Important: #106584 - Asset and image ViewHelper arguments are registered 

Description 

The ViewHelpers <f:asset.css> , <f:asset.script> and <f:image> read the arguments href , src and alt from the tag attributes instead of registering them. They were therefore missing from the generated XSD schema and from the ViewHelper reference, which made IDEs report them as unknown attributes.

All three are now registered as optional string arguments. Templates do not need to be changed, and the arguments keep behaving as before.

One detail changes in the rendered markup of <f:image> : an explicitly given alt attribute used to be written as the first attribute of the <img> tag, because unregistered arguments are added to the tag builder before the ViewHelper renders. It is now written after src , width and height , which is the position the fallback to the "alternative" metadata property has always used:

<!-- before -->
<img alt="alternative text" src="image.jpg" width="400" height="300" />

<!-- after -->
<img src="image.jpg" width="400" height="300" alt="alternative text" />

The attribute order carries no meaning in HTML, so this only affects tests and tooling that compare rendered markup as a string.