图片转base64

/**
 * 查看通行证
 */
public function viewPassCode() {
    $visitor_id = $this->input_data['visitor_id'];
    $customer_visitor = M('customer_visitor');
    $customer_visitor_info = $customer_visitor->where(['id'=>$visitor_id])->find();
    $qr_content = $customer_visitor_info['qr_content'];
    // $qrCode = new QrCode($qr_content);
    // // 指定内容类型
    // header('Content-Type: '.$qrCode->getContentType());
    // // 输出二维码
    // echo $qrCode->writeString();

    $qrCode = new QrCode($qr_content);
    $imgContent = $qrCode->writeString();
    $base64 = ImageUtil::contentToBase64($imgContent);
    $this->json->ok($base64);
}

<?php

/**
 * 图片工具
 * User: Eden
 * Date: 19-4-26 上午9:23
 */

namespace CommonUtil;

class ImageUtil extends CommonUtil
{
    /**
     * 获取网络图片的Base64编码
     * $img_url 网络图片地址
     * $hasPre  是否有前缀
     * @return string
     */
    public static function imgToBase64($img_url,$hasPre = true)
    {
        $img_base64 = '';
        $imageInfo = getimagesize($img_url);
        if (!$imageInfo) {
            return false;
        }
        $img_base64 = "" . chunk_split(base64_encode(file_get_contents($img_url)));
        if ($hasPre) {
            $img_base64 = 'data:' . $imageInfo['mime'] . ';base64,'.$img_base64;
        }
        return $img_base64;
    }

    /**
     * 获取网络图片的Base64编码
     * $img_url 网络图片地址
     * $hasPre  是否有前缀
     * @return string
     */
    public static function contentToBase64($content,$hasPre = true)
    {
        $img_base64 = '';
        $img_base64 = "" . chunk_split(base64_encode($content));
        if ($hasPre) {
            $img_base64 = 'data:image/png;base64,'.$img_base64;
        }
        return $img_base64;
    }
}