RMagick with a direct form submitted Image from Sinatra

Question

I am trying to do something quite simple using Sinatra and RMagick.

1. Take a image, through a simple form file upload
2. Use RMagick to resize it
3. Then store it in a database for persistence (irrelevant)

But after going through the RDocs and endless head banging testing I can't seem to get the form image to a RMagick object cleanly.

This is the horrible thing that is currently working for me:

def image_resize(img_data)
    filecount = rand
    writer = File.new("/tmp/#{filecount}.jpg", "w")
    writer.puts(img_data)
    writer.close

    resized_image = Magick::ImageList.new("/tmp/#{filecount}.jpg").first
    resized_image.crop_resized!(100,100, Magick::NorthGravity)
    resized.format = 'jpeg'
    resized_image.to_blob
end

#call the method with my form image data
image_resize(params[:image][:tempfile].read)

So how do I do the obvious right thing and just stick my form image data straight into a RMagick object without having to write and read the disk.

I have tried various ways of reading in Magick::Image and ImageLists but have only got an abundance of errors barfed at me.

---

Thanks for any kind of direction

-1.2.

Answer 1

You need to get the path from the tempfile and pass that to Magick::Image’s read.

Here’s an example:

post "/upload-photo" do
  image = Magick::Image.read(params[:image][:tempfile].path)[0]
  image.crop_resized! 100, 100, Magick::CenterGravity
  store_image_data image.to_blob

  redirect "/done"
end