PHP实现中文圆形印章特效，

<&#63;php
/*
 * 中文圆形印章类
 * @author lkk/lianq.net
 * @create on 10:03 2012-5-29
 * @example:
 * $seal = new circleSeal('你我他坐站走东西南北中',75,6,24,0,0,16,40);
 * $seal->doImg();
 */
 
class circleSeal {
  private $sealString;  //印章字符
  private $strMaxLeng;  //最大字符长度
  private $sealRadius;  //印章半径
  private $rimWidth;   //边框厚度
  private $innerRadius;  //内圆半径
  private $startRadius;  //五角星半径
  private $startAngle;  //五角星倾斜角度
  private $backGround;  //印章颜色
  private $centerDot;   //圆心坐标
  private $img;      //图形资源句柄
  private $font;     //指定的字体
  private $fontSize;   //指定字体大小
  private $width;     //图片宽度
  private $height;    //图片高度
  private $points;    //五角星各点坐标
  private $charRadius;  //字符串半径
  private $charAngle;   //字符串倾斜角度
  private $spacing;    //字符间隔角度
 
  //构造方法
  public function __construct($str ='', $rad = 75, $rmwidth = 6, $strad = 24, $stang = 0, $crang = 0, $fsize = 16, $inrad =0){
    $this->sealString  = empty($str) &#63; '印章测试字符串' : $str;
    $this->strMaxLeng  = 12;
    $this->sealRadius  = $rad;
    $this->rimWidth   = $rmwidth;
    $this->startRadius = $strad;
    $this->startAngle  = $stang;
    $this->charAngle  = $crang;
    $this->centerDot  = array('x'=>$rad, 'y'=>$rad);
    $this->font     = dirname(__FILE__) .'/simkai.ttf';
    $this->fontSize   = $fsize;
    $this->innerRadius = $inrad;  //默认0,没有
    $this->spacing   = 1;
  }
 
  //创建图片资源
  private function createImg(){
    $this->width    = 2 * $this->sealRadius;
    $this->height    = 2 * $this->sealRadius;
    $this->img     = imagecreate($this->width, $this->height);
    imagecolorresolvealpha($this->img,255,255,255,127);
    $this->backGround  = imagecolorallocate($this->img,255,0,0);
  }
 
  //画印章边框
  private function drawRim(){
    for($i=0;$i<$this->rimWidth;$i++){
      imagearc($this->img,$this->centerDot['x'],$this->centerDot['y'],$this->width - $i,$this->height - $i,0,360,$this->backGround);
    }
  }
 
  //画内圆
  private function drawInnerCircle(){
    imagearc($this->img,$this->centerDot['x'],$this->centerDot['y'],2*$this->innerRadius,2*$this->innerRadius,0,360,$this->backGround);
  }
 
  //画字符串
  private function drawString(){
    //编码处理
    $charset = mb_detect_encoding($this->sealString);
    if($charset != 'UTF-8'){
      $this->sealString = mb_convert_encoding($this->sealString, 'UTF-8', 'GBK');
    }
 
    //相关计量
    $this->charRadius = $this->sealRadius - $this->rimWidth - $this->fontSize; //字符串半径
    $leng  = mb_strlen($this->sealString,'utf8'); //字符串长度
    if($leng > $this->strMaxLeng) $leng = $this->strMaxLeng;
    $avgAngle  = 360 / ($this->strMaxLeng);  //平均字符倾斜度
 
    //拆分并写入字符串
    $words = array(); //字符数组
    for($i=0;$i<$leng;$i++){
      $words[] = mb_substr($this->sealString,$i,1,'utf8');
      $r = 630 + $this->charAngle + $avgAngle*($i - $leng/2) + $this->spacing*($i-1);   //坐标角度
      $R = 720 - $this->charAngle + $avgAngle*($leng-2*$i-1)/2 + $this->spacing*(1-$i);  //字符角度
      $x = $this->centerDot['x'] + $this->charRadius * cos(deg2rad($r)); //字符的x坐标
      $y = $this->centerDot['y'] + $this->charRadius * sin(deg2rad($r)); //字符的y坐标
      imagettftext($this->img, $this->fontSize, $R, $x, $y, $this->backGround, $this->font, $words[$i]);
    }
  }  
 
