php图片按比较生成缩略图片代码

图片按在比较进行放大缩小，这得利用php教程 gd库的函数现实现，我们会利用到imagecreatetruecolor(),imagecopyresampled()来操作

function my_image_resize($src_file, $dst_file, $dst_width=32, $dst_height=32) {
    if($dst_width <1 || $dst_height <1) {
        echo "params width or height error !";
        exit();
    }
    if(!file_exists($src_file)) {
        echo $src_file . " is not exists !";
        exit();
    }

    $type=exif_imagetype($src_file);
    $support_type=array(imagetype_jpeg , imagetype_png , imagetype_gif);

    if(!in_array($type, $support_type,true)) {
        echo "this type of image does not support! only support jpg , gif or png";
        exit();
    }

    switch($type) {
        case imagetype_jpeg :
            $src_img=imagecreatefromjpeg($src_file);
            break;
        case imagetype_png :
            $src_img=imagecreatefrompng($src_file);        
            break;
        case imagetype_gif :
            $src_img=imagecreatefromgif($src_file);
            break;
        default:
            echo "load image error!";
            exit();
    }
    $src_w=imagesx($src_img);
    $src_h=imagesy($src_img);
    $ratio_w=1.0 * $dst_width/$src_w;
    $ratio_h=1.0 * $dst_height/$src_h;
    if ($src_w<=$dst_width && $src_h<=$dst_height) {
        $x = ($dst_width-$src_w)/2;
        $y = ($dst_height-$src_h)/2;
        $new_img=imagecreatetruecolor($dst_width,$dst_height);
        imagecopy($new_img,$src_img,$x,$y,0,0,$dst_width,$dst_height);
        switch($type) {
            case imagetype_jpeg :
                imagejpeg($new_img,$dst_file,100);
                break;
            case imagetype_png :
                imagepng($new_img,$dst_file);
                break;
            case imagetype_gif :
                imagegif($new_img,$dst_file);
                break;
            default:
                break;
        }
    } else {
        $dstwh = $dst_width/$dst_height;
        $srcwh = $src_w/$src_h;
        if ($ratio_w <= $ratio_h) {
            $zoom_w = $dst_width;
            $zoom_h = $zoom_w*($src_h/$src_w);
        } else {
            $zoom_h = $dst_height;
            $zoom_w = $zoom_h*($src_w/$src_h);
        }

        $zoom_img=imagecreatetruecolor($zoom_w, $zoom_h);
        imagecopyresampled($zoom_img,$src_img,0,0,0,0,$zoom_w,$zoom_h,$src_w,$src_h);
        $new_img=imagecreatetruecolor($dst_width,$dst_height);
        $x = ($dst_width-$zoom_w)/2;
        $y = ($dst_height-$zoom_h)/2+1;
        imagecopy($new_img,$zoom_img,$x,$y,0,0,$dst_width,$dst_height);
        switch($type) {
            case imagetype_jpeg :
                imagejpeg($new_img,$dst_file,100);
                break;
            case imagetype_png :
                imagepng($new_img,$dst_file);
                break;
            case imagetype_gif :
                imagegif($new_img,$dst_file);
                break;
            default:
                break;
        }
    }
}

总结，我们要生成比例生成小图就利用$dstwh = $dst_width/$dst_height;
        $srcwh = $src_w/$src_h;进行判断，然后再生成。

先了解files函数

$_files数组内容如下:

