Question

我正在尝试使用nodejs，request和gm模块下载图像后立即调整图像大小但是我很难理解管道内容。

var fs = require('fs');
var path = require('path');
var gm = require('gm').subClass({imageMagick: true});
var request = require('request');
var async = require('async');
var folderImages = './images/';

var q = async.queue(function (task, callback) {

    // Renaming the images
    var thumb350 = task.target.replace('.jpg', '-350.jpg');

    // The target path/images
    var target350 = path.join(folderImages, thumb350);

    // Download the images
    request
        .get(task.PhotoURL)
        .on('response', function(response) {
            console.log(task.PhotoURL + ' : ' + response.statusCode, response.headers['content-type']);
            callback();
        })
        .on('error', function(err) {
            console.log(err);
            callback(err);
        })
        .pipe(fs.createWriteStream(task.target));

    // How can I run this function on files that get downloaded?
    var resizePhotos = gm(task.target)
        .resize('350')
        .write(target350, function (err) {
            if (!err){
                console.log(task.target, ': 350 done');
            }
            else {
                console.log(task.target, ': error');
            }
        });

}, 50);

Answer 1

您可以在writeStream上侦听finish事件，然后在回调中调整大小调整逻辑：

...
.pipe(fs.createWriteStream(task.target))
.on('finish', function(){ 
    //called when writing to disk is complete
    var resizePhotos = gm(task.target)
        .resize('350')
        .write(target350, function (err) {
            if (!err){
                console.log(task.target, ': 350 done');
            }
            else {
                console.log(task.target, ': error');
            }
        });
})

Answer 2

实际上request.get会返回一个流，您只需gm(request.get(url)).resize(350)而不是写入文件系统并重新加载它。

使用request和gm模块在NodeJS中下载后立即调整图像大小

2 个答案: