How make a image using multiple images using Carrierwave and MiniMagick

Question

I have Image model and Movie model and Movie can have many images. I am storing 3 versions of an image, big, medium and small. In my app users can pick images of a particular size lets say 4 images of `medium' size and then user can share them. Minimum 3 images and maximum 5.

I need to create a image with all selected 4 images of medium size. I do not want to send these images individually, I want to send it as a single image.

I am using Carrierwave and MiniMagick.

Thanks for help!

Answer 1

Assuming the real question here is about compositing images with minimagick, here's some code. Note that I've added a field to Movie called "composite_image", and I've decided that the uploader attached to Image is named "file".

def render_composite_image(source_images, coordinates)
  temp_file = TempFile.new(['render_composite_image', '.jpg'])
  img = MiniMagick::Image.new(temp_file.path)
  img.run_command(:convert, "-size", "#{ COMPOSITE_WIDTH }x#{ COMPOSITE_HEIGHT }", "xc:white", img.path)

  source_images.each_with_index do |source_image, i|
    resource = MiniMagick::Image.open(source_image.file.path)
    img = img.composite(resource) do |composite|
      composite.geometry "#{ coordinates[i].x }x#{ coordinates[i].y }"
    end
  end

  img.write(temp_file.path)
  self.update_attributes(composite_image: temp_file)
end

A couple notes on this code:

• source_images is an array of images you want to composite together.

• coordinates is an array of coordinate values for where you want each image to be in the final composition. A coordinate's index corresponds to the respective source_image's index. Also note that if a coordinate is positive, you need to include a "+" character, e.g. "+50". (You may need to experiment to find the coordinates you want.)

• If your images aren't stored locally, you'll need to use source_image.file.url instead of source_image.file.path.

• This code was written to run in the context of a Movie model, but it could be moved wherever you like.