$_files['myfile']['name']   客户端文件的原名称。
$_files['myfile']['type']   文件的 mime 类型，需要浏览器提供该信息的支持，例如"image/gif"。
$_files['myfile']['size']   已上传文件的大小，单位为字节。
$_files['myfile']['tmp_name']   文件被上传后在服务端储存的临时文件名，一般是系统默认。可以在php教程.ini的upload_tmp_dir 指定，但 用 putenv() 函数设置是不起作用的。
$_files['myfile']['error']   和该文件上传相关的错误代码。['error'] 是在 php 4.2.0 版本中增加的。下面是它的说明：(它们在php3.0以后成了常量)
  upload_err_ok
    值：0; 没有错误发生，文件上传成功。
  upload_err_ini_size
    值：1; 上传的文件超过了 php.ini 中 upload_max_filesize 选项限制的值。
  upload_err_form_size
    值：2; 上传文件的大小超过了 html 表单中 max_file_size 选项指定的值。
  upload_err_partial
    值：3; 文件只有部分被上传。
  upload_err_no_file
    值：4; 没有文件被上传。
    值：5; 上传文件大小为0.

php代码

<?php
     $mkdir_file_dir    = mkdir('./img/'.$_post['title'],0777);        　　　//上传文件的时候就开始创建一个图片相关的目录
     $tmp_file_name     = $_files['file']['tmp_name'];                        //上传成功之后取的临时文件名
     $file_name             = $_files['file']['name'];                        //原始的文件名
   
     $file_dir     = './img/'.$_post['title'].'/';                            //把创建的一个目录赋值给你一个变量作为最终的保存目录
    
     if(is_dir($file_dir))
     {
         move_uploaded_file($tmp_file_name,$file_dir.$file_name);　　　　　　　 //开始移动文件
     }
 ?>

html代码

<html>
    <head>
        <title>
            my is upfile app!!
        </title>
        <meta    http-equiv="content-type" content="text/html;charset=utf-8" />
    </head>
    <body>
        <form enctype="multipart/form-data" method="post" action="upfile_add.php">
                标题:     <input type="text" name="title" />
                上传文件: <input type="file" name="file" />
                <input type="submit" vlaue="提交" />
        </form>
    </body>
</html>

非常重要的一点是：文件通过post提交后是保存在c:windowstemp临时文件夹中通过$_files["photo"]["tmp_name"]，我们可以轻松获得上传的临时文件，将它保存到我们指定的路径中 下面是解决方案move_uploaded_file($_files["photo"]["tmp_name"],$path)

下面提供三款生成缩代码，兼容性都相当的不错，也可以自定高度与宽度哦。

function imageresize($srcfile,$tow,$toh,$tofile="")
{
if($tofile==""){ $tofile = $srcfile; }
$info = "";
$data = getimagesize($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='网页特效:go(-1);'>返回</a>";
exit();
}
$im = imagecreatefromgif($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();
}
$im = imagecreatefromjpeg($srcfile);
break;
case 3:
$im = imagecreatefrompng($srcfile);
break;
}
$srcw=imagesx($im);
$srch=imagesy($im);
$towh=$tow/$toh;
$srcwh=$srcw/$srch;
if($towh<=$srcwh){
$ftow=$tow;
$ftoh=$ftow*($srch/$srcw);
}
else{
$ftoh=$toh;
$ftow=$ftoh*($srcw/$srch);
}
if($srcw>$tow||$srch>$toh)
{
if(function_exists("imagecreatetruecolor")){
@$ni = imagecreatetruecolor($ftow,$ftoh);
if($ni) imagecopyresampled($ni,$im,0,0,0,0,$ftow,$ftoh,$srcw,$srch);
else{
$ni=imagecreate($ftow,$ftoh);
imagecopyresized($ni,$im,0,0,0,0,$ftow,$ftoh,$srcw,$srch);
}
}else{
$ni=imagecreate($ftow,$ftoh);
imagecopyresized($ni,$im,0,0,0,0,$ftow,$ftoh,$srcw,$srch);
}
if(function_exists('imagejpeg')) imagejpeg($ni,$tofile);
else imagepng($ni,$tofile);
imagedestroy($ni);
}
imagedestroy($im);
}

