How to optimize images to obtain width and height in php

This article will introduce to you the method of php optimizing images to obtain width and height. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

php Regarding the optimization of image acquisition width and height

Requirements

Respond to front-end Requirements: when entering the article details, all pictures need to be replaced with placeholders, and the placeholders need to correspond to the picture information (mainly need to know the width and height)

Purpose: to create a floating window effect when clicking on the picture

Implementation plan

Before optimization

Regularly match pictures, and then loop to obtain the width and height of each picture

Problem: If the article has fewer pictures, the above operation is not a big problem. But once there are too many pictures, the efficiency will be very low

The code is as follows:

        preg_match_all('//is', $str, $matchs);
       
        if(!empty($matchs[0])){
            $pics = [];
            $i = 0;
            foreach ($matchs[0] as $key => $m) {
                $fileInfo = file_get_contents($matchs[1][$key] . '?x-oss-process=image/info');
                $fileInfo = json_decode($fileInfo, true);
                $data['Width'] = $fileInfo['ImageWidth']['value'];
                $data['Height'] = $fileInfo['ImageHeight']['value'];
                    
                $imgs[$i]['ref'] = '';
                $imgs[$i]['pixel'] = $data['Width'] . '*' . $data['Height'];
                preg_match('/alt="(.*?)"/i', $matchs[0][$key], $mt);
                $imgs[$i]['alt'] = isset($mt[1]) ? $mt[1] : '';   //图片alt
                $imgs[$i]['src'] = $matchs[1][$key];                //图片地址
                $str = str_replace($m, '', $str);
                $i++;

            }
        }

Optimization ideas

Wondering whether there is a way to get pictures quickly? I found some information on the Internet, which basically reads part of the file information of the image without downloading/reading the entire image. I found a class library: [https://github.com/tommoor/fastimage](https://github.com/tommoor/fastimage) and gave it a try. Compared with the previous idea (complete download of pictures), there is indeed a performance improvement. Friends who are interested can try it. If you want to obtain information from a single picture, this is still highly recommended. But the batch implementation seems to be unable to achieve the goal

Analyzing the above operations, in fact, the slow process should still stay in the loop to obtain image resources. So let’s think about it differently, is it ok if I get pictures in batches? Up the code

preg_match_all('//is', $str, $matchs);

if(!empty($matchs[0])){
    //$time = microtime(true);
    //echo  '  ---- start ' . PHP_EOL;

    foreach ($matchs[0] as $key => $m) {
        $urls[] = $matchs[1][$key] . '?x-oss-process=image/info';
    }
    $imageInfos = batchCurl($urls);

    $i = 0;
    foreach ($matchs[0] as $key => $m) {
        $image = json_decode($imageInfos[$key], true);
        $_img['Width'] = $width= $image['ImageWidth']['value'];
        $_img['Height'] = $height = $image['ImageHeight']['value'];

        $imgs[$i]['ref'] = '';
        $imgs[$i]['pixel'] = $_img['Width'] . '*' . $_img['Height'];
        preg_match('/alt="(.*?)"/i', $matchs[0][$key], $mt);
        $imgs[$i]['alt'] = isset($mt[1]) ? $mt[1] : '';   //图片alt
        $imgs[$i]['src'] = $matchs[1][$key];                //图片地址
        $str = str_replace($m, '', $str);

        $i++;
    }
    //echo  " ---- end  px in " . (microtime(true)-$time) . " seconds \n";
    //exit;
}
        
function batchCurl($urls)
{
    $res = $conn = [];

    // 创建批处理cURL句柄
    $mh = curl_multi_init();

    foreach ($urls as $i => $url) {
        // 创建一对cURL资源
        $conn[$i] = curl_init();
        // 设置URL和相应的选项
        curl_setopt($conn[$i], CURLOPT_URL, $url);
        curl_setopt($conn[$i], CURLOPT_HEADER, 0);
        curl_setopt($conn[$i], CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($conn[$i], CURLOPT_TIMEOUT, 10);
        // 302跳转
        curl_setopt($conn[$i], CURLOPT_FOLLOWLOCATION, 1);
        // 增加句柄
        curl_multi_add_handle($mh, $conn[$i]);
    }
    $active = null;
    //防卡死写法：执行批处理句柄
    do {
        $mrc = curl_multi_exec($mh, $active);
    } while ($mrc == CURLM_CALL_MULTI_PERFORM);

    while ($active && $mrc == CURLM_OK) {
        if (curl_multi_select($mh) != -1) {
            do {
                $mrc = curl_multi_exec($mh, $active);
            } while ($mrc == CURLM_CALL_MULTI_PERFORM);
        }
    }
    foreach ($urls as $i => $url) {
        //获取当前解析的cURL的相关传输信息
        $info = curl_multi_info_read($mh);
        //获取请求头信息
        $heards = curl_getinfo($conn[$i]);
        //获取输出的文本流
        $res[$i] = curl_multi_getcontent($conn[$i]);
        // 移除curl批处理句柄资源中的某个句柄资源
        curl_multi_remove_handle($mh, $conn[$i]);
        //关闭cURL会话
        curl_close($conn[$i]);
    }
    //关闭全部句柄
    curl_multi_close($mh);

    return $res;
}

3. Test the performance, the efficiency of 20 pictures can almost reach the second level


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