實現中文圓形印章的PHP類

<?php
/*


中文圓形印章類
@author lkk/lianq.net
@create on 10:03 2012-5-29
@example:
$seal = new circleSeal('你我他坐站走東西南北中',75,6,24,0,0,16,40);
$seal->doImg();
*/

class circleSeal {
    private $sealString;    //印章字符
    private $strMaxLeng;    //最大字符長度
    private $sealRadius;    //印章半徑
    private $rimWidth;      //邊框厚度
    private $innerRadius;   //內圓半徑
    private $startRadius;   //五角星半徑
    private $startAngle;    //五角星傾斜角度
    private $backGround;    //印章顏色
    private $centerDot;     //圓心坐標
    private $img;           //圖形資源句柄
    private $font;          //指定的字體
    private $fontSize;      //指定字體大小
    private $width;         //圖片寬度
    private $height;        //圖片高度
    private $points;        //五角星各點坐標
    private $charRadius;    //字符串半徑
    private $charAngle;     //字符串傾斜角度
    private $spacing;       //字符間隔角度

//構造方法
public function __construct($str ='', $rad = 75, $rmwidth = 6, $strad = 24, $stang = 0, $crang = 0, $fsize = 16, $inrad =0){
    $this->sealString   = empty($str) ? '印章測試字符串' : $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;   //默認0,沒有
    $this->spacing      = 1;
}

//創建圖片資源
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);
}

//畫印章邊框
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);
    }
}

//畫內圓
private function drawInnerCircle(){
    imagearc($this->img,$this->centerDot['x'],$this->centerDot['y'],2*$this->innerRadius,2*$this->innerRadius,0,360,$this->backGround);
}

//畫字符串
private function drawString(){
    //編碼處理
    $charset = mb_detect_encoding($this->sealString);
    if($charset != 'UTF-8'){
        $this->sealString = mb_convert_encoding($this->sealString, 'UTF-8', 'GBK');
    }

    //相關計量
    $this->charRadius = $this->sealRadius - $this->rimWidth - $this->fontSize;  //字符串半徑
    $leng   = mb_strlen($this->sealString,'utf8');  //字符串長度
    if($leng > $this->strMaxLeng) $leng = $this->strMaxLeng;
    $avgAngle   = 360 / ($this->strMaxLeng);    //平均字符傾斜度

    //拆分并寫入字符串
    $words  = array();  //字符數組
    for($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);     //坐標角度
        $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坐標
        $y = $this->centerDot['y'] + $this->charRadius * sin(deg2rad($r));  //字符的y坐標
        imagettftext($this->img, $this->fontSize, $R, $x, $y, $this->backGround, $this->font, $words[$i]);
    }
}   

//畫五角星
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++){
        //五個頂點坐標
        $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'];

        //內凹的點坐標
        $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);
}

//輸出
private function outPut(){
    header('Content-type:image/png');
    imagepng($this->img);
    imagedestroy($this->img);
}

//對外生成
public function doImg(){
    $this->createImg();
    $this->drawRim();
    $this->drawInnerCircle();
    $this->drawString();
    $this->drawStart();
    $this->outPut();
}

}
</pre>