实例代码二

<?php教程
/*构造函数-生成缩略图+水印,参数说明:
$srcfile-图片文件名,
$dstfile-另存文件名,
$markwords-水印文字,
$markimage-水印图片,
$dstw-图片保存宽度,
$dsth-图片保存高度,
$rate-图片保存品质*/
makethumb("a.jpg","b.jpg","50","50");
function makethumb($srcfile,$dstfile,$dstw,$dsth,$rate=100,$markwords=null,$markimage=null)
{
$data = getimagesize($srcfile);
switch($data[2])
{
case 1:
$im=@imagecreatefromgif($srcfile);
break;
case 2:
$im=@imagecreatefromjpeg($srcfile);
break;
case 3:
$im=@imagecreatefrompng($srcfile);
break;
}
if(!$im) return false;
$srcw=imagesx($im);
$srch=imagesy($im);
$dstx=0;
$dsty=0;
if ($srcw*$dsth>$srch*$dstw)
{
$fdsth = round($srch*$dstw/$srcw);
$dsty = floor(($dsth-$fdsth)/2);
$fdstw = $dstw;
}
else
{
$fdstw = round($srcw*$dsth/$srch);
$dstx = floor(($dstw-$fdstw)/2);
$fdsth = $dsth;
}
$ni=imagecreatetruecolor($dstw,$dsth);
$dstx=($dstx<0)?0:$dstx;
$dsty=($dstx<0)?0:$dsty;
$dstx=($dstx>($dstw/2))?floor($dstw/2):$dstx;
$dsty=($dsty>($dsth/2))?floor($dsth/s):$dsty;
$white = imagecolorallocate($ni,255,255,255);
$black = imagecolorallocate($ni,0,0,0);
imagefilledrectangle($ni,0,0,$dstw,$dsth,$white);// 填充背景色
imagecopyresized($ni,$im,$dstx,$dsty,0,0,$fdstw,$fdsth,$srcw,$srch);
if($markwords!=null)
{
$markwords=iconv("gb2312","utf-8",$markwords);
//转换文字编码
imagettftext($ni,20,30,450,560,$black,"simhei.ttf",$markwords); //写入文字水印
//参数依次为，文字大小|偏转度|横坐标|纵坐标|文字颜色|文字类型|文字内容
}
elseif($markimage!=null)
{
$wimage_data = getimagesize($markimage);
switch($wimage_data[2])
{
case 1:
$wimage=@imagecreatefromgif($markimage);
break;
case 2:
$wimage=@imagecreatefromjpeg($markimage);
break;
case 3:
$wimage=@imagecreatefrompng($markimage);
break;
}
imagecopy($ni,$wimage,500,560,0,0,88,31); //写入图片水印,水印图片大小默认为88*31
imagedestroy($wimage);
}
imagejpeg($ni,$dstfile,$rate);
imagejpeg($ni,$srcfile,$rate);
imagedestroy($im);
imagedestroy($ni);
}
?>

支持图片上传代码

<?php

 $pic_name=date("dmyhis");

 // 生成图片的宽度
 $pic_width=$_post['width'];

 // 生成图片的高度
 $pic_height=$_post['length'];

 function resizeimage($im,$maxwidth,$maxheight,$name){
  //取得当前图片大小
  $width = imagesx($im);
  $height = imagesy($im);
  //生成缩略图的大小
  if(($width > $maxwidth) || ($height > $maxheight)){
   $widthratio = $maxwidth/$width;  
   $heightratio = $maxheight/$height; 
   if($widthratio < $heightratio){
    $ratio = $widthratio;
   }else{
    $ratio = $heightratio;
   }
   $newwidth = $width * $ratio;
   $newheight = $height * $ratio;
  
   if(function_exists("imagecopyresampled")){
    $newim = imagecreatetruecolor($newwidth, $newheight);
    imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
   }else{
    $newim = imagecreate($newwidth, $newheight);
    imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
   }
   imagejpeg ($newim,$name . ".jpg");
   imagedestroy ($newim);
  }else{
   imagejpeg ($im,$name . ".jpg");
  }
 }

