CollectionFS 获取转换前的图像尺寸

Question

我想在使用 Meteor CollectionFS 上传图片时调整图片大小。但我想根据图像尺寸调整大小。例如，我想将 1000x500 的图像调整为 1024x512，但将 60x100 的图像调整为 64x128 - 为此我需要知道源尺寸。

我的代码基于 CollectionFS documentation:

var createThumb = function(fileObj, readStream, writeStream) {
  // Transform the image into a 10x10px thumbnail
  gm(readStream, fileObj.name()).resize('10', '10').stream().pipe(writeStream);
};

如何在此处获取源尺寸，以使我的调整大小目标动态化？也许有一些graphicsmagick功能？

Answer 1

有一个异步 GraphicsMagick 函数用于返回图像的大小（尺寸）。

gm(readStream).size({ bufferStream: true }, function(err, value) {
    var w = 100, h = 100;

    //modify logic here to set the desired output width/height, based on the source width/height
    if (value.width == 60 && value.height == 100) {
         w = 64;
         h = 128;
    }

    //"this" is the gm context, so you can chain gm functions to "this" inside the size callback.
    this.resize(w, h).stream().pipe(writeStream);
});

Github 上 gm npm 包页面关于此的注释：

GOTCHA: when working with input streams and any 'identify' operation (size, format, etc), you must pass "{bufferStream: true}" if you also need to convert (write() or stream()) the image afterwards NOTE: this buffers the readStream in memory!

CollectionFS 获取转换前的图像尺寸

CollectionFS get image dimensions before transformation

meteor

graphicsmagick

collectionfs