widget

Has only layout implementation. The widget fragment is inherited from Reaction::UI::Widget. The layout will simply render the "image" fragment. This fragment can be overwritten by your own layout to render, for example, a frame around the image.

image

Is only implemented in the widget. If the viewport has a true value in "value_string", the "uri" argument will be set to the value of the "uri" attribute or method return value of the viewport, and the "has_image" fragment will be rendered.

If "value_string" is false, the "no_image" fragment will be rendered.

has_image

This is only implemented in the layout file. It contains just an image tag and will be rendered when the viewport has a true "value_string".

no_image

This has only an empty implementation in the layout file. It will output nothing and is called when then viewport has a false "value_string".