 if($_files['image']['size']){
  //echo $_files['image']['type'];
  if($_files['image']['type'] == "image/pjpeg"||$_files['image']['type'] == "image/jpg"||$_files['image']['type'] == "image/jpeg"){
   $im = imagecreatefromjpeg($_files['image']['tmp_name']);
  }elseif($_files['image']['type'] == "image/x-png"){
   $im = imagecreatefrompng($_files['image']['tmp_name']);
  }elseif($_files['image']['type'] == "image/gif"){
   $im = imagecreatefromgif($_files['image']['tmp_name']);
  }
  if($im){
   if(file_exists($pic_name.'.jpg')){
    unlink($pic_name.'.jpg');
   }
   resizeimage($im,$pic_width,$pic_height,$pic_name);
   imagedestroy ($im);
  }
 }
?>

<img src="<? echo $pic_name.'.jpg'; ?>"><br><br>
<form enctype="multipart/form-data" method="post" action="small_picture.php">
<br>
<input type="file" name="image" size="50" value="浏览"><p>
生成缩略图宽度：<input type="text" name="width" size="5"><p>
生成缩略图长度：<input type="text" name="length" size="5"><p>
<input type="submit" value="上传图片">
</form>

class securecode
{
    private static $instance=null;
    private $code = '';
    private $fontfile;
    private $validate;
    private $image;
    private $specialadd = 'special string for securecode';
    private $codeexpire=86400;
    private $codecookiename='secure_code';

    /**
     * 构造方法
     */
    private function securecode()
    {
        $this->fontfile = dirname( __file__ ) . '/arial.ttf';
    }

    private function __construct()
    {
        $this->securecode();
    }
   
    public static function getinstance()
    {
        if (self::$instance==null)
            self::$instance=new self();
       
        return self::$instance;
    }

    /**
     * 指定字体文件所在路径，默认为当前文件夹下arial.ttf文件
     * @param $fontfile 文件路径
     * @return void
     */
    function loadfont($fontfile)
    {
        $this->fontfile = $fontfile;
    }

    /**
     * 图片输出方法，在执行本方法前程序不应该有任何形式的输出
     * @return void;
     */
    function stroke()
    {
        $this->savecode();
        self::sendheader();
        imagegif( $this->validate );
        imagedestroy( $this->validate );
        imagedestroy( $this->image );
    }

    /**
     * 图片保存方法
     * @param $filename 保存路径
     * @return void
     */
    function save($filename)
    {
        $this->savecode();
        imagegif( $this->validate , $filename );
        imagedestroy( $this->validate );
        imagedestroy( $this->image );
    }
   
  /**
     * 验证码验证方法
     * @param $input 要验证的字符串，即用户的输入内容
     * @return boolean 验证结果
     */
    function verify($input)
    {
        $input=strtolower($input);
        $targetcode=$this->authcode($input);
        $code=$this->getcookie();
        if (empty($code)||$code!=$targetcode)
            $result= false;
        else
            $result=true;
        $_cookie[$this->codecookiename]='';
        setcookie ( $this->codecookiename, '', - 1 );
        return $result;
    }

    /**
     * 图片创建方法
     * @return void;
     */
    function createimage()
    {
        $this->randcode();
       
        $size = 30;
        $width = 90;
        $height = 35;
        $degrees = array (
            rand( 0 , 30 ), rand( 0 , 30 ), rand( 0 , 30 ), rand( 0 , 30 )
        );
       

        for ($i = 0; $i < 4; ++$i)
        {
            if (rand() % 2);
            else $degrees[$i] = -$degrees[$i];
        }
       
