand()%70,rand()%20,$randcolor);
}
imagepng($numimage);
imagedestroy($numimage);
?>

这个是输出4个验证码的例子，对于汉字，需要font文件和imagettftext函数，用到的时候大家再网上搜索吧。你要产生随机数，那有mt_rand函数；你还要用到session保存这个随机数；如果需要转成utf-8，需要iconv函数。
实例23 缩略图
代码如下:
<?php
class SimpleImage {
var $image;
var $image_type;
function load($filename) {
$image_info = getimagesize($filename);
$this->image_type = $image_info[2];
if( $this->image_type == IMAGETYPE_JPEG ) {
$this->image = imagecreatefromjpeg($filename);
} elseif( $this->image_type == IMAGETYPE_GIF ) {
$this->image = imagecreatefromgif($filename);
} elseif( $this->image_type == IMAGETYPE_PNG ) {
$this->image = imagecreatefrompng($filename);
}
}
function save($filename, $image_type=IMAGETYPE_JPEG, $compression=75, $permissions=null) {
if( $image_type == IMAGETYPE_JPEG ) {
imagejpeg($this->image,$filename,$compression);
} elseif( $image_type == IMAGETYPE_GIF ) {
imagegif($this->image,$filename);
} elseif( $image_type == IMAGETYPE_PNG ) {
imagepng($this->image,$filename);
}
if( $permissions != null) {
chmod($filename,$permissions);
}
}
function output($image_type=IMAGETYPE_JPEG) {
if( $image_type == IMAGETYPE_JPEG ) {
imagejpeg($this->image);
} elseif( $image_type == IMAGETYPE_GIF ) {
imagegif($this->image);
} elseif( $image_type == IMAGETYPE_PNG ) {
imagepng($this->image);
}
}
function getWidth() {
return imagesx($this->image);
}
function getHeight() {
return imagesy($this->image);
}
function resizeToHeight($height) {
$ratio = $height / $this->getHeight();
$width = $this->getWidth() * $ratio;
$this->resize($width,$height);
}
function resizeToWidth($width) {
$ratio = $width / $this->getWidth();
$height = $this->getheight() * $ratio;
$this->resize($width,$height);
}
function scale($scale) {
$width = $this->getWidth() * $scale/100;
$height = $this->getheight() * $scale/100;
$this->resize($width,$height);
}
function resize($width,$height) {
$new_image = imagecreatetruecolor($width, $height);
imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());
$this->image = $new_image;
}
}
$newfile = UPLOAD_DIR."/icons/".md5($_SESSION['USER']->email).".jpg";//上传文件保存的目录
$image = new SimpleImage();
$image->load($_FILES['icons']['tmp_name']);//上传的临时文件名
$image->resizeToWidth(80);设置宽度
$image->save($newfile);
?>
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验证码 PHP 缩略图