<?php

  /**

  * 处理成圆图片,如果图片不是正方形就取最小边的圆半径,从左边开始剪切成圆形

  * @param  string $imgpath [description]

  * @return [type]          [description]

  */

     function yuan_img($imgpath = './code_png/share.jpg') {

         $ext     = pathinfo($imgpath);

         $src_img = null;

         switch ($ext['extension']) {

             case 'jpg':

                 $src_img = imagecreatefromjpeg($imgpath);

                 break;

             case 'png':

                 $src_img = imagecreatefrompng($imgpath);

                 break;

         }

         $wh  = getimagesize($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);

         $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);

                 if (((($x - $r) * ($x - $r) + ($y - $r) * ($y - $r)) < ($r * $r))) {

                     imagesetpixel($img, $x, $y, $rgbColor);

                 }

             }

         }

         return $img;

 }

 Header("Content-Type: image/png");
   $img = yuan_img();

 imagepng($img);

46 imagedestroy($img);