        $this->image = imagecreatetruecolor( $size , $size );
        $this->validate = imagecreatetruecolor( $width , $height );
        $back = imagecolorallocate( $this->image , 255 , 255 , 255 );
        $border = imagecolorallocate( $this->image , 0 , 0 , 0 );
        imagefilledrectangle( $this->validate , 0 , 0 , $width , $height , $back );
       
        for ($i = 0; $i < 4; ++$i)
        {
            $temp = self::rgbtohsv( rand( 0 , 250 ) , rand( 0 , 150 ) , rand( 0 , 250 ) );
           
            if ($temp[2] > 60) $temp[2] = 60;
           
            $temp = self::hsvtorgb( $temp[0] , $temp[1] , $temp[2] );
            $textcolor[$i] = imagecolorallocate( $this->image , $temp[0] , $temp[1] , $temp[2] );
        }
       
        for ($i = 0; $i < 200; ++$i)
        {
            $randpixelcolor = imagecolorallocate( $this->validate , rand( 0 , 255 ) , rand( 0 , 255 ) , rand( 0 , 255 ) );
            imagesetpixel( $this->validate , rand( 1 , 87 ) , rand( 1 , 35 ) , $randpixelcolor );
        }
       
        $temp = self::rgbtohsv( rand( 220 , 255 ) , rand( 220 , 255 ) , rand( 220 , 255 ) );
       
        if ($temp[2] < 200) $temp[2] = 255;
       
        $temp = self::hsvtorgb( $temp[0] , $temp[1] , $temp[2] );
        $randlinecolor = imagecolorallocate( $this->image , $temp[0] , $temp[1] , $temp[2] );
       
        self::imagelinethick( $this->validate , $textcolor[rand( 0 , 3 )] );
       
        imagefilledrectangle( $this->image , 0 , 0 , $size , $size , $back );
        putenv( 'gdfontpath=' . realpath( '.' ) );
       
        // name the font to be used (note the lack of the .ttf extension
        imagettftext( $this->image , 15 , 0 , 8 , 20 , $textcolor[0] , $this->fontfile , $this->code[0] );
       
        $this->image = imagerotate( $this->image , $degrees[0] , $back );
        imagecolortransparent( $this->image , $back );
        imagecopymerge( $this->validate , $this->image , 1 , 4 , 4 , 5 , imagesx( $this->image ) - 10 , imagesy( $this->image ) - 10 , 100 );
       
        $this->image = imagecreatetruecolor( $size , $size );
        imagefilledrectangle( $this->image , 0 , 0 , $size , $size , $back );
        imagettftext( $this->image , 15 , 0 , 8 , 20 , $textcolor[1] , $this->fontfile , $this->code[1] );
        $this->image = imagerotate( $this->image , $degrees[1] , $back );
        imagecolortransparent( $this->image , $back );
        imagecopymerge( $this->validate , $this->image , 21 , 4 , 4 , 5 , imagesx( $this->image ) - 10 , imagesy( $this->image ) - 10 , 100 );
       
        $this->image = imagecreatetruecolor( $size , $size );
        imagefilledrectangle( $this->image , 0 , 0 , $size - 1 , $size - 1 , $back );
        imagettftext( $this->image , 15 , 0 , 8 , 20 , $textcolor[2] , $this->fontfile , $this->code[2] );
        $this->image = imagerotate( $this->image , $degrees[2] , $back );
        imagecolortransparent( $this->image , $back );
        imagecopymerge( $this->validate , $this->image , 41 , 4 , 4 , 5 , imagesx( $this->image ) - 10 , imagesy( $this->image ) - 10 , 100 );
       
        $this->image = imagecreatetruecolor( $size , $size );
        imagefilledrectangle( $this->image , 0 , 0 , $size - 1 , $size - 1 , $back );
        imagettftext( $this->image , 15 , 0 , 8 , 20 , $textcolor[3] , $this->fontfile , $this->code[3] );
        $this->image = imagerotate( $this->image , $degrees[3] , $back );
        imagecolortransparent( $this->image , $back );
        imagecopymerge( $this->validate , $this->image , 61 , 4 , 4 , 5 , imagesx( $this->image ) - 10 , imagesy( $this->image ) - 10 , 100 );
        imagerectangle( $this->validate , 0 , 0 , $width - 1 , $height - 1 , $border );
    }
   
