Does not actually work without downloading the full image

[mhluska]

Instead of doing what the readme recommends:

  add_metadata :dominant_color do |io|
    dominant_color(io.path)
  end

I had to do this:

  add_metadata :dominant_color do |io, **options|
    next unless options[:background]

    Shrine.with_file(io) { |file| dominant_color(file.path) }
  end

With the following background worker:

class ShrinePromoteWorker < ApplicationWorker
  def perform(attacher_class, record_class, record_id, name, file_data)
    attacher_class = Object.const_get(attacher_class)
    record         = Object.const_get(record_class).find(record_id)

    attacher = attacher_class.retrieve(model: record, name: name, file: file_data)
    attacher.refresh_metadata!(background: true)
    attacher.atomic_promote
  end
end

This is after updating to the latest shrine version. The reason is io.path is not defined for UploadedFile objects. We have to ultimately download the full file to get a color from it. And best to do it in a background job.

I'm not sure but this could be a case unique to people doing direct to S3 uploads 🤷‍♂

[mhluska]

Also I'm not sure if it's the custom fork of colorscore that this uses or something in colorscore itself but i always ended up with puke green for many of the dominant colors.

I ended up switching to the miro gem and doing this:

  add_metadata :dominant_color do |io, **options|
    next unless options[:background]

    Shrine.with_file(io) do |file|
      Miro::DominantColors.new(file.path).to_hex.first
    end
  end

I think the reason miro produces better results is it handles the alpha channel of PNGs internally but colorscore doesn't.

My change above does renders this plugin useless for me 😅

[jnylen]

Hello @mhluska

As the s3 direct upload mean that the file doesn't actually end up on the server itself, it does need to download the file and grab the colors.

Yeah colorscore is a mess. I haven't touched any of this except upping the shrine version semver. If you do a PR for addition of Miro i'll merge it.

By the way, you should be able to do:

  add_metadata :dominant_color do |io, **options|
    next unless options[:background]
    Miro::DominantColors.new(io.url).to_hex.first
  end