Help with EXIF data plugin

[andrewboni]

Hi, I'm in the process of writing a plugin to display EXIF information from a photo, for things like camera make, model, focal length, shutter speed, aperture, ISO, etc.

I'm using the gm-exif node plugin, which makes getting EXIF data easy.

I can extract the EXIF data successfully, but the plugin returns nothing, as it's presumably not waiting for the async exif() task. How can I fix this, so that the plugin waits for the EXIF data to be extracted?

Sample plugin usage:

{% exifinfo 2015-01-25-luchadors-in-the-mission/luchadors.jpg %}

Plugin code:

hexo.extend.tag.register('exifinfo', function(args){
    var exif = require('gm-exif');
    var imagePath = args[0];
    exif(imagePath, function(err, exifData) {
        return '<p>' + exifData.Make + ' ' + exifData.Model + ' | ' + exifData.FocalLength +'mm | ' + exifData.ExposureTime + 'sec exposure | ƒ/' + exifData.FNumber + ' | ' + 'ISO' + exifData.ISOSpeedRatings + '</p>';
    });
});

[tommy351]

You can't do async task in tag plugins because Swig render files synchronously.

[andrewboni]

Got it- makes sense. Can you point me in the right direction of how I might
be able to implement EXIF data reading functionality then? Thanks!

On Sun, Jan 25, 2015 at 8:36 PM, Tommy Chen notifications@github.com
wrote:

You can't do async task in tag plugins because Swig render files
synchronously.

—
Reply to this email directly or view it on GitHub.

[tommy351]

You can try to write a filter. But it's more difficult. I'm thinking whether to replace Swig with Nunjucks which supports async rendering.

[andrewboni]

I see okay- yes, I'm all in favor of async support

[tommy351]

You can use async tag plugins since Hexo 3.

https://github.com/hexojs/hexo/wiki/Breaking-Changes-in-Hexo-3.0#async-tag-plugins