[PHP知识库]php中将图片裁剪为圆形

   (codeIgniter框架为基础)
     /**
     * 获取网络图内容
     * @param $url  网络图片url
     * @return bool
     */
   function http_get_data($url)
    {
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'GET');
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        curl_setopt($ch, CURLOPT_URL, $url);
        ob_start();
        curl_exec($ch);
        $return_content = ob_get_contents();
        ob_end_clean();
        $return_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        return $return_content;
    }
     /**
     * 获取网络图片类型
     * @param $url  网络图片url,支持不带后缀名url
     * @return bool
     */
    private function getNetworkImgType($url)
    {
        $ch = curl_init(); //初始化curl
        curl_setopt($ch, CURLOPT_URL, $url); //设置需要获取的URL
        curl_setopt($ch, CURLOPT_NOBODY, 1);
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 3);//设置超时
        curl_setopt($ch, CURLOPT_TIMEOUT, 3);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false); //支持https
        curl_exec($ch);//执行curl会话
        $http_code = curl_getinfo($ch);//获取curl连接资源句柄信息
        curl_close($ch);//关闭资源连接
        if ($http_code['http_code'] == 200) {
            $theImgType = explode('/', $http_code['content_type']);
            if ($theImgType[0] == 'image') {
                return $theImgType[1];
            } else {
                return false;
            }
        } else {
            return false;
        }
    }
   /**
    * 生成图片文件流
    * @param $file  网络图片地址
    * @return bool
    */
   function createImageFromFile($file)
    {
        if (preg_match('/http(s)?:\/\//', $file)) {
            $fileSuffix = $this->getNetworkImgType($file);
        } else {
            $fileSuffix = pathinfo($file, PATHINFO_EXTENSION);
        }
        if (!$fileSuffix) return false;
        switch ($fileSuffix) {
            case 'jpeg':
                if (!strpos($file, 'qnimg.ruwii.com') && !strpos($file, 'upload')) {
                    // imagecreatefromstring:从字符串中的图像流新建一图像, 返回一个图像标识符，其表达了从给定字符串得来的图像
                    $theImage = @imagecreatefromstring($this->http_get_data($file));
                } else {
                    $theImage = @imagecreatefromjpeg($file);
                    if (!$theImage) {
                        $theImage = @imagecreatefromstring($this->http_get_data($file));
                    }
                }
                break;
            case 'jpg':
                if (!strpos($file, 'qnimg.ruwii.com') && !strpos($file, 'upload')) {
                    $theImage = @imagecreatefromstring($this->http_get_data($file));
                } else {
                    $theImage = @imagecreatefromjpeg($file);
                    if (!$theImage) {
                        $theImage = @imagecreatefromstring($this->http_get_data($file));
                    }
                }
                break;
            case 'png':
                if (!strpos($file, 'qnimg.ruwii.com') && !strpos($file, 'upload')) {
                    $theImage = @imagecreatefromstring($this->http_get_data($file));
                } else {
                    $theImage = @imagecreatefrompng($file);
                    if (!$theImage) {
                        $theImage = @imagecreatefromstring($this->http_get_data($file));
                    }
                }
                break;
            case 'gif':
                if (!strpos($file, 'qnimg.ruwii.com') && !strpos($file, 'upload')) {
                    $theImage = @imagecreatefromstring($this->http_get_data($file));
                } else {
                    $theImage = @imagecreatefromgif($file);
                    if (!$theImage) {
                        $theImage = @imagecreatefromstring($this->http_get_data($file));
                    }
                }
                break;
            default:
                $theImage = @imagecreatefromstring($this->http_get_data($file));
                break;
        }
        return $theImage;
    }
    /**
    * 将图片切割为圆形
    * @param imgpath 图片地址(可以为网络地址,也可以为本地图片)
    * @return bool
    */
	function changeCircularImg($imgpath)
	    {
	        $src_img = null;
	        //如果$imgpath为网络地址
	        $src_img = $this->createImageFromFile($imgpath);
	        //如果如果$imgpath为本地图片地址
	        //$src_img = @imagecreatefromstring(file_get_contents($imgpath));(已经测试可用)
	        $wh = getimagesize($imgpath);
	        $w = $wh[0];
	        $h = $wh[1];
	        $w = min($w, $h);
	        $h = $w;
	        $img = imagecreatetruecolor($w, $h); //这一句一定要有
	        imagesavealpha($img, true);
	        //拾取一个完全透明的颜色,最后一个参数127为全透明
	        $bg = imagecolorallocatealpha($img, 255, 255, 255, 127);
	        imagefill($img, 0, 0, $bg);
	        imagesavealpha($img , true);
	        $r = $w / 2;
	       //圆半径
	        $y_x = $r; //圆心X坐标
	        $y_y = $r; //圆心Y坐标
	        for ($x = 0; $x < $w;
	             $x++) {
	            for ($y = 0; $y < $h; $y++) {
	                $rgbColor = imagecolorat($src_img, $x,
	                    $y);
	                    //根据数学公式圆的计算方式 算的 (x-r)(x-r)+(y-r)(y-r)=r*r (x,y坐标点 r半径)
	                if (((($x - $r) * ($x - $r) + ($y - $r) * ($y - $r)) < ($r * $r))) {
	                    imagesetpixel($img, $x, $y, $rgbColor);
	                }
	            }
	        }
	        return $img;
	    }