    /**
     * 获取随机生成的验证码
     * @return string 随机验证码，返回的验证码不进行任何处理
     */
    function getcode()
    {
        return $this->code;
    }

    /**
     * 生成随机码方法
     * @return void;
     */
    protected function randcode()
    {
        $alphastr = 'abcdefghijklmnpqrstuvwxyz123456789';
        $randstr = array (
            $alphastr{rand( 0 , 33 )}, $alphastr{rand( 0 , 33 )}, $alphastr{rand( 0 , 33 )}, $alphastr{rand( 0 , 33 )}
        );
        $this->code = strtolower( $randstr[0] . $randstr[1] . $randstr[2] . $randstr[3] );
    }

    /**
     * rgb色到hsv色转变方法
     * @param $r
     * @param $g
     * @param $b
     * @return array hsv数组
     */
    protected static function rgbtohsv($r, $g, $b)
    {
        $tmp = min( $r , $g );
        $min = min( $tmp , $b );
        $tmp = max( $r , $g );
        $max = max( $tmp , $b );
        $v = $max;
        $delta = $max - $min;
       
        if ($max != 0) $s = $delta / $max; // s
        else
        {
            $s = 0;
            //$h = undefinedcolor;
            return;
        }
        if ($r == $max) $h = ($g - $b) / $delta; // between yellow & magenta
        else if ($g == $max) $h = 2 + ($b - $r) / $delta; // between cyan & yellow
        else $h = 4 + ($r - $g) / $delta; // between magenta & cyan
       

        $h *= 60; // degrees
        if ($h < 0) $h += 360;
        return array (
            $h, $s, $v
        );
    }

    /**
     * 同上一方法功能相反
     * @param $h
     * @param $s
     * @param $v
     * @return array rgb数组
     */
    protected static function hsvtorgb($h, $s, $v)
    {
        if ($s == 0)
        {
            // achromatic (grey)
            $r = $g = $b = $v;
            return;
        }
       
        $h /= 60; // sector 0 to 5
        $i = floor( $h );
        $f = $h - $i; // factorial part of h
        $p = $v * (1 - $s);
        $q = $v * (1 - $s * $f);
        $t = $v * (1 - $s * (1 - $f));
       
        switch ($i)
        {
            case 0 :
                $r = $v;
                $g = $t;
                $b = $p;
                break;
            case 1 :
                $r = $q;
                $g = $v;
                $b = $p;
                break;
            case 2 :
                $r = $p;
                $g = $v;
                $b = $t;
                break;
            case 3 :
                $r = $p;
                $g = $q;
                $b = $v;
                break;
            case 4 :
                $r = $t;
                $g = $p;
                $b = $v;
                break;
            default : // case 5:
                $r = $v;
                $g = $p;
                $b = $q;
                break;
        }
        return array (
            $r, $g, $b
        );
    }

    /**
     * 使用cookie保存验证码的方法
     * @return void
     */
    protected function savecode()
    {
        $code = $this->authcode($this->code);
        $this->setcookie($code);
    }

    /**
     * 验证码cookie值获取方法
     * @return string cookie值
     */
    protected function getcookie()
    {
        if (empty( $_cookie[$this->codecookiename] ))
        {
            return '';
        }
        else
        {
            return addslashes($_cookie[$this->codecookiename]);
        }
    }
   
    /**
     * 验证码cookie创建方法
     * @param string $code 要保存的验证码
     * @return void
     */
    protected function setcookie($code)
    {
        $expire = $this->codeexpire > 0 ? $this->codeexpire + time() : 0;
        setcookie( $this->codecookiename , $code, $expire );
    }
   
    /**
     * 验证码加密方法
     * @param string $code 要加密的随机码
     * @return mixed 执行结果
     */
    protected function authcode($code)
    {
        return md5($code.$this->specialadd);
    }
   
