在nodejs中下载图像并调整大小

Question

我想做的是从谷歌下载一个图像到我的项目文件夹/download中的系统存储库中。接下来，我尝试从download 存储库中获取图像并调整大小并再次将调整后的图像保存在/thumbnail 存储库中。下面是我写的代码

     //Google URL
     var mainuri = 'http://images.sadhguru.org/sites/default/files/media_files/iso/en/64083-natures-temples.jpg';
            var dir = './download';

        if (!fs.existsSync(dir)){
            fs.mkdirSync(dir);
        }
      // CODE TO DOWNLOAD IMAGE FROM GOOGLE 
        var filename = dir+'/file.jpg';
            request.head(mainuri, function(err, res, body){
              console.log('content-type:', res.headers['content-type']);
              console.log('content-length:', res.headers['content-length']);

              request(mainuri).pipe(fs.createWriteStream(filename));
            });


            var resizedir = './thumbnail';

            if (!fs.existsSync(resizedir)){
                fs.mkdirSync(resizedir);
            }

      //CODE TO GET IMAGE FROM '/download' REPOSITORY AND RESIZE
            var inputFile=require('path').join(__dirname,'../download/file.jpg'); //GET IMAGE FROM LOCAL
            var outFile = 'thumbnail/newfile.jpg'; // SAVE RESIZED IMAGE PATH 

// ------- CODE REMOVED - ERROR IS COMING HERE -----------

           imageresize(inputFile, outFile); // FUNCTION THAT CONTAINS IMAGE RESIZE CODE 

//imageresize FUNCTION

            var imageresize = function(inputFile, outFile){
            console.log(inputFile)
            // input stream
            let inStream = fs.createReadStream('C:/Users/rganji/caw/server/download/file.jpg');

            // output stream
            let outStream = fs.createWriteStream(outFile, {flags: "w"});

            // on error of output file being saved
            outStream.on('error', function() {
                console.log("Error");
            });

            // on success of output file being saved
            outStream.on('close', function() {
                console.log("Successfully saved file");
            });

            // input stream transformer
            // "info" event will be emitted on resize
            let transform = sharp()
                                .resize({ width: 50, height: 50 })
                                .on('info', function(fileInfo) {
                                    console.log("Resizing done, file not saved");
                                });

            inStream.pipe(transform).pipe(outStream);
        }   

如果我删除了我评论为 CODE REMOVED - ERROR IS COMING HERE 的代码，则图像是从 google 下载的。如果我调用 imageresize 函数，则 /download 目录正在创建，但我在目录中找不到任何图像。

即，如果我分别调用从 google 下载和 resizeimage 函数，即先从 google 调用图像下载，然后再调用 imageresize，那么它们工作正常，我可以在 /download 和 /thumbnail 目录中找到图像。但是如果我在谷歌下载后调用 resizeimage 函数，那么我在两个存储库中都找不到任何图像。

Answer 1

在调用imageresize 函数之前，您需要等待图像下载完成。试试这个

request(mainuri).on('end', function() {
    var inputFile=require('path').join(__dirname,'../download/file.jpg'); //GET IMAGE FROM LOCAL
    var outFile = 'thumbnail/newfile.jpg'; // SAVE RESIZED IMAGE PATH 
    imageresize(inputFile, outFile);
});