image_overlay(image_overlay_path, options = {})

Adds an overlay to the base image. It’s useful for things like attaching a logo, watermark, or even a border to the image. It will work best with a 24-bit PNG with alpha channel since it will properly deal with partial transparency.

• image_overlay_path
  The path, relative to RAILS_ROOT where the image you want superimposed can be found.

Use the following keys in the options hash:

• :size
  The size of the overlayed image, as "123x456" or [123, 456]. By default the overlay is not resized before compositing. Use this option if you want to resize the overlay, perhaps to have a small logo on thumbnails and a big logo on full size images. Other than just numerical dimensions, the size parameter takes 2 special values :scale_to_fit and :stretch_to_fit. :scale_to_fit will make the overlay fit as much as it can inside the image without changing the aspect ratio. :stretch_to_fit will make the overlay the exact same size as the image but with a distorted aspect ratio to make it fit. :stretch_to_fit is designed to add border to images.

• :alignment
  A symbol that tells Fleximage where to put the overlay. Can be any of the following: :center, :top, :top_right, :right, :bottom_right, :bottom, :bottom_left, :left, :top_left. Default is :center.

• :offset
  The number of pixels to offset the overlay from it’s :alignment anchor, in "123x456" or [123, 456] format. Useful to give a bit a space between your logo and the edge of the image, for instance. NOTE: Due to some unexpected (buggy?) RMagick behaviour :offset will work strangely if :alignment is set to a non-corner value, such as :top or :center. Using :offset in these cases will force the overlay into a corner anyway.

• :blending
  The blending mode governs how the overlay gets composited onto the image. You can get some funky effects with modes like :copy_cyan or :screen. For a full list of blending modes checkout the RMagick documentation. To use a blend mode remove the CompositeOp form the name and unserscorize the rest. For instance, MultiplyCompositeOp becomes :multiply, and CopyBlackCompositeOp becomes :copy_black.

Example

@photo.operate do |image|
  image.image_overlay('images/my_logo_with_alpha.png',
    :size => '25x25',
    :alignment => :top_right,
    :blending => :screen
  )
end

Back to Operators