    /**
     * 干扰线生成方法
     * @param resource $image 图片资源句柄
     * @param string $color 干扰线颜色
     */
    protected static function imagelinethick($image, $color)
    {
        $k = rand( 5 , 20 );
        for ($px = 0; $px < 400; $px = $px + 1)
        {
            $y = $k * sin( 0.1 * ($px) ); //$y=200+10*sin(0.1*($px-200));
            for ($i = 0; $i < 2; $i++)
            {
                imagesetpixel( $image , $px , $y + 10 + $i , $color );
            }
       
        }
    }

    /**
     * http标头设置方法
     * @return void
     */
    protected static function sendheader()
    {
        header( "pragma: no-cache" );
        header( "cache-control: max-age=1, s-maxage=1, no-cache, must-revalidate" );
        header( 'content-type: image/gif' );
    }
}
http://down.111cn.net/down/code/php/qitayuanma/2010/1220/22330.html

imagecreatetruecolor（）返回一个图像标识符代表指定大小的黑色形象。

根据你的php教程和gd版本中函数定义与否。对于php 4.0.6通过4.1.x这个函数总是存在的

，
*/
$im=imagecreatetruecolor(100,100);        //创建图像
$string='n';            //定义字符
$white=imagecolorallocate($im,255,255,255);      //定义白色
$black=imagecolorallocate($im,0,0,0);       //定义黑色
$red=imagecolorallocate($im,255,0,0);       //定义红色
//在白色的背景上输出一个黑色的"z"，其实是颠倒的n
imagecharup($im,6,20,20,$string,$white);
imagechar($im,2,40,40,"r",$red);        //使用红色画出字符
header('content-type: image/png');        //输出头部信息
imagepng($im);            //输出png文件
imagedestroy($im);         //销毁图像

//

$img=imagecreatetruecolor(400,400);      //创建图像
$white=imagecolorallocate($img,255,255,255);     //定义白色
$black=imagecolorallocate($img,0,0,0);      //定义黑色
imagearc($img,200,200,350,350,0,360,$white);     //画椭圆弧
header("content-type: image/png");       //输出头信息
imagepng($img);          //输出为png图像
imagedestroy($img);          //销毁图像

//
$size=300;
$image=imagecreatetruecolor($size,$size);
//用白色背景加黑色边框画个方框
$back=imagecolorallocate($image,255,255,255);
$border=imagecolorallocate($image,0,0,0);
imagefilledrectangle($image,0,0,$size-1,$size-1,$back);
imagerectangle($image,0,0,$size-1,$size-1,$border);
$yellow_x=100;
$yellow_y=75;
$red_x=120;
$red_y=165;
$blue_x=187;
$blue_y=125;
$radius=150;
//用alpha值分配一些颜色
$yellow=imagecolorallocatealpha($image,255,255,0,75);
$red=imagecolorallocatealpha($image,255,0,0,75);
$blue=imagecolorallocatealpha($image,0,0,255,75);
//画三个交迭的圆
imagefilledellips教程e($image,$yellow_x,$yellow_y,$radius,$radius,$yellow);
imagefilledellipse($image,$red_x,$red_y,$radius,$radius,$red);
imagefilledellipse($image,$blue_x,$blue_y,$radius,$radius,$blue);
//输出header文件头
header('content-type: image/png');
//最后输出结果
imagepng($image);
imagedestroy($image);

//

$im=imagecreate(100,100);         //创建图像
$string='php';            //定义字符串
$bg=imagecolorallocate($im,255,255,255);      //定义白色
$black=imagecolorallocate($im,0,0,0);       //定义黑色
//在左上角输出指定字符
imagechar($im,1,0,0,$string,$black);
header('content-type: image/png');        //输出头部信息
imagepng($im);            //输出png文件
imagedestroy($im);           //销毁图像

?>