[PHP知识库]PHP图片旋转验证实现思路

实现思路：PHP从图片库中随机取出一张，使用gd库裁剪并随机旋转0-360°【A】，记下旋转度数。把图片输出给前端。用户将图片旋转至正确的位置（只能朝着一侧旋转，且最大旋转值为360°），前端记下用户旋转的角度【B】传给后端。

验证思路：A = 360 - B 即正常（可以加左右模糊值）。否则验证失败。

代码如下：

<?php

namespace controllers\auth;

use Gd\Imagine;
use File;
use Image;

class ImageVerify extends ApiController {
    const ALLOW_ERROR_RANGE = 15;    // 允许的角度误差范围
    const EXPIRED_TIME = 60;        //操作过期时间
    const IMG_SIZE = 300;        //图片大小

    /**
     * 获取验证图片
     *
     * @return string
     */
    public function actionGetVerifyImage() {

        $phone = $app->request->post('phone');

        if (!$phone){
            return '参数错误';
        }

        //从图片库取图片
        //随机取图（略）
        $imgUrl = $image->url;

//生成验证码图片
        $srcImg = imagecreatefromstring(file_get_contents($imgUrl));

        $imageSize = getimagesize($imgUrl);

        $w = $imageSize[0];
        $h = $imageSize[1];

        $cw = min($w, $h);
        $ch = $cw;

        $circleImg = imagecreatetruecolor($cw, $ch);
        imagealphablending($circleImg,false );
        imagesavealpha($circleImg, true);

        $bg = imagecolorallocatealpha($circleImg, 255, 255, 255, 127);
        imagefill($circleImg, 0, 0, $bg);

        $r = $cw / 2;

        for ($x = 0; $x < $w; $x++) {
            for ($y = 0; $y < $h; $y++) {
                $rgbColor = imagecolorat($srcImg, $x, $y);
                if (((($x - $r) * ($x - $r) + ($y - $r) * ($y - $r)) < ($r * $r))) {
                    imagesetpixel($circleImg, $x, $y, $rgbColor);
                }
            }
        }


        $ip = str_replace('.', '', $app->request->getUserIP());
        $key = $ip . $phone . date('Ymd');

        ob_start();
        imagepng($circleImg);
        $imgContent = ob_get_contents();
        ob_end_clean();
        imagedestroy($circleImg);
//旋转验证码图片
        $randAngle = rand(60, 300);

        $imagineGd = new Imagine();
        $imageInterface = $imagineGd->load($imgContent);

        $imgResource = Image::resize($imageInterface, self::IMG_SIZE, self::IMG_SIZE, true, true)->rotate($randAngle);

        $size = $imgResource->getSize()->getWidth();
        $r_new = self::IMG_SIZE / 2;
        $imgStr = Image::crop($imgResource, self::IMG_SIZE, self::IMG_SIZE, [$size / 2 - $r_new, $size / 2 - $r_new])->get('png');

        $base64ImgString = 'data:image/png;base64,' . chunk_split(base64_encode($imgStr));

        $app->cache->set($key, $randAngle, self::EXPIRED_TIME); //redis记录下旋转角度

//        header('Content-type: image/png');
//        header('Content-Transfer-Encoding: binary');

        echo $base64ImgString;
        exit();
    }

    /**
     * 验证旋转角度
     *
     * @return array|string
     * @throws \Exception
     */
    public function verifyAngle() {
        $data = $app->request->post();

        if (!$data['phone']){
            return [1, '参数错误'];
        }

        $ip = str_replace('.', '', $app->request->getUserIP());
        $key = $ip . $data['phone'] . date('Ymd');

        $angle= $app->cache->get($key); //获取redis中存下来的角度
        if (!$angle){
            return [1, '操作超时'];
        }

        $app->cache->delete($key);  //删除redis记录

        $rightAngle = 360 - $data['angle'];

        if (($angle >= ($rightAngle - self::ALLOW_ERROR_RANGE)) && ($angle <= ($rightAngle + self::ALLOW_ERROR_RANGE))){
            //验证通过........................

            return true;
        }

        return [1, '验证失败'];
    }

}