Using the lazy-gallery components.

gistfile1.rb

gallery = Gallery(findViewById R.id.lazy_gallery)
# Make sure the GallerySelectionListener is only
# triggered when the gallery is stopped on an image.
gallery.setCallbackDuringFling false

# Create our adapter
gallery_adapter = LazyGalleryAdapter.new self

# When the current item is clicked, create a toast with its caption.
this = self
gallery.setOnItemClickListener do |parent, view, pos, id|
  if view.isSelected
    item = Map(gallery_adapter.getItem pos)
    c = String(item.get 'caption') || "Item #{pos} (no caption)"
    Toast.makeText(this, c, Toast.LENGTH_SHORT).show
  end
end

# Add the adapter and the selection listener
gallery.setAdapter gallery_adapter    
gallery.setOnItemSelectedListener GallerySelectionListener.new(TextView(findViewById R.id.lazy_gallery_text))

# Expire any old cached images
LazyImageView.purgeDiskCache(self)

# And finally, send the adapter its data.
# A real application will likely abstract away the JSON string details.
gallery_adapter.update_from_json json_string