  //画五角星
  private function drawStart(){
    $ang_out = 18 + $this->startAngle;
    $ang_in = 56 + $this->startAngle;
    $rad_out = $this->startRadius;
    $rad_in = $rad_out * 0.382;
    for($i=0;$i<5;$i++){
      //五个顶点坐标
      $this->points[] = $rad_out * cos(2*M_PI/5*$i - deg2rad($ang_out)) + $this->centerDot['x'];
      $this->points[] = $rad_out * sin(2*M_PI/5*$i - deg2rad($ang_out)) + $this->centerDot['y'];
 
      //内凹的点坐标
      $this->points[] = $rad_in * cos(2*M_PI/5*($i+1) - deg2rad($ang_in)) + $this->centerDot['x'];
      $this->points[] = $rad_in * sin(2*M_PI/5*($i+1) - deg2rad($ang_in)) + $this->centerDot['y'];
    }
    imagefilledpolygon($this->img, $this->points, 10, $this->backGround);
  }
 
  //输出
  private function outPut(){
    header('Content-type:image/png');
    imagepng($this->img);
    imagedestroy($this->img);
  }
 
  //对外生成
  public function doImg(){
    $this->createImg();
    $this->drawRim();
    $this->drawInnerCircle();
    $this->drawString();
    $this->drawStart();
    $this->outPut();
  }
}

<&#63;php
@$hos=iconv("GBK", "UTF-8", $_GET["hos"]);
if(!isset($hos))
exit;

$im=ImageCreate(150,150);
$gray=ImageColorResolveAlpha($im,200,200,200,127);
$red=ImageColorAllocate($im,230,150,150);

for($i=0;$i<6;$i++)
ImageArc($im,75,75,148-$i,148-$i,0,360,$red);

$stock='C:\WINDOWS\Fonts\simkai.ttf';
$point="★";
$size=30;
ImageTTFText($im,$size,0,72-$size/2,72+$size/2,$red,$stock,$point);

$a=75;$b=-75;//中心点坐标
$r=65;$m=40;//半径，角度
$size=16;//字体大小
$r=$r-$size;

$word=array();
$max=18;
$count=mb_strlen($hos,'utf8');
if($count>$max)$count=$max;
if($count>12)
$m=floor(360/$count);
else if($count>5)
$m-=$count;

for($i=0;$i<$count;$i++)
$word[]=mb_substr($hos,$i,1,'utf8');

$j=floor($count/2);
if($j!=$count/2)
{
 for($i=$j;$i>=0;$i--)
 {
 $arc=$m*($j-$i)+$size/2;
 $x=round($r*cos((90+$arc)*M_PI/180))+$a;
 $y=-1*(round($r*sin((90+$arc)*M_PI/180))+$b);
 if($arc<10)$arc=0; 
 ImageTTFText($im,$size,$arc,$x,$y,$red,$stock,$word[$i]);
 $arc=$m*($j-$i)-$size/2;
 $x=round($r*cos((90-$arc)*M_PI/180))+$a;
 $y=-1*(round($r*sin((90-$arc)*M_PI/180))+$b);
 if($arc<10)$arc=0; 
 ImageTTFText($im,$size,-$arc,$x,$y,$red,$stock,$word[$j+$j-$i]);
 }
}
else
{
 $j=$j-1;
 for($i=$j;$i>=0;$i--)
 {
 $arc=$m/2+$m*($j-$i)+$size/2;
 $x=round($r*cos((90+$arc)*M_PI/180))+$a;
 $y=-1*(round($r*sin((90+$arc)*M_PI/180))+$b);
 ImageTTFText($im,$size,$arc,$x,$y,$red,$stock,$word[$i]); 
 $arc=$m/2+$m*($j-$i)-$size/2;
 $x=round($r*cos((90-$arc)*M_PI/180))+$a;
 $y=-1*(round($r*sin((90-$arc)*M_PI/180))+$b);
 ImageTTFText($im,$size,-$arc,$x,$y,$red,$stock,$word[$j+$j+1-$i]);
 }
}

header('Content-Type:image/png');
ImagePNG($im);
&#63;>